import { Chess, Square, Color } from 'chess.js'
import { GameResult, GameTermination } from '../types/chess'

export function evaluateGameState(chess: Chess): GameResult {
  const isGameOver = chess.isGameOver()
  
  if (!isGameOver) {
    return {
      isGameOver: false,
      winner: null,
      message: '',
      terminationReason: ''
    }
  }

  if (chess.isCheckmate()) {
    const winner = chess.turn() === 'w' ? 'b' : 'w'
    return {
      isGameOver: true,
      winner,
      message: `Checkmate! ${winner === 'w' ? 'White' : 'Black'} wins!`,
      terminationReason: GameTermination.CHECKMATE,
      details: `${winner === 'w' ? 'White' : 'Black'} delivered checkmate`
    }
  }

  if (chess.isStalemate()) {
    return {
      isGameOver: true,
      winner: null,
      message: 'Game drawn by stalemate!',
      terminationReason: GameTermination.STALEMATE,
      details: 'No legal moves available but king is not in check'
    }
  }

  if (chess.isInsufficientMaterial()) {
    return {
      isGameOver: true,
      winner: null,
      message: 'Game drawn by insufficient material!',
      terminationReason: GameTermination.INSUFFICIENT_MATERIAL,
      details: 'Neither side has enough material to checkmate'
    }
  }

  if (chess.isThreefoldRepetition()) {
    return {
      isGameOver: true,
      winner: null,
      message: 'Game drawn by threefold repetition!',
      terminationReason: GameTermination.THREEFOLD_REPETITION,
      details: 'The same position occurred three times'
    }
  }

  if (chess.isDraw()) {
    return {
      isGameOver: true,
      winner: null,
      message: 'Game drawn!',
      terminationReason: GameTermination.FIFTY_MOVE_RULE,
      details: 'Draw by 50-move rule or other draw condition'
    }
  }

  return {
    isGameOver: true,
    winner: null,
    message: 'Game ended',
    terminationReason: 'unknown'
  }
}

export function isPotentialPromotion(chess: Chess, from: Square, to: Square): boolean {
  const piece = chess.get(from)
  if (!piece || piece.type !== 'p') return false

  const toRank = parseInt(to[1])
  return (piece.color === 'w' && toRank === 8) || (piece.color === 'b' && toRank === 1)
}

export function isSquareLight(square: Square): boolean {
  const file = square.charCodeAt(0) - 97
  const rank = parseInt(square[1]) - 1
  return (file + rank) % 2 === 0
}


export function formatMoveTime(timestamp: Date): string {
  return timestamp.toLocaleTimeString([], { 
    hour: '2-digit', 
    minute: '2-digit', 
    second: '2-digit' 
  })
}