hitstar/src/server-deno/application/GameService.ts

import type { GuessResult, ID, Track } from '../domain/types.ts';
import { GameStatus } from '../domain/types.ts';
import type { RoomModel } from '../domain/models/mod.ts';
import { AudioStreamingService } from '../infrastructure/mod.ts';
import { TrackService } from './TrackService.ts';
import { AnswerCheckService } from './AnswerCheckService.ts';
import { logger } from '../shared/logger.ts';
import { ValidationError } from '../shared/errors.ts';

/**
 * Game service for managing game logic and flow
 */
export class GameService {
  constructor(
    private readonly trackService: TrackService,
    private readonly audioStreaming: AudioStreamingService,
    private readonly answerCheck: AnswerCheckService,
  ) {}

  /**
   * Start a game in a room
   */
  async startGame(room: RoomModel): Promise<void> {
    if (room.state.status === ('playing' as GameStatus)) {
      throw new ValidationError('Game already in progress');
    }

    if (!room.state.playlist) {
      throw new ValidationError('No playlist selected');
    }

    if (!room.state.areAllReady()) {
      throw new ValidationError('Not all players are ready');
    }

    // Load shuffled deck
    const tracks = await this.trackService.loadShuffledDeck(room.state.playlist);
    
    if (tracks.length === 0) {
      throw new ValidationError('No tracks available in selected playlist');
    }

    room.setDeck(tracks);

    // Initialize game state
    const playerIds = Array.from(room.players.keys()).filter(
      (id) => !room.state.spectators[id]
    );
    room.state.startGame(playerIds);

    logger.info(`Game started in room ${room.id} with ${playerIds.length} players`);
  }

  /**
   * Draw next track and prepare for guessing
   */
  async drawNextTrack(room: RoomModel): Promise<Track | null> {
    const track = room.drawTrack();
    
    if (!track) {
      // No more tracks - end game
      room.state.endGame();
      return null;
    }

    // Create streaming token
    try {
      const token = await this.audioStreaming.createAudioToken(track.file);
      track.url = `/audio/t/${token}`;
    } catch (error) {
      logger.error(`Failed to create audio token for ${track.file}: ${error}`);
      // Fallback to name-based URL
      track.url = `/audio/${encodeURIComponent(track.file)}`;
    }

    // Update game state
    room.state.currentTrack = track;
    room.state.resetRound();
    room.state.trackStartAt = Date.now() + 800; // Small delay for sync

    logger.info(`Track drawn in room ${room.id}: ${track.title} - ${track.artist}`);

    return track;
  }

  /**
   * Process a guess
   */
  processGuess(
    room: RoomModel,
    playerId: ID,
    guess: string,
    type: 'title' | 'artist' | 'year',
  ): GuessResult {
    const player = room.getPlayer(playerId);
    const track = room.state.currentTrack;

    if (!player || !track) {
      throw new ValidationError('Invalid guess context');
    }

    let result: GuessResult;

    switch (type) {
      case 'title': {
        const scoreResult = this.answerCheck.scoreTitle(guess, track.title);
        result = {
          playerId,
          playerName: player.name,
          guess,
          correct: scoreResult.match,
          type: 'title',
          score: scoreResult.score,
          answer: track.title,
        };
        break;
      }

      case 'artist': {
        const scoreResult = this.answerCheck.scoreArtist(guess, track.artist);
        result = {
          playerId,
          playerName: player.name,
          guess,
          correct: scoreResult.match,
          type: 'artist',
          score: scoreResult.score,
          answer: track.artist,
        };
        break;
      }

      case 'year': {
        const scoreResult = this.answerCheck.scoreYear(guess, track.year);
        result = {
          playerId,
          playerName: player.name,
          guess,
          correct: scoreResult.match,
          type: 'year',
          score: scoreResult.score,
          answer: track.year ? String(track.year) : 'Unknown',
        };
        break;
      }

      default:
        throw new ValidationError('Invalid guess type');
    }

    // NOTE: This method is legacy and no longer awards tokens.
    // Token awarding is now handled by:
    // - checkTitleArtistGuess() for title+artist tokens
    // - placeInTimeline() for placement tokens

    room.state.lastResult = result;
    return result;
  }

  /**
   * Place a card in player's timeline
   */
  placeCard(room: RoomModel, playerId: ID, year: number, position: number): boolean {
    const player = room.getPlayer(playerId);
    
    if (!player) {
      throw new ValidationError('Player not found');
    }

    room.state.addToTimeline(playerId, year, position);

    // Check for winner
    if (room.state.hasPlayerWon(playerId)) {
      room.state.endGame();
      logger.info(`Player ${player.name} won in room ${room.id}!`);
      return true;
    }

    return false;
  }

  /**
   * Skip to next player's turn
   */
  nextTurn(room: RoomModel): ID | null {
    return room.state.nextTurn();
  }

  /**
   * Pause game
   */
  pauseGame(room: RoomModel): void {
    if (!room.state.paused && room.state.trackStartAt) {
      const elapsed = (Date.now() - room.state.trackStartAt) / 1000;
      room.state.pausedPosSec = elapsed;
      room.state.paused = true;
    }
  }

  /**
   * Resume game
   */
  resumeGame(room: RoomModel): void {
    if (room.state.paused) {
      room.state.trackStartAt = Date.now() - (room.state.pausedPosSec * 1000);
      room.state.paused = false;
    }
  }

  /**
   * End game
   */
  endGame(room: RoomModel): void {
    room.state.endGame();
    logger.info(`Game ended in room ${room.id}`);
  }

  /**
   * Get winner
   */
  getWinner(room: RoomModel): ID | null {
    return room.state.getWinner();
  }

  /**
   * Check title and artist guess
   * 
   * SCORING SYSTEM:
   * - Tokens: Awarded ONLY for correctly guessing BOTH title AND artist
   *   - 1 token per round (can only get once per track)
   *   - Used as currency/bonus points
   * 
   * - Score: Number of correctly placed tracks in timeline (timeline.length)
   *   - Increases only when placement is correct
   *   - This is the main win condition
   */
  async checkTitleArtistGuess(
    room: RoomModel,
    playerId: ID,
    guessTitle: string,
    guessArtist: string
  ): Promise<{
    titleCorrect: boolean;
    artistCorrect: boolean;
    awarded: boolean;
    alreadyAwarded: boolean;
  }> {
    const track = room.state.currentTrack;
    if (!track) {
      throw new Error('No current track');
    }

    // Check if title+artist token already awarded this round
    const alreadyAwarded = room.state.titleArtistAwardedThisRound[playerId] || false;

    // Score the guesses
    const titleResult = this.answerCheck.scoreTitle(guessTitle, track.title);
    const artistResult = this.answerCheck.scoreArtist(guessArtist, track.artist);

    const titleCorrect = titleResult.match;
    const artistCorrect = artistResult.match;
    const bothCorrect = titleCorrect && artistCorrect;

    // Award 1 token if BOTH title and artist are correct, and not already awarded this round
    let awarded = false;
    if (bothCorrect && !alreadyAwarded) {
      room.state.tokens[playerId] = (room.state.tokens[playerId] || 0) + 1;
      room.state.titleArtistAwardedThisRound[playerId] = true;
      awarded = true;
      
      logger.info(
        `Player ${playerId} correctly guessed title AND artist. Awarded 1 token for title+artist.`
      );
    }

    return {
      titleCorrect,
      artistCorrect,
      awarded,
      alreadyAwarded: alreadyAwarded && bothCorrect,
    };
  }

  /**
   * Place track in timeline
   * 
   * SCORING SYSTEM:
   * - Correct placement: Adds track to timeline, increasing score (timeline.length)
   * - Incorrect placement: Track is discarded, no score increase
   * - NO tokens awarded here - tokens are only from title+artist guesses
   */
  async placeInTimeline(
    room: RoomModel,
    playerId: ID,
    slot: number
  ): Promise<{ correct: boolean }> {
    const track = room.state.currentTrack;
    if (!track) {
      throw new Error('No current track');
    }

    const timeline = room.state.timeline[playerId] || [];
    const n = timeline.length;

    // Validate slot
    if (slot < 0 || slot > n) {
      slot = n;
    }

    logger.info(`Timeline before placement: ${JSON.stringify(timeline.map(t => ({ year: t.year, title: t.title })))}`);
    logger.info(`Placing track: ${track.title} (${track.year}) at slot ${slot} of ${n}`);

    // Check if placement is correct
    let correct = false;
    if (track.year != null) {
      if (n === 0) {
        correct = true; // First card is always correct
      } else {
        const leftYear = slot > 0 ? timeline[slot - 1]?.year : null;
        const rightYear = slot < n ? timeline[slot]?.year : null;
        
        // Allow equal years (>=, <=) so cards from the same year can be placed anywhere relative to each other
        const leftOk = leftYear == null || track.year >= leftYear;
        const rightOk = rightYear == null || track.year <= rightYear;
        
        correct = leftOk && rightOk;
        
        // Debug logging
        logger.info(`Placement check - Track year: ${track.year}, Slot: ${slot}/${n}, Left: ${leftYear}, Right: ${rightYear}, LeftOk: ${leftOk}, RightOk: ${rightOk}, Correct: ${correct}`);
      }
    } else {
      logger.warn(`Track has no year: ${track.title}`);
    }

    // Update timeline if correct (score is the timeline length)
    if (correct) {
      const newTimeline = [...timeline];
      newTimeline.splice(slot, 0, {
        trackId: track.id,
        year: track.year,
        title: track.title,
        artist: track.artist,
      });
      room.state.timeline[playerId] = newTimeline;
      
      // Score increases automatically (it's the timeline length)
      // NO token awarded here - tokens are only from title+artist guesses
      logger.info(
        `Player ${playerId} correctly placed track in timeline. Score is now ${newTimeline.length}.`
      );
    } else {
      // Discard the track
      room.discard.push(track);
      
      logger.info(
        `Player ${playerId} incorrectly placed track. No score increase.`
      );
    }

    return { correct };
  }
}