import type { Cell, GameRules, SerializedBitBoard } from './types.ts'
import { checkWin } from './checkWin.ts'
import { BOARD_SIZE, isBoardCoordInBounds } from './board.ts'
import { BitBoard } from './bot/BitBoard.ts'

function generateId(): string {
  return Math.random().toString(36).substring(2, 8).toUpperCase()
}

export interface MoveRecord {
  x: number
  y: number
  player: number
  symbol: string
}

export interface Score {
  wins: number
  losses: number
  draws: number
}

export interface GameResult {
  winner: number | null
  winCells?: { x: number; y: number }[]
}

export type PlaceMoveResult =
  | { success: false; error: string }
  | { success: true; kind: 'continue' }
  | { success: true; kind: 'win'; winner: number; winCells: { x: number; y: number }[] }
  | { success: true; kind: 'draw' }
  | { success: true; kind: 'swap2_choice' }

export interface GameExportData {
  id: string
  player1: string
  player2: string
  winner: number | null
  moves: MoveRecord[]
  createdAt: string
}

const DEFAULT_RULES: GameRules = { swap2: false, noOverlines: false }

export class GameManager {
  private _board: BitBoard
  private _currentPlayer = 0
  private _status: 'active' | 'win' | 'draw' = 'active'
  private _moveHistory: MoveRecord[] = []
  private _playerNames: [string, string]
  private _playerSymbols: [string, string]
  private _scores: [Score, Score]
  private _gameId: string
  private _createdAt: string
  private _rules: GameRules
  private _boardSize: number
  private _phase: 'normal' | 'swap2_opening' | 'swap2_choice' | 'swap2_placement' | 'swap2_choice2' = 'normal'
  private _openingCount = 0
  private _additionalCount = 0

  private swapCellOwners(): void {
    this._board.swapPlayers()
  }

  constructor(
    player1Name?: string,
    player2Name?: string,
    symbols?: [string, string],
    rules?: GameRules,
  ) {
    this._rules = rules ?? { ...DEFAULT_RULES }
    this._boardSize = this._rules.boardSize ?? BOARD_SIZE
    this._board = BitBoard.empty(this._boardSize)
    this._playerNames = [player1Name ?? 'Player 1', player2Name ?? 'Player 2']
    this._playerSymbols = symbols ?? ['X', 'O']
    this._scores = [
      { wins: 0, losses: 0, draws: 0 },
      { wins: 0, losses: 0, draws: 0 },
    ]
    this._gameId = generateId()
    this._createdAt = new Date().toISOString()
    if (this._rules.swap2) {
      this._phase = 'swap2_opening'
    }
  }

  placeMove(x: number, y: number): PlaceMoveResult {
    if (this._status !== 'active') {
      return { success: false, error: 'Game is not active' }
    }

    if (this._phase === 'swap2_choice' || this._phase === 'swap2_choice2') {
      return { success: false, error: 'Waiting for swap decision' }
    }

    if (!isBoardCoordInBounds(x, y, this._boardSize)) {
      return { success: false, error: 'Move out of bounds' }
    }

    if (this._board.has(x, y)) {
      return { success: false, error: 'Cell already occupied' }
    }

    let playerId: string
    let symbol: string
    if (this._phase === 'swap2_opening') {
      this._openingCount++
      const isOpponentStone = this._openingCount === 3
      playerId = isOpponentStone ? '1' : '0'
      symbol = isOpponentStone ? this._playerSymbols[1] : this._playerSymbols[0]
    } else if (this._phase === 'swap2_placement') {
      this._additionalCount++
      // 1st additional stone is Player 2 ('1'), 2nd is Player 1 ('0')
      const isPlayer1Stone = this._additionalCount === 2
      playerId = isPlayer1Stone ? '0' : '1'
      symbol = isPlayer1Stone ? this._playerSymbols[0] : this._playerSymbols[1]
    } else {
      playerId = String(this._currentPlayer)
      symbol = this._playerSymbols[this._currentPlayer]
    }

    this._board.place(x, y, Number(playerId) as 0 | 1)
    this._moveHistory.push({
      x,
      y,
      player: Number(playerId),
      symbol,
    })

    const { won, cells: winCells } = checkWin(this._board, x, y, playerId, this._rules.noOverlines)

    if (won) {
      this._status = 'win'
      const winner = this._phase === 'swap2_opening' ? 0 : this._currentPlayer
      this._scores[winner].wins++
      this._scores[winner === 0 ? 1 : 0].losses++
      this._phase = 'normal'
      return { success: true, kind: 'win', winner, winCells }
    }

    if (this._board.occupiedCount >= this._boardSize * this._boardSize) {
      this._status = 'draw'
      this._scores[0].draws++
      this._scores[1].draws++
      return { success: true, kind: 'draw' }
    }

    if (this._phase === 'swap2_opening') {
      if (this._openingCount >= 3) {
        this._phase = 'swap2_choice'
        return { success: true, kind: 'swap2_choice' }
      }
      return { success: true, kind: 'continue' }
    }

    if (this._phase === 'swap2_placement') {
      if (this._additionalCount >= 2) {
        this._phase = 'swap2_choice2'
        return { success: true, kind: 'swap2_choice' }
      }
      return { success: true, kind: 'continue' }
    }

    this._currentPlayer = this._currentPlayer === 0 ? 1 : 0
    return { success: true, kind: 'continue' }
  }

  swapSides(): void {
    if (this._status !== 'active') return
    if (this._phase === 'swap2_choice' || this._phase === 'swap2_choice2') return

    ;[this._playerSymbols[0], this._playerSymbols[1]] = [this._playerSymbols[1], this._playerSymbols[0]]
    this.swapCellOwners()

    this._currentPlayer = this._currentPlayer === 0 ? 1 : 0
  }

  chooseSwap(accept: boolean): void {
    if (this._phase !== 'swap2_choice') return
    this.chooseSwap2Decision(accept ? 'player1' : 'player2')
  }

  chooseSwap2Decision(decision: 'player1' | 'player2' | 'offer'): void {
    if (this._phase === 'swap2_choice') {
      if (decision === 'player1') {
        this._phase = 'normal'
        ;[this._playerSymbols[0], this._playerSymbols[1]] = [this._playerSymbols[1], this._playerSymbols[0]]
        this.swapCellOwners()
        this._currentPlayer = 0
      } else if (decision === 'player2') {
        this._phase = 'normal'
        this._currentPlayer = 1
      } else if (decision === 'offer') {
        this._phase = 'swap2_placement'
        this._additionalCount = 0
        this._currentPlayer = 1
      }
    } else if (this._phase === 'swap2_choice2') {
      this._phase = 'normal'
      if (decision === 'player1') {
        this._currentPlayer = 1
      } else if (decision === 'player2') {
        ;[this._playerSymbols[0], this._playerSymbols[1]] = [this._playerSymbols[1], this._playerSymbols[0]]
        this.swapCellOwners()
        this._currentPlayer = 0
      }
    }
  }

  getBoard(): ReadonlyMap<string, Cell> {
    return this._board.toMap(this._playerSymbols)
  }

  getBitBoard(): BitBoard {
    return this._board
  }

  getBoardSnapshot(): SerializedBitBoard {
    return this._board.serialize()
  }

  getCurrentPlayer(): number {
    return this._currentPlayer
  }

  getStatus(): 'active' | 'win' | 'draw' {
    return this._status
  }

  isGameOver(): boolean {
    return this._status === 'win' || this._status === 'draw'
  }

  getMoveHistory(): readonly MoveRecord[] {
    return this._moveHistory
  }

  getPlayerNames(): readonly [string, string] {
    return this._playerNames
  }

  getPlayerSymbols(): readonly [string, string] {
    return this._playerSymbols
  }

  setPlayerSymbol(playerIndex: number, symbol: string): void {
    if (playerIndex === 0 || playerIndex === 1) {
      this._playerSymbols[playerIndex] = symbol
    }
  }

  setPlayerName(playerIndex: number, name: string): void {
    if (playerIndex === 0 || playerIndex === 1) {
      this._playerNames[playerIndex] = name
    }
  }

  getScores(): [Score, Score] {
    return [
      { ...this._scores[0] },
      { ...this._scores[1] },
    ]
  }

  getWinner(): number | null {
    if (this._status === 'win') {
      return this._currentPlayer
    }
    return null
  }

  getBoardSize(): number {
    return this._boardSize
  }

  getRules(): GameRules {
    return { ...this._rules }
  }

  getPhase(): 'normal' | 'swap2_opening' | 'swap2_choice' | 'swap2_placement' | 'swap2_choice2' {
    return this._phase
  }

  reset(): void {
    this._board = BitBoard.empty(this._boardSize)
    this._currentPlayer = 0
    this._status = 'active'
    this._moveHistory = []
    this._gameId = generateId()
    this._createdAt = new Date().toISOString()
    this._phase = this._rules.swap2 ? 'swap2_opening' : 'normal'
    this._openingCount = 0
    this._additionalCount = 0
  }

  resetWithNewPlayers(
    player1Name?: string,
    player2Name?: string,
    symbols?: [string, string],
    rules?: GameRules,
  ): void {
    if (rules) {
      this._rules = { ...rules }
      this._boardSize = rules.boardSize ?? BOARD_SIZE
    }
    this.reset()
    this._playerNames = [player1Name ?? 'Player 1', player2Name ?? 'Player 2']
    this._playerSymbols = symbols ?? ['X', 'O']
  }

  exportGame(): GameExportData {
    return {
      id: this._gameId,
      player1: this._playerNames[0],
      player2: this._playerNames[1],
      winner: this.getWinner(),
      moves: [...this._moveHistory],
      createdAt: this._createdAt,
    }
  }

  replaceBoard(board: Record<string, Cell> | SerializedBitBoard, currentPlayer: number, status: 'active' | 'win' | 'draw', moveHistory: MoveRecord[]): void {
    this._board = isSerializedBitBoard(board) ? BitBoard.deserialize(board) : BitBoard.fromBoard(board, this._boardSize)
    this._currentPlayer = currentPlayer
    this._status = status
    this._moveHistory = [...moveHistory]
  }

  addMove(x: number, y: number, player: number, symbol: string): void {
    this._board.place(x, y, player as 0 | 1)
    this._moveHistory.push({ x, y, player, symbol })
  }

  setStatus(status: 'active' | 'win' | 'draw'): void {
    this._status = status
  }

  setCurrentPlayer(player: number): void {
    this._currentPlayer = player
  }

  get gameId(): string {
    return this._gameId
  }
}

function isSerializedBitBoard(board: Record<string, Cell> | SerializedBitBoard): board is SerializedBitBoard {
  return Array.isArray((board as SerializedBitBoard).words)
}