// Bitcoin Dev Kit
// Written in 2020 by Alekos Filini <alekos.filini@gmail.com>
//
// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
//
// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// You may not use this file except in accordance with one or both of these
// licenses.

//! Database types
//!
//! This module provides the implementation of some defaults database types, along with traits that
//! can be implemented externally to let [`Wallet`]s use customized databases.
//!
//! It's important to note that the databases defined here only contains "blockchain-related" data.
//! They can be seen more as a cache than a critical piece of storage that contains secrets and
//! keys.
//!
//! The currently recommended database is [`sled`], which is a pretty simple key-value embedded
//! database written in Rust. If the `key-value-db` feature is enabled (which by default is),
//! this library automatically implements all the required traits for [`sled::Tree`].
//!
//! [`Wallet`]: crate::wallet::Wallet

use serde::{Deserialize, Serialize};

use bitcoin::hash_types::Txid;
use bitcoin::{OutPoint, Script, Transaction, TxOut};

use crate::error::Error;
use crate::types::*;

pub mod any;
pub use any::{AnyDatabase, AnyDatabaseConfig};

#[cfg(feature = "key-value-db")]
pub(crate) mod keyvalue;

#[cfg(feature = "sqlite")]
pub(crate) mod sqlite;
#[cfg(feature = "sqlite")]
pub use sqlite::SqliteDatabase;

pub mod memory;
pub use memory::MemoryDatabase;

/// Blockchain state at the time of syncing
///
/// Contains only the block time and height at the moment
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct SyncTime {
    /// Block timestamp and height at the time of sync
    pub block_time: BlockTime,
}

/// Trait for operations that can be batched
///
/// This trait defines the list of operations that must be implemented on the [`Database`] type and
/// the [`BatchDatabase::Batch`] type.
pub trait BatchOperations {
    /// Store a script_pubkey along with its keychain and child number.
    fn set_script_pubkey(
        &mut self,
        script: &Script,
        keychain: KeychainKind,
        child: u32,
    ) -> Result<(), Error>;
    /// Store a [`LocalUtxo`]
    fn set_utxo(&mut self, utxo: &LocalUtxo) -> Result<(), Error>;
    /// Store a raw transaction
    fn set_raw_tx(&mut self, transaction: &Transaction) -> Result<(), Error>;
    /// Store the metadata of a transaction
    fn set_tx(&mut self, transaction: &TransactionDetails) -> Result<(), Error>;
    /// Store the last derivation index for a given keychain.
    fn set_last_index(&mut self, keychain: KeychainKind, value: u32) -> Result<(), Error>;
    /// Store the sync time
    fn set_sync_time(&mut self, sync_time: SyncTime) -> Result<(), Error>;

    /// Delete a script_pubkey given the keychain and its child number.
    fn del_script_pubkey_from_path(
        &mut self,
        keychain: KeychainKind,
        child: u32,
    ) -> Result<Option<Script>, Error>;
    /// Delete the data related to a specific script_pubkey, meaning the keychain and the child
    /// number.
    fn del_path_from_script_pubkey(
        &mut self,
        script: &Script,
    ) -> Result<Option<(KeychainKind, u32)>, Error>;
    /// Delete a [`LocalUtxo`] given its [`OutPoint`]
    fn del_utxo(&mut self, outpoint: &OutPoint) -> Result<Option<LocalUtxo>, Error>;
    /// Delete a raw transaction given its [`Txid`]
    fn del_raw_tx(&mut self, txid: &Txid) -> Result<Option<Transaction>, Error>;
    /// Delete the metadata of a transaction and optionally the raw transaction itself
    fn del_tx(
        &mut self,
        txid: &Txid,
        include_raw: bool,
    ) -> Result<Option<TransactionDetails>, Error>;
    /// Delete the last derivation index for a keychain.
    fn del_last_index(&mut self, keychain: KeychainKind) -> Result<Option<u32>, Error>;
    /// Reset the sync time to `None`
    ///
    /// Returns the removed value
    fn del_sync_time(&mut self) -> Result<Option<SyncTime>, Error>;
}

/// Trait for reading data from a database
///
/// This traits defines the operations that can be used to read data out of a database
pub trait Database: BatchOperations {
    /// Read and checks the descriptor checksum for a given keychain.
    ///
    /// Should return [`Error::ChecksumMismatch`](crate::error::Error::ChecksumMismatch) if the
    /// checksum doesn't match. If there's no checksum in the database, simply store it for the
    /// next time.
    fn check_descriptor_checksum<B: AsRef<[u8]>>(
        &mut self,
        keychain: KeychainKind,
        bytes: B,
    ) -> Result<(), Error>;

    /// Return the list of script_pubkeys
    fn iter_script_pubkeys(&self, keychain: Option<KeychainKind>) -> Result<Vec<Script>, Error>;
    /// Return the list of [`LocalUtxo`]s
    fn iter_utxos(&self) -> Result<Vec<LocalUtxo>, Error>;
    /// Return the list of raw transactions
    fn iter_raw_txs(&self) -> Result<Vec<Transaction>, Error>;
    /// Return the list of transactions metadata
    fn iter_txs(&self, include_raw: bool) -> Result<Vec<TransactionDetails>, Error>;

    /// Fetch a script_pubkey given the child number of a keychain.
    fn get_script_pubkey_from_path(
        &self,
        keychain: KeychainKind,
        child: u32,
    ) -> Result<Option<Script>, Error>;
    /// Fetch the keychain and child number of a given script_pubkey
    fn get_path_from_script_pubkey(
        &self,
        script: &Script,
    ) -> Result<Option<(KeychainKind, u32)>, Error>;
    /// Fetch a [`LocalUtxo`] given its [`OutPoint`]
    fn get_utxo(&self, outpoint: &OutPoint) -> Result<Option<LocalUtxo>, Error>;
    /// Fetch a raw transaction given its [`Txid`]
    fn get_raw_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error>;
    /// Fetch the transaction metadata and optionally also the raw transaction
    fn get_tx(&self, txid: &Txid, include_raw: bool) -> Result<Option<TransactionDetails>, Error>;
    /// Return the last derivation index for a keychain.
    fn get_last_index(&self, keychain: KeychainKind) -> Result<Option<u32>, Error>;
    /// Return the sync time, if present
    fn get_sync_time(&self) -> Result<Option<SyncTime>, Error>;

    /// Increment the last derivation index for a keychain and return it
    ///
    /// It should insert and return `0` if not present in the database
    fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error>;
}

/// Trait for a database that supports batch operations
///
/// This trait defines the methods to start and apply a batch of operations.
pub trait BatchDatabase: Database {
    /// Container for the operations
    type Batch: BatchOperations;

    /// Create a new batch container
    fn begin_batch(&self) -> Self::Batch;
    /// Consume and apply a batch of operations
    fn commit_batch(&mut self, batch: Self::Batch) -> Result<(), Error>;
}

/// Trait for [`Database`] types that can be created given a configuration
pub trait ConfigurableDatabase: Database + Sized {
    /// Type that contains the configuration
    type Config: std::fmt::Debug;

    /// Create a new instance given a configuration
    fn from_config(config: &Self::Config) -> Result<Self, Error>;
}

pub(crate) trait DatabaseUtils: Database {
    fn is_mine(&self, script: &Script) -> Result<bool, Error> {
        self.get_path_from_script_pubkey(script)
            .map(|o| o.is_some())
    }

    fn get_raw_tx_or<D>(&self, txid: &Txid, default: D) -> Result<Option<Transaction>, Error>
    where
        D: FnOnce() -> Result<Option<Transaction>, Error>,
    {
        self.get_tx(txid, true)?
            .and_then(|t| t.transaction)
            .map_or_else(default, |t| Ok(Some(t)))
    }

    fn get_previous_output(&self, outpoint: &OutPoint) -> Result<Option<TxOut>, Error> {
        self.get_raw_tx(&outpoint.txid)?
            .map(|previous_tx| {
                if outpoint.vout as usize >= previous_tx.output.len() {
                    Err(Error::InvalidOutpoint(*outpoint))
                } else {
                    Ok(previous_tx.output[outpoint.vout as usize].clone())
                }
            })
            .transpose()
    }
}

impl<T: Database> DatabaseUtils for T {}

#[cfg(test)]
pub mod test {
    use std::str::FromStr;

    use bitcoin::consensus::encode::deserialize;
    use bitcoin::consensus::serialize;
    use bitcoin::hashes::hex::*;
    use bitcoin::*;

    use super::*;

    pub fn test_script_pubkey<D: Database>(mut db: D) {
        let script = Script::from(
            Vec::<u8>::from_hex("76a91402306a7c23f3e8010de41e9e591348bb83f11daa88ac").unwrap(),
        );
        let path = 42;
        let keychain = KeychainKind::External;

        db.set_script_pubkey(&script, keychain, path).unwrap();

        assert_eq!(
            db.get_script_pubkey_from_path(keychain, path).unwrap(),
            Some(script.clone())
        );
        assert_eq!(
            db.get_path_from_script_pubkey(&script).unwrap(),
            Some((keychain, path))
        );
    }

    pub fn test_batch_script_pubkey<D: BatchDatabase>(mut db: D) {
        let mut batch = db.begin_batch();

        let script = Script::from(
            Vec::<u8>::from_hex("76a91402306a7c23f3e8010de41e9e591348bb83f11daa88ac").unwrap(),
        );
        let path = 42;
        let keychain = KeychainKind::External;

        batch.set_script_pubkey(&script, keychain, path).unwrap();

        assert_eq!(
            db.get_script_pubkey_from_path(keychain, path).unwrap(),
            None
        );
        assert_eq!(db.get_path_from_script_pubkey(&script).unwrap(), None);

        db.commit_batch(batch).unwrap();

        assert_eq!(
            db.get_script_pubkey_from_path(keychain, path).unwrap(),
            Some(script.clone())
        );
        assert_eq!(
            db.get_path_from_script_pubkey(&script).unwrap(),
            Some((keychain, path))
        );
    }

    pub fn test_iter_script_pubkey<D: Database>(mut db: D) {
        let script = Script::from(
            Vec::<u8>::from_hex("76a91402306a7c23f3e8010de41e9e591348bb83f11daa88ac").unwrap(),
        );
        let path = 42;
        let keychain = KeychainKind::External;

        db.set_script_pubkey(&script, keychain, path).unwrap();

        assert_eq!(db.iter_script_pubkeys(None).unwrap().len(), 1);
    }

    pub fn test_del_script_pubkey<D: Database>(mut db: D) {
        let script = Script::from(
            Vec::<u8>::from_hex("76a91402306a7c23f3e8010de41e9e591348bb83f11daa88ac").unwrap(),
        );
        let path = 42;
        let keychain = KeychainKind::External;

        db.set_script_pubkey(&script, keychain, path).unwrap();
        assert_eq!(db.iter_script_pubkeys(None).unwrap().len(), 1);

        db.del_script_pubkey_from_path(keychain, path).unwrap();
        assert_eq!(db.iter_script_pubkeys(None).unwrap().len(), 0);
    }

    pub fn test_utxo<D: Database>(mut db: D) {
        let outpoint = OutPoint::from_str(
            "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:0",
        )
        .unwrap();
        let script = Script::from(
            Vec::<u8>::from_hex("76a91402306a7c23f3e8010de41e9e591348bb83f11daa88ac").unwrap(),
        );
        let txout = TxOut {
            value: 133742,
            script_pubkey: script,
        };
        let utxo = LocalUtxo {
            txout,
            outpoint,
            keychain: KeychainKind::External,
            is_spent: true,
        };

        db.set_utxo(&utxo).unwrap();
        db.set_utxo(&utxo).unwrap();
        assert_eq!(db.iter_utxos().unwrap().len(), 1);
        assert_eq!(db.get_utxo(&outpoint).unwrap(), Some(utxo));
    }

    pub fn test_raw_tx<D: Database>(mut db: D) {
        let hex_tx = Vec::<u8>::from_hex("02000000000101f58c18a90d7a76b30c7e47d4e817adfdd79a6a589a615ef36e360f913adce2cd0000000000feffffff0210270000000000001600145c9a1816d38db5cbdd4b067b689dc19eb7d930e2cf70aa2b080000001600140f48b63160043047f4f60f7f8f551f80458f693f024730440220413f42b7bc979945489a38f5221e5527d4b8e3aa63eae2099e01945896ad6c10022024ceec492d685c31d8adb64e935a06933877c5ae0e21f32efe029850914c5bad012102361caae96f0e9f3a453d354bb37a5c3244422fb22819bf0166c0647a38de39f21fca2300").unwrap();
        let mut tx: Transaction = deserialize(&hex_tx).unwrap();

        db.set_raw_tx(&tx).unwrap();

        let txid = tx.txid();

        assert_eq!(db.get_raw_tx(&txid).unwrap(), Some(tx.clone()));

        // mutate transaction's witnesses
        for tx_in in tx.input.iter_mut() {
            tx_in.witness = Witness::new();
        }

        let updated_hex_tx = serialize(&tx);

        // verify that mutation was successful
        assert_ne!(hex_tx, updated_hex_tx);

        db.set_raw_tx(&tx).unwrap();

        let txid = tx.txid();

        assert_eq!(db.get_raw_tx(&txid).unwrap(), Some(tx));
    }

    pub fn test_tx<D: Database>(mut db: D) {
        let hex_tx = Vec::<u8>::from_hex("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000").unwrap();
        let tx: Transaction = deserialize(&hex_tx).unwrap();
        let txid = tx.txid();
        let mut tx_details = TransactionDetails {
            transaction: Some(tx),
            txid,
            received: 1337,
            sent: 420420,
            fee: Some(140),
            confirmation_time: Some(BlockTime {
                timestamp: 123456,
                height: 1000,
            }),
        };

        db.set_tx(&tx_details).unwrap();

        // get with raw tx too
        assert_eq!(
            db.get_tx(&tx_details.txid, true).unwrap(),
            Some(tx_details.clone())
        );
        // get only raw_tx
        assert_eq!(
            db.get_raw_tx(&tx_details.txid).unwrap(),
            tx_details.transaction
        );

        // now get without raw_tx
        tx_details.transaction = None;
        assert_eq!(
            db.get_tx(&tx_details.txid, false).unwrap(),
            Some(tx_details)
        );
    }

    pub fn test_list_transaction<D: Database>(mut db: D) {
        let hex_tx = Vec::<u8>::from_hex("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000").unwrap();
        let tx: Transaction = deserialize(&hex_tx).unwrap();
        let txid = tx.txid();
        let mut tx_details = TransactionDetails {
            transaction: Some(tx),
            txid,
            received: 1337,
            sent: 420420,
            fee: Some(140),
            confirmation_time: Some(BlockTime {
                timestamp: 123456,
                height: 1000,
            }),
        };

        db.set_tx(&tx_details).unwrap();

        // get raw tx
        assert_eq!(db.iter_txs(true).unwrap(), vec![tx_details.clone()]);

        // now get without raw tx
        tx_details.transaction = None;

        // get not raw tx
        assert_eq!(db.iter_txs(false).unwrap(), vec![tx_details.clone()]);
    }

    pub fn test_last_index<D: Database>(mut db: D) {
        db.set_last_index(KeychainKind::External, 1337).unwrap();

        assert_eq!(
            db.get_last_index(KeychainKind::External).unwrap(),
            Some(1337)
        );
        assert_eq!(db.get_last_index(KeychainKind::Internal).unwrap(), None);

        let res = db.increment_last_index(KeychainKind::External).unwrap();
        assert_eq!(res, 1338);
        let res = db.increment_last_index(KeychainKind::Internal).unwrap();
        assert_eq!(res, 0);

        assert_eq!(
            db.get_last_index(KeychainKind::External).unwrap(),
            Some(1338)
        );
        assert_eq!(db.get_last_index(KeychainKind::Internal).unwrap(), Some(0));
    }

    pub fn test_sync_time<D: Database>(mut db: D) {
        assert!(db.get_sync_time().unwrap().is_none());

        db.set_sync_time(SyncTime {
            block_time: BlockTime {
                height: 100,
                timestamp: 1000,
            },
        })
        .unwrap();

        let extracted = db.get_sync_time().unwrap();
        assert!(extracted.is_some());
        assert_eq!(extracted.as_ref().unwrap().block_time.height, 100);
        assert_eq!(extracted.as_ref().unwrap().block_time.timestamp, 1000);

        db.del_sync_time().unwrap();
        assert!(db.get_sync_time().unwrap().is_none());
    }

    pub fn test_iter_raw_txs<D: Database>(mut db: D) {
        let txs = db.iter_raw_txs().unwrap();
        assert!(txs.is_empty());

        let hex_tx = Vec::<u8>::from_hex("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000").unwrap();
        let first_tx: Transaction = deserialize(&hex_tx).unwrap();

        let hex_tx = Vec::<u8>::from_hex("02000000000101f58c18a90d7a76b30c7e47d4e817adfdd79a6a589a615ef36e360f913adce2cd0000000000feffffff0210270000000000001600145c9a1816d38db5cbdd4b067b689dc19eb7d930e2cf70aa2b080000001600140f48b63160043047f4f60f7f8f551f80458f693f024730440220413f42b7bc979945489a38f5221e5527d4b8e3aa63eae2099e01945896ad6c10022024ceec492d685c31d8adb64e935a06933877c5ae0e21f32efe029850914c5bad012102361caae96f0e9f3a453d354bb37a5c3244422fb22819bf0166c0647a38de39f21fca2300").unwrap();
        let second_tx: Transaction = deserialize(&hex_tx).unwrap();

        db.set_raw_tx(&first_tx).unwrap();
        db.set_raw_tx(&second_tx).unwrap();

        let txs = db.iter_raw_txs().unwrap();

        assert!(txs.contains(&first_tx));
        assert!(txs.contains(&second_tx));
        assert_eq!(txs.len(), 2);
    }

    pub fn test_del_path_from_script_pubkey<D: Database>(mut db: D) {
        let keychain = KeychainKind::External;

        let script = Script::from(
            Vec::<u8>::from_hex("76a91402306a7c23f3e8010de41e9e591348bb83f11daa88ac").unwrap(),
        );
        let path = 42;

        let res = db.del_path_from_script_pubkey(&script).unwrap();

        assert!(res.is_none());

        let _res = db.set_script_pubkey(&script, keychain, path);
        let (chain, child) = db.del_path_from_script_pubkey(&script).unwrap().unwrap();

        assert_eq!(chain, keychain);
        assert_eq!(child, path);

        let res = db.get_path_from_script_pubkey(&script).unwrap();
        assert!(res.is_none());
    }

    pub fn test_iter_script_pubkeys<D: Database>(mut db: D) {
        let keychain = KeychainKind::External;
        let scripts = db.iter_script_pubkeys(Some(keychain)).unwrap();
        assert!(scripts.is_empty());

        let first_script = Script::from(
            Vec::<u8>::from_hex("76a91402306a7c23f3e8010de41e9e591348bb83f11daa88ac").unwrap(),
        );
        let path = 42;

        db.set_script_pubkey(&first_script, keychain, path).unwrap();

        let second_script = Script::from(
            Vec::<u8>::from_hex("00145c9a1816d38db5cbdd4b067b689dc19eb7d930e2").unwrap(),
        );
        let path = 57;

        db.set_script_pubkey(&second_script, keychain, path)
            .unwrap();
        let scripts = db.iter_script_pubkeys(Some(keychain)).unwrap();

        assert!(scripts.contains(&first_script));
        assert!(scripts.contains(&second_script));
        assert_eq!(scripts.len(), 2);
    }

    pub fn test_del_utxo<D: Database>(mut db: D) {
        let outpoint = OutPoint::from_str(
            "5df6e0e2761359d30a8275058e299fcc0381534545f55cf43e41983f5d4c9456:0",
        )
        .unwrap();
        let script = Script::from(
            Vec::<u8>::from_hex("76a91402306a7c23f3e8010de41e9e591348bb83f11daa88ac").unwrap(),
        );
        let txout = TxOut {
            value: 133742,
            script_pubkey: script,
        };
        let utxo = LocalUtxo {
            txout,
            outpoint,
            keychain: KeychainKind::External,
            is_spent: true,
        };

        let res = db.del_utxo(&outpoint).unwrap();
        assert!(res.is_none());

        db.set_utxo(&utxo).unwrap();

        let res = db.del_utxo(&outpoint).unwrap();

        assert_eq!(res.unwrap(), utxo);

        let res = db.get_utxo(&outpoint).unwrap();
        assert!(res.is_none());
    }

    pub fn test_del_raw_tx<D: Database>(mut db: D) {
        let hex_tx = Vec::<u8>::from_hex("02000000000101f58c18a90d7a76b30c7e47d4e817adfdd79a6a589a615ef36e360f913adce2cd0000000000feffffff0210270000000000001600145c9a1816d38db5cbdd4b067b689dc19eb7d930e2cf70aa2b080000001600140f48b63160043047f4f60f7f8f551f80458f693f024730440220413f42b7bc979945489a38f5221e5527d4b8e3aa63eae2099e01945896ad6c10022024ceec492d685c31d8adb64e935a06933877c5ae0e21f32efe029850914c5bad012102361caae96f0e9f3a453d354bb37a5c3244422fb22819bf0166c0647a38de39f21fca2300").unwrap();
        let tx: Transaction = deserialize(&hex_tx).unwrap();

        let res = db.del_raw_tx(&tx.txid()).unwrap();

        assert!(res.is_none());

        db.set_raw_tx(&tx).unwrap();

        let res = db.del_raw_tx(&tx.txid()).unwrap();

        assert_eq!(res.unwrap(), tx);

        let res = db.get_raw_tx(&tx.txid()).unwrap();
        assert!(res.is_none());
    }

    pub fn test_del_tx<D: Database>(mut db: D) {
        let hex_tx = Vec::<u8>::from_hex("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000").unwrap();
        let tx: Transaction = deserialize(&hex_tx).unwrap();
        let txid = tx.txid();
        let mut tx_details = TransactionDetails {
            transaction: Some(tx.clone()),
            txid,
            received: 1337,
            sent: 420420,
            fee: Some(140),
            confirmation_time: Some(BlockTime {
                timestamp: 123456,
                height: 1000,
            }),
        };

        let res = db.del_tx(&tx.txid(), true).unwrap();

        assert!(res.is_none());

        db.set_tx(&tx_details).unwrap();

        let res = db.del_tx(&tx.txid(), false).unwrap();
        tx_details.transaction = None;
        assert_eq!(res.unwrap(), tx_details);

        let res = db.get_tx(&tx.txid(), true).unwrap();
        assert!(res.is_none());

        let res = db.get_raw_tx(&tx.txid()).unwrap();
        assert_eq!(res.unwrap(), tx);

        db.set_tx(&tx_details).unwrap();
        let res = db.del_tx(&tx.txid(), true).unwrap();
        tx_details.transaction = Some(tx.clone());
        assert_eq!(res.unwrap(), tx_details);

        let res = db.get_tx(&tx.txid(), true).unwrap();
        assert!(res.is_none());

        let res = db.get_raw_tx(&tx.txid()).unwrap();
        assert!(res.is_none());
    }

    pub fn test_del_last_index<D: Database>(mut db: D) {
        let keychain = KeychainKind::External;

        let _res = db.increment_last_index(keychain);

        let res = db.get_last_index(keychain).unwrap().unwrap();

        assert_eq!(res, 0);

        let _res = db.increment_last_index(keychain);

        let res = db.del_last_index(keychain).unwrap().unwrap();

        assert_eq!(res, 1);

        let res = db.get_last_index(keychain).unwrap();
        assert!(res.is_none());
    }

    pub fn test_check_descriptor_checksum<D: Database>(mut db: D) {
        // insert checksum associated to keychain
        let checksum = "1cead456".as_bytes();
        let keychain = KeychainKind::External;
        let _res = db.check_descriptor_checksum(keychain, checksum);

        // check if `check_descriptor_checksum` throws
        // `Error::ChecksumMismatch` error if the
        // function is passed a checksum that does
        // not match the one initially inserted
        let checksum = "1cead454".as_bytes();
        let keychain = KeychainKind::External;
        let res = db.check_descriptor_checksum(keychain, checksum);

        assert!(res.is_err());
    }

    // TODO: more tests...
}