//! Data types for text representations of game positions and moves, which may be used for [Portable game notation][1].
//!
//! The terminology used in this module is specific to chess and chess variants, but it can be implemented for any game.
//!
//! [1]: https://en.wikipedia.org/wiki/Portable_Game_Notation

extern crate board_game_traits;

use board_game_traits::{GameResult, Position};
use std::error;
use std::fmt;

/// A list of general categories of errors related to pgn parsing.
///
/// This list is intended to grow over time and it is not recommended to exhaustively match against it.
///
/// It is used with the [`Error`] type.
///
/// [`Error`]: struct.Error.html
#[derive(Clone, Copy, Eq, PartialEq, Debug, PartialOrd, Ord)]
pub enum ErrorKind {
    ParseError,
    AmbiguousMove,
    IllegalMove,
    IllegalPosition,
    IoError,
    Other,
}

/// The error type for operations on a `PgnPosition`.
///
/// The error can be created with an arbitrary payload and optionally an underlying source error for error chaining.
#[derive(Debug)]
pub struct Error {
    kind: ErrorKind,
    error: Box<dyn error::Error + Send + Sync>,
    source: Option<Box<dyn error::Error + Send + Sync>>,
}

impl Error {
    /// Returns a new error of the specific `ErrorKind` with an arbitrary payload.
    pub fn new<E>(kind: ErrorKind, error: E) -> Error
    where
        E: Into<Box<dyn error::Error + Send + Sync>>,
    {
        Error {
            kind,
            error: error.into(),
            source: None,
        }
    }

    /// Returns a new error of the specific `ErrorKind` with an arbitrary payload and source error.
    pub fn new_caused_by<E, F>(kind: ErrorKind, error: E, source: F) -> Error
    where
        E: Into<Box<dyn error::Error + Send + Sync>>,
        F: Into<Box<dyn error::Error + Send + Sync>>,
    {
        Error {
            kind,
            error: error.into(),
            source: Some(source.into()),
        }
    }

    /// Convenience function that returns a `ParseError` with an arbitrary payload. Equivalent to calling `Error::new(ErrorKind::ParseError, error)`
    pub fn new_parse_error<E>(error: E) -> Error
    where
        E: Into<Box<dyn error::Error + Send + Sync>>,
    {
        Error {
            kind: ErrorKind::ParseError,
            error: error.into(),
            source: None,
        }
    }
}

impl error::Error for Error {}

impl fmt::Display for Error {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        match self.kind {
            ErrorKind::ParseError => write!(fmt, "Parse error. "),
            ErrorKind::AmbiguousMove => write!(fmt, "Ambiguous move. "),
            ErrorKind::IllegalMove => write!(fmt, "Illegal move. "),
            ErrorKind::IllegalPosition => write!(fmt, "Illegal position. "),
            ErrorKind::IoError => write!(fmt, "IO error. "),
            ErrorKind::Other => Ok(()),
        }?;
        write!(fmt, "{}", self.error)?;
        if let Some(ref source) = self.source {
            write!(fmt, "\nCaused by: {}", source)?;
        }
        Ok(())
    }
}

/// Trait for text representations of game positions and moves.
///
/// The terminology used in this trait is specific to chess and chess variants, but it can be implemented for any game.
pub trait PgnPosition: Sized + Position + PartialEq {
    /// The required tags, and their default values, for pgn files
    const REQUIRED_TAGS: &'static [(&'static str, &'static str)];

    /// The name of a special tag that allows non-standard start positions for a game
    /// For such games, parsers need to handle this tag to work correctly
    /// In standard chess PGN, this would be `Some("FEN")`
    /// Can be `None` to disable its usage
    const START_POSITION_TAG_NAME: Option<&'static str>;

    /// Each possible game result in the pgn
    const POSSIBLE_GAME_RESULTS: &'static [(&'static str, Option<GameResult>)] = &[
        ("*", None),
        ("1-0", Some(GameResult::WhiteWin)),
        ("0-1", Some(GameResult::BlackWin)),
        ("1/2-1/2", Some(GameResult::Draw)),
    ];

    /// Returns a more detailed game result string, for games that use these.
    /// Must correspond with `POSSIBLE_GAME_RESULTS`
    #[inline]
    fn pgn_game_result(&self) -> Option<&'static str> {
        self.game_result().map(|game_result| match game_result {
            GameResult::WhiteWin => "1-0",
            GameResult::BlackWin => "0-1",
            GameResult::Draw => "1/2-1/2",
        })
    }

    /// Each possible move annotation that can appear at the end of a move
    /// A move can have multiple annotations.
    /// If one annotation is a substring of another, the longer one must be written first
    const POSSIBLE_MOVE_ANNOTATIONS: &'static [&'static str] = &["!!", "!?", "?!", "??", "!", "?"];

    /// Constructs a position from [Forsyth–Edwards Notation][1].
    ///
    /// Extensions to this notation exist for all large chess variants
    ///
    /// [1]: https://en.wikipedia.org/wiki/Forsyth%E2%80%93Edwards_Notation
    #[inline]
    fn from_fen(fen: &str) -> Result<Self, Error> {
        Self::from_fen_with_settings(fen, &Self::Settings::default())
    }

    /// The number of full moves in the position
    /// It starts at 1 and is incremented after the second player's move
    #[inline]
    fn full_move_number(&self) -> Option<u32> {
        None
    }

    /// Constructs a position from [Forsyth–Edwards Notation][1] with the given settings.
    ///
    /// Extensions to this notation exist for all large chess variants
    ///
    /// [1]: https://en.wikipedia.org/wiki/Forsyth%E2%80%93Edwards_Notation
    fn from_fen_with_settings(fen: &str, settings: &Self::Settings) -> Result<Self, Error>;

    /// Returns a string representation of the position in [Forsyth–Edwards Notation][1].
    ///
    /// Extensions to this notation exist for all large chess variants.
    ///
    /// [1]: https://en.wikipedia.org/wiki/Forsyth%E2%80%93Edwards_Notation
    fn to_fen(&self) -> String;

    /// Construct a game move from [Standard Algebraic Notation][1], specifically the format used in [pgn notation][2].
    ///
    /// Extensions to this notation exist for all large chess variants.
    ///
    /// [1]: https://en.wikipedia.org/wiki/Algebraic_notation_(chess)
    /// [2]: https://en.wikipedia.org/wiki/Portable_Game_Notation
    fn move_from_san(&self, input: &str) -> Result<Self::Move, Error>;

    /// Returns a string representation of the move in [Standard Algebraic Notation][1], specifically the format used in [pgn notation][2].
    ///
    /// Extensions to this notation exist for all large chess variants.
    ///
    /// [1]: https://en.wikipedia.org/wiki/Algebraic_notation_(chess)
    /// [2]: https://en.wikipedia.org/wiki/Portable_Game_Notation
    fn move_to_san(&self, mv: &Self::Move) -> String;

    /// Construct a move from an alternative, [long algebraic notation][1].
    ///
    /// This is mostly used for chess and chess variations in the uci interface, or for convenient debugging.
    /// Implementations may simply wrap this function around `move_from_san` where appropriate.
    ///
    /// [1]: https://en.wikipedia.org/wiki/Algebraic_notation_(chess)#Long_algebraic_notation
    fn move_from_lan(&self, input: &str) -> Result<Self::Move, Error>;

    /// Returns a string representation of the move in an alternative, [long algebraic notation][1].
    ///
    /// This is mostly used for chess and chess variations in the uci interface, or for convenient debugging.
    /// Implementations may simply wrap this function around `move_to_san` where appropriate.
    ///
    /// [1]: https://en.wikipedia.org/wiki/Algebraic_notation_(chess)#Long_algebraic_notation
    fn move_to_lan(&self, mv: &Self::Move) -> String;
}