fedimint_wallet_client/

lib.rs

#![deny(clippy::pedantic)]
#![allow(clippy::cast_possible_truncation)]
#![allow(clippy::missing_errors_doc)]
#![allow(clippy::missing_panics_doc)]
#![allow(clippy::module_name_repetitions)]
#![allow(clippy::must_use_candidate)]

#[cfg(feature = "uniffi")]
::uniffi::setup_scaffolding!();

pub mod api;
#[cfg(feature = "cli")]
mod cli;

mod backup;

pub mod client_db;
/// Legacy, state-machine based peg-ins, replaced by `pegin_monitor`
/// but retained for time being to ensure existing peg-ins complete.
mod deposit;
/// Error types of the wallet client.
pub mod error;
pub mod events;
use events::SendPaymentEvent;
#[cfg(feature = "uniffi")]
pub mod ffi;
/// Peg-in monitor: a task monitoring deposit addresses for peg-ins.
mod pegin_monitor;
mod withdraw;

use std::collections::{BTreeMap, BTreeSet};
use std::future;
use std::sync::Arc;
use std::time::{Duration, SystemTime};

use async_stream::{stream, try_stream};
use backup::WalletModuleBackup;
use bitcoin::address::NetworkUnchecked;
use bitcoin::secp256k1::{All, SECP256K1, Secp256k1};
use bitcoin::{Address, Network, ScriptBuf};
use client_db::{DbKeyPrefix, PegInTweakIndexKey, SupportsSafeDepositKey, TweakIdx};
use fedimint_api_client::api::{DynModuleApi, FederationResult};
use fedimint_bitcoind::{
    BitcoinRpcError, BitcoindTracked, DynBitcoindRpc, IBitcoindRpc, create_esplora_rpc,
};
use fedimint_client_module::error::{ClientModuleError, TransactionSubmitError};
use fedimint_client_module::module::init::{
    ClientModuleInit, ClientModuleInitArgs, ClientModuleRecoverArgs, RecoveryMode,
};
use fedimint_client_module::module::recovery::RecoveryProgress;
use fedimint_client_module::module::{ClientContext, ClientModule, IClientModule, OutPointRange};
use fedimint_client_module::oplog::UpdateStreamOrOutcome;
use fedimint_client_module::sm::{Context, DynState, ModuleNotifier, State, StateTransition};
use fedimint_client_module::transaction::{
    ClientOutput, ClientOutputBundle, ClientOutputSM, FeeQuote, FeeQuoteRequest,
    TransactionBuilder, max_affordable_send_amount,
};
use fedimint_client_module::{DynGlobalClientContext, sm_enum_variant_translation};
use fedimint_core::core::{Decoder, IntoDynInstance, ModuleInstanceId, ModuleKind, OperationId};
use fedimint_core::db::{
    Committable, Database, DatabaseError, DatabaseTransaction, IDatabaseTransactionOpsCoreTyped,
};
use fedimint_core::encoding::{Decodable, Encodable};
use fedimint_core::envs::{BitcoinRpcConfig, is_running_in_test_env};
use fedimint_core::module::{
    Amounts, ApiAuth, ApiVersion, CommonModuleInit, ModuleCommon, ModuleConsensusVersion,
    ModuleInit, MultiApiVersion,
};
use fedimint_core::task::{MaybeSend, MaybeSync, TaskGroup, sleep};
use fedimint_core::util::backoff_util::background_backoff;
use fedimint_core::util::{BoxStream, FmtCompact as _, backoff_util, retry};
use fedimint_core::{
    BitcoinHash, OutPoint, TransactionId, apply, async_trait_maybe_send, push_db_pair_items,
    runtime, secp256k1,
};
use fedimint_derive_secret::{ChildId, DerivableSecret};
use fedimint_logging::LOG_CLIENT_MODULE_WALLET;
pub use fedimint_wallet_common as common;
use fedimint_wallet_common::config::{FeeConsensus, WalletClientConfig};
use fedimint_wallet_common::tweakable::Tweakable;
pub use fedimint_wallet_common::*;
use futures::{Stream, StreamExt, TryStreamExt as _};
use rand::{Rng, thread_rng};
use secp256k1::Keypair;
use serde::{Deserialize, Serialize};
use strum::IntoEnumIterator;
use tokio::sync::watch;
use tracing::{debug, instrument, warn};

use crate::api::WalletFederationApi;
use crate::backup::{FEDERATION_RECOVER_MAX_GAP, RecoveryStateV2, WalletRecovery};
use crate::client_db::{
    ClaimedPegInData, ClaimedPegInKey, ClaimedPegInPrefix, NextPegInTweakIndexKey,
    PegInPoolCursorKey, PegInTweakIndexData, PegInTweakIndexPrefix, RecoveryFinalizedKey,
    RecoveryStateKey, SupportsSafeDepositPrefix,
};
use crate::deposit::DepositStateMachine;
pub use crate::error::{
    ConsensusVersionVotingError, DepositAddressError, MaxWithdrawableAmountError, PegInError,
    PegOutError, SubscribeDepositError, SubscribeWithdrawError, WithdrawFeesError,
};
use crate::withdraw::{CreatedWithdrawState, WithdrawStateMachine, WithdrawStates};

const WALLET_TWEAK_CHILD_ID: ChildId = ChildId(0);

#[derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize)]
pub struct BitcoinTransactionData {
    /// The bitcoin transaction is saved as soon as we see it so the transaction
    /// can be re-transmitted if it's evicted from the mempool.
    pub btc_transaction: bitcoin::Transaction,
    /// Index of the deposit output
    pub out_idx: u32,
}

#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq)]
pub enum DepositStateV1 {
    WaitingForTransaction,
    WaitingForConfirmation(BitcoinTransactionData),
    Confirmed(BitcoinTransactionData),
    Claimed(BitcoinTransactionData),
    Failed(String),
}

#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq)]
#[cfg_attr(feature = "uniffi", derive(uniffi::Enum))]
pub enum DepositStateV2 {
    WaitingForTransaction,
    WaitingForConfirmation {
        #[serde(with = "bitcoin::amount::serde::as_sat")]
        btc_deposited: bitcoin::Amount,
        btc_out_point: bitcoin::OutPoint,
    },
    Confirmed {
        #[serde(with = "bitcoin::amount::serde::as_sat")]
        btc_deposited: bitcoin::Amount,
        btc_out_point: bitcoin::OutPoint,
    },
    Claimed {
        #[serde(with = "bitcoin::amount::serde::as_sat")]
        btc_deposited: bitcoin::Amount,
        btc_out_point: bitcoin::OutPoint,
    },
    Failed(String),
}

/// Deposit address allocated by this client.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DepositAddressInfo {
    pub operation_id: OperationId,
    pub address: Address,
    pub tweak_idx: TweakIdx,
}

/// Result of [`WalletClientModule::allocate_deposit_address_pooled_stateless`].
///
/// Callers that need a custom address-picking strategy can use
/// [`MaybeNewAddress::TooManyUnusedAddresses`] to see all currently reusable
/// addresses instead of relying on this crate's round-robin policy.
#[allow(clippy::enum_variant_names)]
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum MaybeNewAddress {
    /// A new tweak/operation was created on this call.
    NewAddress(DepositAddressInfo),
    /// The unused-address gap is full. No new address was allocated.
    ///
    /// Reusable unused addresses are ordered by `creation_time` ascending.
    TooManyUnusedAddresses(Vec<DepositAddressInfo>),
}

/// Outcome of [`WalletClientModule::allocate_deposit_address_pooled`], so
/// callers can decide whether to perform per-operation initialization (notes,
/// fee bookkeeping, metadata writes) — for `Reused` returns, that work was
/// already done at the time of the original `Fresh` allocation and must not be
/// repeated.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum AllocateDepositOutcome {
    /// A new tweak/operation was created on this call.
    Fresh,
    /// An existing unused address was returned. The carried `TweakIdx` is the
    /// same as the one returned in the tuple and refers to the original
    /// allocation; it's exposed here as well for explicit diagnostic use.
    Reused { original_tweak_idx: TweakIdx },
}

#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq)]
#[cfg_attr(feature = "uniffi", derive(uniffi::Enum))]
pub enum WithdrawState {
    Created,
    Succeeded(bitcoin::Txid),
    Failed(String),
    // TODO: track refund
    // Refunded,
    // RefundFailed(String),
}

async fn next_withdraw_state<S>(stream: &mut S) -> Option<WithdrawStates>
where
    S: Stream<Item = WalletClientStates> + Unpin,
{
    loop {
        if let WalletClientStates::Withdraw(ds) = stream.next().await? {
            return Some(ds.state);
        }
        tokio::task::yield_now().await;
    }
}

#[derive(Debug, Clone, Default)]
// TODO: should probably move to DB
pub struct WalletClientInit(pub Option<DynBitcoindRpc>);

const SLICE_SIZE: u64 = 1000;

impl WalletClientInit {
    pub fn new(rpc: DynBitcoindRpc) -> Self {
        Self(Some(rpc))
    }

    async fn recover_from_slices(
        &self,
        args: &ClientModuleRecoverArgs<Self>,
        total_items: u64,
    ) -> Option<fedimint_core::Amount> {
        let data = WalletClientModuleData {
            cfg: args.cfg().clone(),
            module_root_secret: args.module_root_secret().clone(),
        };

        let mut state = RecoveryStateV2::new();

        state.refill_pending_pool_up_to(&data, TweakIdx(FEDERATION_RECOVER_MAX_GAP));

        for start in (0..total_items).step_by(SLICE_SIZE as usize) {
            let end = std::cmp::min(start + SLICE_SIZE, total_items);

            let items = args.module_api().fetch_recovery_slice(start, end).await;

            for item in &items {
                match item {
                    RecoveryItem::Input { outpoint, script } => {
                        state.handle_item(*outpoint, script, &data);
                    }
                }
            }

            args.update_recovery_progress(RecoveryProgress {
                complete: end.try_into().unwrap_or(u32::MAX),
                total: total_items.try_into().unwrap_or(u32::MAX),
            });
        }

        let mut dbtx = args.db().begin_transaction().await;

        for tweak_idx in 0..state.new_start_idx().0 {
            let operation_id = data.derive_peg_in_script(TweakIdx(tweak_idx)).3;

            let claimed = state
                .claimed_outpoints
                .get(&TweakIdx(tweak_idx))
                .cloned()
                .unwrap_or_default();

            dbtx.insert_new_entry(
                &PegInTweakIndexKey(TweakIdx(tweak_idx)),
                &PegInTweakIndexData {
                    operation_id,
                    creation_time: fedimint_core::time::now(),
                    last_check_time: None,
                    next_check_time: Some(fedimint_core::time::now()),
                    claimed,
                },
            )
            .await;
        }

        dbtx.insert_new_entry(&NextPegInTweakIndexKey, &state.new_start_idx())
            .await;

        dbtx.commit_tx().await;

        // The wallet only discovers which on-chain outputs belonged to the
        // client during recovery; their value isn't known until the deposits
        // are later claimed, so no amount is reported here.
        None
    }
}

impl ModuleInit for WalletClientInit {
    type Common = WalletCommonInit;

    async fn dump_database(
        &self,
        dbtx: &mut DatabaseTransaction<'_>,
        prefix_names: Vec<String>,
    ) -> Box<dyn Iterator<Item = (String, Box<dyn erased_serde::Serialize + Send>)> + '_> {
        let mut wallet_client_items: BTreeMap<String, Box<dyn erased_serde::Serialize + Send>> =
            BTreeMap::new();
        let filtered_prefixes = DbKeyPrefix::iter().filter(|f| {
            prefix_names.is_empty() || prefix_names.contains(&f.to_string().to_lowercase())
        });

        for table in filtered_prefixes {
            match table {
                DbKeyPrefix::NextPegInTweakIndex => {
                    if let Some(index) = dbtx.get_value(&NextPegInTweakIndexKey).await {
                        wallet_client_items
                            .insert("NextPegInTweakIndex".to_string(), Box::new(index));
                    }
                }
                DbKeyPrefix::PegInTweakIndex => {
                    push_db_pair_items!(
                        dbtx,
                        PegInTweakIndexPrefix,
                        PegInTweakIndexKey,
                        PegInTweakIndexData,
                        wallet_client_items,
                        "Peg-In Tweak Index"
                    );
                }
                DbKeyPrefix::ClaimedPegIn => {
                    push_db_pair_items!(
                        dbtx,
                        ClaimedPegInPrefix,
                        ClaimedPegInKey,
                        ClaimedPegInData,
                        wallet_client_items,
                        "Claimed Peg-In"
                    );
                }
                DbKeyPrefix::RecoveryFinalized => {
                    if let Some(val) = dbtx.get_value(&RecoveryFinalizedKey).await {
                        wallet_client_items.insert("RecoveryFinalized".to_string(), Box::new(val));
                    }
                }
                DbKeyPrefix::SupportsSafeDeposit => {
                    push_db_pair_items!(
                        dbtx,
                        SupportsSafeDepositPrefix,
                        SupportsSafeDepositKey,
                        (),
                        wallet_client_items,
                        "Supports Safe Deposit"
                    );
                }
                DbKeyPrefix::PegInPoolCursor => {
                    if let Some(cursor) = dbtx.get_value(&PegInPoolCursorKey).await {
                        wallet_client_items.insert("PegInPoolCursor".to_string(), Box::new(cursor));
                    }
                }
                DbKeyPrefix::RecoveryState
                | DbKeyPrefix::ExternalReservedStart
                | DbKeyPrefix::CoreInternalReservedStart
                | DbKeyPrefix::CoreInternalReservedEnd => {}
            }
        }

        Box::new(wallet_client_items.into_iter())
    }
}

#[apply(async_trait_maybe_send!)]
impl ClientModuleInit for WalletClientInit {
    type Module = WalletClientModule;

    fn supported_api_versions(&self) -> MultiApiVersion {
        MultiApiVersion::try_from_iter([ApiVersion { major: 0, minor: 0 }])
            .expect("no version conflicts")
    }

    async fn init(
        &self,
        args: &ClientModuleInitArgs<Self>,
    ) -> Result<Self::Module, ClientModuleError> {
        let data = WalletClientModuleData {
            cfg: args.cfg().clone(),
            module_root_secret: args.module_root_secret().clone(),
        };

        let db = args.db().clone();

        let rpc_config = WalletClientModule::get_rpc_config(args.cfg());

        // Priority:
        // 1. user-provided bitcoind RPC from ClientBuilder::with_bitcoind_rpc
        // 2. user-provided no-chain-id factory from
        //    ClientBuilder::with_bitcoind_rpc_no_chain_id
        // 3. WalletClientInit constructor
        // 4. create from config (esplora)
        let btc_rpc = if let Some(user_rpc) = args.user_bitcoind_rpc() {
            user_rpc.clone()
        } else if let Some(factory) = args.user_bitcoind_rpc_no_chain_id() {
            if let Some(rpc) = factory(rpc_config.url.clone()).await {
                rpc
            } else {
                self.0.clone().unwrap_or(
                    create_esplora_rpc(&rpc_config.url).map_err(ClientModuleError::other)?,
                )
            }
        } else {
            self.0
                .clone()
                .unwrap_or(create_esplora_rpc(&rpc_config.url).map_err(ClientModuleError::other)?)
        };
        let btc_rpc = BitcoindTracked::new(btc_rpc, "wallet-client").into_dyn();

        let module_api = args.module_api().clone();

        let (pegin_claimed_sender, pegin_claimed_receiver) = watch::channel(());
        let (pegin_monitor_wakeup_sender, pegin_monitor_wakeup_receiver) = watch::channel(());

        Ok(WalletClientModule {
            db,
            data,
            module_api,
            notifier: args.notifier().clone(),
            rpc: btc_rpc,
            client_ctx: args.context(),
            pegin_monitor_wakeup_sender,
            pegin_monitor_wakeup_receiver,
            pegin_claimed_receiver,
            pegin_claimed_sender,
            task_group: args.task_group().clone(),
            client_span: args.client_span().clone(),
            admin_auth: args.admin_auth().cloned(),
        })
    }

    fn recovery_mode(&self) -> RecoveryMode {
        RecoveryMode::Unusable
    }

    /// Wallet recovery
    ///
    /// Uses slice-based recovery if supported by the federation, otherwise
    /// falls back to session-based history recovery.
    async fn recover(
        &self,
        args: &ClientModuleRecoverArgs<Self>,
        snapshot: Option<&<Self::Module as ClientModule>::Backup>,
    ) -> Result<Option<fedimint_core::Amount>, ClientModuleError> {
        // Check if V1 (session-based) recovery state exists (resuming interrupted
        // recovery)
        if args
            .db()
            .begin_transaction_nc()
            .await
            .get_value(&RecoveryStateKey)
            .await
            .is_some()
        {
            return args
                .recover_from_history::<WalletRecovery>(self, snapshot)
                .await;
        }

        // Determine which method to use based on endpoint availability. The
        // count fetched here is reused by the slice recovery so that it is not
        // requested a second time (and cannot transiently fail there).
        match args.module_api().fetch_recovery_count().await {
            Ok(total_items) => Ok(self.recover_from_slices(args, total_items).await),
            Err(_) => {
                args.recover_from_history::<WalletRecovery>(self, snapshot)
                    .await
            }
        }
    }

    fn used_db_prefixes(&self) -> Option<BTreeSet<u8>> {
        Some(
            DbKeyPrefix::iter()
                .map(|p| p as u8)
                .chain(
                    DbKeyPrefix::ExternalReservedStart as u8
                        ..=DbKeyPrefix::CoreInternalReservedEnd as u8,
                )
                .collect(),
        )
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct WalletOperationMeta {
    pub variant: WalletOperationMetaVariant,
    pub extra_meta: serde_json::Value,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum WalletOperationMetaVariant {
    Deposit {
        address: Address<NetworkUnchecked>,
        /// Added in 0.4.2, can be `None` for old deposits or `Some` for ones
        /// using the pegin monitor. The value is the child index of the key
        /// used to generate the address, so we can re-generate the secret key
        /// from our root secret.
        #[serde(default)]
        tweak_idx: Option<TweakIdx>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        expires_at: Option<SystemTime>,
    },
    Withdraw {
        address: Address<NetworkUnchecked>,
        #[serde(with = "bitcoin::amount::serde::as_sat")]
        amount: bitcoin::Amount,
        fee: PegOutFees,
        change: Vec<OutPoint>,
    },

    RbfWithdraw {
        rbf: Rbf,
        change: Vec<OutPoint>,
    },
}

/// The non-resource, just plain-data parts of [`WalletClientModule`]
#[derive(Debug, Clone)]
pub struct WalletClientModuleData {
    cfg: WalletClientConfig,
    module_root_secret: DerivableSecret,
}

impl WalletClientModuleData {
    fn derive_deposit_address(
        &self,
        idx: TweakIdx,
    ) -> (Keypair, secp256k1::PublicKey, Address, OperationId) {
        let idx = ChildId(idx.0);

        let secret_tweak_key = self
            .module_root_secret
            .child_key(WALLET_TWEAK_CHILD_ID)
            .child_key(idx)
            .to_secp_key(fedimint_core::secp256k1::SECP256K1);

        let public_tweak_key = secret_tweak_key.public_key();

        let address = self
            .cfg
            .peg_in_descriptor
            .tweak(&public_tweak_key, bitcoin::secp256k1::SECP256K1)
            .address(self.cfg.network.0)
            .unwrap();

        // TODO: make hash?
        let operation_id = OperationId(public_tweak_key.x_only_public_key().0.serialize());

        (secret_tweak_key, public_tweak_key, address, operation_id)
    }

    fn derive_peg_in_script(
        &self,
        idx: TweakIdx,
    ) -> (ScriptBuf, bitcoin::Address, Keypair, OperationId) {
        let (secret_tweak_key, _, address, operation_id) = self.derive_deposit_address(idx);

        (
            self.cfg
                .peg_in_descriptor
                .tweak(&secret_tweak_key.public_key(), SECP256K1)
                .script_pubkey(),
            address,
            secret_tweak_key,
            operation_id,
        )
    }
}

#[derive(Debug)]
#[cfg_attr(feature = "uniffi", derive(uniffi::Object))]
pub struct WalletClientModule {
    data: WalletClientModuleData,
    db: Database,
    module_api: DynModuleApi,
    notifier: ModuleNotifier<WalletClientStates>,
    rpc: DynBitcoindRpc,
    client_ctx: ClientContext<Self>,
    /// Updated to wake up pegin monitor
    pegin_monitor_wakeup_sender: watch::Sender<()>,
    pegin_monitor_wakeup_receiver: watch::Receiver<()>,
    /// Called every time a peg-in was claimed
    pegin_claimed_sender: watch::Sender<()>,
    pegin_claimed_receiver: watch::Receiver<()>,
    task_group: TaskGroup,
    client_span: tracing::Span,
    admin_auth: Option<ApiAuth>,
}

#[apply(async_trait_maybe_send!)]
impl ClientModule for WalletClientModule {
    type Init = WalletClientInit;
    type Common = WalletModuleTypes;
    type Backup = WalletModuleBackup;
    type ModuleStateMachineContext = WalletClientContext;
    type States = WalletClientStates;

    fn context(&self) -> Self::ModuleStateMachineContext {
        WalletClientContext {
            rpc: self.rpc.clone(),
            wallet_descriptor: self.cfg().peg_in_descriptor.clone(),
            wallet_decoder: self.decoder(),
            secp: Secp256k1::default(),
            client_ctx: self.client_ctx.clone(),
        }
    }

    async fn start(&self) {
        self.task_group
            .spawn_cancellable_with_span(self.client_span.clone(), "peg-in monitor", {
                let client_ctx = self.client_ctx.clone();
                let db = self.db.clone();
                let btc_rpc = self.rpc.clone();
                let module_api = self.module_api.clone();
                let data = self.data.clone();
                let pegin_claimed_sender = self.pegin_claimed_sender.clone();
                let pegin_monitor_wakeup_receiver = self.pegin_monitor_wakeup_receiver.clone();
                pegin_monitor::run_peg_in_monitor(
                    client_ctx,
                    db,
                    btc_rpc,
                    module_api,
                    data,
                    pegin_claimed_sender,
                    pegin_monitor_wakeup_receiver,
                )
            });

        self.task_group.spawn_cancellable_with_span(
            self.client_span.clone(),
            "supports-safe-deposit-version",
            {
                let db = self.db.clone();
                let module_api = self.module_api.clone();

                poll_supports_safe_deposit_version(db, module_api)
            },
        );
    }

    fn supports_backup(&self) -> bool {
        true
    }

    async fn backup(&self) -> Result<backup::WalletModuleBackup, ClientModuleError> {
        // fetch consensus height first
        let session_count = self
            .client_ctx
            .global_api()
            .session_count()
            .await
            .map_err(ClientModuleError::other)?;

        let mut dbtx = self.db.begin_transaction_nc().await;
        let next_pegin_tweak_idx = dbtx
            .get_value(&NextPegInTweakIndexKey)
            .await
            .unwrap_or_default();
        let claimed = dbtx
            .find_by_prefix(&PegInTweakIndexPrefix)
            .await
            .filter_map(|(k, v)| async move {
                if v.claimed.is_empty() {
                    None
                } else {
                    Some(k.0)
                }
            })
            .collect()
            .await;
        Ok(backup::WalletModuleBackup::new_v1(
            session_count,
            next_pegin_tweak_idx,
            claimed,
        ))
    }

    fn input_fee(
        &self,
        _amount: &Amounts,
        _input: &<Self::Common as ModuleCommon>::Input,
    ) -> Option<Amounts> {
        Some(Amounts::new_bitcoin(self.cfg().fee_consensus.peg_in_abs))
    }

    fn output_fee(
        &self,
        _amount: &Amounts,
        _output: &<Self::Common as ModuleCommon>::Output,
    ) -> Option<Amounts> {
        Some(Amounts::new_bitcoin(self.cfg().fee_consensus.peg_out_abs))
    }

    async fn handle_rpc(
        &self,
        method: String,
        request: serde_json::Value,
    ) -> BoxStream<'_, Result<serde_json::Value, ClientModuleError>> {
        let stream: BoxStream<'_, Result<serde_json::Value, RpcError>> = Box::pin(try_stream! {
            match method.as_str() {
                "get_wallet_summary" => {
                    let _req: WalletSummaryRequest = serde_json::from_value(request)?;
                    let wallet_summary = self.get_wallet_summary()
                        .await
                        .expect("Failed to fetch wallet summary");
                    let result = serde_json::to_value(&wallet_summary)
                        .expect("Serialization error");
                    yield result;
                }
                "get_block_count_local" => {
                    let block_count = self.get_block_count_local().await
                        .expect("Failed to fetch block count");
                    yield serde_json::to_value(block_count)?;
                }
                "peg_in" => {
                    let req: PegInRequest = serde_json::from_value(request)?;
                    let response = self.peg_in(req)
                        .await
                        .map_err(RpcError::PegIn)?;
                    let result = serde_json::to_value(&response)?;
                    yield result;
                },
                "peg_out" => {
                    let req: PegOutRequest = serde_json::from_value(request)?;
                    let response = self.peg_out(req)
                        .await
                        .map_err(RpcError::PegOut)?;
                    let result = serde_json::to_value(&response)?;
                    yield result;
                },
                "subscribe_deposit" => {
                    let req: SubscribeDepositRequest = serde_json::from_value(request)?;
                    for await state in self.subscribe_deposit(req.operation_id).await?.into_stream() {
                        yield serde_json::to_value(state)?;
                    }
                },
                "subscribe_withdraw" => {
                    let req: SubscribeWithdrawRequest = serde_json::from_value(request)?;
                    for await state in self.subscribe_withdraw_updates(req.operation_id).await?.into_stream(){
                        yield serde_json::to_value(state)?;
                    }
                }
                _ => {
                    Err(RpcError::UnknownMethod { method: method.clone() })?;
                }
            }
        });
        Box::pin(stream.map_err(ClientModuleError::other))
    }

    #[cfg(feature = "cli")]
    async fn handle_cli_command(
        &self,
        args: &[std::ffi::OsString],
    ) -> Result<serde_json::Value, ClientModuleError> {
        cli::handle_cli_command(self, args)
            .await
            .map_err(ClientModuleError::other)
    }
}

/// A failure of a wallet module RPC request.
#[derive(Debug, thiserror::Error)]
enum RpcError {
    /// The request's parameters do not fit the method, or its response could
    /// not be serialized.
    #[error(transparent)]
    Json(#[from] serde_json::Error),

    /// The peg-in could not be started.
    #[error("peg_in failed")]
    PegIn(#[source] DepositAddressError),

    /// The peg-out could not be started.
    #[error("peg_out failed")]
    PegOut(#[source] PegOutError),

    /// The deposit's updates could not be followed.
    #[error(transparent)]
    SubscribeDeposit(#[from] SubscribeDepositError),

    /// The withdrawal's updates could not be followed.
    #[error(transparent)]
    SubscribeWithdraw(#[from] SubscribeWithdrawError),

    /// The request names a method the module does not have.
    #[error("Unknown method: {method}")]
    UnknownMethod { method: String },
}

#[derive(Deserialize)]
struct WalletSummaryRequest {}

#[derive(Debug, Clone)]
pub struct WalletClientContext {
    rpc: DynBitcoindRpc,
    wallet_descriptor: PegInDescriptor,
    wallet_decoder: Decoder,
    secp: Secp256k1<All>,
    pub client_ctx: ClientContext<WalletClientModule>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PegInRequest {
    pub extra_meta: serde_json::Value,
}

#[cfg(feature = "uniffi")]
uniffi::custom_type!(PegInRequest, String, {
    lower: |v| serde_json::to_string(&v).expect("PegInRequest serialization cannot fail"),
    try_lift: |s| serde_json::from_str::<PegInRequest>(&s)
        .map_err(|e| uniffi::deps::anyhow::anyhow!("Failed to parse PegInRequest: {e}")),
});

#[derive(Deserialize)]
struct SubscribeDepositRequest {
    operation_id: OperationId,
}

#[derive(Deserialize)]
struct SubscribeWithdrawRequest {
    operation_id: OperationId,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[cfg_attr(feature = "uniffi", derive(uniffi::Record))]
pub struct PegInResponse {
    pub deposit_address: Address<NetworkUnchecked>,
    pub operation_id: OperationId,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[cfg_attr(feature = "uniffi", derive(uniffi::Record))]
pub struct PegOutRequest {
    pub amount_sat: u64,
    pub destination_address: Address<NetworkUnchecked>,
    pub extra_meta: serde_json::Value,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[cfg_attr(feature = "uniffi", derive(uniffi::Record))]
pub struct PegOutResponse {
    pub operation_id: OperationId,
}

impl Context for WalletClientContext {
    const KIND: Option<ModuleKind> = Some(KIND);
}

impl WalletClientModule {
    fn cfg(&self) -> &WalletClientConfig {
        &self.data.cfg
    }

    fn get_rpc_config(cfg: &WalletClientConfig) -> BitcoinRpcConfig {
        match BitcoinRpcConfig::get_defaults_from_env_vars() {
            Ok(rpc_config) => {
                // TODO: Wallet client cannot support bitcoind RPC until the bitcoin dep is
                // updated to 0.30
                if rpc_config.kind == "bitcoind" {
                    cfg.default_bitcoin_rpc.clone()
                } else {
                    rpc_config
                }
            }
            _ => cfg.default_bitcoin_rpc.clone(),
        }
    }

    pub fn get_network(&self) -> Network {
        self.cfg().network.0
    }

    pub fn get_finality_delay(&self) -> u32 {
        self.cfg().finality_delay
    }

    pub fn get_fee_consensus(&self) -> FeeConsensus {
        self.cfg().fee_consensus
    }

    async fn allocate_deposit_address_inner(
        &self,
        dbtx: &mut DatabaseTransaction<'_>,
    ) -> DepositAddressInfo {
        dbtx.ensure_isolated().expect("Must be isolated db");

        let tweak_idx = get_next_peg_in_tweak_child_id(dbtx).await;
        let (_secret_tweak_key, _, address, operation_id) =
            self.data.derive_deposit_address(tweak_idx);

        let now = fedimint_core::time::now();

        dbtx.insert_new_entry(
            &PegInTweakIndexKey(tweak_idx),
            &PegInTweakIndexData {
                creation_time: now,
                next_check_time: Some(now),
                last_check_time: None,
                operation_id,
                claimed: vec![],
            },
        )
        .await;

        DepositAddressInfo {
            operation_id,
            address,
            tweak_idx,
        }
    }

    /// Fetches the fees that would need to be paid to make the withdraw request
    /// using [`Self::withdraw`] work *right now*.
    ///
    /// Note that we do not receive a guarantee that these fees will be valid in
    /// the future, thus even the next second using these fees *may* fail.
    /// The caller should be prepared to retry with a new fee estimate.
    pub async fn get_withdraw_fees(
        &self,
        address: &bitcoin::Address,
        amount: bitcoin::Amount,
    ) -> Result<PegOutFees, WithdrawFeesError> {
        self.module_api
            .fetch_peg_out_fees(address, amount)
            .await?
            .ok_or(WithdrawFeesError::NoQuote)
    }

    /// Computes the federation fee a peg-out of an on-chain output worth
    /// `amount` (the withdrawal amount plus the on-chain miner fee) would
    /// incur, without submitting anything.
    ///
    /// A peg-out submits a single wallet output worth `amount`; the primary
    /// module balances it by spending ecash to fund the output and minting any
    /// change. This quotes the fee of that transaction — the wallet (peg-out)
    /// output fee, the mint input fees on the funding notes, any mint change
    /// output fees, and sub-denomination dust — via the shared, module-agnostic
    /// fee quote.
    ///
    /// The on-chain Bitcoin miner fee is deliberately excluded: it is part of
    /// the output `amount` (see [`Self::get_withdraw_fees`]), not the
    /// on-federation transaction fee.
    pub async fn send_fee_quote(
        &self,
        amount: bitcoin::Amount,
    ) -> Result<FeeQuote, TransactionSubmitError> {
        let amount = fedimint_core::Amount::from_sats(amount.to_sat());
        self.client_ctx
            .fee_quote(
                OperationId::new_random(),
                FeeQuoteRequest {
                    input_amount: Amounts::ZERO,
                    output_amount: Amounts::new_bitcoin(amount),
                    input_fee: Amounts::ZERO,
                    output_fee: Amounts::new_bitcoin(self.cfg().fee_consensus.peg_out_abs),
                },
            )
            .await
    }

    /// Finds the largest amount that can be withdrawn in full out of
    /// `balance` — the amount a "withdraw everything" sweep should use —
    /// together with the peg-out fees to submit it with.
    ///
    /// Withdrawing `amount` submits a peg-out output worth `amount +
    /// peg_out_fees` (the on-chain miner fee is carried inside the output, see
    /// [`WalletOutputV0::amount`]) and funding that output costs an additional
    /// federation fee — the peg-out output fee, the mint input fees on the
    /// funding notes, any mint change output fees and sub-denomination dust —
    /// as quoted by [`Self::send_fee_quote`].
    ///
    /// Both returned values must be passed to [`Self::withdraw`] together. The
    /// federation rebuilds the peg-out for the exact amount submitted and
    /// rejects it unless the declared `total_weight` matches what it computed
    /// (`WalletOutputError::TxWeightIncorrect`), so the fees are re-quoted here
    /// at the amount being returned rather than at the balance.
    ///
    /// This costs exactly two [`Self::get_withdraw_fees`] round trips. The
    /// first, at the full balance, is an upper bound on the miner fee — the
    /// federation selects UTXOs until they cover the amount, so the weight is
    /// monotone in it — and sizing the withdrawal against that upper bound can
    /// only leave the result more affordable once the true, smaller fee
    /// replaces it. The maximum itself is then found by binary search over the
    /// real fee quote (see [`max_affordable_send_amount`]), which needs no
    /// further round trips because [`Self::send_fee_quote`] is a local dry-run.
    ///
    /// Sizing against the upper bound means a sweep may leave a small
    /// remainder behind. The quote is point-in-time: if the federation's UTXO
    /// set or feerate moves before the peg-out is processed it is rejected, and
    /// the caller should retry with a fresh quote.
    ///
    /// Returns [`MaxWithdrawableAmountError::BalanceTooLow`] if the balance
    /// cannot cover the destination's dust limit plus fees, or
    /// [`MaxWithdrawableAmountError::Quote`] if the fee probe itself failed.
    pub async fn max_withdrawable_amount(
        &self,
        address: &bitcoin::Address,
        balance: fedimint_core::Amount,
    ) -> Result<(bitcoin::Amount, PegOutFees), MaxWithdrawableAmountError> {
        // Upper bound on the miner fee: the weight only grows as the federation
        // has to reach for more UTXOs, so no smaller withdrawal costs more.
        let max_fees = self
            .get_withdraw_fees(
                address,
                bitcoin::Amount::from_sat(balance.sats_round_down()),
            )
            .await?;
        let max_fee_msats = fedimint_core::Amount::from_sats(max_fees.amount().to_sat());
        let dust_limit = address.script_pubkey().minimal_non_dust();

        let max = max_affordable_send_amount(
            balance,
            fedimint_core::Amount::from_sats(dust_limit.to_sat()),
            balance,
            // A peg-out funds a whole number of sats, so round the probe up to
            // the next sat before adding the miner fee; the solver searches
            // millisatoshis.
            |amount: fedimint_core::Amount| {
                fedimint_core::Amount::from_sats(amount.msats.div_ceil(1000)) + max_fee_msats
            },
            |funded: fedimint_core::Amount| {
                self.send_fee_quote(bitcoin::Amount::from_sat(funded.msats / 1000))
            },
        )
        .await
        .map_err(MaxWithdrawableAmountError::Quote)?
        .ok_or(MaxWithdrawableAmountError::BalanceTooLow {
            balance,
            dust_limit,
        })?;

        // `gross_up` rounded up to whole satoshis, so the largest affordable
        // amount already sits on a satoshi boundary; no value is lost here.
        let amount = bitcoin::Amount::from_sat(max.msats.div_ceil(1000));

        // Re-quote at the amount actually being withdrawn. This is the fee the
        // federation recomputes for that amount, so the declared weight
        // matches; it is at most `max_fees`, which is what keeps `amount`
        // affordable.
        let fees = self.get_withdraw_fees(address, amount).await?;

        Ok((amount, fees))
    }

    /// Returns a summary of the wallet's coins
    pub async fn get_wallet_summary(&self) -> FederationResult<WalletSummary> {
        self.module_api.fetch_wallet_summary().await
    }

    pub async fn get_block_count_local(&self) -> FederationResult<u32> {
        self.module_api.fetch_block_count_local().await
    }

    pub fn create_withdraw_output(
        &self,
        operation_id: OperationId,
        address: bitcoin::Address,
        amount: bitcoin::Amount,
        fees: PegOutFees,
    ) -> ClientOutputBundle<WalletOutput, WalletClientStates> {
        let output = WalletOutput::new_v0_peg_out(address, amount, fees);

        let amount = output.maybe_v0_ref().expect("v0 output").amount().into();

        let sm_gen = move |out_point_range: OutPointRange| {
            assert_eq!(out_point_range.count(), 1);
            let out_idx = out_point_range.start_idx();
            vec![WalletClientStates::Withdraw(WithdrawStateMachine {
                operation_id,
                state: WithdrawStates::Created(CreatedWithdrawState {
                    fm_outpoint: OutPoint {
                        txid: out_point_range.txid(),
                        out_idx,
                    },
                }),
            })]
        };

        ClientOutputBundle::new(
            vec![ClientOutput::<WalletOutput> {
                output,
                amounts: Amounts::new_bitcoin(amount),
            }],
            vec![ClientOutputSM::<WalletClientStates> {
                state_machines: Arc::new(sm_gen),
            }],
        )
    }

    pub async fn peg_in(&self, req: PegInRequest) -> Result<PegInResponse, DepositAddressError> {
        let deposit_address = self.safe_allocate_deposit_address(req.extra_meta).await?;

        Ok(PegInResponse {
            deposit_address: deposit_address.address.into_unchecked(),
            operation_id: deposit_address.operation_id,
        })
    }

    pub async fn peg_out(&self, req: PegOutRequest) -> Result<PegOutResponse, PegOutError> {
        let amount = bitcoin::Amount::from_sat(req.amount_sat);
        let network = self.get_network();
        let destination = req
            .destination_address
            .require_network(network)
            .map_err(|_| PegOutError::WrongNetwork { expected: network })?;

        let fees = self.get_withdraw_fees(&destination, amount).await?;
        let operation_id = self
            .withdraw(&destination, amount, fees, req.extra_meta)
            .await?;

        Ok(PegOutResponse { operation_id })
    }

    pub fn create_rbf_withdraw_output(
        &self,
        operation_id: OperationId,
        rbf: &Rbf,
    ) -> ClientOutputBundle<WalletOutput, WalletClientStates> {
        let output = WalletOutput::new_v0_rbf(rbf.fees, rbf.txid);

        let amount = output.maybe_v0_ref().expect("v0 output").amount().into();

        let sm_gen = move |out_point_range: OutPointRange| {
            assert_eq!(out_point_range.count(), 1);
            let out_idx = out_point_range.start_idx();
            vec![WalletClientStates::Withdraw(WithdrawStateMachine {
                operation_id,
                state: WithdrawStates::Created(CreatedWithdrawState {
                    fm_outpoint: OutPoint {
                        txid: out_point_range.txid(),
                        out_idx,
                    },
                }),
            })]
        };

        ClientOutputBundle::new(
            vec![ClientOutput::<WalletOutput> {
                output,
                amounts: Amounts::new_bitcoin(amount),
            }],
            vec![ClientOutputSM::<WalletClientStates> {
                state_machines: Arc::new(sm_gen),
            }],
        )
    }

    pub async fn btc_tx_has_no_size_limit(&self) -> FederationResult<bool> {
        Ok(self.module_api.module_consensus_version().await? >= ModuleConsensusVersion::new(2, 2))
    }

    /// Returns true if the federation's wallet module consensus version
    /// supports processing all deposits.
    ///
    /// This method is safe to call offline, since it first attempts to read a
    /// key from the db that represents the client has previously been able to
    /// verify the wallet module consensus version. If the client has not
    /// verified the version, it must be online to fetch the latest wallet
    /// module consensus version.
    pub async fn supports_safe_deposit(&self) -> bool {
        if supports_safe_deposit_verified(&self.db).await {
            return true;
        }

        verify_supports_safe_deposit(&self.db, &self.module_api)
            .await
            .unwrap_or(false)
    }

    /// Allocates a deposit address controlled by the federation, guaranteeing
    /// safe handling of all deposits, including on-chain transactions exceeding
    /// `ALEPH_BFT_UNIT_BYTE_LIMIT`.
    ///
    /// Returns an error if the client has never been online to verify the
    /// federation's wallet module consensus version supports processing all
    /// deposits.
    pub async fn safe_allocate_deposit_address<M>(
        &self,
        extra_meta: M,
    ) -> Result<DepositAddressInfo, DepositAddressError>
    where
        M: Serialize + MaybeSend + MaybeSync,
    {
        if !self.supports_safe_deposit().await {
            return Err(DepositAddressError::SafeDepositUnverified);
        }

        self.allocate_deposit_address_expert_only(extra_meta).await
    }

    /// Allocates a deposit address that is controlled by the federation.
    ///
    /// This is an EXPERT ONLY method intended for power users such as Lightning
    /// gateways allocating liquidity, and we discourage exposing peg-in
    /// functionality to everyday users of a Fedimint wallet due to the
    /// following two limitations:
    ///
    /// The transaction sending to this address needs to be smaller than 40KB in
    /// order for the peg-in to be claimable. If the transaction is too large,
    /// funds will be lost.
    ///
    /// In the future, federations will also enforce a minimum peg-in amount to
    /// prevent accumulation of dust UTXOs. Peg-ins under this minimum cannot be
    /// claimed and funds will be lost.
    ///
    /// Everyday users should rely on Lightning to move funds into the
    /// federation.
    pub async fn allocate_deposit_address_expert_only<M>(
        &self,
        extra_meta: M,
    ) -> Result<DepositAddressInfo, DepositAddressError>
    where
        M: Serialize + MaybeSend + MaybeSync,
    {
        let extra_meta_value =
            serde_json::to_value(extra_meta).expect("Failed to serialize extra meta");
        let deposit_address = self
            .db
            .autocommit(
                move |dbtx, _| {
                    let extra_meta_value_inner = extra_meta_value.clone();
                    Box::pin(async move {
                        let deposit_address = self.allocate_deposit_address_inner(dbtx).await;

                        self.client_ctx
                            .manual_operation_start_dbtx(
                                dbtx,
                                deposit_address.operation_id,
                                WalletCommonInit::KIND.as_str(),
                                WalletOperationMeta {
                                    variant: WalletOperationMetaVariant::Deposit {
                                        address: deposit_address.address.clone().into_unchecked(),
                                        tweak_idx: Some(deposit_address.tweak_idx),
                                        expires_at: None,
                                    },
                                    extra_meta: extra_meta_value_inner,
                                },
                                vec![],
                            )
                            .await?;

                        debug!(
                            target: LOG_CLIENT_MODULE_WALLET,
                            tweak_idx = %deposit_address.tweak_idx,
                            address = %deposit_address.address,
                            "Derived a new deposit address"
                        );

                        // Begin watching the script address
                        self.rpc
                            .watch_script_history(&deposit_address.address.script_pubkey())
                            .await?;

                        let sender = self.pegin_monitor_wakeup_sender.clone();
                        dbtx.on_commit(move || {
                            sender.send_replace(());
                        });

                        Ok(deposit_address)
                    })
                },
                Some(100),
            )
            .await?;

        Ok(deposit_address)
    }

    /// Allocate a deposit address, bounding the gap of consecutive unused
    /// addresses past the last-used one, without selecting a reusable address.
    ///
    /// "Unused" here means `PegInTweakIndexData::claimed.is_empty()` — the
    /// `pegin_monitor` has not yet successfully claimed any deposit on this
    /// address. There is a small race window where a deposit has been
    /// observed in the mempool / awaiting confirmations but not yet claimed,
    /// in which case the address still looks unused. Reusing such an address
    /// is benign in practice: `pegin_monitor` claims any number of deposits
    /// per address.
    ///
    /// Let `gap` be the count of unused tweak indices strictly greater than
    /// the highest used index (or the count of all allocated tweaks if none
    /// have been used yet). Semantics:
    ///   - If `gap >= max_gap_size` and there is at least one unused address,
    ///     returns all those addresses with
    ///     [`MaybeNewAddress::TooManyUnusedAddresses`].
    ///   - Otherwise, allocates a new address (equivalent to
    ///     [`Self::allocate_deposit_address_expert_only`]) and returns it with
    ///     [`MaybeNewAddress::NewAddress`].
    ///
    /// `max_gap_size == 0` therefore means "only allocate fresh when the
    /// previous address was already used". The very first call still
    /// allocates fresh because there are no addresses to reuse.
    ///
    /// `max_gap_size == usize::MAX` makes this method behave like
    /// [`Self::allocate_deposit_address_expert_only`] — always allocating a new
    /// address.
    ///
    /// Reusable addresses are ordered by `creation_time` ascending. This lets
    /// callers that need a custom selection strategy choose from all available
    /// candidates.
    ///
    /// Caveats inherited from
    /// [`Self::allocate_deposit_address_expert_only`] (40KB tx limit, future
    /// minimum peg-in amount) apply equally to newly allocated and reused
    /// addresses.
    pub async fn allocate_deposit_address_pooled_stateless(
        &self,
        max_gap_size: usize,
    ) -> Result<MaybeNewAddress, DepositAddressError> {
        let max_gap_size_u64 = u64::try_from(max_gap_size).unwrap_or(u64::MAX);
        let extra_meta_value = serde_json::Value::Null;
        let result = self
            .db
            .autocommit(
                move |dbtx, _| {
                    let extra_meta_value_inner = extra_meta_value.clone();
                    Box::pin(async move {
                        let unused = self.unused_pooled_deposit_addresses(dbtx).await;

                        if max_gap_size_u64 <= unused.len() as u64 && !unused.is_empty() {
                            let addresses = unused
                                .into_iter()
                                .map(|(tweak_idx, data)| {
                                    let (_script, address, _key, operation_id) =
                                        self.data.derive_peg_in_script(tweak_idx);

                                    debug_assert_eq!(operation_id, data.operation_id);

                                    DepositAddressInfo {
                                        operation_id,
                                        address,
                                        tweak_idx,
                                    }
                                })
                                .collect();

                            return Ok::<_, DepositAddressError>(
                                MaybeNewAddress::TooManyUnusedAddresses(addresses),
                            );
                        }

                        let deposit_address = self.allocate_deposit_address_inner(dbtx).await;

                        self.client_ctx
                            .manual_operation_start_dbtx(
                                dbtx,
                                deposit_address.operation_id,
                                WalletCommonInit::KIND.as_str(),
                                WalletOperationMeta {
                                    variant: WalletOperationMetaVariant::Deposit {
                                        address: deposit_address.address.clone().into_unchecked(),
                                        tweak_idx: Some(deposit_address.tweak_idx),
                                        expires_at: None,
                                    },
                                    extra_meta: extra_meta_value_inner,
                                },
                                vec![],
                            )
                            .await?;

                        debug!(
                            target: LOG_CLIENT_MODULE_WALLET,
                            tweak_idx = %deposit_address.tweak_idx,
                            address = %deposit_address.address,
                            "Derived a new pooled deposit address"
                        );

                        self.rpc
                            .watch_script_history(&deposit_address.address.script_pubkey())
                            .await?;

                        let sender = self.pegin_monitor_wakeup_sender.clone();
                        dbtx.on_commit(move || {
                            sender.send_replace(());
                        });

                        Ok(MaybeNewAddress::NewAddress(deposit_address))
                    })
                },
                Some(100),
            )
            .await?;

        Ok(result)
    }

    async fn unused_pooled_deposit_addresses(
        &self,
        dbtx: &mut DatabaseTransaction<'_>,
    ) -> Vec<(TweakIdx, PegInTweakIndexData)> {
        // Walk peg-in tweaks in descending order, taking unused ones
        // (`claimed.is_empty()`) until we hit a used one. That gives us exactly
        // the trailing gap — `gap + 1` reads regardless of total tweak count.
        // No RPC and no separately-maintained `last_used` index needed.
        let mut unused: Vec<(TweakIdx, PegInTweakIndexData)> = dbtx
            .find_by_prefix_sorted_descending(&PegInTweakIndexPrefix)
            .await
            .take_while(|(_, d)| std::future::ready(d.claimed.is_empty()))
            .map(|(k, v)| (k.0, v))
            .collect()
            .await;

        // Order by `creation_time` ascending for caller selection and stable
        // wraparound after stateful reuse mutates `creation_time`.
        unused.sort_by_key(|(t, d)| (d.creation_time, *t));
        unused
    }

    /// Allocate a deposit address, bounding the gap of consecutive unused
    /// addresses past the last-used one.
    ///
    /// This is a stateful wrapper over
    /// [`Self::allocate_deposit_address_pooled_stateless`]. If the stateless
    /// method returns [`MaybeNewAddress::TooManyUnusedAddresses`], this method
    /// picks one of those addresses with a persisted round-robin cursor and
    /// returns it with [`AllocateDepositOutcome::Reused`].
    ///
    /// Selection policy when reusing: round-robin over unused addresses
    /// ordered by `creation_time` ascending, with the cursor persisted
    /// per-client in the wallet module's DB. The cursor stores the next
    /// tweak index to consider; after picking idx X it advances to X+1, and
    /// when no candidate has `tweak_idx >= cursor` it wraps to the
    /// oldest-by-`creation_time` candidate. This gives the caller the
    /// predictable "cycle through the unused addresses" behavior.
    ///
    /// On reuse the `creation_time` and check-schedule fields of the
    /// underlying tweak entry are reset to "now", so `pegin_monitor`'s
    /// age-proportional polling delay restarts from zero. Without this an
    /// old entry would keep its long stale next-check delay and a user
    /// sending to it could wait a long time before the client noticed.
    #[allow(clippy::too_many_lines)]
    pub async fn allocate_deposit_address_pooled(
        &self,
        max_gap_size: usize,
    ) -> Result<(DepositAddressInfo, AllocateDepositOutcome), DepositAddressError> {
        let stateless = self
            .allocate_deposit_address_pooled_stateless(max_gap_size)
            .await?;

        let reused_addresses = match stateless {
            MaybeNewAddress::NewAddress(deposit_address) => {
                return Ok((deposit_address, AllocateDepositOutcome::Fresh));
            }
            MaybeNewAddress::TooManyUnusedAddresses(addresses) => addresses,
        };

        let result = self
            .db
            .autocommit(
                move |dbtx, _| {
                    let reused_addresses = reused_addresses.clone();
                    Box::pin(async move {
                        let cursor = dbtx
                            .get_value(&PegInPoolCursorKey)
                            .await
                            .unwrap_or(TweakIdx(0));

                        let pick_pos = reused_addresses
                            .iter()
                            .position(|a| cursor <= a.tweak_idx)
                            .unwrap_or(0);
                        let reused_address = reused_addresses[pick_pos].clone();

                        let existing_tweak_idx = reused_address.tweak_idx;
                        let existing = dbtx
                            .get_value(&PegInTweakIndexKey(reused_address.tweak_idx))
                            .await
                            .ok_or(DepositAddressError::PooledAddressDisappeared {
                                tweak_idx: reused_address.tweak_idx,
                            })?;

                        if !existing.claimed.is_empty() {
                            return Err(DepositAddressError::PooledAddressUsed {
                                tweak_idx: reused_address.tweak_idx,
                            });
                        }

                        dbtx.insert_entry(&PegInPoolCursorKey, &reused_address.tweak_idx.next())
                            .await;

                        // Reset the monitoring schedule so the reused address
                        // gets checked as aggressively as a freshly-allocated
                        // one. Without this, an old entry would retain its
                        // `age/10` next-check delay from `pegin_monitor`,
                        // meaning a user who sends to a long-idle pool address
                        // could wait hours before the client polls for the
                        // deposit.
                        let now = fedimint_core::time::now();
                        dbtx.insert_entry(
                            &PegInTweakIndexKey(reused_address.tweak_idx),
                            &PegInTweakIndexData {
                                creation_time: now,
                                last_check_time: None,
                                next_check_time: Some(now),
                                operation_id: existing.operation_id,
                                claimed: existing.claimed,
                            },
                        )
                        .await;

                        let sender = self.pegin_monitor_wakeup_sender.clone();
                        dbtx.on_commit(move || {
                            sender.send_replace(());
                        });

                        Ok::<_, DepositAddressError>((
                            reused_address,
                            AllocateDepositOutcome::Reused {
                                original_tweak_idx: existing_tweak_idx,
                            },
                        ))
                    })
                },
                Some(100),
            )
            .await?;

        Ok(result)
    }

    /// Returns a stream of updates about an ongoing deposit operation created
    /// with [`WalletClientModule::allocate_deposit_address_expert_only`].
    /// Returns an error for old deposit operations created prior to the 0.4
    /// release and not driven to completion yet. This should be rare enough
    /// that an indeterminate state is ok here.
    pub async fn subscribe_deposit(
        &self,
        operation_id: OperationId,
    ) -> Result<UpdateStreamOrOutcome<DepositStateV2>, SubscribeDepositError> {
        let operation = self.client_ctx.get_operation(operation_id).await?;

        let operation_meta = operation.meta::<WalletOperationMeta>();

        let WalletOperationMetaVariant::Deposit {
            address, tweak_idx, ..
        } = operation_meta.variant
        else {
            return Err(SubscribeDepositError::NotADeposit);
        };

        let network = self.cfg().network.0;
        let address = address
            .require_network(network)
            .map_err(|_| SubscribeDepositError::WrongNetwork { expected: network })?;

        // The old deposit operations don't have tweak_idx set
        let Some(tweak_idx) = tweak_idx else {
            // In case we are dealing with an old deposit that still uses state machines we
            // don't have the logic here anymore to subscribe to updates. We can still read
            // the final state though if it reached any.
            let outcome_v1 = operation
                .outcome::<DepositStateV1>()
                .ok_or(SubscribeDepositError::OldPendingDeposit)?;

            let outcome_v2 = match outcome_v1 {
                DepositStateV1::Claimed(tx_info) => DepositStateV2::Claimed {
                    btc_deposited: tx_info.btc_transaction.output[tx_info.out_idx as usize].value,
                    btc_out_point: bitcoin::OutPoint {
                        txid: tx_info.btc_transaction.compute_txid(),
                        vout: tx_info.out_idx,
                    },
                },
                DepositStateV1::Failed(error) => DepositStateV2::Failed(error),
                _ => return Err(SubscribeDepositError::NonFinalOutcome),
            };

            return Ok(UpdateStreamOrOutcome::Outcome(outcome_v2));
        };

        Ok(self.client_ctx.outcome_or_updates(
            &operation,
            operation_id,
            |state| match state {
                DepositStateV2::WaitingForTransaction
                | DepositStateV2::WaitingForConfirmation { .. }
                | DepositStateV2::Confirmed { .. } => false,
                DepositStateV2::Claimed { .. } | DepositStateV2::Failed(_) => true,
            },
            {
            let stream_rpc = self.rpc.clone();
            let stream_client_ctx = self.client_ctx.clone();
            let stream_script_pub_key = address.script_pubkey();
            move || {

            stream! {
                yield DepositStateV2::WaitingForTransaction;

                retry(
                    "subscribe script history",
                    background_backoff(),
                    || stream_rpc.watch_script_history(&stream_script_pub_key)
                ).await.expect("Will never give up");
                let (btc_out_point, btc_deposited) = retry(
                    "fetch history",
                    background_backoff(),
                    || async {
                        let history = stream_rpc.get_script_history(&stream_script_pub_key).await?;
                        history.first().and_then(|tx| {
                            let (out_idx, amount) = tx.output
                                .iter()
                                .enumerate()
                                .find_map(|(idx, output)| (output.script_pubkey == stream_script_pub_key).then_some((idx, output.value)))?;
                            let txid = tx.compute_txid();

                            Some((
                                bitcoin::OutPoint {
                                    txid,
                                    vout: out_idx as u32,
                                },
                                amount
                            ))
                        }).ok_or(FetchDepositTransactionError::NotFound)
                    }
                ).await.expect("Will never give up");

                yield DepositStateV2::WaitingForConfirmation {
                    btc_deposited,
                    btc_out_point
                };

                let claim_data = stream_client_ctx.module_db().wait_key_exists(&ClaimedPegInKey {
                    peg_in_index: tweak_idx,
                    btc_out_point,
                }).await;

                yield DepositStateV2::Confirmed {
                    btc_deposited,
                    btc_out_point
                };

                match stream_client_ctx.await_primary_module_outputs(operation_id, claim_data.change).await {
                    Ok(()) => yield DepositStateV2::Claimed {
                        btc_deposited,
                        btc_out_point
                    },
                    Err(e) => yield DepositStateV2::Failed(e.fmt_compact().to_string())
                }
            }
        }}))
    }

    pub async fn list_peg_in_tweak_idxes(&self) -> BTreeMap<TweakIdx, PegInTweakIndexData> {
        self.client_ctx
            .module_db()
            .clone()
            .begin_transaction_nc()
            .await
            .find_by_prefix(&PegInTweakIndexPrefix)
            .await
            .map(|(key, data)| (key.0, data))
            .collect()
            .await
    }

    pub async fn find_tweak_idx_by_address(
        &self,
        address: bitcoin::Address<NetworkUnchecked>,
    ) -> Result<TweakIdx, PegInError> {
        let data = self.data.clone();
        let Some((tweak_idx, _)) = self
            .db
            .begin_transaction_nc()
            .await
            .find_by_prefix(&PegInTweakIndexPrefix)
            .await
            .filter(|(k, _)| {
                let (_, derived_address, _tweak_key, _) = data.derive_peg_in_script(k.0);
                future::ready(derived_address.into_unchecked() == address)
            })
            .next()
            .await
        else {
            return Err(PegInError::AddressNotDerived);
        };

        Ok(tweak_idx.0)
    }
    pub async fn find_tweak_idx_by_operation_id(
        &self,
        operation_id: OperationId,
    ) -> Result<TweakIdx, PegInError> {
        Ok(self
            .client_ctx
            .module_db()
            .clone()
            .begin_transaction_nc()
            .await
            .find_by_prefix(&PegInTweakIndexPrefix)
            .await
            .filter(|(_k, v)| future::ready(v.operation_id == operation_id))
            .next()
            .await
            .ok_or(PegInError::NoAddressForOperation { operation_id })?
            .0
            .0)
    }

    pub async fn get_pegin_tweak_idx(
        &self,
        tweak_idx: TweakIdx,
    ) -> Result<PegInTweakIndexData, PegInError> {
        self.client_ctx
            .module_db()
            .clone()
            .begin_transaction_nc()
            .await
            .get_value(&PegInTweakIndexKey(tweak_idx))
            .await
            .ok_or(PegInError::TweakIdxNotFound { tweak_idx })
    }

    pub async fn get_claimed_pegins(
        &self,
        dbtx: &mut DatabaseTransaction<'_>,
        tweak_idx: TweakIdx,
    ) -> Vec<(
        bitcoin::OutPoint,
        TransactionId,
        Vec<fedimint_core::OutPoint>,
    )> {
        let outpoints = dbtx
            .get_value(&PegInTweakIndexKey(tweak_idx))
            .await
            .map(|v| v.claimed)
            .unwrap_or_default();

        let mut res = vec![];

        for outpoint in outpoints {
            let claimed_peg_in_data = dbtx
                .get_value(&ClaimedPegInKey {
                    peg_in_index: tweak_idx,
                    btc_out_point: outpoint,
                })
                .await
                .expect("Must have a corresponding claim record");
            res.push((
                outpoint,
                claimed_peg_in_data.claim_txid,
                claimed_peg_in_data.change,
            ));
        }

        res
    }

    /// Like [`Self::recheck_pegin_address`] but by `operation_id`
    pub async fn recheck_pegin_address_by_op_id(
        &self,
        operation_id: OperationId,
    ) -> Result<(), PegInError> {
        let tweak_idx = self.find_tweak_idx_by_operation_id(operation_id).await?;

        self.recheck_pegin_address(tweak_idx).await
    }

    /// Schedule given address for immediate re-check for deposits
    pub async fn recheck_pegin_address_by_address(
        &self,
        address: bitcoin::Address<NetworkUnchecked>,
    ) -> Result<(), PegInError> {
        self.recheck_pegin_address(self.find_tweak_idx_by_address(address).await?)
            .await
    }

    /// Schedule given address for immediate re-check for deposits
    pub async fn recheck_pegin_address(&self, tweak_idx: TweakIdx) -> Result<(), PegInError> {
        self.db
            .autocommit(
                |dbtx, _| {
                    Box::pin(async {
                        let db_key = PegInTweakIndexKey(tweak_idx);
                        let db_val = dbtx
                            .get_value(&db_key)
                            .await
                            .ok_or(PegInError::TweakIdxNotFound { tweak_idx })?;

                        dbtx.insert_entry(
                            &db_key,
                            &PegInTweakIndexData {
                                next_check_time: Some(fedimint_core::time::now()),
                                ..db_val
                            },
                        )
                        .await;

                        let sender = self.pegin_monitor_wakeup_sender.clone();
                        dbtx.on_commit(move || {
                            sender.send_replace(());
                        });

                        Ok::<_, PegInError>(())
                    })
                },
                Some(100),
            )
            .await?;

        Ok(())
    }

    /// Await for num deposit by [`OperationId`]
    pub async fn await_num_deposits_by_operation_id(
        &self,
        operation_id: OperationId,
        num_deposits: usize,
    ) -> Result<(), PegInError> {
        let tweak_idx = self.find_tweak_idx_by_operation_id(operation_id).await?;
        self.await_num_deposits(tweak_idx, num_deposits).await
    }

    pub async fn await_num_deposits_by_address(
        &self,
        address: bitcoin::Address<NetworkUnchecked>,
        num_deposits: usize,
    ) -> Result<(), PegInError> {
        self.await_num_deposits(self.find_tweak_idx_by_address(address).await?, num_deposits)
            .await
    }

    #[instrument(target = LOG_CLIENT_MODULE_WALLET, skip_all, fields(tweak_idx=?tweak_idx, num_deposists=num_deposits))]
    pub async fn await_num_deposits(
        &self,
        tweak_idx: TweakIdx,
        num_deposits: usize,
    ) -> Result<(), PegInError> {
        let operation_id = self.get_pegin_tweak_idx(tweak_idx).await?.operation_id;

        let mut receiver = self.pegin_claimed_receiver.clone();
        let mut backoff = backoff_util::aggressive_backoff();

        loop {
            let pegins = self
                .get_claimed_pegins(
                    &mut self.client_ctx.module_db().begin_transaction_nc().await,
                    tweak_idx,
                )
                .await;

            if pegins.len() < num_deposits {
                debug!(target: LOG_CLIENT_MODULE_WALLET, has=pegins.len(), "Not enough deposits");
                self.recheck_pegin_address(tweak_idx).await?;
                runtime::sleep(backoff.next().unwrap_or_default()).await;
                receiver
                    .changed()
                    .await
                    .map_err(|_| PegInError::MonitorStopped)?;
                continue;
            }

            debug!(target: LOG_CLIENT_MODULE_WALLET, has=pegins.len(), "Enough deposits detected");

            for (_outpoint, transaction_id, change) in pegins {
                if transaction_id == TransactionId::from_byte_array([0; 32]) && change.is_empty() {
                    debug!(target: LOG_CLIENT_MODULE_WALLET, "Deposited amount was too low, skipping");
                    continue;
                }

                debug!(target: LOG_CLIENT_MODULE_WALLET, out_points=?change, "Ensuring deposists claimed");
                let tx_subscriber = self.client_ctx.transaction_updates(operation_id).await;

                if let Err(reason) = tx_subscriber.await_tx_accepted(transaction_id).await {
                    return Err(PegInError::TransactionRejected { reason });
                }

                debug!(target: LOG_CLIENT_MODULE_WALLET, out_points=?change, "Ensuring outputs claimed");
                self.client_ctx
                    .await_primary_module_outputs(operation_id, change)
                    .await
                    .expect("Cannot fail if tx was accepted and federation is honest");
            }

            return Ok(());
        }
    }

    /// Attempt to withdraw a given `amount` of Bitcoin to a destination
    /// `address`. The caller has to supply the fee rate to be used which can be
    /// fetched using [`Self::get_withdraw_fees`] and should be
    /// acknowledged by the user since it can be unexpectedly high.
    pub async fn withdraw<M: Serialize + MaybeSend + MaybeSync>(
        &self,
        address: &bitcoin::Address,
        amount: bitcoin::Amount,
        fee: PegOutFees,
        extra_meta: M,
    ) -> Result<OperationId, TransactionSubmitError> {
        {
            let operation_id = OperationId(thread_rng().r#gen());

            let withdraw_output =
                self.create_withdraw_output(operation_id, address.clone(), amount, fee);
            let tx_builder = TransactionBuilder::new()
                .with_outputs(self.client_ctx.make_client_outputs(withdraw_output));

            let extra_meta =
                serde_json::to_value(extra_meta).expect("Failed to serialize extra meta");
            self.client_ctx
                .finalize_and_submit_transaction(
                    operation_id,
                    WalletCommonInit::KIND.as_str(),
                    {
                        let address = address.clone();
                        move |change_range: OutPointRange| WalletOperationMeta {
                            variant: WalletOperationMetaVariant::Withdraw {
                                address: address.clone().into_unchecked(),
                                amount,
                                fee,
                                change: change_range.into_iter().collect(),
                            },
                            extra_meta: extra_meta.clone(),
                        }
                    },
                    tx_builder,
                )
                .await?;

            let mut dbtx = self.client_ctx.module_db().begin_transaction().await;

            self.client_ctx
                .log_event(
                    &mut dbtx,
                    SendPaymentEvent {
                        operation_id,
                        amount: amount + fee.amount(),
                        fee: fee.amount(),
                    },
                )
                .await;

            dbtx.commit_tx().await;

            Ok(operation_id)
        }
    }

    /// Attempt to increase the fee of a onchain withdraw transaction using
    /// replace by fee (RBF).
    /// This can prevent transactions from getting stuck
    /// in the mempool
    #[deprecated(
        since = "0.4.0",
        note = "RBF withdrawals are rejected by the federation"
    )]
    pub async fn rbf_withdraw<M: Serialize + MaybeSync + MaybeSend>(
        &self,
        rbf: Rbf,
        extra_meta: M,
    ) -> Result<OperationId, TransactionSubmitError> {
        let operation_id = OperationId(thread_rng().r#gen());

        let withdraw_output = self.create_rbf_withdraw_output(operation_id, &rbf);
        let tx_builder = TransactionBuilder::new()
            .with_outputs(self.client_ctx.make_client_outputs(withdraw_output));

        let extra_meta = serde_json::to_value(extra_meta).expect("Failed to serialize extra meta");
        self.client_ctx
            .finalize_and_submit_transaction(
                operation_id,
                WalletCommonInit::KIND.as_str(),
                move |change_range: OutPointRange| WalletOperationMeta {
                    variant: WalletOperationMetaVariant::RbfWithdraw {
                        rbf: rbf.clone(),
                        change: change_range.into_iter().collect(),
                    },
                    extra_meta: extra_meta.clone(),
                },
                tx_builder,
            )
            .await?;

        Ok(operation_id)
    }

    pub async fn subscribe_withdraw_updates(
        &self,
        operation_id: OperationId,
    ) -> Result<UpdateStreamOrOutcome<WithdrawState>, SubscribeWithdrawError> {
        let operation = self.client_ctx.get_operation(operation_id).await?;

        let operation_meta = operation.meta::<WalletOperationMeta>();

        let (WalletOperationMetaVariant::Withdraw { change, .. }
        | WalletOperationMetaVariant::RbfWithdraw { change, .. }) = operation_meta.variant
        else {
            return Err(SubscribeWithdrawError::NotAWithdrawal);
        };

        let mut operation_stream = self.notifier.subscribe(operation_id).await;
        let client_ctx = self.client_ctx.clone();

        Ok(self.client_ctx.outcome_or_updates(
            &operation,
            operation_id,
            |state| match state {
                WithdrawState::Created => false,
                WithdrawState::Succeeded(_) | WithdrawState::Failed(_) => true,
            },
            move || {
                stream! {
                    match next_withdraw_state(&mut operation_stream).await {
                        Some(WithdrawStates::Created(_)) => {
                            yield WithdrawState::Created;
                        },
                        Some(s) => {
                            panic!("Unexpected state {s:?}")
                        },
                        None => return,
                    }

                    // TODO: get rid of awaiting change here, there has to be a better way to make tests deterministic

                        // Swallowing potential errors since the transaction failing  is handled by
                        // output outcome fetching already
                        let _ = client_ctx
                            .await_primary_module_outputs(operation_id, change)
                            .await;


                    match next_withdraw_state(&mut operation_stream).await {
                        Some(WithdrawStates::Aborted(inner)) => {
                            yield WithdrawState::Failed(inner.error);
                        },
                        Some(WithdrawStates::Success(inner)) => {
                            yield WithdrawState::Succeeded(inner.txid);
                        },
                        Some(s) => {
                            panic!("Unexpected state {s:?}")
                        },
                        None => {},
                    }
                }
            },
        ))
    }

    fn admin_auth(&self) -> Result<ApiAuth, ConsensusVersionVotingError> {
        self.admin_auth
            .clone()
            .ok_or(ConsensusVersionVotingError::AdminAuthMissing)
    }

    pub async fn activate_consensus_version_voting(
        &self,
    ) -> Result<(), ConsensusVersionVotingError> {
        self.module_api
            .activate_consensus_version_voting(self.admin_auth()?)
            .await?;

        Ok(())
    }
}

/// Why a deposit address's funding transaction was not found, so that it is
/// looked up again.
#[derive(Debug, thiserror::Error)]
enum FetchDepositTransactionError {
    /// The Bitcoin backend could not report the address's history.
    #[error(transparent)]
    BitcoinRpc(#[from] BitcoinRpcError),

    /// The address's history holds no transaction paying to it yet.
    #[error("No deposit transaction found")]
    NotFound,
}

/// Polls the federation checking if the activated module consensus version
/// supports safe deposits, saving the result in the db once it does.
async fn poll_supports_safe_deposit_version(db: Database, module_api: DynModuleApi) {
    loop {
        if supports_safe_deposit_verified(&db).await {
            break;
        }

        module_api.wait_for_initialized_connections().await;

        if verify_supports_safe_deposit(&db, &module_api).await == Some(true) {
            break;
        }

        if is_running_in_test_env() {
            // Even in tests we don't want to spam the federation with requests about it
            sleep(Duration::from_secs(10)).await;
        } else {
            sleep(Duration::from_hours(1)).await;
        }
    }
}

/// Whether the federation's wallet module consensus version was already
/// verified to support safe deposits.
async fn supports_safe_deposit_verified(db: &Database) -> bool {
    db.begin_transaction_nc()
        .await
        .get_value(&SupportsSafeDepositKey)
        .await
        .is_some()
}

/// Fetches the federation's wallet module consensus version and records the
/// marker if it supports safe deposits.
///
/// Returns `None` if the version could not be fetched, e.g. while offline.
async fn verify_supports_safe_deposit(db: &Database, module_api: &DynModuleApi) -> Option<bool> {
    let module_consensus_version = match module_api.module_consensus_version().await {
        Ok(module_consensus_version) => module_consensus_version,
        Err(err) => {
            debug!(
                target: LOG_CLIENT_MODULE_WALLET,
                err = %err.fmt_compact(),
                "Could not fetch the wallet module consensus version"
            );
            return None;
        }
    };

    let supported_version = SAFE_DEPOSIT_MODULE_CONSENSUS_VERSION <= module_consensus_version;

    if supported_version {
        store_supports_safe_deposit(db.begin_transaction().await).await;
    }

    Some(supported_version)
}

/// Records in `dbtx` that the federation's wallet module consensus version
/// was verified to support safe deposits, and commits it.
///
/// The marker is written by both the background version poller and
/// [`WalletClientModule::supports_safe_deposit`], which race right after
/// joining a federation. The loser's commit fails with a write conflict, but
/// the winner stored the very same marker and nothing ever removes it, so the
/// conflict is treated as success. That is only sound for a fresh `dbtx` whose
/// sole write is the marker: any other write in it would be lost as well.
///
/// Any other commit error is logged rather than escalated: the marker only
/// lets future checks skip re-verifying the version, callers already have
/// their answer, and the next verification simply writes it again — an
/// optional write is not worth crashing over.
async fn store_supports_safe_deposit(mut dbtx: DatabaseTransaction<'_, Committable>) {
    if dbtx.get_value(&SupportsSafeDepositKey).await.is_some() {
        // The other writer won before this transaction started.
        return;
    }

    dbtx.insert_entry(&SupportsSafeDepositKey, &()).await;

    match dbtx.commit_tx_result().await {
        Ok(()) | Err(DatabaseError::WriteConflict) => {}
        Err(err) => {
            warn!(
                target: LOG_CLIENT_MODULE_WALLET,
                err = %err.fmt_compact(),
                "Failed to store the safe-deposit marker"
            );
        }
    }
}

/// Returns the child index to derive the next peg-in tweak key from.
async fn get_next_peg_in_tweak_child_id(dbtx: &mut DatabaseTransaction<'_>) -> TweakIdx {
    let index = dbtx
        .get_value(&NextPegInTweakIndexKey)
        .await
        .unwrap_or_default();
    dbtx.insert_entry(&NextPegInTweakIndexKey, &(index.next()))
        .await;
    index
}

#[derive(Debug, Clone, Eq, PartialEq, Hash, Decodable, Encodable)]
pub enum WalletClientStates {
    Deposit(DepositStateMachine),
    Withdraw(WithdrawStateMachine),
}

impl IntoDynInstance for WalletClientStates {
    type DynType = DynState;

    fn into_dyn(self, instance_id: ModuleInstanceId) -> Self::DynType {
        DynState::from_typed(instance_id, self)
    }
}

impl State for WalletClientStates {
    type ModuleContext = WalletClientContext;

    fn transitions(
        &self,
        context: &Self::ModuleContext,
        global_context: &DynGlobalClientContext,
    ) -> Vec<StateTransition<Self>> {
        match self {
            WalletClientStates::Deposit(sm) => {
                sm_enum_variant_translation!(
                    sm.transitions(context, global_context),
                    WalletClientStates::Deposit
                )
            }
            WalletClientStates::Withdraw(sm) => {
                sm_enum_variant_translation!(
                    sm.transitions(context, global_context),
                    WalletClientStates::Withdraw
                )
            }
        }
    }

    fn operation_id(&self) -> OperationId {
        match self {
            WalletClientStates::Deposit(sm) => sm.operation_id(),
            WalletClientStates::Withdraw(sm) => sm.operation_id(),
        }
    }
}

#[cfg(all(test, not(target_family = "wasm")))]
mod tests {
    use std::collections::BTreeSet;
    use std::sync::atomic::{AtomicBool, Ordering};

    use fedimint_core::db::mem_impl::MemDatabase;
    use fedimint_core::module::registry::ModuleDecoderRegistry;

    use super::*;
    use crate::backup::{
        RECOVER_NUM_IDX_ADD_TO_LAST_USED, RecoverScanOutcome, recover_scan_idxes_for_activity,
    };

    #[allow(clippy::too_many_lines)] // shut-up clippy, it's a test
    #[tokio::test(flavor = "multi_thread")]
    async fn sanity_test_recover_inner() {
        {
            let last_checked = AtomicBool::new(false);
            let last_checked = &last_checked;
            assert_eq!(
                recover_scan_idxes_for_activity(
                    TweakIdx(0),
                    &BTreeSet::new(),
                    |cur_idx| async move {
                        Ok(match cur_idx {
                            TweakIdx(9) => {
                                last_checked.store(true, Ordering::SeqCst);
                                vec![]
                            }
                            TweakIdx(10) => panic!("Shouldn't happen"),
                            TweakIdx(11) => {
                                vec![0usize] /* just for type inference */
                            }
                            _ => vec![],
                        })
                    }
                )
                .await
                .unwrap(),
                RecoverScanOutcome {
                    last_used_idx: None,
                    new_start_idx: TweakIdx(RECOVER_NUM_IDX_ADD_TO_LAST_USED),
                    tweak_idxes_with_pegins: BTreeSet::from([])
                }
            );
            assert!(last_checked.load(Ordering::SeqCst));
        }

        {
            let last_checked = AtomicBool::new(false);
            let last_checked = &last_checked;
            assert_eq!(
                recover_scan_idxes_for_activity(
                    TweakIdx(0),
                    &BTreeSet::from([TweakIdx(1), TweakIdx(2)]),
                    |cur_idx| async move {
                        Ok(match cur_idx {
                            TweakIdx(1) => panic!("Shouldn't happen: already used (1)"),
                            TweakIdx(2) => panic!("Shouldn't happen: already used (2)"),
                            TweakIdx(11) => {
                                last_checked.store(true, Ordering::SeqCst);
                                vec![]
                            }
                            TweakIdx(12) => panic!("Shouldn't happen"),
                            TweakIdx(13) => {
                                vec![0usize] /* just for type inference */
                            }
                            _ => vec![],
                        })
                    }
                )
                .await
                .unwrap(),
                RecoverScanOutcome {
                    last_used_idx: Some(TweakIdx(2)),
                    new_start_idx: TweakIdx(2 + RECOVER_NUM_IDX_ADD_TO_LAST_USED),
                    tweak_idxes_with_pegins: BTreeSet::from([])
                }
            );
            assert!(last_checked.load(Ordering::SeqCst));
        }

        {
            let last_checked = AtomicBool::new(false);
            let last_checked = &last_checked;
            assert_eq!(
                recover_scan_idxes_for_activity(
                    TweakIdx(10),
                    &BTreeSet::new(),
                    |cur_idx| async move {
                        Ok(match cur_idx {
                            TweakIdx(10) => vec![()],
                            TweakIdx(19) => {
                                last_checked.store(true, Ordering::SeqCst);
                                vec![]
                            }
                            TweakIdx(20) => panic!("Shouldn't happen"),
                            _ => vec![],
                        })
                    }
                )
                .await
                .unwrap(),
                RecoverScanOutcome {
                    last_used_idx: Some(TweakIdx(10)),
                    new_start_idx: TweakIdx(10 + RECOVER_NUM_IDX_ADD_TO_LAST_USED),
                    tweak_idxes_with_pegins: BTreeSet::from([TweakIdx(10)])
                }
            );
            assert!(last_checked.load(Ordering::SeqCst));
        }

        assert_eq!(
            recover_scan_idxes_for_activity(TweakIdx(0), &BTreeSet::new(), |cur_idx| async move {
                Ok(match cur_idx {
                    TweakIdx(6 | 15) => vec![()],
                    _ => vec![],
                })
            })
            .await
            .unwrap(),
            RecoverScanOutcome {
                last_used_idx: Some(TweakIdx(15)),
                new_start_idx: TweakIdx(15 + RECOVER_NUM_IDX_ADD_TO_LAST_USED),
                tweak_idxes_with_pegins: BTreeSet::from([TweakIdx(6), TweakIdx(15)])
            }
        );
        assert_eq!(
            recover_scan_idxes_for_activity(TweakIdx(10), &BTreeSet::new(), |cur_idx| async move {
                Ok(match cur_idx {
                    TweakIdx(8) => {
                        vec![()] /* for type inference only */
                    }
                    TweakIdx(9) => {
                        panic!("Shouldn't happen")
                    }
                    _ => vec![],
                })
            })
            .await
            .unwrap(),
            RecoverScanOutcome {
                last_used_idx: None,
                new_start_idx: TweakIdx(9 + RECOVER_NUM_IDX_ADD_TO_LAST_USED),
                tweak_idxes_with_pegins: BTreeSet::from([])
            }
        );
        assert_eq!(
            recover_scan_idxes_for_activity(TweakIdx(10), &BTreeSet::new(), |cur_idx| async move {
                Ok(match cur_idx {
                    TweakIdx(9) => panic!("Shouldn't happen"),
                    TweakIdx(15) => vec![()],
                    _ => vec![],
                })
            })
            .await
            .unwrap(),
            RecoverScanOutcome {
                last_used_idx: Some(TweakIdx(15)),
                new_start_idx: TweakIdx(15 + RECOVER_NUM_IDX_ADD_TO_LAST_USED),
                tweak_idxes_with_pegins: BTreeSet::from([TweakIdx(15)])
            }
        );
    }

    #[tokio::test]
    async fn store_supports_safe_deposit_tolerates_a_lost_race() {
        let db = Database::new(MemDatabase::new(), ModuleDecoderRegistry::default());

        // Both opened before the competing write below, so committing either
        // of them must run into a write conflict.
        let racing_dbtx = db.begin_transaction().await;
        let mut sibling_dbtx = db.begin_transaction().await;

        let mut competing_dbtx = db.begin_transaction().await;
        competing_dbtx
            .insert_entry(&SupportsSafeDepositKey, &())
            .await;
        competing_dbtx.commit_tx().await;

        // Proves the setup: a plain commit of the stale sibling is rejected.
        sibling_dbtx
            .insert_entry(&SupportsSafeDepositKey, &())
            .await;
        assert!(matches!(
            sibling_dbtx.commit_tx_result().await,
            Err(DatabaseError::WriteConflict)
        ));

        store_supports_safe_deposit(racing_dbtx).await;

        assert!(supports_safe_deposit_verified(&db).await);
    }
}