use bitcoin::{hashes::Hash, Address, Amount as BtcAmount, BlockHash, SignedAmount, Txid};
use btc_wire::{
    config::BitcoinConfig,
    rpc::{self, BtcRpc, Category, ErrorCode},
    rpc_utils::{default_data_dir, sender_address},
    segwit::DecodeSegWitErr,
    GetOpReturnErr, GetSegwitErr,
};
use info::decode_info;
use postgres::{fallible_iterator::FallibleIterator, Client};
use rand::{rngs::OsRng, RngCore};
use reconnect::{AutoReconnectRPC, AutoReconnectSql};
use std::{
    collections::{HashMap, HashSet},
    path::PathBuf,
    process::exit,
    str::FromStr,
    time::{Duration, SystemTime},
};
use taler_api::api_common::{base32, Amount};
use taler_config::Config;
use taler_log::log::{error, info, warn};
use url::Url;

use crate::{
    fail_point::fail_point,
    info::{encode_info, Info},
    status::{BounceStatus, TxStatus},
};

mod fail_point;
mod info;
mod reconnect;
mod status;

fn btc_payto_url(addr: &Address) -> Url {
    Url::from_str(&format!("payto://bitcoin/{}", addr)).unwrap()
}

fn btc_payto_addr(url: &Url) -> Result<Address, String> {
    if url.domain() != Some("bitcoin") {
        return Err("".to_string());
    }
    let str = url.path().trim_start_matches('/');
    return Address::from_str(str).map_err(|_| "".to_string());
}

fn btc_amount_to_taler_amount(amount: &SignedAmount) -> Amount {
    let unsigned = amount.abs().to_unsigned().unwrap();
    let sat = unsigned.as_sat();
    return Amount::new("BTC", sat / 100_000_000, (sat % 100_000_000) as u32);
}

fn taler_amount_to_btc_amount(amount: &Amount) -> Result<BtcAmount, String> {
    if amount.currency != "BTC" {
        return Err("Wrong currency".to_string());
    }

    let sat = amount.value * 100_000_000 + amount.fraction as u64;
    return Ok(BtcAmount::from_sat(sat));
}

fn last_hash(db: &mut Client) -> Result<Option<BlockHash>, postgres::Error> {
    Ok(db
        .query_opt("SELECT value FROM state WHERE name='last_hash'", &[])?
        .map(|r| BlockHash::from_slice(r.get(0)).unwrap()))
}

/// Listen for new proposed transactions and announce them on the bitcoin network
fn worker(mut rpc: AutoReconnectRPC, mut db: AutoReconnectSql, config: &Config) {
    // Send a transaction on the blockchain, return true if more transactions with the same status remains
    fn send(
        db: &mut Client,
        rpc: &mut BtcRpc,
        status: TxStatus,
    ) -> Result<bool, Box<dyn std::error::Error>> {
        assert!(status == TxStatus::Delayed || status == TxStatus::Requested);
        let mut tx = db.transaction()?;
        // We lock the row with FOR UPDATE to prevent sending same transaction multiple time
        let row = tx.query_opt(
            "SELECT id, amount, wtid, credit_acc, exchange_url FROM tx_out WHERE status=$1 LIMIT 1 FOR UPDATE",
            &[&(status as i16)],
        )?;
        if let Some(row) = &row {
            let id: i32 = row.get(0);
            let amount = taler_amount_to_btc_amount(&Amount::from_str(row.get(1))?)?;
            let wtid: &[u8] = row.get(2);
            let addr: Address = btc_payto_addr(&Url::parse(row.get(3))?)?;
            let exchange_base_url: Url = Url::parse(row.get(4))?;
            let info = Info::Transaction {
                wtid: wtid.try_into()?,
                url: exchange_base_url,
            };
            let metadata = encode_info(&info);

            fail_point("Skip send_op_return", 0.2)?;
            match rpc.send_op_return(&addr, &amount, &metadata, false) {
                Ok(tx_id) => {
                    fail_point("Fail update db", 0.2)?;
                    tx.execute(
                        "UPDATE tx_out SET status=$1, txid=$2 WHERE id=$3",
                        &[&(TxStatus::Sent as i16), &tx_id.as_ref(), &id],
                    )?;
                    let amount = btc_amount_to_taler_amount(&amount.to_signed().unwrap());
                    info!(">> {} {} in {} to {}", amount, base32(&wtid), tx_id, addr);
                }
                Err(e) => {
                    info!("sender: RPC -  {}", e);
                    tx.execute(
                        "UPDATE tx_out SET status=$1 WHERE id=$2",
                        &[&(TxStatus::Delayed as i16), &id],
                    )?;
                }
            }
            tx.commit()?;
        }
        Ok(row.is_some())
    }

    // Bounce a transaction on the blockchain, return true if more bounce with the same status remains
    fn bounce(
        db: &mut Client,
        rpc: &mut BtcRpc,
        status: BounceStatus,
        fee: &BtcAmount,
    ) -> Result<bool, Box<dyn std::error::Error>> {
        assert!(status == BounceStatus::Delayed || status == BounceStatus::Requested);
        let mut tx = db.transaction()?;
        // We lock the row with FOR UPDATE to prevent sending same transaction multiple time
        let row = tx.query_opt(
            "SELECT id, bounced FROM bounce WHERE status=$1 LIMIT 1 FOR UPDATE",
            &[&(status as i16)],
        )?;
        if let Some(row) = &row {
            let id: i32 = row.get(0);
            let bounced: Txid = Txid::from_slice(row.get(1))?;
            let info = Info::Bounce { bounced };
            let metadata = encode_info(&info);

            fail_point("Skip send_op_return", 0.2)?;
            match rpc.bounce(&bounced, &fee, &metadata) {
                Ok(it) => {
                    info!("|| {} in {}", &bounced, &it);
                    tx.execute(
                        "UPDATE bounce SET txid = $1, status = $2 WHERE id = $3",
                        &[&it.as_ref(), &(BounceStatus::Sent as i16), &id],
                    )?;
                }
                Err(err) => match err {
                    rpc::Error::RPC {
                        code: ErrorCode::RpcWalletInsufficientFunds | ErrorCode::RpcWalletError,
                        msg,
                    } => {
                        info!("|| (ignore) {} because {}", &bounced, msg);
                        tx.execute(
                            "UPDATE bounce SET status = $1 WHERE id = $2",
                            &[&(BounceStatus::Ignored as i16), &id],
                        )?;
                    }
                    _ => Err(err)?,
                },
            }
            tx.commit()?;
        }
        Ok(row.is_some())
    }

    // TODO check if transactions are abandoned

    // Alway start with a sync work
    let mut skip_notification = true;
    loop {
        let rpc = rpc.client();
        let db = db.client();
        let result: Result<(), Box<dyn std::error::Error>> = (|| {
            // Listen to all channels
            db.batch_execute("LISTEN new_block; LISTEN new_tx")?;
            // Wait for the next notification
            {
                let mut ntf = db.notifications();
                if !skip_notification && ntf.is_empty() {
                    // Block until next notification
                    ntf.blocking_iter().next()?;
                }
                // Conflate all notifications
                let mut iter = ntf.iter();
                while let Some(_) = iter.next()? {}
            }
            // Sync chain
            sync_chain(rpc, db, config)?;

            // As we are now in sync with the blockchain if a transaction is in requested or delayed state it have not been sent

            // Send delayed transactions
            while send(db, rpc, TxStatus::Delayed)? {}
            // Send requested transactions
            while send(db, rpc, TxStatus::Requested)? {}

            let bounce_fee = BtcAmount::from_sat(config.bounce_fee);
            // Send delayed bounce
            while bounce(db, rpc, BounceStatus::Delayed, &bounce_fee)? {}
            // Send requested bounce
            while bounce(db, rpc, BounceStatus::Requested, &bounce_fee)? {}

            Ok(())
        })();
        if let Err(e) = result {
            error!("worker: DB - {}", e);
            // On failure retry without waiting for notifications
            skip_notification = true;
        } else {
            skip_notification = false;
        }
    }
}

/// Parse new transactions, if exit whiteout failing the database is up to date with the latest mined block
fn sync_chain(
    rpc: &mut BtcRpc,
    db: &mut Client,
    config: &Config,
) -> Result<(), Box<dyn std::error::Error>> {
    // Get stored last_hash
    let last_hash = last_hash(db)?;
    let min_confirmations = config.confirmation;

    // Get a set of transactions ids to parse
    let (txs, removed, lastblock): (HashMap<Txid, (Category, i32)>, HashSet<Txid>, BlockHash) = {
        // Get all transactions made since this block
        let list = rpc.list_since_block(last_hash.as_ref(), min_confirmations, true)?;
        // Only keep ids and category
        let txs = list
            .transactions
            .into_iter()
            .map(|tx| (tx.txid, (tx.category, tx.confirmations)))
            .collect();
        let removed = list
            .removed
            .into_iter()
            .filter_map(|tx| (tx.category == Category::Receive).then(|| tx.txid))
            .collect();
        (txs, removed, list.lastblock)
    };

    // Check if a confirmed incoming transaction have been removed by a blockchain reorganisation
    if !removed.is_empty() {
        for id in removed {
            if let Ok((full, key)) = rpc.get_tx_segwit_key(&id) {
                // If the removed tx is not in confirmed the txs list and the tx is stored in the database hard error
                if txs
                    .get(&id)
                    .map(|(_, confirmations)| *confirmations < min_confirmations as i32)
                    .unwrap_or(true)
                    && db
                        .query_opt("SELECT 1 FROM tx_in WHERE reserve_pub=$1", &[&key.as_ref()])?
                        .is_some()
                {
                    let credit_addr = full.details[0].address.as_ref().unwrap();
                    error!("Received transaction {} in {} from {} have been removed from the blockchain, bitcoin backing is compromised until the transaction reappear", base32(&key), id, credit_addr);
                    exit(1);
                }
            }
        }
    }

    for (id, (category, confirmations)) in txs {
        match category {
            Category::Send => {
                match rpc.get_tx_op_return(&id) {
                    Ok((full, bytes)) => {
                        let mut tx = db.transaction()?;
                        match decode_info(&bytes) {
                            Ok(info) => {
                                match info {
                                    Info::Transaction { wtid, .. } => {
                                        let addr = full.details[0].address.as_ref().unwrap();
                                        let amount = btc_amount_to_taler_amount(&full.amount);

                                        let row = tx.query_opt(
                                            "SELECT id, status FROM tx_out WHERE wtid=$1 FOR UPDATE",
                                            &[&wtid.as_ref()],
                                        )?;
                                        if let Some(row) = row {
                                            let _id: i32 = row.get(0);
                                            let status: i16 = row.get(1);
                                            match TxStatus::try_from(status as u8).unwrap() {
                                                TxStatus::Requested | TxStatus::Delayed => {
                                                    tx.execute(
                                                        "UPDATE tx_out SET status=$1 where id=$2",
                                                        &[&(TxStatus::Sent as i16), &_id],
                                                    )?;
                                                    warn!(
                                                        ">> (recovered) {} {} in {} to {}",
                                                        amount,
                                                        base32(&wtid),
                                                        id,
                                                        addr
                                                    );
                                                }
                                                TxStatus::Sent => {}
                                            }
                                        } else {
                                            let debit_addr = sender_address(rpc, &full)?;
                                            let date = SystemTime::UNIX_EPOCH
                                                + Duration::from_secs(full.time);
                                            // Generate a random request_uid
                                            let mut request_uid = [0; 64];
                                            OsRng.fill_bytes(&mut request_uid);
                                            let nb = tx.execute(
                                                "INSERT INTO tx_out (_date, amount, wtid, debit_acc, credit_acc, exchange_url, status, txid, request_uid) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9) ON CONFLICT (wtid) DO NOTHING",
                                                &[&date, &amount.to_string(), &wtid.as_ref(), &btc_payto_url(&debit_addr).as_ref(), &btc_payto_url(addr).as_ref(), &config.base_url.as_ref(), &(TxStatus::Sent as i16), &id.as_ref(), &request_uid.as_ref()],
                                            )?;
                                            if nb > 0 {
                                                warn!(
                                                    ">> (onchain) {} {} in {} to {}",
                                                    amount,
                                                    base32(&wtid),
                                                    id,
                                                    addr
                                                );
                                            }
                                        }
                                    }
                                    Info::Bounce { bounced } => {
                                        let row = tx.query_opt(
                                        "SELECT id, status FROM bounce WHERE bounced=$1 FOR UPDATE",
                                        &[&bounced.as_ref()],
                                    )?;
                                        if let Some(row) = row {
                                            let _id: i32 = row.get(0);
                                            let status: i16 = row.get(1);
                                            match BounceStatus::try_from(status as u8).unwrap() {
                                                BounceStatus::Requested | BounceStatus::Delayed => {
                                                    tx.execute(
                                                        "UPDATE bounce SET status=$1 where id=$2",
                                                        &[&(BounceStatus::Sent as i16), &_id],
                                                    )?;
                                                    warn!("|| (recovered) {} in {}", &bounced, &id);
                                                }
                                                BounceStatus::Ignored => error!("watcher: ignored bounce {} found in chain at {}", bounced, id),
                                                BounceStatus::Sent => {}
                                            }
                                        } else {
                                            let nb = tx.execute(
                                                "INSERT INTO bounce (bounced, txid, status) VALUES ($1, $2, $3) ON CONFLICT (txid) DO NOTHING",
                                                &[&bounced.as_ref(), &id.as_ref(), &(BounceStatus::Sent as i16)],
                                            )?;
                                            if nb > 0 {
                                                warn!("|| (onchain) {} in {}", &bounced, &id);
                                            }
                                        }
                                    }
                                }
                            }
                            Err(err) => warn!("send: decode-info {} - {}", id, err),
                        }
                        tx.commit()?;
                    }
                    Err(err) => match err {
                        GetOpReturnErr::MissingOpReturn => {} // ignore
                        err => warn!("send: {} {}", id, err),
                    },
                }
            }
            Category::Receive if confirmations >= min_confirmations as i32 => {
                match rpc.get_tx_segwit_key(&id) {
                    Ok((full, reserve_pub)) => {
                        let debit_addr = sender_address(rpc, &full)?;
                        let credit_addr = full.details[0].address.as_ref().unwrap();
                        let date = SystemTime::UNIX_EPOCH + Duration::from_secs(full.time);
                        let amount = btc_amount_to_taler_amount(&full.amount);
                        let nb = db.execute("INSERT INTO tx_in (_date, amount, reserve_pub, debit_acc, credit_acc) VALUES ($1, $2, $3, $4, $5) ON CONFLICT (reserve_pub) DO NOTHING ", &[
                            &date, &amount.to_string(), &reserve_pub.as_ref(), &btc_payto_url(&debit_addr).as_ref(), &btc_payto_url(credit_addr).as_ref()
                        ])?;
                        if nb > 0 {
                            info!(
                                "<< {} {} in {} from {}",
                                amount,
                                base32(&reserve_pub),
                                id,
                                debit_addr
                            );
                        }
                    }
                    Err(err) => match err {
                        GetSegwitErr::Decode(
                            DecodeSegWitErr::MissingSegWitAddress | DecodeSegWitErr::NoMagicIdMatch,
                        ) => {
                            // Request a bounce
                            db.execute("INSERT INTO bounce (bounced) VALUES ($1) ON CONFLICT (bounced) DO NOTHING", &[&id.as_ref()])?;
                        }
                        err => warn!("receive: {} {}", id, err),
                    },
                }
            }
            _ => {
                // Ignore coinbase and unconfirmed send transactions
            }
        }
    }
    // Move last_hash forward if no error have been caught
    {
        let mut tx = db.transaction()?;
        let curr_hash: Option<BlockHash> = tx
            .query_opt(
                "SELECT value FROM state WHERE name='last_hash' FOR UPDATE",
                &[],
            )?
            .map(|r| BlockHash::from_slice(r.get(0)).unwrap());

        if last_hash != curr_hash {
            error!("watcher: hash state collision, database have been altered by another process");
        }

        if curr_hash.is_some() {
            tx.execute(
                "UPDATE state SET value=$1 WHERE name='last_hash'",
                &[&lastblock.as_ref()],
            )?;
        } else {
            tx.execute(
                "INSERT INTO state (name, value) VALUES ('last_hash', $1)",
                &[&lastblock.as_ref()],
            )?;
        };
        tx.commit()?;
    }
    Ok(())
}

fn block_listener(mut rpc: AutoReconnectRPC, mut db: AutoReconnectSql) {
    loop {
        let result: Result<(), Box<dyn std::error::Error>> = (|| {
            let rpc = rpc.client();
            let db = db.client();
            rpc.wait_for_new_block(0).ok();
            db.execute("NOTIFY new_block", &[])?;
            Ok(())
        })();
        if let Err(e) = result {
            error!("listener: DB - {}", e);
        }
    }
}

fn main() {
    taler_log::init();

    #[cfg(feature = "fail")]
    taler_log::log::warn!("Running with random failures is unsuitable for production");

    // Guess network by trying to connect to a JSON RPC server
    let data_dir = std::env::args()
        .nth(1)
        .map(|str| PathBuf::from_str(&str).unwrap())
        .unwrap_or_else(default_data_dir);
    let config = taler_config::Config::from_path("test.conf");
    let config: &'static Config = Box::leak(Box::new(config));
    let btc_config = BitcoinConfig::load(&data_dir).unwrap();
    let mut rpc = BtcRpc::common(&btc_config).unwrap();
    rpc.load_wallet(&config.btc_wallet).ok();
    let rpc_listener = AutoReconnectRPC::new(
        btc_config.clone(),
        &config.btc_wallet,
        Duration::from_secs(5),
    );
    let rpc_worker = AutoReconnectRPC::new(btc_config, &config.btc_wallet, Duration::from_secs(5));

    let db_listener = AutoReconnectSql::new(&config.db_url, Duration::from_secs(5));
    let db_worker = AutoReconnectSql::new(&config.db_url, Duration::from_secs(5));
    std::thread::spawn(move || block_listener(rpc_listener, db_listener));
    worker(rpc_worker, db_worker, config);
}