const Database = require('better-sqlite3');
const path = require('path');
const fs = require('fs');

// Lazy import for auditService — cannot require at top level due to circular dependency
// (auditService -> database.js -> auditService). Use getLogAudit() instead of logAudit directly.
let _logAudit = null;
function getLogAudit() {
  if (!_logAudit) {
    try { _logAudit = require('../services/auditService').logAudit; } catch { _logAudit = () => {}; }
  }
  return _logAudit;
}

const DB_PATH = process.env.DB_PATH || path.join(__dirname, 'bills.db');
const SCHEMA_PATH = path.join(__dirname, 'schema.sql');
const DEFAULT_CATEGORIES = [
  'Housing',
  'Utilities',
  'Credit Cards',
  'Food',
  'Loans',
  'Insurance',
  'Beauty',
  'Entertainment',
  'Subscriptions',
  'Pets',
  'Phone & Internet',
  'Transportation',
  'Medical',
  'Other',
];

// ── SQL Whitelist Mappings ────────────────────────────────────────────────────
// Security FIX (2026-05-08): Whitelist all allowed column names to prevent SQL injection
// in migrations that use dynamic ALTER TABLE statements.

const COLUMN_WHITELIST = new Set([
  // users table columns
  'active', 'is_default_admin', 'notification_email', 'notifications_enabled',
  'notify_3d', 'notify_1d', 'notify_due', 'notify_overdue', 'notify_amount_change',
  'display_name', 'last_password_change_at', 'auth_provider', 'external_subject',
  'email', 'last_login_at',
  // payments table columns
  'deleted_at', 'payment_source', 'transaction_id',
  // monthly_starting_amounts table columns
  'other_amount',
  // bills table columns
  'history_visibility', 'interest_rate', 'user_id',
  'current_balance', 'minimum_payment', 'snowball_order', 'snowball_include',
  'sort_order', 'snowball_exempt', 'is_subscription', 'subscription_type', 'reminder_days_before',
  'subscription_source', 'subscription_detected_at', 'deleted_at', 'drift_snoozed_until',
  // categories table columns
  'sort_order',
  // sessions table columns
  'created_at',
  // financial_accounts table columns
  'monitored',
]);

// Security validation function for column names
function isValidColumnName(col) {
  if (!col || typeof col !== 'string') return false;
  // Must be in whitelist AND match valid SQL identifier pattern
  return COLUMN_WHITELIST.has(col) && /^[a-z0-9_]+$/i.test(col);
}

// Security validation function for SQL definition fragments
function isValidSqlDefinition(def) {
  if (!def || typeof def !== 'string') return false;
  // Allow standard column definitions but reject any user input
  // This is safe because all definitions are hardcoded here
  return /^[\w\s\(\)\',!@#$%^&*+=\[\]<>\-.]+$/i.test(def);
}

// Subscription catalog seed rows live in their own module (pure data, no logic).
const { SUBSCRIPTION_CATALOG_ROWS, SUBSCRIPTION_CATALOG_V2_ROWS } = require('./subscriptionCatalogSeed');
// The versioned migration list lives in its own module (a factory injected with db + helpers).
const buildVersionedMigrations = require('./migrations/versionedMigrations');
// The legacy-reconcile migration list (same factory pattern, legacy DBs only).
const buildLegacyReconcileMigrations = require('./migrations/legacyReconcileMigrations');

function runSubscriptionCatalogV2Migration(database) {
  // Category fixes for existing rows
  database.prepare(`
    UPDATE subscription_catalog SET subscription_type = 'software'
    WHERE name = 'Discord Nitro' AND subscription_type = 'news'
  `).run();
  database.prepare(`
    UPDATE subscription_catalog SET subscription_type = 'streaming'
    WHERE name = 'Twitch Turbo' AND subscription_type = 'news'
  `).run();
  database.prepare(`
    UPDATE subscription_catalog SET subscription_type = 'software'
    WHERE name = 'X Premium' AND subscription_type = 'news'
  `).run();

  // New entries — skip any name already in the catalog
  const existing = new Set(
    database.prepare('SELECT name FROM subscription_catalog').all().map(r => r.name)
  );
  const toInsert = SUBSCRIPTION_CATALOG_V2_ROWS.filter(r => !existing.has(r[1]));
  if (toInsert.length > 0) {
    const insert = database.prepare(
      'INSERT INTO subscription_catalog (rank, name, category, subscription_type, website, domain) VALUES (?,?,?,?,?,?)'
    );
    const insertMany = database.transaction((rows) => {
      for (const row of rows) insert.run(...row);
    });
    insertMany(toInsert);
    console.log(`[migration] subscription_catalog v2: added ${toInsert.length} new entries`);
  }
}

function runAdvisoryFiltersMigration(database) {
  database.exec(`
    CREATE TABLE IF NOT EXISTS advisory_non_bill_filters (
      id TEXT PRIMARY KEY,
      pattern TEXT NOT NULL,
      confidence TEXT NOT NULL CHECK(confidence IN ('high', 'medium')),
      category TEXT NOT NULL,
      rationale TEXT
    );
    CREATE INDEX IF NOT EXISTS idx_advisory_filters_confidence
      ON advisory_non_bill_filters(confidence);

    CREATE TABLE IF NOT EXISTS advisory_bill_like_overrides (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      term TEXT NOT NULL UNIQUE
    );
  `);

  const filterCount = database.prepare('SELECT COUNT(*) as n FROM advisory_non_bill_filters').get();
  if (filterCount.n === 0) {
    const jsonPath = path.join(__dirname, '..', 'docs', 'advisory_non_bill_transaction_filters_us_ms_5000.json');
    const raw = fs.readFileSync(jsonPath, 'utf8');
    const data = JSON.parse(raw);

    const insertFilter = database.prepare(
      'INSERT INTO advisory_non_bill_filters (id, pattern, confidence, category, rationale) VALUES (?,?,?,?,?)'
    );
    const insertFilters = database.transaction((rows) => {
      for (const row of rows) {
        insertFilter.run(row.id, row.pattern, row.confidence, row.category, row.rationale || null);
      }
    });
    insertFilters(data.patterns || []);
    console.log(`[migration] advisory_non_bill_filters: seeded ${(data.patterns || []).length} rows`);

    const overrideTerms = data.bill_like_override_terms || [];
    if (overrideTerms.length > 0) {
      const insertOverride = database.prepare(
        'INSERT OR IGNORE INTO advisory_bill_like_overrides (term) VALUES (?)'
      );
      const insertOverrides = database.transaction((terms) => {
        for (const term of terms) insertOverride.run(term);
      });
      insertOverrides(overrideTerms);
      console.log(`[migration] advisory_bill_like_overrides: seeded ${overrideTerms.length} rows`);
    }
  }
}

function runMerchantStoreMatchMigration(database) {
  database.exec(`
    CREATE TABLE IF NOT EXISTS merchant_store_matches (
      id TEXT PRIMARY KEY,
      entry_kind TEXT NOT NULL,
      canonical_merchant_id TEXT NOT NULL,
      canonical_name TEXT NOT NULL,
      display_name TEXT NOT NULL,
      category TEXT NOT NULL,
      merchant_type TEXT,
      scope TEXT NOT NULL,
      priority INTEGER NOT NULL DEFAULT 0,
      match_patterns TEXT NOT NULL,
      negative_patterns TEXT,
      locality_city TEXT,
      locality_state TEXT
    );
    CREATE INDEX IF NOT EXISTS idx_merchant_store_matches_canonical
      ON merchant_store_matches(canonical_merchant_id);
  `);

  const count = database.prepare('SELECT COUNT(*) as n FROM merchant_store_matches').get();
  if (count.n === 0) {
    const jsonPath = path.join(__dirname, '..', 'docs', 'merchant_store_match_us_nems_online_5k_v0_2.json');
    const raw = fs.readFileSync(jsonPath, 'utf8');
    const data = JSON.parse(raw);

    const insertEntry = database.prepare(`
      INSERT INTO merchant_store_matches
        (id, entry_kind, canonical_merchant_id, canonical_name, display_name, category,
         merchant_type, scope, priority, match_patterns, negative_patterns,
         locality_city, locality_state)
      VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?)
    `);
    const insertEntries = database.transaction((rows) => {
      for (const row of rows) {
        insertEntry.run(
          row.id,
          row.entry_kind,
          row.canonical_merchant_id,
          row.canonical_name,
          row.display_name,
          row.category,
          row.merchant_type || null,
          row.scope,
          row.priority || 0,
          JSON.stringify(row.match_patterns || []),
          JSON.stringify(row.negative_patterns || []),
          row.locality?.city || null,
          row.locality?.state || null,
        );
      }
    });
    insertEntries(data.merchant_store_entries || []);
    console.log(`[migration] merchant_store_matches: seeded ${(data.merchant_store_entries || []).length} rows`);
  }
}

function runSubscriptionCatalogMigration(database) {
  database.exec(`
    CREATE TABLE IF NOT EXISTS subscription_catalog (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      rank INTEGER NOT NULL,
      name TEXT NOT NULL,
      category TEXT NOT NULL,
      subscription_type TEXT NOT NULL,
      website TEXT,
      domain TEXT,
      created_at TEXT NOT NULL DEFAULT (datetime('now'))
    );
    CREATE INDEX IF NOT EXISTS idx_subscription_catalog_rank ON subscription_catalog(rank);
    CREATE INDEX IF NOT EXISTS idx_subscription_catalog_type ON subscription_catalog(subscription_type);
  `);

  const existing = database.prepare('SELECT COUNT(*) as n FROM subscription_catalog').get();
  if (existing.n === 0) {
    const insert = database.prepare(
      'INSERT INTO subscription_catalog (rank, name, category, subscription_type, website, domain) VALUES (?,?,?,?,?,?)'
    );
    const insertMany = database.transaction((rows) => {
      for (const row of rows) insert.run(...row);
    });
    insertMany(SUBSCRIPTION_CATALOG_ROWS);
    console.log(`[migration] subscription_catalog: seeded ${SUBSCRIPTION_CATALOG_ROWS.length} rows`);
  }
}

function seedManualDataSources(database = db) {
  if (!database) return;
  const hasDataSources = database.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='data_sources'").get();
  const hasUsers = database.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='users'").get();
  if (!hasDataSources || !hasUsers) return;

  database.exec(`
    INSERT INTO data_sources (user_id, type, provider, name, status)
    SELECT u.id, 'manual', 'manual', 'Manual Entry', 'active'
    FROM users u
    WHERE NOT EXISTS (
      SELECT 1
      FROM data_sources ds
      WHERE ds.user_id = u.id
        AND ds.type = 'manual'
        AND ds.provider = 'manual'
    )
  `);
}

function ensureTransactionFoundationSchema(database = db) {
  database.exec(`
    CREATE TABLE IF NOT EXISTS data_sources (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
      type TEXT NOT NULL,
      provider TEXT,
      name TEXT NOT NULL,
      status TEXT NOT NULL DEFAULT 'active',
      config_json TEXT,
      encrypted_secret TEXT,
      last_sync_at TEXT,
      last_error TEXT,
      created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
      updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
    );

    CREATE TABLE IF NOT EXISTS financial_accounts (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
      data_source_id INTEGER,
      provider_account_id TEXT,
      name TEXT NOT NULL,
      org_name TEXT,
      account_type TEXT,
      currency TEXT,
      balance INTEGER,
      available_balance INTEGER,
      monitored INTEGER NOT NULL DEFAULT 1,
      raw_data TEXT,
      created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
      updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,

      FOREIGN KEY (data_source_id) REFERENCES data_sources(id) ON DELETE SET NULL,
      UNIQUE(data_source_id, provider_account_id)
    );

    CREATE TABLE IF NOT EXISTS transactions (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
      data_source_id INTEGER,
      account_id INTEGER,
      provider_transaction_id TEXT,
      source_type TEXT NOT NULL,
      transaction_type TEXT,
      posted_date TEXT,
      transacted_at TEXT,
      amount INTEGER NOT NULL,
      currency TEXT,
      description TEXT,
      payee TEXT,
      memo TEXT,
      category TEXT,
      raw_data TEXT,
      matched_bill_id INTEGER,
      match_status TEXT NOT NULL DEFAULT 'unmatched',
      ignored INTEGER NOT NULL DEFAULT 0,
      created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
      updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,

      FOREIGN KEY (data_source_id) REFERENCES data_sources(id) ON DELETE SET NULL,
      FOREIGN KEY (account_id) REFERENCES financial_accounts(id) ON DELETE SET NULL,
      FOREIGN KEY (matched_bill_id) REFERENCES bills(id) ON DELETE SET NULL
    );

    CREATE INDEX IF NOT EXISTS idx_data_sources_user_type ON data_sources(user_id, type, status);
    CREATE UNIQUE INDEX IF NOT EXISTS idx_data_sources_user_manual
      ON data_sources(user_id, type, provider)
      WHERE type = 'manual' AND provider = 'manual';
    CREATE INDEX IF NOT EXISTS idx_financial_accounts_user_source ON financial_accounts(user_id, data_source_id);
    CREATE INDEX IF NOT EXISTS idx_transactions_user_date ON transactions(user_id, posted_date, transacted_at);
    CREATE INDEX IF NOT EXISTS idx_transactions_user_match ON transactions(user_id, match_status, ignored);
    CREATE INDEX IF NOT EXISTS idx_transactions_account ON transactions(account_id);
    CREATE INDEX IF NOT EXISTS idx_transactions_matched_bill ON transactions(matched_bill_id);
    CREATE UNIQUE INDEX IF NOT EXISTS idx_transactions_provider_dedupe
      ON transactions (data_source_id, provider_transaction_id)
      WHERE provider_transaction_id IS NOT NULL;
  `);

  seedManualDataSources(database);
}

fs.mkdirSync(path.dirname(DB_PATH), { recursive: true });

let db = null;
let initializing = false;

// Populated by runMigrations() so reconcileLegacyMigrations() can assert
// its own version list matches. Catches drift between the two arrays at startup
// on any legacy-DB upgrade path, rather than silently misconfiguring the schema.
let _runMigrationVersions = null;

function assertWritableDbPath() {
  const dir = path.dirname(DB_PATH);
  const probe = path.join(dir, `.write-test-${process.pid}-${Date.now()}`);

  try {
    fs.mkdirSync(dir, { recursive: true });
    fs.writeFileSync(probe, 'ok');
    fs.unlinkSync(probe);

    if (fs.existsSync(DB_PATH)) {
      fs.accessSync(DB_PATH, fs.constants.R_OK | fs.constants.W_OK);
    }
  } catch (err) {
    const message = [
      `Database path is not writable: ${DB_PATH}`,
      `Ensure the DB directory is writable by the app user. In Docker, rebuild the image and recreate the container so the entrypoint can chown /data.`,
      `Original error: ${err.message}`,
    ].join('\n');
    const wrapped = new Error(message);
    wrapped.code = err.code;
    throw wrapped;
  } finally {
    try {
      if (fs.existsSync(probe)) fs.unlinkSync(probe);
    } catch {}
  }
}

function getDb() {
  // already ready
  if (db) return db;

  // Node is single-threaded and initialization below is fully synchronous, so
  // the only way to observe `initializing === true` here is a re-entrant call
  // from inside init itself (e.g. a migration requiring a module that calls
  // getDb() at load time). Blocking/spinning can never resolve that — it would
  // deadlock the process — so fail fast with a clear message instead.
  if (initializing) {
    throw new Error('getDb() called re-entrantly during database initialization');
  }

  initializing = true;

  try {
    console.log('Opening DB at:', path.basename(DB_PATH));
    assertWritableDbPath();

    db = new Database(DB_PATH, {
      timeout: 5000
    });

    db.pragma('busy_timeout = 5000');

    try {
      db.pragma('journal_mode = WAL');
    } catch (e) {
      console.warn('WAL failed:', e.message);
    }

    db.pragma('foreign_keys = ON');

    initSchema();
    seedDefaults();

    console.log('DB initialized successfully');

    return db;
  } catch (err) {
    console.error('DB init failed:', err);
    throw err;
  } finally {
    initializing = false;
  }
}

function initSchema() {
  const schema = fs.readFileSync(SCHEMA_PATH, 'utf8');
  db.exec(schema);
  
  // Create schema_migrations table for tracking applied migrations
  db.exec(`
    CREATE TABLE IF NOT EXISTS schema_migrations (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      version TEXT NOT NULL UNIQUE,
      description TEXT NOT NULL,
      applied_at TEXT NOT NULL DEFAULT (datetime('now'))
    )
  `);
  
  // Check if this is a legacy database (tables exist but no migration tracking)
  handleLegacyDatabase();
  
  // After legacy reconciliation and user seeding, reset the default admin password
  // when INIT_ADMIN_PASS is set. This ensures legacy DBs can be accessed after migration.
  // The must_change_password flag forces the admin to pick a new password on first login.
  if (process.env.INIT_ADMIN_PASS) {
    const initUser = process.env.INIT_ADMIN_USER || 'admin';
    const initPass = process.env.INIT_ADMIN_PASS;
    const bcrypt = require('bcryptjs');
    const newPasswordHash = bcrypt.hashSync(initPass, 12);
    
    // Reset password for the default admin user if INIT_ADMIN_PASS is set
    const result = db.prepare(`
      UPDATE users SET password_hash = ?, first_login = 0, must_change_password = 0 
      WHERE username = ? AND is_default_admin = 1
    `).run(newPasswordHash, initUser);
    
    if (result.changes > 0) {
      console.log('[init] Reset password and flags for default admin user');
    }
  }
  
  runMigrations();
}

function hasMigrationBeenApplied(version) {
  const stmt = db.prepare('SELECT 1 FROM schema_migrations WHERE version = ?');
  return !!stmt.get(version);
}

function handleLegacyDatabase() {
  // Check if schema_migrations table exists but is empty
  // This indicates a legacy database that predates migration tracking
  const migrationCount = db.prepare('SELECT COUNT(*) as count FROM schema_migrations').get().count;
  
  if (migrationCount === 0) {
    // This might be a legacy database. Check if core tables exist.
    const tableCheck = db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name IN ('users', 'bills', 'payments', 'categories', 'settings')").all();
    
    // If we have core tables but no migrations tracked, this is likely a legacy DB
    if (tableCheck.length >= 3) { // At least some core tables exist
      console.log('[migration] Detected legacy database, reconciling schema migrations...');
      
      // For each migration, check if its changes are already present and mark as applied if so
      reconcileLegacyMigrations();
    }
  }
}

function reconcileLegacyMigrations() {
  // Define all migrations with explicit version tracking
  const migrations = buildLegacyReconcileMigrations({
    db,
    isValidColumnName,
    isValidSqlDefinition,
    ensureTransactionFoundationSchema,
    runSubscriptionCatalogMigration,
    runSubscriptionCatalogV2Migration,
    runAdvisoryFiltersMigration,
    runMerchantStoreMatchMigration,
  });

  // Check for legacy notification columns
  const userCols = db.prepare('PRAGMA table_info(users)').all().map(c => c.name);
  const newUserCols = [
    'active', 'is_default_admin', 'notification_email', 'notifications_enabled',
    'notify_3d', 'notify_1d', 'notify_due', 'notify_overdue'
  ];
  const hasNotificationColumns = newUserCols.every(col => userCols.includes(col));
  
  // If notification columns exist, mark that migration as applied
  if (hasNotificationColumns) {
    try {
      recordMigration('legacy-notification-columns', 'users: notification columns');
      console.log('[migration] Recorded legacy notification columns migration');
    } catch (e) {
      // Ignore if already recorded
    }
  }
  
  // Assert version sync with runMigrations() to catch drift between the two arrays.
  // runMigrations() always runs first and populates _runMigrationVersions.
  if (_runMigrationVersions !== null) {
    const reconcileVersions = migrations.map(m => m.version);
    const runSet        = new Set(_runMigrationVersions);
    const reconcileSet  = new Set(reconcileVersions);
    const onlyInRun     = _runMigrationVersions.filter(v => !reconcileSet.has(v));
    const onlyInReconcile = reconcileVersions.filter(v => !runSet.has(v));
    if (onlyInRun.length || onlyInReconcile.length) {
      const msg =
        '[migration-sync] reconcileLegacyMigrations and runMigrations version lists are out of sync.' +
        (onlyInRun.length      ? ` Only in runMigrations: ${onlyInRun.join(', ')}.`      : '') +
        (onlyInReconcile.length ? ` Only in reconcile: ${onlyInReconcile.join(', ')}.` : '') +
        ' Add the missing version to both arrays.';
      console.error(msg);
      throw new Error(msg);
    }
  }

  // Process all versioned migrations
  for (const migration of migrations) {
    if (migration.check()) {
      try {
        recordMigration(migration.version, migration.description);
        console.log(`[migration] Recorded legacy migration ${migration.version}: ${migration.description}`);
      } catch (e) {
        // Ignore if already recorded
      }
    } else {
      // Migration changes are NOT present - run the migration to apply them
      try {
        console.log(`[migration] Running legacy migration ${migration.version}: ${migration.description}`);
        // Wrap legacy migration in transaction
        db.exec('BEGIN');
        console.log(`[migration] Transaction BEGIN for legacy ${migration.version}`);
        migration.run();
        recordMigration(migration.version, migration.description);
        db.exec('COMMIT');
        console.log(`[migration] Transaction COMMIT for legacy ${migration.version}`);
      } catch (err) {
        db.exec('ROLLBACK');
        console.error(`[migration-error] Failed to apply legacy migration ${migration.version}: ${err.message}. Rolled back.`);
        throw err;
      }
    }
  }
  
  console.log('[migration] Legacy database reconciliation complete');
}

function recordMigration(version, description) {
  const stmt = db.prepare('INSERT INTO schema_migrations (version, description) VALUES (?, ?)');
  stmt.run(version, description);
  console.log(`[migration] Applied ${version}: ${description}`);
}

function validateMigrationDependencies(migration, appliedVersions) {
  // Validate that all dependencies for a migration have been applied
  const deps = migration.dependsOn || [];
  const missing = deps.filter(dep => !appliedVersions.has(dep));
  if (missing.length === 0) {
    return { valid: true };
  }
  return { valid: false, missing };
}

function runMigrations() {
  console.log('[migration] Starting database migrations');
  const startTime = Date.now();
  
  
  // Log start of migrations to audit log
  try {
    getLogAudit()({
      action: 'migration.start',
      entity_type: 'migration',
      entity_id: null,
      details: { message: 'Starting database migrations' }
    });
  } catch (auditErr) {
    console.error(`[audit-error] Failed to log migration start to audit log: ${auditErr.message}`);
  }
  // Define all migrations with explicit version tracking and dependency chains
  const migrations = buildVersionedMigrations({
    db,
    isValidColumnName,
    isValidSqlDefinition,
    ensureTransactionFoundationSchema,
    runSubscriptionCatalogMigration,
    runSubscriptionCatalogV2Migration,
    runAdvisoryFiltersMigration,
    runMerchantStoreMatchMigration,
  });

  // ── users: notification columns ───────────────────────────────────────────
  // This migration needs to run first since it's not versioned in the schema
  console.log('[migration] Applying unversioned user notification columns');
  const unversionedStartTime = Date.now();
  
  try {
    db.exec('BEGIN');
    console.log('[migration] Transaction BEGIN for unversioned user notification columns');
    const userCols = db.prepare('PRAGMA table_info(users)').all().map(c => c.name);
    const newUserCols = [
      ['active',                'INTEGER NOT NULL DEFAULT 1'],
      ['is_default_admin',      'INTEGER NOT NULL DEFAULT 0'],
      ['notification_email',    'TEXT'],
      ['notifications_enabled', 'INTEGER NOT NULL DEFAULT 0'],
      ['notify_3d',             'INTEGER NOT NULL DEFAULT 1'],
      ['notify_1d',             'INTEGER NOT NULL DEFAULT 1'],
      ['notify_due',            'INTEGER NOT NULL DEFAULT 1'],
      ['notify_overdue',        'INTEGER NOT NULL DEFAULT 1'],
    ];
    for (const [col, def] of newUserCols) {
      if (!userCols.includes(col)) {
        // Security FIX (2026-05-08): Validate column name and definition to prevent SQL injection
        if (!isValidColumnName(col) || !isValidSqlDefinition(def)) {
          throw new Error(`Invalid migration: column '${col}' not in whitelist`);
        }
        db.exec(`ALTER TABLE users ADD COLUMN ${col} ${def}`);
      }
    }
    const defaultAdminName = process.env.INIT_ADMIN_USER || 'admin';
    db.prepare(`
      UPDATE users
      SET is_default_admin = 1
      WHERE role = 'admin'
        AND username = ?
        AND NOT EXISTS (SELECT 1 FROM users WHERE is_default_admin = 1)
    `).run(defaultAdminName);
    db.exec(`
      UPDATE users
      SET is_default_admin = 1
      WHERE id = (
        SELECT id FROM users
        WHERE role = 'admin'
        ORDER BY id
        LIMIT 1
      )
        AND NOT EXISTS (SELECT 1 FROM users WHERE is_default_admin = 1)
    `);
    db.exec('COMMIT');
    console.log('[migration] Transaction COMMIT for unversioned user notification columns');
    
    // Log successful completion with timing
    const elapsed = Date.now() - unversionedStartTime;
    console.log(`[migration] Unversioned user notification columns completed in ${elapsed}ms`);
  } catch (err) {
    db.exec('ROLLBACK');
    const elapsed = Date.now() - unversionedStartTime;
    console.error(`[migration-error] Failed to apply unversioned user notification columns after ${elapsed}ms: ${err.message}. Rolled back.`);
    
    // Log migration failure to audit log (only safe after initSchema completes)
    try {
      getLogAudit()({
        action: 'migration.failure',
        entity_type: 'migration',
        entity_id: null,
        details: {
          version: 'unversioned-user-notification-columns',
          description: 'users: notification columns',
          error: err.message,
          elapsed_ms: elapsed
        }
      });
    } catch (auditErr) {
      console.error(`[audit-error] Failed to log migration failure to audit log: ${auditErr.message}`);
    }
    
    throw err;
  }
  
  // Store version list so reconcileLegacyMigrations() can assert sync.
  _runMigrationVersions = migrations.map(m => m.version);

  // Build set of already-applied versions for dependency checking
  const appliedVersions = new Set(
    db.prepare('SELECT version FROM schema_migrations').all().map(r => r.version)
  );

  // Process all versioned migrations
  for (const migration of migrations) {
    if (!hasMigrationBeenApplied(migration.version)) {
      // Validate dependencies before applying
      const depCheck = validateMigrationDependencies(migration, appliedVersions);
      if (!depCheck.valid) {
        console.error(`[migration-error] ${migration.version} depends on [${depCheck.missing.join(', ')}] which have not been applied. Skipping.`);
        continue;
      }

      console.log(`[migration] Applying ${migration.version}: ${migration.description}`);
      if (migration.dependsOn && migration.dependsOn.length > 0) {
        console.log(`[migration] ${migration.version} depends on [${migration.dependsOn.join(', ')}] — satisfied`);
      }
      
      // Timing for migration execution
      const migrationStartTime = Date.now();
      
      try {
        // Special handling for v0.40 migration which uses PRAGMA statements
        if (migration.version === 'v0.40') {
          // PRAGMA foreign_keys cannot run inside a transaction, so we
          // disable FK checks before BEGIN and re-enable in a finally block
          // to guarantee FK is always restored even on failure.
          const billCols = db.prepare('PRAGMA table_info(bills)').all().map(c => c.name);
          const categoryCols = db.prepare('PRAGMA table_info(categories)').all().map(c => c.name);
          const needsForeignKeyOff = !billCols.includes('user_id') || !categoryCols.includes('user_id');
          
          if (needsForeignKeyOff) {
            db.exec('PRAGMA foreign_keys = OFF');
          }
          try {
            db.exec('BEGIN');
            console.log(`[migration] Transaction BEGIN for ${migration.version}`);
            migration.run();
            recordMigration(migration.version, migration.description);
            db.exec('COMMIT');
            console.log(`[migration] Transaction COMMIT for ${migration.version}`);
            
            // Log successful completion with timing
            const elapsed = Date.now() - migrationStartTime;
            console.log(`[migration] ${migration.version} completed in ${elapsed}ms`);
            appliedVersions.add(migration.version);
          } catch (innerErr) {
            db.exec('ROLLBACK');
            const elapsed = Date.now() - migrationStartTime;
            console.error(`[migration-error] ${migration.version} failed after ${elapsed}ms: ${innerErr.message}. Rolled back.`);
            
            // Log migration failure to audit log (only safe after initSchema completes)
            try {
              getLogAudit()({
                action: 'migration.failure',
                entity_type: 'migration',
                entity_id: null,
                details: {
                  version: migration.version,
                  description: migration.description,
                  error: innerErr.message,
                  elapsed_ms: elapsed
                }
              });
            } catch (auditErr) {
              console.error(`[audit-error] Failed to log migration failure to audit log: ${auditErr.message}`);
            }
            
            throw innerErr;
          } finally {
            // Always restore FK checks — even on failure path
            if (needsForeignKeyOff) {
              db.exec('PRAGMA foreign_keys = ON');
            }
          }
        } else {
          // Standard transaction wrapping for other migrations
          db.exec('BEGIN');
          console.log(`[migration] Transaction BEGIN for ${migration.version}`);
          migration.run();
          recordMigration(migration.version, migration.description);
          db.exec('COMMIT');
          console.log(`[migration] Transaction COMMIT for ${migration.version}`);
          
          // Log successful completion with timing
          const elapsed = Date.now() - migrationStartTime;
          console.log(`[migration] ${migration.version} completed in ${elapsed}ms`);
          appliedVersions.add(migration.version);
        }
      } catch (err) {
        db.exec('ROLLBACK');
        const elapsed = Date.now() - migrationStartTime;
        console.error(`[migration-error] Failed to apply ${migration.version} after ${elapsed}ms: ${err.message}. Rolled back.`);
        
        // Log migration failure to audit log (only safe after initSchema completes)
        try {
          getLogAudit()({
            action: 'migration.failure',
            entity_type: 'migration',
            entity_id: null,
            details: {
              version: migration.version,
              description: migration.description,
              error: err.message,
              elapsed_ms: elapsed
            }
          });
        } catch (auditErr) {
          console.error(`[audit-error] Failed to log migration failure to audit log: ${auditErr.message}`);
        }
        
        throw err;
      }
    } else {
      console.log(`[migration] Skipping already applied ${migration.version}: ${migration.description}`);
    }
  }
  
  // Log total migration time
  
  // Log completion of all migrations to audit log
  try {
    getLogAudit()({
      action: 'migration.complete',
      entity_type: 'migration',
      entity_id: null,
      details: {
        total_time_ms: Date.now() - startTime,
        message: 'All migrations completed successfully'
      }
    });
  } catch (auditErr) {
    console.error(`[audit-error] Failed to log migration completion to audit log: ${auditErr.message}`);
  }
  const totalTime = Date.now() - startTime;
  console.log(`[migration] All migrations completed in ${totalTime}ms`);
  
  // All migrations are now versioned
}

function seedDefaults() {
  const defaults = [
    ['currency', 'USD'],
    ['date_format', 'MM/DD/YYYY'],
    ['grace_period_days', '5'],
    ['notify_days_before', '3'],
    ['backup_enabled', 'false'],
    ['backup_frequency_days', '1'],
    ['backup_keep_count', '14'],
    ['backup_path', process.env.BACKUP_PATH || path.join(__dirname, '..', 'backups')],
    ['backup_schedule_enabled', 'false'],
    ['backup_schedule_frequency', 'daily'],
    ['backup_schedule_time', '02:00'],
    ['backup_schedule_retention_count', '2'],
    ['backup_schedule_last_run_at', ''],
    ['backup_schedule_last_error', ''],
    ['auth_mode', 'multi'],
    ['default_user_id', ''],
    ['notify_smtp_enabled', 'false'],
    ['notify_sender_name', 'Bill Tracker'],
    ['notify_sender_address', ''],
    ['notify_smtp_host', ''],
    ['notify_smtp_port', '587'],
    ['notify_smtp_encryption', 'starttls'],
    ['notify_smtp_self_signed', 'false'],
    ['notify_smtp_username', ''],
    ['notify_smtp_password', ''],
    ['notify_allow_user_config', 'false'],
    ['notify_global_recipient', ''],
    // Cleanup worker settings (v0.15)
    ['cleanup_import_sessions_enabled',     'true'],
    ['cleanup_temp_exports_enabled',        'true'],
    ['cleanup_temp_export_max_age_hours',   '2'],
    ['cleanup_backup_partials_enabled',     'true'],
    ['cleanup_import_history_enabled',      'false'],
    ['cleanup_import_history_max_age_days', '365'],
    ['cleanup_last_run_at',  ''],
    ['cleanup_last_result',  ''],
    // Auth method settings (v0.18)
    ['local_login_enabled',  'true'],
    ['oidc_login_enabled',   'false'],
    ['oidc_provider_name',   'authentik'],
    ['oidc_issuer_url',      ''],
    ['oidc_client_id',       ''],
    ['oidc_client_secret',   ''],
    ['oidc_token_auth_method', 'client_secret_basic'],
    ['oidc_redirect_uri',    ''],
    ['oidc_scopes',          'openid email profile groups'],
    ['oidc_auto_provision',  'true'],
    ['oidc_admin_group',     ''],
    ['oidc_default_role',    'user'],
    // Privacy settings (v0.94)
    ['geolocation_enabled',  'false'],
  ];

  const insert = db.prepare(
    'INSERT OR IGNORE INTO settings (key, value) VALUES (?, ?)'
  );

  for (const [key, value] of defaults) {
    insert.run(key, value);
  }

  // Category defaults are user-scoped. They are applied by
  // ensureUserDefaultCategories(userId) when user-owned category/bill data is read.

  // ── Create initial admin user if none exists ─────────────────────────────
  const userCount = db.prepare('SELECT COUNT(*) as cnt FROM users').get().cnt;
  if (userCount === 0) {
    const initUser = process.env.INIT_ADMIN_USER || 'admin';
    const initPass = process.env.INIT_ADMIN_PASS || 'admin123';
    // Use bcryptjs sync for database init (safe, runs once at startup)
    const bcrypt = require('bcryptjs');
    const password_hash = bcrypt.hashSync(initPass, 12);
    db.prepare(`
      INSERT INTO users (username, password_hash, role, is_default_admin, active, email, created_at, updated_at)
      VALUES (?, ?, 'admin', 1, 1, ?, datetime('now'), datetime('now'))
    `).run(initUser, password_hash, initUser + '@local');
    console.log(`[seed] Created initial admin user: ${initUser}`);
  }

  seedManualDataSources(db);
}

function ensureUserDefaultCategories(userId) {
  const db = getDb();
  const insert = db.prepare('INSERT INTO categories (user_id, name) VALUES (?, ?)');
  for (const name of DEFAULT_CATEGORIES) {
    const existing = db.prepare('SELECT id FROM categories WHERE user_id = ? AND name = ? COLLATE NOCASE')
      .get(userId, name);
    if (!existing) insert.run(userId, name);
  }
}

function getSetting(key) {
  const db = getDb();
  const row = db.prepare('SELECT value FROM settings WHERE key = ?').get(key);
  return row ? row.value : null;
}

function setSetting(key, value) {
  const db = getDb();
  db.prepare(
    "INSERT OR REPLACE INTO settings (key, value, updated_at) VALUES (?, ?, datetime('now'))"
  ).run(key, String(value));
}

function closeDb() {
  if (!db) return;
  db.close();
  db = null;
}

function getDbPath() {
  return DB_PATH;
}

// Rollback SQL definitions
const ROLLBACK_SQL_MAP = {
  'v1.04': {
    description: 'bill_templates.data JSON: money fields dollars -> integer cents',
    sql: [
      "UPDATE bill_templates SET data = json_set(data, '$.expected_amount', ROUND(json_extract(data, '$.expected_amount') / 100.0, 2)) WHERE json_extract(data, '$.expected_amount') IS NOT NULL",
      "UPDATE bill_templates SET data = json_set(data, '$.current_balance', ROUND(json_extract(data, '$.current_balance') / 100.0, 2)) WHERE json_extract(data, '$.current_balance') IS NOT NULL",
      "UPDATE bill_templates SET data = json_set(data, '$.minimum_payment', ROUND(json_extract(data, '$.minimum_payment') / 100.0, 2)) WHERE json_extract(data, '$.minimum_payment') IS NOT NULL",
    ]
  },
  'v1.03': {
    description: 'money columns: dollars (REAL) -> integer cents',
    sql: [
      'UPDATE bills SET expected_amount = ROUND(expected_amount / 100.0, 2) WHERE expected_amount IS NOT NULL',
      'UPDATE bills SET current_balance = ROUND(current_balance / 100.0, 2) WHERE current_balance IS NOT NULL',
      'UPDATE bills SET minimum_payment = ROUND(minimum_payment / 100.0, 2) WHERE minimum_payment IS NOT NULL',
      'UPDATE payments SET amount = ROUND(amount / 100.0, 2) WHERE amount IS NOT NULL',
      'UPDATE payments SET balance_delta = ROUND(balance_delta / 100.0, 2) WHERE balance_delta IS NOT NULL',
      'UPDATE payments SET interest_delta = ROUND(interest_delta / 100.0, 2) WHERE interest_delta IS NOT NULL',
      'UPDATE monthly_bill_state SET actual_amount = ROUND(actual_amount / 100.0, 2) WHERE actual_amount IS NOT NULL',
      'UPDATE monthly_starting_amounts SET first_amount = ROUND(first_amount / 100.0, 2) WHERE first_amount IS NOT NULL',
      'UPDATE monthly_starting_amounts SET fifteenth_amount = ROUND(fifteenth_amount / 100.0, 2) WHERE fifteenth_amount IS NOT NULL',
      'UPDATE monthly_starting_amounts SET other_amount = ROUND(other_amount / 100.0, 2) WHERE other_amount IS NOT NULL',
      'UPDATE monthly_income SET amount = ROUND(amount / 100.0, 2) WHERE amount IS NOT NULL',
      'UPDATE spending_budgets SET amount = ROUND(amount / 100.0, 2) WHERE amount IS NOT NULL',
      'UPDATE snowball_plans SET extra_payment = ROUND(extra_payment / 100.0, 2) WHERE extra_payment IS NOT NULL',
      'UPDATE users SET snowball_extra_payment = ROUND(snowball_extra_payment / 100.0, 2) WHERE snowball_extra_payment IS NOT NULL',
    ]
  },
  'v0.98': {
    description: 'payments: bank override metadata for provisional manual payments',
    sql: [
      'DROP INDEX IF EXISTS idx_payments_overridden_by',
      'DROP INDEX IF EXISTS idx_payments_accounting_active',
      'ALTER TABLE payments DROP COLUMN IF EXISTS overridden_by_payment_id',
      'ALTER TABLE payments DROP COLUMN IF EXISTS excluded_at',
      'ALTER TABLE payments DROP COLUMN IF EXISTS exclusion_reason',
      'ALTER TABLE payments DROP COLUMN IF EXISTS accounting_excluded',
    ]
  },
  'v0.97': {
    description: 'subscription recommendation feedback: per-user learning signals',
    sql: [
      'DROP TABLE IF EXISTS subscription_recommendation_feedback',
    ]
  },
  'v0.96': {
    description: 'bills: catalog_id FK; user_catalog_descriptors',
    sql: [
      'DROP TABLE IF EXISTS user_catalog_descriptors',
      'ALTER TABLE bills DROP COLUMN IF EXISTS catalog_id',
    ]
  },
  'v0.95': {
    description: 'subscription_catalog: bank descriptors + pricing',
    sql: [
      'DROP TABLE IF EXISTS subscription_catalog_descriptors',
    ]
  },
  'v0.94': {
    description: 'security: session token hashing + geolocation opt-in setting',
    sql: [
      "DELETE FROM settings WHERE key = 'geolocation_enabled'",
      // Sessions were cleared; rollback cannot restore them
    ]
  },
  'v0.93': {
    description: 'bills: interest_accrued_month; payments: interest_delta; transactions: stable provider key',
    sql: [
      'ALTER TABLE bills    DROP COLUMN IF EXISTS interest_accrued_month',
      'ALTER TABLE payments DROP COLUMN IF EXISTS interest_delta',
      // Restore the old (data_source_id, provider_transaction_id) dedupe index.
      // The key format change and deleted duplicates cannot be reversed.
      'DROP INDEX IF EXISTS idx_transactions_provider_dedupe',
      `CREATE UNIQUE INDEX IF NOT EXISTS idx_transactions_provider_dedupe
         ON transactions (data_source_id, provider_transaction_id)
         WHERE provider_transaction_id IS NOT NULL`,
    ]
  },
  'v0.44': {
    description: 'performance: add missing indexes for frequently queried columns',
    sql: [
      'DROP INDEX IF EXISTS idx_bills_user_name',
      'DROP INDEX IF EXISTS idx_payments_method',
      'DROP INDEX IF EXISTS idx_monthly_starting_amounts_user',
      'DROP INDEX IF EXISTS idx_import_history_imported_at'
    ]
  },
  'v0.45': {
    description: 'audit: add audit_log table for security event tracking',
    sql: [
      'DROP INDEX IF EXISTS idx_audit_log_user',
      'DROP INDEX IF EXISTS idx_audit_log_action',
      'DROP TABLE IF EXISTS audit_log'
    ]
  },
  'v0.46': {
    description: 'billing: add cycle_type and cycle_day columns to bills',
    sql: [
      'ALTER TABLE bills DROP COLUMN cycle_day',
      'ALTER TABLE bills DROP COLUMN cycle_type'
    ]
  },
  'v0.47': {
    description: 'settings: reset backup_schedule_retention_count default from 14 to 2',
    sql: [
      "UPDATE settings SET value = '14' WHERE key = 'backup_schedule_retention_count' AND value = '2'"
    ]
  },
  'v0.48': {
    description: 'bills: debt snowball fields',
    sql: [
      'ALTER TABLE bills DROP COLUMN snowball_include',
      'ALTER TABLE bills DROP COLUMN snowball_order',
      'ALTER TABLE bills DROP COLUMN minimum_payment',
      'ALTER TABLE bills DROP COLUMN current_balance',
    ]
  },
  'v0.49': {
    description: 'users: snowball extra payment field',
    sql: ['ALTER TABLE users DROP COLUMN snowball_extra_payment']
  },
  'v0.50': {
    description: 'payments: balance_delta column',
    sql: ['ALTER TABLE payments DROP COLUMN balance_delta']
  },
  'v0.59': {
    description: 'payments: source metadata columns',
    sql: [
      'ALTER TABLE payments DROP COLUMN transaction_id',
      'ALTER TABLE payments DROP COLUMN payment_source',
    ]
  },
  'v0.60': {
    description: 'transactions: shared transaction foundation tables',
    sql: [
      'DROP INDEX IF EXISTS idx_transactions_provider_dedupe',
      'DROP INDEX IF EXISTS idx_transactions_matched_bill',
      'DROP INDEX IF EXISTS idx_transactions_account',
      'DROP INDEX IF EXISTS idx_transactions_user_match',
      'DROP INDEX IF EXISTS idx_transactions_user_date',
      'DROP INDEX IF EXISTS idx_financial_accounts_user_source',
      'DROP INDEX IF EXISTS idx_data_sources_user_manual',
      'DROP INDEX IF EXISTS idx_data_sources_user_type',
      'DROP TABLE IF EXISTS transactions',
      'DROP TABLE IF EXISTS financial_accounts',
      'DROP TABLE IF EXISTS data_sources',
    ]
  },
  'v0.61': {
    description: 'payments: one active payment per linked transaction',
    sql: ['DROP INDEX IF EXISTS idx_payments_transaction_active']
  },
  'v0.62': {
    description: 'matches: rejected transaction match suggestions',
    sql: [
      'DROP INDEX IF EXISTS idx_match_suggestion_rejections_user',
      'DROP TABLE IF EXISTS match_suggestion_rejections',
    ]
  },
  'v0.63': {
    description: 'bills: subscription metadata fields',
    sql: [
      'DROP INDEX IF EXISTS idx_bills_user_subscription',
      'ALTER TABLE bills DROP COLUMN subscription_detected_at',
      'ALTER TABLE bills DROP COLUMN subscription_source',
      'ALTER TABLE bills DROP COLUMN reminder_days_before',
      'ALTER TABLE bills DROP COLUMN subscription_type',
      'ALTER TABLE bills DROP COLUMN is_subscription',
    ]
  },
  'v0.72': {
    description: 'bills: persistent tracker sort order',
    sql: [
      'DROP INDEX IF EXISTS idx_bills_user_sort',
      'ALTER TABLE bills DROP COLUMN sort_order',
    ]
  },
  'v0.75': {
    description: 'categories: persistent sort order',
    sql: [
      'DROP INDEX IF EXISTS idx_categories_user_sort',
      'ALTER TABLE categories DROP COLUMN sort_order',
    ]
  },
  'v0.76': {
    description: 'bills: canonical billing schedule cleanup',
    sql: [
      `UPDATE bills
       SET billing_cycle = CASE
         WHEN cycle_type = 'quarterly' THEN 'quarterly'
         WHEN cycle_type = 'annual' THEN 'annually'
         WHEN cycle_type IN ('weekly', 'biweekly') THEN 'irregular'
         ELSE 'monthly'
       END`,
    ]
  },
  'v0.51': {
    description: 'bills: snowball_exempt column',
    sql: ['ALTER TABLE bills DROP COLUMN snowball_exempt']
  },
  'v0.52': {
    description: 'users: last_seen_version column',
    sql: ['ALTER TABLE users DROP COLUMN last_seen_version']
  },
  'v0.53': {
    description: 'user_login_history table',
    sql: ['DROP TABLE IF EXISTS user_login_history']
  },
  'v0.54': {
    description: 'user_settings table',
    sql: ['DROP TABLE IF EXISTS user_settings']
  },
  'v0.55': {
    description: 'user_login_history device metadata columns',
    sql: [
      'ALTER TABLE user_login_history DROP COLUMN device_fingerprint',
      'ALTER TABLE user_login_history DROP COLUMN device_type',
      'ALTER TABLE user_login_history DROP COLUMN os',
      'ALTER TABLE user_login_history DROP COLUMN browser',
    ]
  },
  'v0.56': {
    description: 'bills/categories soft-delete columns',
    sql: [
      'DROP INDEX IF EXISTS idx_categories_deleted',
      'DROP INDEX IF EXISTS idx_bills_deleted',
      'ALTER TABLE categories DROP COLUMN deleted_at',
      'ALTER TABLE bills DROP COLUMN deleted_at',
    ]
  },
  'v0.57': {
    description: 'autopay suggestions and auto-mark paid',
    sql: [
      'DROP INDEX IF EXISTS idx_autopay_suggestion_dismissals_user_month',
      'DROP TABLE IF EXISTS autopay_suggestion_dismissals',
      'ALTER TABLE bills DROP COLUMN auto_mark_paid',
    ]
  },
  'v0.58': {
    description: 'saved bill templates',
    sql: [
      'DROP INDEX IF EXISTS idx_bill_templates_user_name',
      'DROP TABLE IF EXISTS bill_templates',
    ]
  }
};

function rollbackMigration(version) {
  if (!db) throw new Error('Database not initialized');

  // Check the migration was actually applied
  const applied = db.prepare('SELECT 1 FROM schema_migrations WHERE version = ?').get(version);
  if (!applied) {
    const err = new Error(`Migration ${version} has not been applied — cannot rollback`);
    err.code = 'NOT_APPLIED';
    throw err;
  }

  const rollback = ROLLBACK_SQL_MAP[version];
  if (!rollback) {
    const err = new Error(`Migration ${version} does not support rollback`);
    err.code = 'ROLLBACK_NOT_SUPPORTED';
    throw err;
  }

  console.log(`[rollback] Rolling back ${version}: ${rollback.description}`);
  const startTime = Date.now();

  try {
    db.exec('BEGIN');
    console.log(`[rollback] Transaction BEGIN for ${version}`);

    for (const stmt of rollback.sql) {
      console.log(`[rollback] Executing: ${stmt}`);
      db.exec(stmt);
    }

    // Remove migration record
    db.prepare('DELETE FROM schema_migrations WHERE version = ?').run(version);
    console.log(`[rollback] Removed ${version} from schema_migrations`);

    db.exec('COMMIT');
    console.log(`[rollback] Transaction COMMIT for ${version}`);

    const elapsed = Date.now() - startTime;
    console.log(`[rollback] ${version} rolled back in ${elapsed}ms`);

    // Audit log
    try {
      getLogAudit()({
        action: 'migration.rollback',
        entity_type: 'migration',
        entity_id: null,
        details: { version, description: rollback.description, elapsed_ms: elapsed }
      });
    } catch (auditErr) {
      console.error(`[audit-error] Failed to log rollback to audit log: ${auditErr.message}`);
    }

    return { success: true, version, description: rollback.description, elapsed_ms: elapsed };
  } catch (err) {
    db.exec('ROLLBACK');
    const elapsed = Date.now() - startTime;
    console.error(`[rollback-error] ${version} failed after ${elapsed}ms: ${err.message}`);

    // Audit log
    try {
      getLogAudit()({
        action: 'migration.rollback.failure',
        entity_type: 'migration',
        entity_id: null,
        details: { version, description: rollback.description, error: err.message, elapsed_ms: elapsed }
      });
    } catch (auditErr) {
      console.error(`[audit-error] Failed to log rollback failure to audit log: ${auditErr.message}`);
    }

    throw err;
  }
}

/**
 * Cleanup expired sessions from the database
 * @returns {Object} Result object with changes count
 */
function cleanupExpiredSessions() {
  const result = db.prepare("DELETE FROM sessions WHERE expires_at < datetime('now')").run();
  console.log(`[cleanup] Purged ${result.changes} expired sessions`);
  return result;
}

module.exports = { getDb, getSetting, setSetting, closeDb, getDbPath, ensureUserDefaultCategories, cleanupExpiredSessions, rollbackMigration };