import Database from 'better-sqlite3';
import { join, dirname } from 'path';
import { existsSync, mkdirSync } from 'fs';
import { fileURLToPath } from 'url';
import type { CV, CVData, CVSettings } from '../types';
import { DEFAULT_DATA, DEFAULT_SETTINGS } from '../types';

const DB_PATH = import.meta.env.DB_PATH || join(process.cwd(), 'data', 'lebenslauf.db');
const dir = dirname(DB_PATH);
if (!existsSync(dir)) mkdirSync(dir, { recursive: true });

let _db: Database.Database | null = null;

export function getDb(): Database.Database {
  if (!_db) {
    _db = new Database(DB_PATH);
    _db.pragma('journal_mode = WAL');
    _db.pragma('foreign_keys = ON');
    initSchema(_db);
  }
  return _db;
}

function initSchema(db: Database.Database) {
  db.exec(`
    CREATE TABLE IF NOT EXISTS users (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      email TEXT UNIQUE NOT NULL,
      otp TEXT,
      otp_expires INTEGER,
      created_at INTEGER DEFAULT (unixepoch())
    );

    CREATE TABLE IF NOT EXISTS sessions (
      id TEXT PRIMARY KEY,
      user_id INTEGER NOT NULL,
      expires_at INTEGER NOT NULL,
      FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
    );

    CREATE TABLE IF NOT EXISTS profiles (
      id TEXT PRIMARY KEY,
      user_id INTEGER NOT NULL,
      title TEXT NOT NULL DEFAULT 'Mein Profil',
      language TEXT NOT NULL DEFAULT 'de',
      data TEXT NOT NULL DEFAULT '{}',
      created_at INTEGER DEFAULT (unixepoch()),
      updated_at INTEGER DEFAULT (unixepoch()),
      FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
    );

    CREATE TABLE IF NOT EXISTS cvs (
      id TEXT PRIMARY KEY,
      user_id INTEGER NOT NULL,
      profile_id TEXT NOT NULL,
      hash TEXT UNIQUE NOT NULL,
      title TEXT NOT NULL DEFAULT 'Mein Lebenslauf',
      template INTEGER NOT NULL DEFAULT 1,
      settings TEXT NOT NULL DEFAULT '{}',
      public INTEGER NOT NULL DEFAULT 0,
      created_at INTEGER DEFAULT (unixepoch()),
      updated_at INTEGER DEFAULT (unixepoch()),
      FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
      FOREIGN KEY (profile_id) REFERENCES profiles(id) ON DELETE CASCADE
    );
  `);

  // Migration for cvs: add profile_id if not exists
  try {
    const tableInfo = db.prepare('PRAGMA table_info(cvs)').all() as any[];
    const hasProfileId = tableInfo.some(col => col.name === 'profile_id');
    if (!hasProfileId) {
      db.prepare('ALTER TABLE cvs ADD COLUMN profile_id TEXT').run();
      
      // Migrate embedded data into profiles
      const allOldCVs = db.prepare('SELECT * FROM cvs WHERE profile_id IS NULL').all() as any[];
      for (const old of allOldCVs) {
        const profId = Math.random().toString(36).slice(2, 10);
        db.prepare('INSERT INTO profiles (id, user_id, title, language, data, created_at, updated_at) VALUES (?, ?, ?, ?, ?, ?, ?)')
          .run(profId, old.user_id, old.title + ' (Data)', 'de', old.data || '{}', old.created_at, old.updated_at);
        db.prepare('UPDATE cvs SET profile_id = ? WHERE id = ?').run(profId, old.id);
      }
    }
  } catch(e) { console.error("Migration error:", e); }
}

// ── Users ─────────────────────────────────────────────────────────────
export function getUser(email: string) {
  const db = getDb();
  return db.prepare('SELECT * FROM users WHERE email = ?').get(email) as any;
}

export function upsertUser(email: string) {
  const db = getDb();
  db.prepare('INSERT OR IGNORE INTO users (email) VALUES (?)').run(email);
  return getUser(email);
}

export function setOTP(email: string, otp: string, expiresAt: number) {
  const db = getDb();
  db.prepare('UPDATE users SET otp = ?, otp_expires = ? WHERE email = ?').run(otp, expiresAt, email);
}

export function consumeOTP(email: string, otp: string): boolean {
  const db = getDb();
  const now = Math.floor(Date.now() / 1000);
  const user = db.prepare(
    'SELECT id FROM users WHERE email = ? AND otp = ? AND otp_expires > ?'
  ).get(email, otp, now) as any;
  if (user) {
    db.prepare('UPDATE users SET otp = NULL, otp_expires = NULL WHERE email = ?').run(email);
    return true;
  }
  return false;
}

// ── Sessions ──────────────────────────────────────────────────────────
export function createSession(userId: number, sessionId: string, expiresAt: number) {
  const db = getDb();
  db.prepare('INSERT INTO sessions (id, user_id, expires_at) VALUES (?, ?, ?)').run(sessionId, userId, expiresAt);
}

export function getSession(sessionId: string) {
  const db = getDb();
  const now = Math.floor(Date.now() / 1000);
  return db.prepare(`
    SELECT s.*, u.email, u.id as user_id FROM sessions s
    JOIN users u ON s.user_id = u.id
    WHERE s.id = ? AND s.expires_at > ?
  `).get(sessionId, now) as any;
}

export function deleteSession(sessionId: string) {
  const db = getDb();
  db.prepare('DELETE FROM sessions WHERE id = ?').run(sessionId);
}

// ── Profiles ──────────────────────────────────────────────────────────
export function getProfilesByUser(userId: number): any[] {
  const db = getDb();
  const rows = db.prepare('SELECT * FROM profiles WHERE user_id = ? ORDER BY updated_at DESC').all(userId) as any[];
  return rows.map(r => ({ ...r, data: JSON.parse(r.data || '{}') }));
}

export function getProfileById(id: string, userId?: number): any | undefined {
  const db = getDb();
  const row = userId
    ? db.prepare('SELECT * FROM profiles WHERE id = ? AND user_id = ?').get(id, userId) as any
    : db.prepare('SELECT * FROM profiles WHERE id = ?').get(id) as any;
  return row ? { ...row, data: JSON.parse(row.data || '{}') } : undefined;
}

export function createProfile(userId: number, id: string, title: string, language: string): any {
  const db = getDb();
  db.prepare(`
    INSERT INTO profiles (id, user_id, title, language, data)
    VALUES (?, ?, ?, ?, ?)
  `).run(id, userId, title, language, JSON.stringify(DEFAULT_DATA));
  return getProfileById(id)!;
}

export function updateProfile(id: string, userId: number, updates: Partial<{ title: string; language: string; data: any; }>) {
  const db = getDb();
  const fields: string[] = [];
  const values: any[] = [];

  if (updates.title !== undefined) { fields.push('title = ?'); values.push(updates.title); }
  if (updates.language !== undefined) { fields.push('language = ?'); values.push(updates.language); }
  if (updates.data !== undefined) { fields.push('data = ?'); values.push(JSON.stringify(updates.data)); }

  if (fields.length === 0) return;
  fields.push('updated_at = unixepoch()');
  values.push(id, userId);

  db.prepare(`UPDATE profiles SET ${fields.join(', ')} WHERE id = ? AND user_id = ?`).run(...values);
}

export function deleteProfile(id: string, userId: number) {
  const db = getDb();
  db.prepare('DELETE FROM profiles WHERE id = ? AND user_id = ?').run(id, userId);
}

// ── CVs ───────────────────────────────────────────────────────────────
export function getCVsByUser(userId: number): CV[] {
  const db = getDb();
  const rows = db.prepare('SELECT * FROM cvs WHERE user_id = ? ORDER BY updated_at DESC').all(userId) as any[];
  return rows.map(parseCV);
}

export function getCVById(id: string, userId?: number): CV | undefined {
  const db = getDb();
  const row = userId
    ? db.prepare('SELECT * FROM cvs WHERE id = ? AND user_id = ?').get(id, userId)
    : db.prepare('SELECT * FROM cvs WHERE id = ?').get(id);
  return row ? parseCV(row as any) : undefined;
}

export function getCVByHash(hash: string): CV | undefined {
  const db = getDb();
  const row = db.prepare('SELECT * FROM cvs WHERE hash = ? AND public = 1').get(hash);
  return row ? parseCV(row as any) : undefined;
}

export function createCV(userId: number, id: string, profile_id: string, hash: string, title: string): CV {
  const db = getDb();
  db.prepare(`
    INSERT INTO cvs (id, user_id, profile_id, hash, title, template, settings)
    VALUES (?, ?, ?, ?, ?, 1, ?)
  `).run(id, userId, profile_id, hash, title,
    JSON.stringify(DEFAULT_SETTINGS)
  );
  return getCVById(id)!;
}

export function updateCV(id: string, userId: number, updates: Partial<{
  title: string; template: number; settings: CVSettings; public: boolean;
}>) {
  const db = getDb();
  const fields: string[] = [];
  const values: any[] = [];

  if (updates.title !== undefined)    { fields.push('title = ?');    values.push(updates.title); }
  if (updates.template !== undefined) { fields.push('template = ?'); values.push(updates.template); }
  if (updates.settings !== undefined) { fields.push('settings = ?'); values.push(JSON.stringify(updates.settings)); }
  if (updates.public !== undefined)   { fields.push('public = ?');   values.push(updates.public ? 1 : 0); }

  if (fields.length === 0) return;
  fields.push('updated_at = unixepoch()');
  values.push(id, userId);

  db.prepare(`UPDATE cvs SET ${fields.join(', ')} WHERE id = ? AND user_id = ?`).run(...values);
}

export function deleteCV(id: string, userId: number) {
  const db = getDb();
  db.prepare('DELETE FROM cvs WHERE id = ? AND user_id = ?').run(id, userId);
}

function parseCV(row: any): CV {
  return {
    ...row,
    settings: JSON.parse(row.settings || '{}'),
    public: Boolean(row.public),
  };
}