//! Parser contains the command parser for handling receiving commands from the GUI


use std::collections::HashMap;
use commands;

use either::Either;
pub use either::Left;
pub use either::Right;

/// Token represents a parsable token in the string sent via STDIN from the GUI
#[derive(Debug, Eq, PartialEq)]
pub enum Token {
  UCI,
  DEBUG,
  ISREADY,
  SETOPTION,
  REGISTER,
  UCINEWGAME,
  POSITION,
  GO,
  STOP,
  PONDERHIT,
  QUIT,
}

#[derive(Clone, Debug, PartialEq, PartialOrd)]
pub enum CommandValue {
  Int(i32),
  Float(f64),
  Text(String),
  Boolean(bool),
}

pub struct Parser {}

/// TokenResult is a convenient way to package an entire command string. It is identified by it's associated
/// Token, and the arguments.
///
/// Example:
///
/// setoption name Hash value 32
/// --------- ---- ---- ----- --
///   Token   arg  val  arg  val
///
/// debug on
/// ----- --
/// Token val
///
///
/// The user is still responsible for knowing what to look for in the hashmap but this structure makes it far
/// easier to work with commands. Some commands don't have arguments, in that case the args will be None.
#[derive(Debug, PartialEq)]
pub struct TokenResult {
  token: Token,
  args: Either<Option<HashMap<&'static str, CommandValue>>, &'static str>,
}

impl TokenResult {

  /// Intantiates a new TokenResult
  pub fn new(token: Token, args: Either<Option<HashMap<&'static str, CommandValue>>, &'static str>>) -> TokenResult {
    TokenResult { token, args }
  }
}

impl Parser {

  /// Instantiates a new Parser
  pub fn new() -> Parser {
    Parser{}
  }

  /// Parses a single string from the GUI and turns it into a neatly packaged TokenResult for processing
  /// by the engine.
  pub fn parse(&self, s: &str) -> Result<TokenResult, &'static str> {

    // TODO: Remove the /n from the end

    let tokens: Vec<&str> = s.split_whitespace().collect::<Vec<&str>>();

    // TODO: Parse things based on the token, probably need a special function for each token based on a switch
    //       of tokens[0].


    // remove this when it's working
    Ok(TokenResult::new(Token::SETOPTION, Left(Some(HashMap::new()))))
  }
}