#![allow(dead_code)]

/// Manage UCI messages and link into chess component
mod uci_command;

use log::{info, warn};
use std::io::*;
use crate::uci_command::*;

use chess::{Game, Board, ChessMove};

/// Structure used to manage a chess game with a uci engine.
///
/// It needs a in / out communication channel to read / push line by line uci commands
///c
/// ```rust
/// use chess_uci::UciEngine;
/// use std::process::{Command, Stdio};
/// use std::io::BufReader;
///
/// let process = match Command::new("stockfish")
///     .stdin(Stdio::piped())
///     .stdout(Stdio::piped())
///    .spawn() {
///        Err(why) => panic!("couldn't spawn stockfish: {}", why),
///        Ok(process) => process,
///    };
/// let (sf_in,sf_out) = (process.stdin.expect("Program stdin"), process.stdout.expect("Program stdout"));
///
/// let mut uci = UciEngine::new(BufReader::new(sf_out), sf_in);
/// // .. uci.init(); ..
/// uci.push_raw("quit\n");
/// ```
pub struct UciEngine<Fi: Read, Fo: Write> {
    source: BufReader<Fi>,
    destination: Fo,
    uciok: bool,
    id: Id,
    initial: Board,
    game: Game,
}

impl<Fi: Read, Fo:  Write> UciEngine<Fi, Fo> {

    /// Create new game manager
    ///
    /// Requires line by line input and output streams to communicate with uci engine
    pub fn new(source: Fi, destination: Fo) -> UciEngine<Fi, Fo> {
        UciEngine::<Fi, Fo>{
            source: BufReader::new(source),
            destination,
            id: Id::new(),
            uciok: false,
            initial: Board::default(),
            game: Game::new()
        }
    }

    /// Launch uci engine initialisation
    ///
    /// Retrieve data from uci engine (until uciok command from engine)
    pub fn init(&mut self){
        self.push(GuiCommand::Uci);

        // Consume commands until uciok messages
        while !self.uciok {
            self.pull();
        }
    }

    /// Initialize a new game
    ///
    /// Set a new board internally and tell the engine
    pub fn new_game(&mut self) {
        self.initial = Board::default();
        self.game = Game::new_with_board(self.initial);
        self.push(GuiCommand::UciNewGame);
    }

    /// Play a move
    ///
    /// Update internal game reference and tell the uci engine
    ///
    /// ```rust
    /// use chess::ChessMove;
    /// use std::str::FromStr;
    /// use chess_uci::*;
    /// use std::io;
    ///
    /// let mut uci = UciEngine::new(io::empty(), io::sink());
    ///
    /// uci.make_move(ChessMove::from_str("e2e4").expect("error converting e2e4"));
    /// ```
    pub fn make_move(&mut self, chess_move: ChessMove) {
        self.game.make_move(chess_move);
        self.push(GuiCommand::Position { position: Some(self.initial), moves: self.game.actions().to_vec() })
    }


    fn terminate(&mut self, reason: &str) {
        self.uciok = false;
        info!("UCI termination: {}", reason);
    }

    /// Provides the name of the uci engine
    pub fn name(&self) -> Option<String> {
        self.id.name()
    }

    /// Provides the author sof the uci engine
    pub fn author(&self) -> Option<String> {
        self.id.author()
    }

    fn update(&mut self, id: &Id){
        if self.is_uciok() {warn!("Engine info should not be updated now (uciok)");}
        self.id.update(id);
    }

    fn update_from_str(&mut self, name: Option<&str>, author: Option<&str>){
        if self.is_uciok() {warn!("Engine info should not be updated now (uciok)");}
        self.id.update_from_str(name, author);
    }

    fn uciok(&mut self){
        self.uciok = true;
    }

    /// Tell whether the uci engine has initialized
    pub fn is_uciok(&self) -> bool {
        self.uciok
    }

    /// Execute a uci command
    ///
    /// if `EngineCommand::Id`: update name or authorship of the engine
    /// if `EngineCommand::UciOk`: end engine initialization phase
    pub fn exec(&mut self, command: &str){
        match parse (&mut command.to_string()) {
            Ok(EngineCommand::Id{id}) => self.update(&id),
            Ok(EngineCommand::UciOk) => self.uciok(),
            Ok(EngineCommand::Opt { options: _ }) => {},
            Ok(_) => {unimplemented!("command not implemented")},
            Err(_) => warn!("Not a command"),
        }
    }

    /// Retrieve a line from the uci engine input stream and parse it
    pub fn pull(&mut self) {

        let mut command = String::new();
        match self.source.read_line(&mut command) {
            Ok(0) => self.terminate("Chess engine closed connection."),
            Ok(_) => {
                info!("← {}", command);
                self.exec(&command)
            },
            Err(reason) => warn!("Unable to read from engine: {reason}"),
        }
    }

    /// Read a line from the uci engine input stream (do not parse)
    pub fn pull_raw(&mut self) -> Option<String> {
        let mut data = String::new();
        match self.source.read_line(&mut data) {
            Ok(0) => {self.terminate("Chess engine closed connection."); None},
            Ok(_) => {info!("↜ {}", data); Some(data.clone())},
            Err(reason) => {warn!("Unable to read from engine: {reason}"); None},
        }
    }

    /// Push a Uci Gui command to the engine
    fn push(&mut self, command: GuiCommand) {
        let command_str = command.to_string();
        match self.destination.write(&command_str.as_bytes()){
            Ok(n) if n == command_str.len() => info!("→ gui: {command_str}"),
            Ok(n) => warn!("⚠ gui: {command_str} truncated at {n}"),
            Err(reason) => warn!("Unable to send command {command_str}: {reason}"),
        }
    }

    /// Push string (not a game manager integrated command) to the Uci engine output stream
    pub fn push_raw(&mut self, data: &str){
        match self.destination.write(data.as_bytes()) {
            Ok(n) if n == data.len() => info!("↝ raw: {data}"),
            Ok(n) => warn!("⚠ raw: {data} truncated at {n}"),
            Err(reason) => warn!("Unable to send raw {data}: {reason}"),
        }
    }
}

//  LocalWords:  uci