import Database from 'better-sqlite3'
import { mkdirSync, readdirSync, unlinkSync } from 'fs'
import path from 'path'
import { fileURLToPath } from 'url'

const __dirname = path.dirname(fileURLToPath(import.meta.url))
const dataDir = path.join(__dirname, 'data')
mkdirSync(dataDir, { recursive: true })

const db = new Database(path.join(dataDir, 'stories.db'))
db.pragma('journal_mode = WAL')
db.pragma('foreign_keys = ON')
db.pragma('busy_timeout = 5000')    // wait up to 5 s instead of failing immediately

// Merge the WAL back into the main DB file once an hour.
// Without this, all writes live in the WAL indefinitely, and losing
// that file means losing all data written since the last checkpoint.
setInterval(() => {
  try { db.pragma('wal_checkpoint(PASSIVE)') }
  catch (err) { console.warn('[db] WAL checkpoint failed:', err.message) }
}, 60 * 60 * 1000)   // every hour

// Daily backup — keeps the last 7 daily snapshots in data/backups/
const backupDir = path.join(dataDir, 'backups')
mkdirSync(backupDir, { recursive: true })

async function runBackup() {
  try {
    const stamp = new Date().toISOString().slice(0, 10)   // YYYY-MM-DD
    const dest  = path.join(backupDir, `stories-${stamp}.db`)
    await db.backup(dest)
    console.log(`[db] Backup written → ${dest}`)

    // Prune backups older than 7 days
    const files = readdirSync(backupDir)
      .filter(f => f.startsWith('stories-') && f.endsWith('.db'))
      .sort()
    for (const old of files.slice(0, -7)) {
      try { unlinkSync(path.join(backupDir, old)) } catch {}
    }
  } catch (err) {
    console.warn('[db] Backup failed:', err.message)
  }
}

// Run once on startup, then every 24 h
runBackup()
setInterval(runBackup, 24 * 60 * 60 * 1000)

db.exec(`
  CREATE TABLE IF NOT EXISTS users (
    id       INTEGER PRIMARY KEY AUTOINCREMENT,
    name     TEXT NOT NULL,
    username TEXT UNIQUE NOT NULL COLLATE NOCASE,
    password TEXT NOT NULL,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS stories (
    id          INTEGER PRIMARY KEY AUTOINCREMENT,
    user_id     INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    title       TEXT NOT NULL DEFAULT 'Untitled Story',
    content     TEXT DEFAULT '{}',
    cover_image TEXT,
    updated_at  DATETIME DEFAULT CURRENT_TIMESTAMP,
    created_at  DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS images (
    id       INTEGER PRIMARY KEY AUTOINCREMENT,
    user_id  INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    filename TEXT NOT NULL,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );

  CREATE TABLE IF NOT EXISTS notes (
    id         INTEGER PRIMARY KEY AUTOINCREMENT,
    story_id   INTEGER NOT NULL REFERENCES stories(id) ON DELETE CASCADE,
    user_id    INTEGER NOT NULL REFERENCES users(id)   ON DELETE CASCADE,
    title      TEXT    NOT NULL DEFAULT 'Untitled Note',
    content    TEXT    DEFAULT '{}',
    updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );
`)

// Migrate: rename email -> username for existing databases
const userCols = db.pragma('table_info(users)').map(c => c.name)
if (userCols.includes('email') && !userCols.includes('username')) {
  db.exec('ALTER TABLE users RENAME COLUMN email TO username')
}

export default db