/*
  This file is part of TALER
  Copyright (C) 2022 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU Affero General Public License as published by the Free Software
  Foundation; either version 3, or (at your option) any later version.

  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details.

  You should have received a copy of the GNU Affero General Public License along with
  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
*/
use std::path::{Path, PathBuf};
use std::str::FromStr;

use bitcoin::{hashes::hex::FromHex, Address, Amount, Network, Txid};
use btc_config::BitcoinConfig;
use common::api_common::Amount as TalerAmount;
use common::config::TalerConfig;
use common::currency::{Currency, CurrencyBtc};
use common::log::{fail, OrFail};
use common::postgres;
use common::url::Url;
use rpc::{Category, Rpc, Transaction};
use rpc_utils::{default_data_dir, segwit_min_amount, sender_address};
use segwit::{decode_segwit_msg, encode_segwit_key};
use taler_utils::taler_to_btc;

pub mod btc_config;
pub mod rpc;
pub mod rpc_utils;
pub mod segwit;
pub mod taler_utils;

#[derive(Debug, thiserror::Error)]
pub enum GetSegwitErr {
    #[error(transparent)]
    Decode(#[from] segwit::DecodeSegWitErr),
    #[error(transparent)]
    RPC(#[from] rpc::Error),
}

#[derive(Debug, thiserror::Error)]
pub enum GetOpReturnErr {
    #[error("Missing opreturn")]
    MissingOpReturn,
    #[error(transparent)]
    RPC(#[from] rpc::Error),
}

/// An extended bitcoincore JSON-RPC api client who can send and retrieve metadata with their transaction
impl Rpc {
    /// Send a transaction with a 32B key as metadata encoded using fake segwit addresses
    pub fn send_segwit_key(
        &mut self,
        to: &Address,
        amount: &Amount,
        metadata: &[u8; 32],
    ) -> rpc::Result<Txid> {
        let hrp = match to.network() {
            Network::Bitcoin => "bc",
            Network::Testnet | Network::Signet => "tb",
            Network::Regtest => "bcrt",
            _ => unimplemented!(),
        };
        let addresses = encode_segwit_key(hrp, metadata);
        let addresses = [
            Address::from_str(&addresses[0])
                .unwrap()
                .require_network(*to.network())
                .unwrap(),
            Address::from_str(&addresses[1])
                .unwrap()
                .require_network(*to.network())
                .unwrap(),
        ];
        let mut recipients = vec![(to, amount)];
        let min = segwit_min_amount();
        recipients.extend(addresses.iter().map(|addr| (addr, &min)));
        self.send_many(recipients)
    }

    /// Get detailed information about an in-wallet transaction and it's 32B metadata key encoded using fake segwit addresses
    pub fn get_tx_segwit_key(
        &mut self,
        id: &Txid,
    ) -> Result<(Transaction, [u8; 32]), GetSegwitErr> {
        let full = self.get_tx(id)?;

        let addresses: Vec<String> = full
            .decoded
            .vout
            .iter()
            .filter_map(|it| {
                it.script_pub_key
                    .address
                    .as_ref()
                    .map(|addr| addr.clone().assume_checked().to_string())
            })
            .collect();

        let metadata = decode_segwit_msg(&addresses)?;

        Ok((full, metadata))
    }

    /// Get detailed information about an in-wallet transaction and its op_return metadata
    pub fn get_tx_op_return(
        &mut self,
        id: &Txid,
    ) -> Result<(Transaction, Vec<u8>), GetOpReturnErr> {
        let full = self.get_tx(id)?;

        let op_return_out = full
            .decoded
            .vout
            .iter()
            .find(|it| it.script_pub_key.asm.starts_with("OP_RETURN"))
            .ok_or(GetOpReturnErr::MissingOpReturn)?;

        let hex = op_return_out.script_pub_key.asm.split_once(' ').unwrap().1;
        // Op return payload is always encoded in hexadecimal
        let metadata = Vec::from_hex(hex).unwrap();

        Ok((full, metadata))
    }

    /// Bounce a transaction bask to its sender
    ///
    /// There is no reliable way to bounce a transaction as you cannot know if the addresses
    /// used are shared or come from a third-party service. We only send back to the first input
    /// address as a best-effort gesture.
    pub fn bounce(
        &mut self,
        id: &Txid,
        bounce_fee: &Amount,
        metadata: Option<&[u8]>,
    ) -> Result<Txid, rpc::Error> {
        let full = self.get_tx(id)?;
        let detail = &full.details[0];
        assert!(detail.category == Category::Receive);

        let amount = detail.amount.to_unsigned().unwrap();
        let sender = sender_address(self, &full)?;
        let bounce_amount = Amount::from_sat(amount.to_sat().saturating_sub(bounce_fee.to_sat()));
        // Send refund making recipient pay the transaction fees
        self.send(&sender, &bounce_amount, metadata, true)
    }
}

const DEFAULT_CONFIRMATION: u16 = 6;
const DEFAULT_BOUNCE_FEE: &str = "0.00001";

pub struct WireState {
    pub confirmation: u32,
    pub max_confirmation: u32,
    pub btc_config: BitcoinConfig,
    pub bounce_fee: Amount,
    pub lifetime: Option<u32>,
    pub bump_delay: Option<u32>,
    pub base_url: Url,
    pub db_config: postgres::Config,
    pub currency: CurrencyBtc,
}

impl WireState {
    pub fn load_taler_config(file: Option<&Path>) -> Self {
        let (taler_config, path, currency) = load_taler_config(file);
        let btc_config =
            BitcoinConfig::load(path, currency).or_fail(|e| format!("bitcoin config: {}", e));
        let init_confirmation = taler_config.confirmation().unwrap_or(DEFAULT_CONFIRMATION) as u32;
        Self {
            confirmation: init_confirmation,
            max_confirmation: init_confirmation * 2,
            bounce_fee: config_bounce_fee(&taler_config.bounce_fee(), currency),
            lifetime: taler_config.wire_lifetime(),
            bump_delay: taler_config.bump_delay(),
            base_url: taler_config.base_url(),
            db_config: taler_config.db_config(),
            currency,
            btc_config,
        }
    }
}

// Load taler config with btc-wire specific config
pub fn load_taler_config(file: Option<&Path>) -> (TalerConfig, PathBuf, CurrencyBtc) {
    let config = TalerConfig::load(file);
    let path = config.path("CONF_PATH").unwrap_or_else(default_data_dir);
    let currency = match config.currency {
        Currency::BTC(it) => it,
        _ => fail(format!(
            "currency {} is not supported by btc-wire",
            config.currency.to_str()
        )),
    };
    (config, path, currency)
}

// Parse bitcoin amount from config bounce fee
fn config_bounce_fee(bounce_fee: &Option<String>, currency: CurrencyBtc) -> Amount {
    let config = bounce_fee.as_deref().unwrap_or(DEFAULT_BOUNCE_FEE);
    TalerAmount::from_str(&format!("{}:{}", currency.to_str(), config))
        .map_err(|s| s.to_string())
        .and_then(|a| taler_to_btc(&a, currency))
        .or_fail(|a| {
            format!(
                "config BOUNCE_FEE={} is not a valid bitcoin amount: {}",
                config, a
            )
        })
}

// Check network match config currency
fn check_network_currency(network: Network, currency: CurrencyBtc) {
    let expected = match network {
        Network::Bitcoin => CurrencyBtc::Main,
        Network::Testnet => CurrencyBtc::Test,
        Network::Regtest => CurrencyBtc::Dev,
        _ => unimplemented!(),
    };
    if currency != expected {
        fail(format_args!(
            "config currency is incompatible with node network, CURRENCY = {} expected {}",
            currency.to_str(),
            expected.to_str()
        ))
    }
}