// 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.

//! In-memory ephemeral database
//!
//! This module defines an in-memory database type called [`MemoryDatabase`] that is based on a
//! [`BTreeMap`].

use std::collections::BTreeMap;
use std::ops::Bound::{Excluded, Included};

use bitcoin::consensus::encode::{deserialize, serialize};
use bitcoin::hash_types::Txid;
use bitcoin::{OutPoint, Script, Transaction};

use crate::database::{BatchDatabase, BatchOperations, ConfigurableDatabase, Database};
use crate::error::Error;
use crate::types::*;

// path -> script       p{i,e}<path> -> script
// script -> path       s<script> -> {i,e}<path>
// outpoint             u<outpoint> -> txout
// rawtx                r<txid> -> tx
// transactions         t<txid> -> tx details
// deriv indexes        c{i,e} -> u32
// descriptor checksum  d{i,e} -> vec<u8>

pub(crate) enum MapKey<'a> {
    Path((Option<KeychainKind>, Option<u32>)),
    Script(Option<&'a Script>),
    Utxo(Option<&'a OutPoint>),
    RawTx(Option<&'a Txid>),
    Transaction(Option<&'a Txid>),
    LastIndex(KeychainKind),
    DescriptorChecksum(KeychainKind),
}

impl MapKey<'_> {
    fn as_prefix(&self) -> Vec<u8> {
        match self {
            MapKey::Path((st, _)) => {
                let mut v = b"p".to_vec();
                if let Some(st) = st {
                    v.push(st.as_byte());
                }
                v
            }
            MapKey::Script(_) => b"s".to_vec(),
            MapKey::Utxo(_) => b"u".to_vec(),
            MapKey::RawTx(_) => b"r".to_vec(),
            MapKey::Transaction(_) => b"t".to_vec(),
            MapKey::LastIndex(st) => [b"c", st.as_ref()].concat(),
            MapKey::DescriptorChecksum(st) => [b"d", st.as_ref()].concat(),
        }
    }

    fn serialize_content(&self) -> Vec<u8> {
        match self {
            MapKey::Path((_, Some(child))) => child.to_be_bytes().to_vec(),
            MapKey::Script(Some(s)) => serialize(*s),
            MapKey::Utxo(Some(s)) => serialize(*s),
            MapKey::RawTx(Some(s)) => serialize(*s),
            MapKey::Transaction(Some(s)) => serialize(*s),
            _ => vec![],
        }
    }

    pub fn as_map_key(&self) -> Vec<u8> {
        let mut v = self.as_prefix();
        v.extend_from_slice(&self.serialize_content());

        v
    }
}

fn after(key: &[u8]) -> Vec<u8> {
    let mut key = key.to_owned();
    let mut idx = key.len();
    while idx > 0 {
        if key[idx - 1] == 0xFF {
            idx -= 1;
            continue;
        } else {
            key[idx - 1] += 1;
            break;
        }
    }

    key
}

/// In-memory ephemeral database
///
/// This database can be used as a temporary storage for wallets that are not kept permanently on
/// a device, or on platforms that don't provide a filesystem, like `wasm32`.
///
/// Once it's dropped its content will be lost.
///
/// If you are looking for a permanent storage solution, you can try with the default key-value
/// database called [`sled`]. See the [`database`] module documentation for more defailts.
///
/// [`database`]: crate::database
#[derive(Debug, Default)]
pub struct MemoryDatabase {
    map: BTreeMap<Vec<u8>, Box<dyn std::any::Any>>,
    deleted_keys: Vec<Vec<u8>>,
}

impl MemoryDatabase {
    /// Create a new empty database
    pub fn new() -> Self {
        MemoryDatabase {
            map: BTreeMap::new(),
            deleted_keys: Vec::new(),
        }
    }
}

impl BatchOperations for MemoryDatabase {
    fn set_script_pubkey(
        &mut self,
        script: &Script,
        keychain: KeychainKind,
        path: u32,
    ) -> Result<(), Error> {
        let key = MapKey::Path((Some(keychain), Some(path))).as_map_key();
        self.map.insert(key, Box::new(script.clone()));

        let key = MapKey::Script(Some(script)).as_map_key();
        let value = json!({
            "t": keychain,
            "p": path,
        });
        self.map.insert(key, Box::new(value));

        Ok(())
    }

    fn set_utxo(&mut self, utxo: &LocalUtxo) -> Result<(), Error> {
        let key = MapKey::Utxo(Some(&utxo.outpoint)).as_map_key();
        self.map
            .insert(key, Box::new((utxo.txout.clone(), utxo.keychain)));

        Ok(())
    }
    fn set_raw_tx(&mut self, transaction: &Transaction) -> Result<(), Error> {
        let key = MapKey::RawTx(Some(&transaction.txid())).as_map_key();
        self.map.insert(key, Box::new(transaction.clone()));

        Ok(())
    }
    fn set_tx(&mut self, transaction: &TransactionDetails) -> Result<(), Error> {
        let key = MapKey::Transaction(Some(&transaction.txid)).as_map_key();

        // insert the raw_tx if present
        if let Some(ref tx) = transaction.transaction {
            self.set_raw_tx(tx)?;
        }

        // remove the raw tx from the serialized version
        let mut transaction = transaction.clone();
        transaction.transaction = None;

        self.map.insert(key, Box::new(transaction));

        Ok(())
    }
    fn set_last_index(&mut self, keychain: KeychainKind, value: u32) -> Result<(), Error> {
        let key = MapKey::LastIndex(keychain).as_map_key();
        self.map.insert(key, Box::new(value));

        Ok(())
    }

    fn del_script_pubkey_from_path(
        &mut self,
        keychain: KeychainKind,
        path: u32,
    ) -> Result<Option<Script>, Error> {
        let key = MapKey::Path((Some(keychain), Some(path))).as_map_key();
        let res = self.map.remove(&key);
        self.deleted_keys.push(key);

        Ok(res.map(|x| x.downcast_ref().cloned().unwrap()))
    }
    fn del_path_from_script_pubkey(
        &mut self,
        script: &Script,
    ) -> Result<Option<(KeychainKind, u32)>, Error> {
        let key = MapKey::Script(Some(script)).as_map_key();
        let res = self.map.remove(&key);
        self.deleted_keys.push(key);

        match res {
            None => Ok(None),
            Some(b) => {
                let mut val: serde_json::Value = b.downcast_ref().cloned().unwrap();
                let st = serde_json::from_value(val["t"].take())?;
                let path = serde_json::from_value(val["p"].take())?;

                Ok(Some((st, path)))
            }
        }
    }
    fn del_utxo(&mut self, outpoint: &OutPoint) -> Result<Option<LocalUtxo>, Error> {
        let key = MapKey::Utxo(Some(outpoint)).as_map_key();
        let res = self.map.remove(&key);
        self.deleted_keys.push(key);

        match res {
            None => Ok(None),
            Some(b) => {
                let (txout, keychain) = b.downcast_ref().cloned().unwrap();
                Ok(Some(LocalUtxo {
                    outpoint: *outpoint,
                    txout,
                    keychain,
                }))
            }
        }
    }
    fn del_raw_tx(&mut self, txid: &Txid) -> Result<Option<Transaction>, Error> {
        let key = MapKey::RawTx(Some(txid)).as_map_key();
        let res = self.map.remove(&key);
        self.deleted_keys.push(key);

        Ok(res.map(|x| x.downcast_ref().cloned().unwrap()))
    }
    fn del_tx(
        &mut self,
        txid: &Txid,
        include_raw: bool,
    ) -> Result<Option<TransactionDetails>, Error> {
        let raw_tx = if include_raw {
            self.del_raw_tx(txid)?
        } else {
            None
        };

        let key = MapKey::Transaction(Some(txid)).as_map_key();
        let res = self.map.remove(&key);
        self.deleted_keys.push(key);

        match res {
            None => Ok(None),
            Some(b) => {
                let mut val: TransactionDetails = b.downcast_ref().cloned().unwrap();
                val.transaction = raw_tx;

                Ok(Some(val))
            }
        }
    }
    fn del_last_index(&mut self, keychain: KeychainKind) -> Result<Option<u32>, Error> {
        let key = MapKey::LastIndex(keychain).as_map_key();
        let res = self.map.remove(&key);
        self.deleted_keys.push(key);

        match res {
            None => Ok(None),
            Some(b) => Ok(Some(*b.downcast_ref().unwrap())),
        }
    }
}

impl Database for MemoryDatabase {
    fn check_descriptor_checksum<B: AsRef<[u8]>>(
        &mut self,
        keychain: KeychainKind,
        bytes: B,
    ) -> Result<(), Error> {
        let key = MapKey::DescriptorChecksum(keychain).as_map_key();

        let prev = self
            .map
            .get(&key)
            .map(|x| x.downcast_ref::<Vec<u8>>().unwrap());
        if let Some(val) = prev {
            if val == &bytes.as_ref().to_vec() {
                Ok(())
            } else {
                Err(Error::ChecksumMismatch)
            }
        } else {
            self.map.insert(key, Box::new(bytes.as_ref().to_vec()));
            Ok(())
        }
    }

    fn iter_script_pubkeys(&self, keychain: Option<KeychainKind>) -> Result<Vec<Script>, Error> {
        let key = MapKey::Path((keychain, None)).as_map_key();
        self.map
            .range::<Vec<u8>, _>((Included(&key), Excluded(&after(&key))))
            .map(|(_, v)| Ok(v.downcast_ref().cloned().unwrap()))
            .collect()
    }

    fn iter_utxos(&self) -> Result<Vec<LocalUtxo>, Error> {
        let key = MapKey::Utxo(None).as_map_key();
        self.map
            .range::<Vec<u8>, _>((Included(&key), Excluded(&after(&key))))
            .map(|(k, v)| {
                let outpoint = deserialize(&k[1..]).unwrap();
                let (txout, keychain) = v.downcast_ref().cloned().unwrap();
                Ok(LocalUtxo {
                    outpoint,
                    txout,
                    keychain,
                })
            })
            .collect()
    }

    fn iter_raw_txs(&self) -> Result<Vec<Transaction>, Error> {
        let key = MapKey::RawTx(None).as_map_key();
        self.map
            .range::<Vec<u8>, _>((Included(&key), Excluded(&after(&key))))
            .map(|(_, v)| Ok(v.downcast_ref().cloned().unwrap()))
            .collect()
    }

    fn iter_txs(&self, include_raw: bool) -> Result<Vec<TransactionDetails>, Error> {
        let key = MapKey::Transaction(None).as_map_key();
        self.map
            .range::<Vec<u8>, _>((Included(&key), Excluded(&after(&key))))
            .map(|(k, v)| {
                let mut txdetails: TransactionDetails = v.downcast_ref().cloned().unwrap();
                if include_raw {
                    let txid = deserialize(&k[1..])?;
                    txdetails.transaction = self.get_raw_tx(&txid)?;
                }

                Ok(txdetails)
            })
            .collect()
    }

    fn get_script_pubkey_from_path(
        &self,
        keychain: KeychainKind,
        path: u32,
    ) -> Result<Option<Script>, Error> {
        let key = MapKey::Path((Some(keychain), Some(path))).as_map_key();
        Ok(self
            .map
            .get(&key)
            .map(|b| b.downcast_ref().cloned().unwrap()))
    }

    fn get_path_from_script_pubkey(
        &self,
        script: &Script,
    ) -> Result<Option<(KeychainKind, u32)>, Error> {
        let key = MapKey::Script(Some(script)).as_map_key();
        Ok(self.map.get(&key).map(|b| {
            let mut val: serde_json::Value = b.downcast_ref().cloned().unwrap();
            let st = serde_json::from_value(val["t"].take()).unwrap();
            let path = serde_json::from_value(val["p"].take()).unwrap();

            (st, path)
        }))
    }

    fn get_utxo(&self, outpoint: &OutPoint) -> Result<Option<LocalUtxo>, Error> {
        let key = MapKey::Utxo(Some(outpoint)).as_map_key();
        Ok(self.map.get(&key).map(|b| {
            let (txout, keychain) = b.downcast_ref().cloned().unwrap();
            LocalUtxo {
                outpoint: *outpoint,
                txout,
                keychain,
            }
        }))
    }

    fn get_raw_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
        let key = MapKey::RawTx(Some(txid)).as_map_key();
        Ok(self
            .map
            .get(&key)
            .map(|b| b.downcast_ref().cloned().unwrap()))
    }

    fn get_tx(&self, txid: &Txid, include_raw: bool) -> Result<Option<TransactionDetails>, Error> {
        let key = MapKey::Transaction(Some(txid)).as_map_key();
        Ok(self.map.get(&key).map(|b| {
            let mut txdetails: TransactionDetails = b.downcast_ref().cloned().unwrap();
            if include_raw {
                txdetails.transaction = self.get_raw_tx(&txid).unwrap();
            }

            txdetails
        }))
    }

    fn get_last_index(&self, keychain: KeychainKind) -> Result<Option<u32>, Error> {
        let key = MapKey::LastIndex(keychain).as_map_key();
        Ok(self.map.get(&key).map(|b| *b.downcast_ref().unwrap()))
    }

    // inserts 0 if not present
    fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error> {
        let key = MapKey::LastIndex(keychain).as_map_key();
        let value = self
            .map
            .entry(key)
            .and_modify(|x| *x.downcast_mut::<u32>().unwrap() += 1)
            .or_insert_with(|| Box::<u32>::new(0))
            .downcast_mut()
            .unwrap();

        Ok(*value)
    }
}

impl BatchDatabase for MemoryDatabase {
    type Batch = Self;

    fn begin_batch(&self) -> Self::Batch {
        MemoryDatabase::new()
    }

    fn commit_batch(&mut self, mut batch: Self::Batch) -> Result<(), Error> {
        for key in batch.deleted_keys {
            self.map.remove(&key);
        }
        self.map.append(&mut batch.map);
        Ok(())
    }
}

impl ConfigurableDatabase for MemoryDatabase {
    type Config = ();

    fn from_config(_config: &Self::Config) -> Result<Self, Error> {
        Ok(MemoryDatabase::default())
    }
}

#[macro_export]
#[doc(hidden)]
/// Artificially insert a tx in the database, as if we had found it with a `sync`. This is a hidden
/// macro and not a `[cfg(test)]` function so it can be called within the context of doctests which
/// don't have `test` set.
macro_rules! populate_test_db {
    ($db:expr, $tx_meta:expr, $current_height:expr$(,)?) => {{
        use $crate::database::BatchOperations;
        let mut db = $db;
        let tx_meta = $tx_meta;
        let current_height: Option<u32> = $current_height;
        let tx = Transaction {
            version: 1,
            lock_time: 0,
            input: vec![],
            output: tx_meta
                .output
                .iter()
                .map(|out_meta| bitcoin::TxOut {
                    value: out_meta.value,
                    script_pubkey: bitcoin::Address::from_str(&out_meta.to_address)
                        .unwrap()
                        .script_pubkey(),
                })
                .collect(),
        };

        let txid = tx.txid();
        let height = tx_meta
            .min_confirmations
            .map(|conf| current_height.unwrap().checked_sub(conf as u32).unwrap());

        let tx_details = TransactionDetails {
            transaction: Some(tx.clone()),
            txid,
            timestamp: 0,
            height,
            received: 0,
            sent: 0,
            fees: 0,
        };

        db.set_tx(&tx_details).unwrap();
        for (vout, out) in tx.output.iter().enumerate() {
            db.set_utxo(&LocalUtxo {
                txout: out.clone(),
                outpoint: OutPoint {
                    txid,
                    vout: vout as u32,
                },
                keychain: KeychainKind::External,
            })
            .unwrap();
        }

        txid
    }};
}

#[macro_export]
#[doc(hidden)]
/// Macro for getting a wallet for use in a doctest
macro_rules! doctest_wallet {
    () => {{
        use $crate::bitcoin::Network;
        use $crate::database::MemoryDatabase;
        use testutils::testutils;
        let descriptor = "wpkh(cVpPVruEDdmutPzisEsYvtST1usBR3ntr8pXSyt6D2YYqXRyPcFW)";
        let descriptors = testutils!(@descriptors (descriptor) (descriptor));

        let mut db = MemoryDatabase::new();
        let txid = populate_test_db!(
            &mut db,
            testutils! {
                @tx ( (@external descriptors, 0) => 500_000 ) (@confirmations 1)
            },
            Some(100),
        );

        $crate::Wallet::new_offline(
            &descriptors.0,
            descriptors.1.as_ref(),
            Network::Regtest,
            db
        )
        .unwrap()
    }}
}

#[cfg(test)]
mod test {
    use super::MemoryDatabase;

    fn get_tree() -> MemoryDatabase {
        MemoryDatabase::new()
    }

    #[test]
    fn test_script_pubkey() {
        crate::database::test::test_script_pubkey(get_tree());
    }

    #[test]
    fn test_batch_script_pubkey() {
        crate::database::test::test_batch_script_pubkey(get_tree());
    }

    #[test]
    fn test_iter_script_pubkey() {
        crate::database::test::test_iter_script_pubkey(get_tree());
    }

    #[test]
    fn test_del_script_pubkey() {
        crate::database::test::test_del_script_pubkey(get_tree());
    }

    #[test]
    fn test_utxo() {
        crate::database::test::test_utxo(get_tree());
    }

    #[test]
    fn test_raw_tx() {
        crate::database::test::test_raw_tx(get_tree());
    }

    #[test]
    fn test_tx() {
        crate::database::test::test_tx(get_tree());
    }

    #[test]
    fn test_last_index() {
        crate::database::test::test_last_index(get_tree());
    }
}