import fs from 'fs';
import path from 'path';
import { StoreData, Session, Team, Juror, Score } from '../shared/types.js';

const DATA_DIR = path.join(process.cwd(), 'server', 'data');
const SESSION_FILE = path.join(DATA_DIR, 'session.json');
const SEED_FILE = path.join(DATA_DIR, 'seed.json');
const BACKUP_FILE = path.join(DATA_DIR, 'session.json.bak');

/**
 * Ensure the data directory exists.
 */
function ensureDataDir(): void {
  if (!fs.existsSync(DATA_DIR)) {
    fs.mkdirSync(DATA_DIR, { recursive: true });
  }
}

/**
 * Initialize session.json from seed.json if it doesn't exist.
 */
function initializeStore(): void {
  ensureDataDir();
  if (!fs.existsSync(SESSION_FILE)) {
    const seedData = fs.readFileSync(SEED_FILE, 'utf-8');
    fs.writeFileSync(SESSION_FILE, seedData, 'utf-8');
  }
}

// Initialize on module load
initializeStore();

/**
 * Read the current store data from session.json.
 */
export function getStore(): StoreData {
  const raw = fs.readFileSync(SESSION_FILE, 'utf-8');
  return JSON.parse(raw) as StoreData;
}

/**
 * Write store data atomically: write to temp file, then rename.
 * Creates a .bak backup before each write.
 */
export function saveStore(data: StoreData): void {
  ensureDataDir();

  // Create backup of current file if it exists
  if (fs.existsSync(SESSION_FILE)) {
    fs.copyFileSync(SESSION_FILE, BACKUP_FILE);
  }

  // Write to temp file, then rename (atomic on most filesystems)
  const tempFile = path.join(DATA_DIR, 'session.json.tmp');
  fs.writeFileSync(tempFile, JSON.stringify(data, null, 2), 'utf-8');
  fs.renameSync(tempFile, SESSION_FILE);
}

/**
 * Get the current session.
 */
export function getSession(): Session {
  const store = getStore();
  return store.session;
}

/**
 * Get all teams.
 */
export function getTeams(): Team[] {
  const store = getStore();
  return store.teams;
}

/**
 * Get all jurors.
 */
export function getJurors(): Juror[] {
  const store = getStore();
  return store.jurors;
}

/**
 * Get all scores.
 */
export function getScores(): Score[] {
  const store = getStore();
  return store.scores;
}

/**
 * Add or update a score. Matches by jurorId + teamId + criterionId.
 */
export function addScore(score: Score): void {
  const store = getStore();
  const existingIndex = store.scores.findIndex(
    (s) =>
      s.jurorId === score.jurorId &&
      s.teamId === score.teamId &&
      s.criterionId === score.criterionId
  );

  if (existingIndex >= 0) {
    store.scores[existingIndex] = score;
  } else {
    store.scores.push(score);
  }

  saveStore(store);
}

/**
 * Update session with partial updates. Returns the updated session.
 */
export function updateSession(updates: Partial<Session>): Session {
  const store = getStore();
  store.session = { ...store.session, ...updates };
  saveStore(store);
  return store.session;
}

/**
 * Update a juror by ID with partial updates. Returns the updated juror or null if not found.
 */
export function updateJuror(jurorId: string, updates: Partial<Juror>): Juror | null {
  const store = getStore();
  const jurorIndex = store.jurors.findIndex((j) => j.id === jurorId);

  if (jurorIndex < 0) {
    return null;
  }

  store.jurors[jurorIndex] = { ...store.jurors[jurorIndex], ...updates };
  saveStore(store);
  return store.jurors[jurorIndex];
}