gowebmail/internal/db/db.go

// Package db provides encrypted SQLite storage for GoWebMail.
package db

import (
	"database/sql"
	"fmt"
	"strings"
	"time"

	"github.com/ghostersk/gowebmail/internal/crypto"
	"github.com/ghostersk/gowebmail/internal/models"

	_ "github.com/mattn/go-sqlite3"
)

// DB wraps a SQLite database with field-level AES-256 encryption.
type DB struct {
	sql *sql.DB
	enc *crypto.Encryptor
}

// New opens (or creates) a SQLite database at path, using encKey for field encryption.
func New(path string, encKey []byte) (*DB, error) {
	enc, err := crypto.New(encKey)
	if err != nil {
		return nil, fmt.Errorf("encryptor init: %w", err)
	}

	// Enable WAL mode and foreign keys for performance and integrity
	// sqlite file path must start with `file:` for package mattn/go-sqlite3
	dsn := fmt.Sprintf("file:%s?_journal_mode=WAL&_foreign_keys=on&_busy_timeout=5000", path)
	sqlDB, err := sql.Open("sqlite3", dsn)
	if err != nil {
		return nil, fmt.Errorf("open sqlite: %w", err)
	}
	sqlDB.SetMaxOpenConns(1) // SQLite is single-writer

	return &DB{sql: sqlDB, enc: enc}, nil
}

// Close closes the underlying database.
func (d *DB) Close() error {
	return d.sql.Close()
}

// ---- Migrations ----

// Migrate creates all required tables and bootstraps the admin account.
func (d *DB) Migrate() error {
	stmts := []string{
		`CREATE TABLE IF NOT EXISTS users (
			id            INTEGER PRIMARY KEY AUTOINCREMENT,
			email         TEXT    NOT NULL UNIQUE COLLATE NOCASE,
			username      TEXT    NOT NULL DEFAULT '',
			password_hash TEXT    NOT NULL,
			role          TEXT    NOT NULL DEFAULT 'user',
			is_active     INTEGER NOT NULL DEFAULT 1,
			mfa_enabled   INTEGER NOT NULL DEFAULT 0,
			mfa_secret    TEXT    NOT NULL DEFAULT '',
			mfa_pending   TEXT    NOT NULL DEFAULT '',
			sync_interval INTEGER NOT NULL DEFAULT 15,
			last_login_at DATETIME,
			created_at    DATETIME DEFAULT (datetime('now')),
			updated_at    DATETIME DEFAULT (datetime('now'))
		)`,
		`CREATE TABLE IF NOT EXISTS email_accounts (
			id            INTEGER PRIMARY KEY AUTOINCREMENT,
			user_id       INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
			provider      TEXT    NOT NULL,
			email_address TEXT    NOT NULL,
			display_name  TEXT    NOT NULL DEFAULT '',
			access_token  TEXT    NOT NULL DEFAULT '',
			refresh_token TEXT    NOT NULL DEFAULT '',
			token_expiry  DATETIME,
			imap_host     TEXT    NOT NULL DEFAULT '',
			imap_port     INTEGER NOT NULL DEFAULT 0,
			smtp_host     TEXT    NOT NULL DEFAULT '',
			smtp_port     INTEGER NOT NULL DEFAULT 0,
			last_error    TEXT    NOT NULL DEFAULT '',
			color         TEXT    NOT NULL DEFAULT '#4A90D9',
			is_active     INTEGER NOT NULL DEFAULT 1,
			last_sync     DATETIME,
			created_at    DATETIME DEFAULT (datetime('now'))
		)`,
		`CREATE INDEX IF NOT EXISTS idx_accounts_user ON email_accounts(user_id)`,
		`CREATE TABLE IF NOT EXISTS folders (
			id           INTEGER PRIMARY KEY AUTOINCREMENT,
			account_id   INTEGER NOT NULL REFERENCES email_accounts(id) ON DELETE CASCADE,
			name         TEXT    NOT NULL,
			full_path    TEXT    NOT NULL,
			folder_type  TEXT    NOT NULL DEFAULT 'custom',
			unread_count INTEGER NOT NULL DEFAULT 0,
			total_count  INTEGER NOT NULL DEFAULT 0
		)`,
		`CREATE UNIQUE INDEX IF NOT EXISTS idx_folders_account_path ON folders(account_id, full_path)`,
		`CREATE TABLE IF NOT EXISTS messages (
			id             INTEGER PRIMARY KEY AUTOINCREMENT,
			account_id     INTEGER NOT NULL REFERENCES email_accounts(id) ON DELETE CASCADE,
			folder_id      INTEGER NOT NULL REFERENCES folders(id) ON DELETE CASCADE,
			remote_uid     TEXT    NOT NULL,
			thread_id      TEXT    NOT NULL DEFAULT '',
			message_id     TEXT    NOT NULL DEFAULT '',
			subject        TEXT    NOT NULL DEFAULT '',
			from_name      TEXT    NOT NULL DEFAULT '',
			from_email     TEXT    NOT NULL DEFAULT '',
			to_list        TEXT    NOT NULL DEFAULT '',
			cc_list        TEXT    NOT NULL DEFAULT '',
			bcc_list       TEXT    NOT NULL DEFAULT '',
			reply_to       TEXT    NOT NULL DEFAULT '',
			body_text      TEXT    NOT NULL DEFAULT '',
			body_html      TEXT    NOT NULL DEFAULT '',
			date           DATETIME NOT NULL,
			is_read        INTEGER  NOT NULL DEFAULT 0,
			is_starred     INTEGER  NOT NULL DEFAULT 0,
			is_draft       INTEGER  NOT NULL DEFAULT 0,
			has_attachment INTEGER  NOT NULL DEFAULT 0,
			created_at     DATETIME DEFAULT (datetime('now'))
		)`,
		`CREATE UNIQUE INDEX IF NOT EXISTS idx_messages_uid ON messages(account_id, folder_id, remote_uid)`,
		`CREATE INDEX IF NOT EXISTS idx_messages_date ON messages(date DESC)`,
		`CREATE INDEX IF NOT EXISTS idx_messages_account ON messages(account_id)`,
		`CREATE TABLE IF NOT EXISTS attachments (
			id           INTEGER PRIMARY KEY AUTOINCREMENT,
			message_id   INTEGER NOT NULL REFERENCES messages(id) ON DELETE CASCADE,
			filename     TEXT    NOT NULL DEFAULT '',
			content_type TEXT    NOT NULL DEFAULT '',
			size         INTEGER NOT NULL DEFAULT 0,
			content_id   TEXT    NOT NULL DEFAULT '',
			data         BLOB
		)`,
		`CREATE TABLE IF NOT EXISTS sessions (
			token         TEXT    PRIMARY KEY,
			user_id       INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
			mfa_verified  INTEGER NOT NULL DEFAULT 0,
			expires_at    DATETIME NOT NULL,
			created_at    DATETIME DEFAULT (datetime('now'))
		)`,
		`CREATE INDEX IF NOT EXISTS idx_sessions_user ON sessions(user_id)`,
		`CREATE TABLE IF NOT EXISTS audit_log (
			id         INTEGER PRIMARY KEY AUTOINCREMENT,
			user_id    INTEGER REFERENCES users(id) ON DELETE SET NULL,
			event      TEXT    NOT NULL,
			detail     TEXT    NOT NULL DEFAULT '',
			ip_address TEXT    NOT NULL DEFAULT '',
			user_agent TEXT    NOT NULL DEFAULT '',
			created_at DATETIME DEFAULT (datetime('now'))
		)`,
		`CREATE INDEX IF NOT EXISTS idx_audit_created ON audit_log(created_at DESC)`,
		`CREATE INDEX IF NOT EXISTS idx_audit_event ON audit_log(event)`,
		`CREATE TABLE IF NOT EXISTS remote_content_whitelist (
			id         INTEGER PRIMARY KEY AUTOINCREMENT,
			user_id    INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
			sender     TEXT    NOT NULL,
			created_at DATETIME DEFAULT (datetime('now')),
			UNIQUE(user_id, sender)
		)`,
	}

	for _, stmt := range stmts {
		if _, err := d.sql.Exec(stmt); err != nil {
			return fmt.Errorf("migration error (%s...): %w", stmt[:40], err)
		}
	}

	// Additive ALTER TABLE migrations — safe to re-run (SQLite ignores duplicate column errors)
	alterStmts := []string{
		`ALTER TABLE email_accounts ADD COLUMN sync_days INTEGER NOT NULL DEFAULT 30`,
		`ALTER TABLE email_accounts ADD COLUMN sync_mode TEXT NOT NULL DEFAULT 'days'`,
		`ALTER TABLE email_accounts ADD COLUMN sync_all_folders INTEGER NOT NULL DEFAULT 0`,
		`ALTER TABLE users ADD COLUMN compose_popup INTEGER NOT NULL DEFAULT 0`,
		`ALTER TABLE messages ADD COLUMN folder_path TEXT NOT NULL DEFAULT ''`,
		// Folder visibility: is_hidden hides from sidebar; sync_enabled controls auto-sync.
		// Default: primary folder types sync by default, others don't.
		`ALTER TABLE folders ADD COLUMN is_hidden INTEGER NOT NULL DEFAULT 0`,
		`ALTER TABLE folders ADD COLUMN sync_enabled INTEGER NOT NULL DEFAULT 1`,
		// Plaintext search index column — stores decrypted subject+from+preview for LIKE search.
		`ALTER TABLE messages ADD COLUMN search_text TEXT NOT NULL DEFAULT ''`,
		// Per-folder IMAP sync state for incremental/delta sync.
		`ALTER TABLE folders ADD COLUMN uid_validity INTEGER NOT NULL DEFAULT 0`,
		`ALTER TABLE folders ADD COLUMN last_seen_uid INTEGER NOT NULL DEFAULT 0`,
	}
	for _, stmt := range alterStmts {
		d.sql.Exec(stmt) // ignore "duplicate column" errors intentionally
	}

	// Pending IMAP operations queue — survives server restarts.
	// op_type: "delete" | "move" | "flag_read" | "flag_star"
	_, err := d.sql.Exec(`CREATE TABLE IF NOT EXISTS pending_imap_ops (
		id          INTEGER PRIMARY KEY AUTOINCREMENT,
		account_id  INTEGER NOT NULL REFERENCES email_accounts(id) ON DELETE CASCADE,
		op_type     TEXT    NOT NULL,
		remote_uid  INTEGER NOT NULL,
		folder_path TEXT    NOT NULL DEFAULT '',
		extra       TEXT    NOT NULL DEFAULT '',
		attempts    INTEGER NOT NULL DEFAULT 0,
		created_at  DATETIME DEFAULT (datetime('now'))
	)`)
	if err != nil {
		return fmt.Errorf("create pending_imap_ops: %w", err)
	}

	// Login attempt tracking for brute-force protection.
	if _, err := d.sql.Exec(`CREATE TABLE IF NOT EXISTS login_attempts (
		id         INTEGER PRIMARY KEY AUTOINCREMENT,
		ip         TEXT    NOT NULL,
		username   TEXT    NOT NULL DEFAULT '',
		success    INTEGER NOT NULL DEFAULT 0,
		country    TEXT    NOT NULL DEFAULT '',
		country_code TEXT  NOT NULL DEFAULT '',
		created_at DATETIME DEFAULT (datetime('now'))
	)`); err != nil {
		return fmt.Errorf("create login_attempts: %w", err)
	}
	if _, err := d.sql.Exec(`CREATE INDEX IF NOT EXISTS idx_login_attempts_ip_time ON login_attempts(ip, created_at)`); err != nil {
		return fmt.Errorf("create login_attempts index: %w", err)
	}

	// IP block list — manually added or auto-created by brute force protection.
	if _, err := d.sql.Exec(`CREATE TABLE IF NOT EXISTS ip_blocks (
		id           INTEGER PRIMARY KEY AUTOINCREMENT,
		ip           TEXT    NOT NULL UNIQUE,
		reason       TEXT    NOT NULL DEFAULT '',
		country      TEXT    NOT NULL DEFAULT '',
		country_code TEXT    NOT NULL DEFAULT '',
		attempts     INTEGER NOT NULL DEFAULT 0,
		blocked_at   DATETIME DEFAULT (datetime('now')),
		expires_at   DATETIME,
		is_permanent INTEGER NOT NULL DEFAULT 0
	)`); err != nil {
		return fmt.Errorf("create ip_blocks: %w", err)
	}

	// Per-user IP access rules.
	// mode: "brute_skip" = skip brute force check for this user from listed IPs
	//       "allow_only" = only allow login from listed IPs (all others get 403)
	if _, err := d.sql.Exec(`CREATE TABLE IF NOT EXISTS user_ip_rules (
		id         INTEGER PRIMARY KEY AUTOINCREMENT,
		user_id    INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
		mode       TEXT    NOT NULL DEFAULT 'brute_skip',
		ip_list    TEXT    NOT NULL DEFAULT '',
		created_at DATETIME DEFAULT (datetime('now')),
		updated_at DATETIME DEFAULT (datetime('now')),
		UNIQUE(user_id)
	)`); err != nil {
		return fmt.Errorf("create user_ip_rules: %w", err)
	}

	// Bootstrap admin account if no users exist
	return d.bootstrapAdmin()
}

// bootstrapAdmin creates the default admin/admin account on first run.
func (d *DB) bootstrapAdmin() error {
	var count int
	d.sql.QueryRow(`SELECT COUNT(*) FROM users`).Scan(&count)
	if count > 0 {
		return nil
	}
	hash, err := crypto.HashPassword("admin")
	if err != nil {
		return err
	}
	_, err = d.sql.Exec(
		`INSERT INTO users (email, username, password_hash, role, is_active)
		 VALUES ('admin', 'admin', ?, 'admin', 1)`, hash,
	)
	if err != nil {
		return fmt.Errorf("bootstrap admin: %w", err)
	}
	fmt.Println("WARNING: Default admin account created: username=admin password=admin — CHANGE THIS IMMEDIATELY")
	return nil
}

// ---- Users ----

func (d *DB) CreateUser(username, email, password string, role models.UserRole) (*models.User, error) {
	hash, err := crypto.HashPassword(password)
	if err != nil {
		return nil, err
	}
	res, err := d.sql.Exec(
		`INSERT INTO users (email, username, password_hash, role) VALUES (?, ?, ?, ?)`,
		email, username, hash, role,
	)
	if err != nil {
		if strings.Contains(err.Error(), "UNIQUE") {
			return nil, fmt.Errorf("email already registered")
		}
		return nil, err
	}
	id, _ := res.LastInsertId()
	return d.GetUserByID(id)
}

func (d *DB) scanUser(row *sql.Row) (*models.User, error) {
	u := &models.User{}
	var mfaSecretEnc, mfaPendingEnc string
	var lastLogin sql.NullTime
	var composePopup int
	err := row.Scan(
		&u.ID, &u.Email, &u.Username, &u.PasswordHash, &u.Role, &u.IsActive,
		&u.MFAEnabled, &mfaSecretEnc, &mfaPendingEnc, &lastLogin,
		&u.CreatedAt, &u.UpdatedAt, &u.SyncInterval, &composePopup,
	)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	u.MFASecret, _ = d.enc.Decrypt(mfaSecretEnc)
	u.MFAPending, _ = d.enc.Decrypt(mfaPendingEnc)
	if lastLogin.Valid {
		u.LastLoginAt = &lastLogin.Time
	}
	u.ComposePopup = composePopup == 1
	return u, nil
}

const userSelectCols = `SELECT id, email, username, password_hash, role, is_active,
	mfa_enabled, mfa_secret, mfa_pending, last_login_at, created_at, updated_at,
	COALESCE(sync_interval,15), COALESCE(compose_popup,0) FROM users`

func (d *DB) GetUserByEmail(email string) (*models.User, error) {
	return d.scanUser(d.sql.QueryRow(userSelectCols+` WHERE email=?`, email))
}

func (d *DB) GetUserByUsername(username string) (*models.User, error) {
	return d.scanUser(d.sql.QueryRow(userSelectCols+` WHERE username=?`, username))
}

func (d *DB) GetUserByID(id int64) (*models.User, error) {
	return d.scanUser(d.sql.QueryRow(userSelectCols+` WHERE id=?`, id))
}

func (d *DB) ListUsers() ([]*models.User, error) {
	rows, err := d.sql.Query(userSelectCols + ` ORDER BY created_at`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var users []*models.User
	for rows.Next() {
		u := &models.User{}
		var mfaSecretEnc, mfaPendingEnc string
		var lastLogin sql.NullTime
		var composePopup int
		if err := rows.Scan(
			&u.ID, &u.Email, &u.Username, &u.PasswordHash, &u.Role, &u.IsActive,
			&u.MFAEnabled, &mfaSecretEnc, &mfaPendingEnc, &lastLogin,
			&u.CreatedAt, &u.UpdatedAt, &u.SyncInterval, &composePopup,
		); err != nil {
			return nil, err
		}
		u.ComposePopup = composePopup == 1
		u.MFASecret, _ = d.enc.Decrypt(mfaSecretEnc)
		u.MFAPending, _ = d.enc.Decrypt(mfaPendingEnc)
		if lastLogin.Valid {
			u.LastLoginAt = &lastLogin.Time
		}
		users = append(users, u)
	}
	return users, rows.Err()
}

func (d *DB) UpdateUserPassword(userID int64, newPassword string) error {
	hash, err := crypto.HashPassword(newPassword)
	if err != nil {
		return err
	}
	_, err = d.sql.Exec(
		`UPDATE users SET password_hash=?, updated_at=datetime('now') WHERE id=?`, hash, userID,
	)
	return err
}

// AdminListAdmins returns (username, email, mfa_enabled) for all admin-role users.
func (d *DB) AdminListAdmins() ([]struct {
	Username   string
	Email      string
	MFAEnabled bool
}, error) {
	rows, err := d.sql.Query(`SELECT username, email, mfa_enabled FROM users WHERE role='admin' ORDER BY username`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []struct {
		Username   string
		Email      string
		MFAEnabled bool
	}
	for rows.Next() {
		var r struct {
			Username   string
			Email      string
			MFAEnabled bool
		}
		rows.Scan(&r.Username, &r.Email, &r.MFAEnabled)
		out = append(out, r)
	}
	return out, rows.Err()
}

// AdminResetPassword sets a new password for an admin user by username (admin-only check).
func (d *DB) AdminResetPassword(username, newPassword string) error {
	// Verify user exists and is admin
	var id int64
	var role string
	err := d.sql.QueryRow(`SELECT id, role FROM users WHERE username=?`, username).Scan(&id, &role)
	if err != nil || id == 0 {
		return fmt.Errorf("user %q not found", username)
	}
	if role != "admin" {
		return fmt.Errorf("user %q is not an admin (use the web UI for regular users)", username)
	}
	return d.UpdateUserPassword(id, newPassword)
}

// AdminDisableMFA disables MFA for an admin user by username (admin-only check).
func (d *DB) AdminDisableMFA(username string) error {
	var id int64
	var role string
	err := d.sql.QueryRow(`SELECT id, role FROM users WHERE username=?`, username).Scan(&id, &role)
	if err != nil || id == 0 {
		return fmt.Errorf("user %q not found", username)
	}
	if role != "admin" {
		return fmt.Errorf("user %q is not an admin (use the web UI for regular users)", username)
	}
	return d.DisableMFA(id)
}

func (d *DB) SetUserActive(userID int64, active bool) error {
	v := 0
	if active {
		v = 1
	}
	_, err := d.sql.Exec(`UPDATE users SET is_active=?, updated_at=datetime('now') WHERE id=?`, v, userID)
	return err
}

func (d *DB) DeleteUser(userID int64) error {
	_, err := d.sql.Exec(`DELETE FROM users WHERE id=? AND role != 'admin'`, userID)
	return err
}

func (d *DB) TouchLastLogin(userID int64) {
	d.sql.Exec(`UPDATE users SET last_login_at=datetime('now') WHERE id=?`, userID)
}

// ---- MFA ----

func (d *DB) SetMFAPending(userID int64, secret string) error {
	enc, err := d.enc.Encrypt(secret)
	if err != nil {
		return err
	}
	_, err = d.sql.Exec(`UPDATE users SET mfa_pending=?, updated_at=datetime('now') WHERE id=?`, enc, userID)
	return err
}

func (d *DB) EnableMFA(userID int64, secret string) error {
	enc, err := d.enc.Encrypt(secret)
	if err != nil {
		return err
	}
	_, err = d.sql.Exec(
		`UPDATE users SET mfa_enabled=1, mfa_secret=?, mfa_pending='', updated_at=datetime('now') WHERE id=?`,
		enc, userID,
	)
	return err
}

func (d *DB) DisableMFA(userID int64) error {
	_, err := d.sql.Exec(
		`UPDATE users SET mfa_enabled=0, mfa_secret='', mfa_pending='', updated_at=datetime('now') WHERE id=?`,
		userID,
	)
	return err
}

// ---- Sessions ----

func (d *DB) CreateSession(userID int64, ttl time.Duration) (string, error) {
	token, err := crypto.GenerateToken(32)
	if err != nil {
		return "", err
	}
	expiry := time.Now().Add(ttl)
	_, err = d.sql.Exec(
		`INSERT INTO sessions (token, user_id, mfa_verified, expires_at) VALUES (?, ?, 0, ?)`,
		token, userID, expiry,
	)
	return token, err
}

func (d *DB) SetSessionMFAVerified(token string) error {
	_, err := d.sql.Exec(`UPDATE sessions SET mfa_verified=1 WHERE token=?`, token)
	return err
}

func (d *DB) GetSession(token string) (userID int64, mfaVerified bool, err error) {
	var expiresAt time.Time
	err = d.sql.QueryRow(
		`SELECT user_id, mfa_verified, expires_at FROM sessions WHERE token=?`, token,
	).Scan(&userID, &mfaVerified, &expiresAt)
	if err == sql.ErrNoRows {
		return 0, false, nil
	}
	if err != nil {
		return 0, false, err
	}
	if time.Now().After(expiresAt) {
		d.sql.Exec(`DELETE FROM sessions WHERE token=?`, token)
		return 0, false, nil
	}
	return userID, mfaVerified, nil
}

func (d *DB) DeleteSession(token string) error {
	_, err := d.sql.Exec(`DELETE FROM sessions WHERE token=?`, token)
	return err
}

// ---- Audit Log ----

func (d *DB) WriteAudit(userID *int64, event models.AuditEventType, detail, ip, ua string) {
	d.sql.Exec(
		`INSERT INTO audit_log (user_id, event, detail, ip_address, user_agent) VALUES (?,?,?,?,?)`,
		userID, string(event), detail, ip, ua,
	)
}

func (d *DB) ListAuditLogs(page, pageSize int, eventFilter string) (*models.AuditPage, error) {
	offset := (page - 1) * pageSize
	where := ""
	args := []interface{}{}
	if eventFilter != "" {
		where = " WHERE a.event=?"
		args = append(args, eventFilter)
	}

	var total int
	d.sql.QueryRow(`SELECT COUNT(*) FROM audit_log a`+where, args...).Scan(&total)

	args = append(args, pageSize, offset)
	rows, err := d.sql.Query(`
		SELECT a.id, a.user_id, COALESCE(u.email,''), a.event, a.detail, a.ip_address, a.user_agent, a.created_at
		FROM audit_log a LEFT JOIN users u ON u.id=a.user_id`+where+`
		ORDER BY a.created_at DESC LIMIT ? OFFSET ?`, args...,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var logs []models.AuditLog
	for rows.Next() {
		l := models.AuditLog{}
		var uid sql.NullInt64
		if err := rows.Scan(&l.ID, &uid, &l.UserEmail, &l.Event, &l.Detail, &l.IPAddress, &l.UserAgent, &l.CreatedAt); err != nil {
			return nil, err
		}
		if uid.Valid {
			l.UserID = &uid.Int64
		}
		logs = append(logs, l)
	}
	return &models.AuditPage{
		Logs: logs, Total: total, Page: page, PageSize: pageSize,
		HasMore: offset+len(logs) < total,
	}, rows.Err()
}

// ---- Email Accounts ----

func (d *DB) CreateAccount(a *models.EmailAccount) error {
	accessEnc, _ := d.enc.Encrypt(a.AccessToken)
	refreshEnc, _ := d.enc.Encrypt(a.RefreshToken)
	imapHostEnc, _ := d.enc.Encrypt(a.IMAPHost)
	smtpHostEnc, _ := d.enc.Encrypt(a.SMTPHost)

	res, err := d.sql.Exec(`
		INSERT INTO email_accounts
			(user_id, provider, email_address, display_name, access_token, refresh_token,
			 token_expiry, imap_host, imap_port, smtp_host, smtp_port, color)
		VALUES (?,?,?,?,?,?,?,?,?,?,?,?)`,
		a.UserID, a.Provider, a.EmailAddress, a.DisplayName,
		accessEnc, refreshEnc, a.TokenExpiry,
		imapHostEnc, a.IMAPPort, smtpHostEnc, a.SMTPPort,
		a.Color,
	)
	if err != nil {
		return err
	}
	id, _ := res.LastInsertId()
	a.ID = id
	return nil
}

func (d *DB) UpdateAccountTokens(accountID int64, accessToken, refreshToken string, expiry time.Time) error {
	accessEnc, _ := d.enc.Encrypt(accessToken)
	refreshEnc, _ := d.enc.Encrypt(refreshToken)
	_, err := d.sql.Exec(
		`UPDATE email_accounts SET access_token=?, refresh_token=?, token_expiry=? WHERE id=?`,
		accessEnc, refreshEnc, expiry, accountID,
	)
	return err
}

func (d *DB) UpdateAccountLastSync(accountID int64) error {
	_, err := d.sql.Exec(`UPDATE email_accounts SET last_sync=? WHERE id=?`, time.Now(), accountID)
	return err
}

func (d *DB) GetAccount(accountID int64) (*models.EmailAccount, error) {
	a := &models.EmailAccount{}
	var accessEnc, refreshEnc, imapHostEnc, smtpHostEnc string
	var lastSync sql.NullTime
	err := d.sql.QueryRow(`
		SELECT id, user_id, provider, email_address, display_name,
		       access_token, refresh_token, token_expiry,
		       imap_host, imap_port, smtp_host, smtp_port,
		       last_error, color, is_active, last_sync, created_at,
		       COALESCE(sync_days,30), COALESCE(sync_mode,'days')
		FROM email_accounts WHERE id=?`, accountID,
	).Scan(
		&a.ID, &a.UserID, &a.Provider, &a.EmailAddress, &a.DisplayName,
		&accessEnc, &refreshEnc, &a.TokenExpiry,
		&imapHostEnc, &a.IMAPPort, &smtpHostEnc, &a.SMTPPort,
		&a.LastError, &a.Color, &a.IsActive, &lastSync, &a.CreatedAt,
		&a.SyncDays, &a.SyncMode,
	)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	a.AccessToken, _ = d.enc.Decrypt(accessEnc)
	a.RefreshToken, _ = d.enc.Decrypt(refreshEnc)
	a.IMAPHost, _ = d.enc.Decrypt(imapHostEnc)
	a.SMTPHost, _ = d.enc.Decrypt(smtpHostEnc)
	if lastSync.Valid {
		a.LastSync = lastSync.Time
	}
	if a.SyncDays == 0 {
		a.SyncDays = 30
	}
	return a, nil
}

func (d *DB) GetUserSyncInterval(userID int64) (int, error) {
	var interval int
	err := d.sql.QueryRow(`SELECT sync_interval FROM users WHERE id=?`, userID).Scan(&interval)
	if err != nil {
		return 15, err
	}
	return interval, nil
}

func (d *DB) SetUserSyncInterval(userID int64, minutes int) error {
	_, err := d.sql.Exec(`UPDATE users SET sync_interval=? WHERE id=?`, minutes, userID)
	return err
}

func (d *DB) SetComposePopup(userID int64, popup bool) error {
	v := 0
	if popup {
		v = 1
	}
	_, err := d.sql.Exec(`UPDATE users SET compose_popup=? WHERE id=?`, v, userID)
	return err
}

func (d *DB) SetAccountSyncSettings(accountID, userID int64, syncDays int, syncMode string) error {
	if syncMode == "" {
		syncMode = "days"
	}
	_, err := d.sql.Exec(`UPDATE email_accounts SET sync_days=?, sync_mode=? WHERE id=? AND user_id=?`,
		syncDays, syncMode, accountID, userID)
	return err
}

func (d *DB) UpdateAccount(a *models.EmailAccount) error {
	accessEnc, _ := d.enc.Encrypt(a.AccessToken)
	imapHostEnc, _ := d.enc.Encrypt(a.IMAPHost)
	smtpHostEnc, _ := d.enc.Encrypt(a.SMTPHost)
	syncMode := a.SyncMode
	if syncMode == "" {
		syncMode = "days"
	}
	syncDays := a.SyncDays
	if syncDays == 0 {
		syncDays = 30
	}
	_, err := d.sql.Exec(`
		UPDATE email_accounts SET
			display_name=?, access_token=?,
			imap_host=?, imap_port=?, smtp_host=?, smtp_port=?,
			color=?, sync_days=?, sync_mode=?
		WHERE id=? AND user_id=?`,
		a.DisplayName, accessEnc,
		imapHostEnc, a.IMAPPort, smtpHostEnc, a.SMTPPort,
		a.Color, syncDays, syncMode, a.ID, a.UserID,
	)
	return err
}

func (d *DB) SetAccountError(accountID int64, errMsg string) {
	d.sql.Exec(`UPDATE email_accounts SET last_error=? WHERE id=?`, errMsg, accountID)
}

func (d *DB) ClearAccountError(accountID int64) {
	d.sql.Exec(`UPDATE email_accounts SET last_error='' WHERE id=?`, accountID)
}

// ListAllActiveAccounts returns all active accounts joined with their user's sync_interval.
func (d *DB) ListAllActiveAccounts() ([]*models.EmailAccount, error) {
	rows, err := d.sql.Query(`
		SELECT a.id, a.user_id, a.provider, a.email_address, a.display_name,
		       a.access_token, a.refresh_token, a.token_expiry,
		       a.imap_host, a.imap_port, a.smtp_host, a.smtp_port,
		       a.last_error, a.color, a.is_active, a.last_sync, a.created_at,
		       u.sync_interval
		FROM email_accounts a
		JOIN users u ON u.id = a.user_id
		WHERE a.is_active=1 AND u.is_active=1`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var accounts []*models.EmailAccount
	for rows.Next() {
		a := &models.EmailAccount{}
		var accessEnc, refreshEnc, imapHostEnc, smtpHostEnc string
		var lastSync sql.NullTime
		if err := rows.Scan(
			&a.ID, &a.UserID, &a.Provider, &a.EmailAddress, &a.DisplayName,
			&accessEnc, &refreshEnc, &a.TokenExpiry,
			&imapHostEnc, &a.IMAPPort, &smtpHostEnc, &a.SMTPPort,
			&a.LastError, &a.Color, &a.IsActive, &lastSync, &a.CreatedAt,
			&a.SyncInterval,
		); err != nil {
			return nil, err
		}
		a.AccessToken, _ = d.enc.Decrypt(accessEnc)
		a.RefreshToken, _ = d.enc.Decrypt(refreshEnc)
		a.IMAPHost, _ = d.enc.Decrypt(imapHostEnc)
		a.SMTPHost, _ = d.enc.Decrypt(smtpHostEnc)
		if lastSync.Valid {
			a.LastSync = lastSync.Time
		}
		accounts = append(accounts, a)
	}
	return accounts, rows.Err()
}

func (d *DB) ListAccountsByUser(userID int64) ([]*models.EmailAccount, error) {
	rows, err := d.sql.Query(`
		SELECT id, user_id, provider, email_address, display_name,
		       access_token, refresh_token, token_expiry,
		       imap_host, imap_port, smtp_host, smtp_port,
		       last_error, color, is_active, last_sync, created_at
		FROM email_accounts WHERE user_id=? AND is_active=1 ORDER BY created_at`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	return d.scanAccounts(rows)
}

func (d *DB) scanAccounts(rows *sql.Rows) ([]*models.EmailAccount, error) {
	var accounts []*models.EmailAccount
	for rows.Next() {
		a := &models.EmailAccount{}
		var accessEnc, refreshEnc, imapHostEnc, smtpHostEnc string
		var lastSync sql.NullTime
		if err := rows.Scan(
			&a.ID, &a.UserID, &a.Provider, &a.EmailAddress, &a.DisplayName,
			&accessEnc, &refreshEnc, &a.TokenExpiry,
			&imapHostEnc, &a.IMAPPort, &smtpHostEnc, &a.SMTPPort,
			&a.LastError, &a.Color, &a.IsActive, &lastSync, &a.CreatedAt,
		); err != nil {
			return nil, err
		}
		a.AccessToken, _ = d.enc.Decrypt(accessEnc)
		a.RefreshToken, _ = d.enc.Decrypt(refreshEnc)
		a.IMAPHost, _ = d.enc.Decrypt(imapHostEnc)
		a.SMTPHost, _ = d.enc.Decrypt(smtpHostEnc)
		if lastSync.Valid {
			a.LastSync = lastSync.Time
		}
		accounts = append(accounts, a)
	}
	return accounts, rows.Err()
}

func (d *DB) DeleteAccount(accountID, userID int64) error {
	_, err := d.sql.Exec(
		`DELETE FROM email_accounts WHERE id=? AND user_id=?`, accountID, userID,
	)
	return err
}

func (d *DB) UpdateFolderCounts(folderID int64) {
	d.sql.Exec(`
		UPDATE folders SET
			total_count  = (SELECT COUNT(*) FROM messages WHERE folder_id=?),
			unread_count = (SELECT COUNT(*) FROM messages WHERE folder_id=? AND is_read=0)
		WHERE id=?`, folderID, folderID, folderID)
}

// ---- Folders ----

func (d *DB) UpsertFolder(f *models.Folder) error {
	// On insert: set sync_enabled based on folder type (primary types sync by default)
	defaultSync := 0
	switch f.FolderType {
	case "inbox", "sent", "drafts", "trash", "spam":
		defaultSync = 1
	}
	_, err := d.sql.Exec(`
		INSERT INTO folders (account_id, name, full_path, folder_type, unread_count, total_count, sync_enabled)
		VALUES (?,?,?,?,?,?,?)
		ON CONFLICT(account_id, full_path) DO UPDATE SET
			name=excluded.name,
			folder_type=excluded.folder_type,
			unread_count=excluded.unread_count,
			total_count=excluded.total_count`,
		f.AccountID, f.Name, f.FullPath, f.FolderType, f.UnreadCount, f.TotalCount, defaultSync,
	)
	return err
}

func (d *DB) GetFolderByPath(accountID int64, fullPath string) (*models.Folder, error) {
	f := &models.Folder{}
	var isHidden, syncEnabled int
	err := d.sql.QueryRow(
		`SELECT id, account_id, name, full_path, folder_type, unread_count, total_count,
		       COALESCE(is_hidden,0), COALESCE(sync_enabled,1)
		 FROM folders WHERE account_id=? AND full_path=?`, accountID, fullPath,
	).Scan(&f.ID, &f.AccountID, &f.Name, &f.FullPath, &f.FolderType, &f.UnreadCount, &f.TotalCount, &isHidden, &syncEnabled)
	f.IsHidden = isHidden == 1
	f.SyncEnabled = syncEnabled == 1
	if err == sql.ErrNoRows {
		return nil, nil
	}
	return f, err
}

func (d *DB) ListFoldersByAccount(accountID int64) ([]*models.Folder, error) {
	rows, err := d.sql.Query(
		`SELECT id, account_id, name, full_path, folder_type, unread_count, total_count,
		       COALESCE(is_hidden,0), COALESCE(sync_enabled,1)
		 FROM folders WHERE account_id=? ORDER BY folder_type, name`, accountID,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var folders []*models.Folder
	for rows.Next() {
		f := &models.Folder{}
		var isHidden, syncEnabled int
		if err := rows.Scan(&f.ID, &f.AccountID, &f.Name, &f.FullPath, &f.FolderType, &f.UnreadCount, &f.TotalCount, &isHidden, &syncEnabled); err != nil {
			return nil, err
		}
		f.IsHidden = isHidden == 1
		f.SyncEnabled = syncEnabled == 1
		folders = append(folders, f)
	}
	return folders, rows.Err()
}

// ---- Messages ----

func (d *DB) UpsertMessage(m *models.Message) error {
	subjectEnc, _ := d.enc.Encrypt(m.Subject)
	fromNameEnc, _ := d.enc.Encrypt(m.FromName)
	fromEmailEnc, _ := d.enc.Encrypt(m.FromEmail)
	toEnc, _ := d.enc.Encrypt(m.ToList)
	ccEnc, _ := d.enc.Encrypt(m.CCList)
	bccEnc, _ := d.enc.Encrypt(m.BCCList)
	replyToEnc, _ := d.enc.Encrypt(m.ReplyTo)
	bodyTextEnc, _ := d.enc.Encrypt(m.BodyText)
	bodyHTMLEnc, _ := d.enc.Encrypt(m.BodyHTML)

	// Build plaintext search index: subject + from name + from email + first 200 chars of body
	preview := m.BodyText
	if len(preview) > 200 {
		preview = preview[:200]
	}
	searchText := strings.ToLower(m.Subject + " " + m.FromName + " " + m.FromEmail + " " + preview)

	res, err := d.sql.Exec(`
		INSERT INTO messages
			(account_id, folder_id, remote_uid, thread_id, message_id,
			 subject, from_name, from_email, to_list, cc_list, bcc_list, reply_to,
			 body_text, body_html, date, is_read, is_starred, is_draft, has_attachment, search_text)
		VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)
		ON CONFLICT(account_id, folder_id, remote_uid) DO UPDATE SET
			is_read=excluded.is_read,
			is_starred=excluded.is_starred,
			has_attachment=excluded.has_attachment,
			search_text=excluded.search_text`,
		m.AccountID, m.FolderID, m.RemoteUID, m.ThreadID, m.MessageID,
		subjectEnc, fromNameEnc, fromEmailEnc, toEnc, ccEnc, bccEnc, replyToEnc,
		bodyTextEnc, bodyHTMLEnc, m.Date,
		m.IsRead, m.IsStarred, m.IsDraft, m.HasAttachment, searchText,
	)
	if err != nil {
		return err
	}
	// LastInsertId returns 0 on conflict in SQLite — always look up the real ID.
	id, _ := res.LastInsertId()
	if id == 0 {
		d.sql.QueryRow(
			`SELECT id FROM messages WHERE account_id=? AND folder_id=? AND remote_uid=?`,
			m.AccountID, m.FolderID, m.RemoteUID,
		).Scan(&id)
	}
	if m.ID == 0 {
		m.ID = id
	}
	return nil
}

func (d *DB) GetMessage(messageID, userID int64) (*models.Message, error) {
	m := &models.Message{}
	var subjectEnc, fromNameEnc, fromEmailEnc, toEnc, ccEnc, bccEnc, replyToEnc, bodyTextEnc, bodyHTMLEnc string

	err := d.sql.QueryRow(`
		SELECT m.id, m.account_id, m.folder_id, m.remote_uid, m.thread_id, m.message_id,
		       m.subject, m.from_name, m.from_email, m.to_list, m.cc_list, m.bcc_list,
		       m.reply_to, m.body_text, m.body_html,
		       m.date, m.is_read, m.is_starred, m.is_draft, m.has_attachment, m.created_at
		FROM messages m
		JOIN email_accounts a ON a.id = m.account_id
		WHERE m.id=? AND a.user_id=?`, messageID, userID,
	).Scan(
		&m.ID, &m.AccountID, &m.FolderID, &m.RemoteUID, &m.ThreadID, &m.MessageID,
		&subjectEnc, &fromNameEnc, &fromEmailEnc, &toEnc, &ccEnc, &bccEnc,
		&replyToEnc, &bodyTextEnc, &bodyHTMLEnc,
		&m.Date, &m.IsRead, &m.IsStarred, &m.IsDraft, &m.HasAttachment, &m.CreatedAt,
	)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	m.Subject, _ = d.enc.Decrypt(subjectEnc)
	m.FromName, _ = d.enc.Decrypt(fromNameEnc)
	m.FromEmail, _ = d.enc.Decrypt(fromEmailEnc)
	m.ToList, _ = d.enc.Decrypt(toEnc)
	m.CCList, _ = d.enc.Decrypt(ccEnc)
	m.BCCList, _ = d.enc.Decrypt(bccEnc)
	m.ReplyTo, _ = d.enc.Decrypt(replyToEnc)
	m.BodyText, _ = d.enc.Decrypt(bodyTextEnc)
	m.BodyHTML, _ = d.enc.Decrypt(bodyHTMLEnc)

	// Load attachment metadata
	if m.HasAttachment {
		atts, _ := d.GetAttachmentsByMessage(m.ID, userID)
		m.Attachments = atts
	}

	return m, nil
}

func (d *DB) ListMessages(userID int64, folderIDs []int64, accountID int64, page, pageSize int) (*models.PagedMessages, error) {
	offset := (page - 1) * pageSize
	args := []interface{}{userID}

	where := "a.user_id=?"
	if accountID > 0 {
		where += " AND m.account_id=?"
		args = append(args, accountID)
	}
	if len(folderIDs) > 0 {
		placeholders := make([]string, len(folderIDs))
		for i, fid := range folderIDs {
			placeholders[i] = "?"
			args = append(args, fid)
		}
		where += " AND m.folder_id IN (" + strings.Join(placeholders, ",") + ")"
	}

	countArgs := make([]interface{}, len(args))
	copy(countArgs, args)

	var total int
	d.sql.QueryRow("SELECT COUNT(*) FROM messages m JOIN email_accounts a ON a.id=m.account_id WHERE "+where, countArgs...).Scan(&total)

	args = append(args, pageSize, offset)
	rows, err := d.sql.Query(`
		SELECT m.id, m.account_id, a.email_address, a.color, m.folder_id, f.name,
		       m.subject, m.from_name, m.from_email, m.body_text,
		       m.date, m.is_read, m.is_starred, m.has_attachment
		FROM messages m
		JOIN email_accounts a ON a.id = m.account_id
		JOIN folders f ON f.id = m.folder_id
		WHERE `+where+`
		ORDER BY m.date DESC
		LIMIT ? OFFSET ?`, args...,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var summaries []models.MessageSummary
	for rows.Next() {
		s := models.MessageSummary{}
		var subjectEnc, fromNameEnc, fromEmailEnc, bodyTextEnc string
		if err := rows.Scan(
			&s.ID, &s.AccountID, &s.AccountEmail, &s.AccountColor, &s.FolderID, &s.FolderName,
			&subjectEnc, &fromNameEnc, &fromEmailEnc, &bodyTextEnc,
			&s.Date, &s.IsRead, &s.IsStarred, &s.HasAttachment,
		); err != nil {
			return nil, err
		}
		s.Subject, _ = d.enc.Decrypt(subjectEnc)
		s.FromName, _ = d.enc.Decrypt(fromNameEnc)
		s.FromEmail, _ = d.enc.Decrypt(fromEmailEnc)
		bodyText, _ := d.enc.Decrypt(bodyTextEnc)
		if len(bodyText) > 120 {
			bodyText = bodyText[:120] + "…"
		}
		s.Preview = bodyText
		summaries = append(summaries, s)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	return &models.PagedMessages{
		Messages: summaries,
		Total:    total,
		Page:     page,
		PageSize: pageSize,
		HasMore:  offset+len(summaries) < total,
	}, nil
}

func (d *DB) SearchMessages(userID int64, q string, page, pageSize int) (*models.PagedMessages, error) {
	offset := (page - 1) * pageSize
	like := "%" + strings.ToLower(q) + "%"
	args := []interface{}{userID, like, pageSize, offset}

	var total int
	d.sql.QueryRow(`
		SELECT COUNT(*) FROM messages m
		JOIN email_accounts a ON a.id=m.account_id
		WHERE a.user_id=? AND m.search_text LIKE ?`,
		userID, like,
	).Scan(&total)

	rows, err := d.sql.Query(`
		SELECT m.id, m.account_id, a.email_address, a.color, m.folder_id, f.name,
		       m.subject, m.from_name, m.from_email, m.body_text,
		       m.date, m.is_read, m.is_starred, m.has_attachment
		FROM messages m
		JOIN email_accounts a ON a.id=m.account_id
		JOIN folders f ON f.id=m.folder_id
		WHERE a.user_id=? AND m.search_text LIKE ?
		ORDER BY m.date DESC LIMIT ? OFFSET ?`, args...,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var summaries []models.MessageSummary
	for rows.Next() {
		s := models.MessageSummary{}
		var subjectEnc, fromNameEnc, fromEmailEnc, bodyTextEnc string
		if err := rows.Scan(
			&s.ID, &s.AccountID, &s.AccountEmail, &s.AccountColor, &s.FolderID, &s.FolderName,
			&subjectEnc, &fromNameEnc, &fromEmailEnc, &bodyTextEnc,
			&s.Date, &s.IsRead, &s.IsStarred, &s.HasAttachment,
		); err != nil {
			return nil, err
		}
		s.Subject, _ = d.enc.Decrypt(subjectEnc)
		s.FromName, _ = d.enc.Decrypt(fromNameEnc)
		s.FromEmail, _ = d.enc.Decrypt(fromEmailEnc)
		bodyText, _ := d.enc.Decrypt(bodyTextEnc)
		if len(bodyText) > 120 {
			bodyText = bodyText[:120] + "…"
		}
		s.Preview = bodyText
		summaries = append(summaries, s)
	}

	return &models.PagedMessages{
		Messages: summaries, Total: total, Page: page, PageSize: pageSize,
		HasMore: offset+len(summaries) < total,
	}, rows.Err()
}

func (d *DB) MarkMessageRead(messageID, userID int64, read bool) error {
	val := 0
	if read {
		val = 1
	}
	_, err := d.sql.Exec(`
		UPDATE messages SET is_read=?
		WHERE id=? AND account_id IN (SELECT id FROM email_accounts WHERE user_id=?)`,
		val, messageID, userID,
	)
	return err
}

func (d *DB) ToggleMessageStar(messageID, userID int64) (bool, error) {
	var current bool
	err := d.sql.QueryRow(`
		SELECT is_starred FROM messages
		WHERE id=? AND account_id IN (SELECT id FROM email_accounts WHERE user_id=?)`,
		messageID, userID,
	).Scan(&current)
	if err != nil {
		return false, err
	}
	newVal := !current
	intVal := 0
	if newVal {
		intVal = 1
	}
	_, err = d.sql.Exec(`UPDATE messages SET is_starred=? WHERE id=?`, intVal, messageID)
	return newVal, err
}

func (d *DB) MoveMessage(messageID, userID, folderID int64) error {
	_, err := d.sql.Exec(`
		UPDATE messages SET folder_id=?
		WHERE id=? AND account_id IN (SELECT id FROM email_accounts WHERE user_id=?)`,
		folderID, messageID, userID,
	)
	return err
}

func (d *DB) DeleteMessage(messageID, userID int64) error {
	_, err := d.sql.Exec(`
		DELETE FROM messages WHERE id=?
		AND account_id IN (SELECT id FROM email_accounts WHERE user_id=?)`,
		messageID, userID,
	)
	return err
}

func (d *DB) GetFoldersByUser(userID int64) ([]*models.Folder, error) {
	rows, err := d.sql.Query(`
		SELECT f.id, f.account_id, f.name, f.full_path, f.folder_type, f.unread_count, f.total_count,
		       COALESCE(f.is_hidden,0), COALESCE(f.sync_enabled,1)
		FROM folders f
		JOIN email_accounts a ON a.id=f.account_id
		WHERE a.user_id=?
		ORDER BY a.created_at, f.folder_type, f.name`, userID,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var folders []*models.Folder
	for rows.Next() {
		f := &models.Folder{}
		var isHidden, syncEnabled int
		if err := rows.Scan(&f.ID, &f.AccountID, &f.Name, &f.FullPath, &f.FolderType, &f.UnreadCount, &f.TotalCount, &isHidden, &syncEnabled); err != nil {
			return nil, err
		}
		f.IsHidden = isHidden == 1
		f.SyncEnabled = syncEnabled == 1
		folders = append(folders, f)
	}
	return folders, rows.Err()
}

// ---- Remote Content Whitelist ----

func (d *DB) GetRemoteContentWhitelist(userID int64) ([]string, error) {
	rows, err := d.sql.Query(
		`SELECT sender FROM remote_content_whitelist WHERE user_id=? ORDER BY sender`,
		userID,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var list []string
	for rows.Next() {
		var s string
		if err := rows.Scan(&s); err == nil {
			list = append(list, s)
		}
	}
	return list, rows.Err()
}

func (d *DB) AddRemoteContentWhitelist(userID int64, sender string) error {
	_, err := d.sql.Exec(
		`INSERT OR IGNORE INTO remote_content_whitelist (user_id, sender) VALUES (?, ?)`,
		userID, sender,
	)
	return err
}

func (d *DB) IsRemoteContentAllowed(userID int64, sender string) (bool, error) {
	var count int
	err := d.sql.QueryRow(
		`SELECT COUNT(*) FROM remote_content_whitelist WHERE user_id=? AND sender=?`,
		userID, sender,
	).Scan(&count)
	return count > 0, err
}

// SetFolderVisibility sets is_hidden and sync_enabled for a folder owned by the user.
func (d *DB) SetFolderVisibility(folderID, userID int64, isHidden, syncEnabled bool) error {
	ih, se := 0, 0
	if isHidden {
		ih = 1
	}
	if syncEnabled {
		se = 1
	}
	_, err := d.sql.Exec(`
		UPDATE folders SET is_hidden=?, sync_enabled=?
		WHERE id=? AND account_id IN (SELECT id FROM email_accounts WHERE user_id=?)`,
		ih, se, folderID, userID)
	return err
}

// CountFolderMessages returns how many messages are in a folder (owned by user).
func (d *DB) CountFolderMessages(folderID, userID int64) (int, error) {
	var count int
	err := d.sql.QueryRow(`
		SELECT COUNT(*) FROM messages m
		JOIN folders f ON f.id=m.folder_id
		JOIN email_accounts a ON a.id=f.account_id
		WHERE m.folder_id=? AND a.user_id=?`, folderID, userID).Scan(&count)
	return count, err
}

// DeleteFolder removes a folder and all its messages (cascade).
func (d *DB) DeleteFolder(folderID, userID int64) error {
	_, err := d.sql.Exec(`
		DELETE FROM folders WHERE id=?
		AND account_id IN (SELECT id FROM email_accounts WHERE user_id=?)`,
		folderID, userID)
	return err
}

// MoveFolderContents moves all messages from one folder to another (both must belong to user).
func (d *DB) MoveFolderContents(fromID, toID, userID int64) (int64, error) {
	res, err := d.sql.Exec(`
		UPDATE messages SET folder_id=?
		WHERE folder_id=?
		AND folder_id IN (SELECT f.id FROM folders f JOIN email_accounts a ON a.id=f.account_id WHERE a.user_id=?)`,
		toID, fromID, userID)
	if err != nil {
		return 0, err
	}
	n, _ := res.RowsAffected()
	return n, nil
}

func (d *DB) GetFolderByID(folderID int64) (*models.Folder, error) {
	f := &models.Folder{}
	var isHidden, syncEnabled int
	err := d.sql.QueryRow(
		`SELECT id, account_id, name, full_path, folder_type, unread_count, total_count,
		       COALESCE(is_hidden,0), COALESCE(sync_enabled,1)
		 FROM folders WHERE id=?`, folderID,
	).Scan(&f.ID, &f.AccountID, &f.Name, &f.FullPath, &f.FolderType, &f.UnreadCount, &f.TotalCount, &isHidden, &syncEnabled)
	f.IsHidden = isHidden == 1
	f.SyncEnabled = syncEnabled == 1
	if err == sql.ErrNoRows {
		return nil, nil
	}
	return f, err
}

// GetMessageIMAPInfo returns the remote_uid, folder full_path, account info needed for IMAP ops.
func (d *DB) GetMessageIMAPInfo(messageID, userID int64) (remoteUID uint32, folderPath string, account *models.EmailAccount, err error) {
	var uidStr string
	var accountID int64
	var folderID int64
	err = d.sql.QueryRow(`
		SELECT m.remote_uid, m.account_id, m.folder_id
		FROM messages m
		JOIN email_accounts a ON a.id = m.account_id
		WHERE m.id=? AND a.user_id=?`, messageID, userID,
	).Scan(&uidStr, &accountID, &folderID)
	if err != nil {
		return 0, "", nil, err
	}
	// Parse uid
	var uid uint64
	fmt.Sscanf(uidStr, "%d", &uid)
	remoteUID = uint32(uid)

	folder, err := d.GetFolderByID(folderID)
	if err != nil || folder == nil {
		return remoteUID, "", nil, fmt.Errorf("folder not found")
	}
	account, err = d.GetAccount(accountID)
	return remoteUID, folder.FullPath, account, err
}

// ListStarredMessages returns all starred messages for a user, newest first.
func (d *DB) ListStarredMessages(userID int64, page, pageSize int) (*models.PagedMessages, error) {
	offset := (page - 1) * pageSize
	var total int
	d.sql.QueryRow(`SELECT COUNT(*) FROM messages m JOIN email_accounts a ON a.id=m.account_id WHERE a.user_id=? AND m.is_starred=1`, userID).Scan(&total)

	rows, err := d.sql.Query(`
		SELECT m.id, m.account_id, a.email_address, a.color, m.folder_id, f.name,
		       m.subject, m.from_name, m.from_email, m.body_text,
		       m.date, m.is_read, m.is_starred, m.has_attachment
		FROM messages m
		JOIN email_accounts a ON a.id = m.account_id
		JOIN folders f ON f.id = m.folder_id
		WHERE a.user_id=? AND m.is_starred=1
		ORDER BY m.date DESC
		LIMIT ? OFFSET ?`, userID, pageSize, offset)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var summaries []models.MessageSummary
	for rows.Next() {
		s := models.MessageSummary{}
		var subjectEnc, fromNameEnc, fromEmailEnc, bodyTextEnc string
		if err := rows.Scan(
			&s.ID, &s.AccountID, &s.AccountEmail, &s.AccountColor, &s.FolderID, &s.FolderName,
			&subjectEnc, &fromNameEnc, &fromEmailEnc, &bodyTextEnc,
			&s.Date, &s.IsRead, &s.IsStarred, &s.HasAttachment,
		); err != nil {
			return nil, err
		}
		s.Subject, _ = d.enc.Decrypt(subjectEnc)
		s.FromName, _ = d.enc.Decrypt(fromNameEnc)
		s.FromEmail, _ = d.enc.Decrypt(fromEmailEnc)
		bodyText, _ := d.enc.Decrypt(bodyTextEnc)
		if len(bodyText) > 120 {
			bodyText = bodyText[:120] + "…"
		}
		s.Preview = bodyText
		summaries = append(summaries, s)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	return &models.PagedMessages{
		Messages: summaries,
		Total:    total,
		Page:     page,
		PageSize: pageSize,
		HasMore:  offset+len(summaries) < total,
	}, nil
}

// ---- Pending IMAP ops queue ----

// PendingIMAPOp represents an IMAP write operation that needs to be applied to the server.
type PendingIMAPOp struct {
	ID         int64
	AccountID  int64
	OpType     string // "delete" | "move" | "flag_read" | "flag_star"
	RemoteUID  uint32
	FolderPath string
	Extra      string // for move: dest folder path; for flag_*: "1" or "0"
	Attempts   int
}

// EnqueueIMAPOp adds an operation to the pending queue atomically.
func (d *DB) EnqueueIMAPOp(op *PendingIMAPOp) error {
	_, err := d.sql.Exec(
		`INSERT INTO pending_imap_ops (account_id, op_type, remote_uid, folder_path, extra) VALUES (?,?,?,?,?)`,
		op.AccountID, op.OpType, op.RemoteUID, op.FolderPath, op.Extra,
	)
	return err
}

// DequeuePendingOps returns up to `limit` pending ops for a given account.
func (d *DB) DequeuePendingOps(accountID int64, limit int) ([]*PendingIMAPOp, error) {
	rows, err := d.sql.Query(
		`SELECT id, account_id, op_type, remote_uid, folder_path, extra, attempts
		 FROM pending_imap_ops WHERE account_id=? ORDER BY id ASC LIMIT ?`,
		accountID, limit,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var ops []*PendingIMAPOp
	for rows.Next() {
		op := &PendingIMAPOp{}
		rows.Scan(&op.ID, &op.AccountID, &op.OpType, &op.RemoteUID, &op.FolderPath, &op.Extra, &op.Attempts)
		ops = append(ops, op)
	}
	return ops, rows.Err()
}

// DeletePendingOp removes a successfully applied op.
func (d *DB) DeletePendingOp(id int64) error {
	_, err := d.sql.Exec(`DELETE FROM pending_imap_ops WHERE id=?`, id)
	return err
}

// IncrementPendingOpAttempts bumps attempt count; ops with >5 attempts are abandoned.
func (d *DB) IncrementPendingOpAttempts(id int64) {
	d.sql.Exec(`UPDATE pending_imap_ops SET attempts=attempts+1 WHERE id=?`, id)
	d.sql.Exec(`DELETE FROM pending_imap_ops WHERE id=? AND attempts>5`, id)
}

// CountPendingOps returns number of queued ops for an account (for logging).
func (d *DB) CountPendingOps(accountID int64) int {
	var n int
	d.sql.QueryRow(`SELECT COUNT(*) FROM pending_imap_ops WHERE account_id=?`, accountID).Scan(&n)
	return n
}

// ---- Folder delta-sync state ----

// GetFolderSyncState returns uid_validity and last_seen_uid for incremental sync.
func (d *DB) GetFolderSyncState(folderID int64) (uidValidity, lastSeenUID uint32) {
	d.sql.QueryRow(`SELECT COALESCE(uid_validity,0), COALESCE(last_seen_uid,0) FROM folders WHERE id=?`, folderID).
		Scan(&uidValidity, &lastSeenUID)
	return
}

// SetFolderSyncState persists uid_validity and last_seen_uid after a successful sync.
func (d *DB) SetFolderSyncState(folderID int64, uidValidity, lastSeenUID uint32) {
	d.sql.Exec(`UPDATE folders SET uid_validity=?, last_seen_uid=? WHERE id=?`, uidValidity, lastSeenUID, folderID)
}

// PurgeDeletedMessages removes local messages whose remote_uid is no longer
// in the server's UID list for a folder. Returns count purged.
func (d *DB) PurgeDeletedMessages(folderID int64, serverUIDs []uint32) (int, error) {
	if len(serverUIDs) == 0 {
		// Don't purge everything if server returned empty (connection issue)
		return 0, nil
	}
	// Build placeholder list
	args := make([]interface{}, len(serverUIDs)+1)
	args[0] = folderID
	placeholders := make([]string, len(serverUIDs))
	for i, uid := range serverUIDs {
		args[i+1] = fmt.Sprintf("%d", uid)
		placeholders[i] = "?"
	}
	q := fmt.Sprintf(
		`DELETE FROM messages WHERE folder_id=? AND remote_uid NOT IN (%s)`,
		strings.Join(placeholders, ","),
	)
	res, err := d.sql.Exec(q, args...)
	if err != nil {
		return 0, err
	}
	n, _ := res.RowsAffected()
	return int(n), nil
}

// DeleteAllFolderMessages removes all messages from a folder (used on UIDVALIDITY change).
func (d *DB) DeleteAllFolderMessages(folderID int64) {
	d.sql.Exec(`DELETE FROM messages WHERE folder_id=?`, folderID)
}

// GetFolderMessageCount returns the local message count for a folder by account and path.
func (d *DB) GetFolderMessageCount(accountID int64, folderPath string) int {
	var n int
	d.sql.QueryRow(`
		SELECT COUNT(*) FROM messages m
		JOIN folders f ON f.id=m.folder_id
		WHERE f.account_id=? AND f.full_path=?`, accountID, folderPath,
	).Scan(&n)
	return n
}

// ReconcileFlags updates is_read and is_starred from server flags, but ONLY for
// messages that do NOT have a pending local write op (to avoid overwriting in-flight changes).
func (d *DB) ReconcileFlags(folderID int64, serverFlags map[uint32][]string) {
	// Get set of UIDs with pending ops so we don't overwrite them
	rows, _ := d.sql.Query(
		`SELECT DISTINCT remote_uid FROM pending_imap_ops po
		 JOIN folders f ON f.account_id=po.account_id
		 WHERE f.id=? AND (po.op_type='flag_read' OR po.op_type='flag_star')`, folderID,
	)
	pendingUIDs := make(map[uint32]bool)
	if rows != nil {
		for rows.Next() {
			var uid uint32
			rows.Scan(&uid)
			pendingUIDs[uid] = true
		}
		rows.Close()
	}

	for uid, flags := range serverFlags {
		if pendingUIDs[uid] {
			continue // don't reconcile — we have a pending write for this message
		}
		isRead := false
		isStarred := false
		for _, f := range flags {
			switch f {
			case `\Seen`:
				isRead = true
			case `\Flagged`:
				isStarred = true
			}
		}
		d.sql.Exec(
			`UPDATE messages SET is_read=?, is_starred=?
			 WHERE folder_id=? AND remote_uid=?`,
			boolToInt(isRead), boolToInt(isStarred),
			folderID, fmt.Sprintf("%d", uid),
		)
	}
}

func boolToInt(b bool) int {
	if b {
		return 1
	}
	return 0
}

// EmptyFolder deletes all messages in a folder (Trash/Spam).
// Returns count deleted.
func (d *DB) EmptyFolder(folderID, userID int64) (int, error) {
	res, err := d.sql.Exec(`
		DELETE FROM messages WHERE folder_id=?
		AND folder_id IN (SELECT id FROM folders WHERE account_id IN
			(SELECT id FROM email_accounts WHERE user_id=?))`,
		folderID, userID,
	)
	if err != nil {
		return 0, err
	}
	n, _ := res.RowsAffected()
	return int(n), nil
}

// EnableAllFolderSync enables sync for all currently-disabled folders belonging
// to accounts owned by userID. Returns count updated.
func (d *DB) EnableAllFolderSync(accountID, userID int64) (int, error) {
	res, err := d.sql.Exec(`
		UPDATE folders SET sync_enabled=1
		WHERE account_id=? AND sync_enabled=0
		AND account_id IN (SELECT id FROM email_accounts WHERE user_id=?)`,
		accountID, userID,
	)
	if err != nil {
		return 0, err
	}
	n, _ := res.RowsAffected()
	return int(n), nil
}

// PollUnread returns inbox unread count + total unread, and whether there are
// new messages since `sinceID`. Used by the client-side poller.
func (d *DB) PollUnread(userID int64, sinceID int64) (inboxUnread int, totalUnread int, newestID int64, err error) {
	// Inbox unread count
	d.sql.QueryRow(`
		SELECT COALESCE(SUM(f.unread_count),0) FROM folders f
		JOIN email_accounts a ON a.id=f.account_id
		WHERE a.user_id=? AND f.folder_type='inbox'`, userID,
	).Scan(&inboxUnread)

	// Total unread (all folders except trash/spam)
	d.sql.QueryRow(`
		SELECT COALESCE(SUM(f.unread_count),0) FROM folders f
		JOIN email_accounts a ON a.id=f.account_id
		WHERE a.user_id=? AND f.folder_type NOT IN ('trash','spam')`, userID,
	).Scan(&totalUnread)

	// Newest message ID in inbox
	d.sql.QueryRow(`
		SELECT COALESCE(MAX(m.id),0) FROM messages m
		JOIN folders f ON f.id=m.folder_id
		JOIN email_accounts a ON a.id=f.account_id
		WHERE a.user_id=? AND f.folder_type='inbox'`, userID,
	).Scan(&newestID)

	return
}

// GetNewMessagesSince returns inbox message summaries with id > sinceID for notifications.
func (d *DB) GetNewMessagesSince(userID int64, sinceID int64) ([]map[string]interface{}, error) {
	rows, err := d.sql.Query(`
		SELECT m.id, m.subject, m.from_name, m.from_email
		FROM messages m
		JOIN folders f ON f.id=m.folder_id
		JOIN email_accounts a ON a.id=f.account_id
		WHERE a.user_id=? AND f.folder_type='inbox' AND m.id>?
		ORDER BY m.id DESC LIMIT 5`, userID, sinceID,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var result []map[string]interface{}
	for rows.Next() {
		var id int64
		var subject, fromName, fromEmail string
		rows.Scan(&id, &subject, &fromName, &fromEmail)
		// Decrypt
		subject, _ = d.enc.Decrypt(subject)
		fromName, _ = d.enc.Decrypt(fromName)
		fromEmail, _ = d.enc.Decrypt(fromEmail)
		result = append(result, map[string]interface{}{
			"id": id, "subject": subject, "from_name": fromName, "from_email": fromEmail,
		})
	}
	if result == nil {
		result = []map[string]interface{}{}
	}
	return result, rows.Err()
}

// ---- Attachment metadata ----

// SaveAttachmentMeta saves attachment metadata for a message (no binary data).
// Uses INSERT OR REPLACE so a re-sync always refreshes the part path (ContentID).
func (d *DB) SaveAttachmentMeta(messageID int64, atts []models.Attachment) error {
	// Delete stale rows first so re-syncs don't leave orphans
	d.sql.Exec(`DELETE FROM attachments WHERE message_id=?`, messageID)
	for _, a := range atts {
		_, err := d.sql.Exec(`
			INSERT INTO attachments (message_id, filename, content_type, size, content_id)
			VALUES (?,?,?,?,?)`,
			messageID, a.Filename, a.ContentType, a.Size, a.ContentID,
		)
		if err != nil {
			return err
		}
	}
	return nil
}

// GetAttachmentsByMessage returns attachment metadata for a message.
func (d *DB) GetAttachmentsByMessage(messageID, userID int64) ([]models.Attachment, error) {
	rows, err := d.sql.Query(`
		SELECT a.id, a.message_id, a.filename, a.content_type, a.size, a.content_id
		FROM attachments a
		JOIN messages m ON m.id=a.message_id
		JOIN email_accounts ac ON ac.id=m.account_id
		WHERE a.message_id=? AND ac.user_id=?`, messageID, userID,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var result []models.Attachment
	for rows.Next() {
		var a models.Attachment
		rows.Scan(&a.ID, &a.MessageID, &a.Filename, &a.ContentType, &a.Size, &a.ContentID)
		result = append(result, a)
	}
	return result, rows.Err()
}

// GetAttachment returns a single attachment record (ownership via userID check).
func (d *DB) GetAttachment(attachmentID, userID int64) (*models.Attachment, error) {
	var a models.Attachment
	err := d.sql.QueryRow(`
		SELECT a.id, a.message_id, a.filename, a.content_type, a.size, a.content_id
		FROM attachments a
		JOIN messages m ON m.id=a.message_id
		JOIN email_accounts ac ON ac.id=m.account_id
		WHERE a.id=? AND ac.user_id=?`, attachmentID, userID,
	).Scan(&a.ID, &a.MessageID, &a.Filename, &a.ContentType, &a.Size, &a.ContentID)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	return &a, err
}

// ---- Mark all read ----

// MarkFolderAllRead marks every message in a folder as read and enqueues IMAP flag ops.
// Returns the list of (remoteUID, folderPath, accountID) for IMAP ops.
func (d *DB) MarkFolderAllRead(folderID, userID int64) ([]PendingIMAPOp, error) {
	// Verify folder ownership
	var accountID int64
	var fullPath string
	err := d.sql.QueryRow(`
		SELECT f.account_id, f.full_path FROM folders f
		JOIN email_accounts a ON a.id=f.account_id
		WHERE f.id=? AND a.user_id=?`, folderID, userID,
	).Scan(&accountID, &fullPath)
	if err != nil {
		return nil, fmt.Errorf("folder not found or not owned: %w", err)
	}

	// Get all unread messages in folder for IMAP ops
	rows, err := d.sql.Query(`
		SELECT remote_uid FROM messages WHERE folder_id=? AND is_read=0`, folderID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var ops []PendingIMAPOp
	for rows.Next() {
		var uid string
		rows.Scan(&uid)
		var uidNum uint32
		fmt.Sscanf(uid, "%d", &uidNum)
		if uidNum > 0 {
			ops = append(ops, PendingIMAPOp{
				AccountID: accountID, OpType: "flag_read",
				RemoteUID: uidNum, FolderPath: fullPath, Extra: "1",
			})
		}
	}
	rows.Close()

	// Bulk mark read in DB
	_, err = d.sql.Exec(`UPDATE messages SET is_read=1 WHERE folder_id=?`, folderID)
	if err != nil {
		return nil, err
	}
	d.UpdateFolderCounts(folderID)
	return ops, nil
}

// ---- Admin MFA disable ----

// AdminDisableMFAByID disables MFA for a user by ID (admin action).
func (d *DB) AdminDisableMFAByID(targetUserID int64) error {
	_, err := d.sql.Exec(`
		UPDATE users SET mfa_enabled=0, mfa_secret='', mfa_pending=''
		WHERE id=?`, targetUserID)
	return err
}

// ---- Brute Force / IP Block ----

// IPBlock represents a blocked IP entry.
type IPBlock struct {
	ID          int64     `json:"id"`
	IP          string    `json:"ip"`
	Reason      string    `json:"reason"`
	Country     string    `json:"country"`
	CountryCode string    `json:"country_code"`
	Attempts    int       `json:"attempts"`
	BlockedAt   time.Time `json:"blocked_at"`
	ExpiresAt   *time.Time `json:"expires_at"`
	IsPermanent bool      `json:"is_permanent"`
}

// LoginAttemptStat is used for summary display.
type LoginAttemptStat struct {
	IP          string `json:"ip"`
	Country     string `json:"country"`
	CountryCode string `json:"country_code"`
	Total       int    `json:"total"`
	Failures    int    `json:"failures"`
	LastSeen    string `json:"last_seen"`
}

// RecordLoginAttempt saves a login attempt for an IP.
func (d *DB) RecordLoginAttempt(ip, username, country, countryCode string, success bool) {
	suc := 0
	if success {
		suc = 1
	}
	d.sql.Exec(`INSERT INTO login_attempts (ip, username, success, country, country_code) VALUES (?,?,?,?,?)`,
		ip, username, suc, country, countryCode)
}

// CountRecentFailures returns the number of failed logins from an IP in the last windowMinutes.
func (d *DB) CountRecentFailures(ip string, windowMinutes int) int {
	var count int
	d.sql.QueryRow(`
		SELECT COUNT(*) FROM login_attempts
		WHERE ip=? AND success=0 AND created_at >= datetime('now', ? || ' minutes')`,
		ip, fmt.Sprintf("-%d", windowMinutes),
	).Scan(&count)
	return count
}

// IsIPBlocked returns true if the IP is currently blocked (non-expired entry).
func (d *DB) IsIPBlocked(ip string) bool {
	var count int
	d.sql.QueryRow(`
		SELECT COUNT(*) FROM ip_blocks
		WHERE ip=? AND (is_permanent=1 OR expires_at IS NULL OR expires_at > datetime('now'))`,
		ip,
	).Scan(&count)
	return count > 0
}

// BlockIP adds or updates a block entry for an IP.
// banHours=0 means permanent block (admin must remove manually).
func (d *DB) BlockIP(ip, reason, country, countryCode string, attempts int, banHours int) {
	isPermanent := 0
	var expiresExpr string
	if banHours == 0 {
		isPermanent = 1
		expiresExpr = "NULL"
	} else {
		expiresExpr = fmt.Sprintf("datetime('now', '+%d hours')", banHours)
	}
	d.sql.Exec(fmt.Sprintf(`
		INSERT INTO ip_blocks (ip, reason, country, country_code, attempts, is_permanent, expires_at)
		VALUES (?,?,?,?,?,%d,%s)
		ON CONFLICT(ip) DO UPDATE SET
			reason=excluded.reason, attempts=excluded.attempts,
			blocked_at=datetime('now'), is_permanent=%d, expires_at=%s`,
		isPermanent, expiresExpr, isPermanent, expiresExpr,
	), ip, reason, country, countryCode, attempts)
}

// UnblockIP removes a block entry.
func (d *DB) UnblockIP(ip string) error {
	_, err := d.sql.Exec(`DELETE FROM ip_blocks WHERE ip=?`, ip)
	return err
}

// ListIPBlocks returns all current (non-expired or permanent) blocked IPs.
func (d *DB) ListIPBlocks() ([]IPBlock, error) {
	rows, err := d.sql.Query(`
		SELECT id, ip, reason, country, country_code, attempts, blocked_at, expires_at, is_permanent
		FROM ip_blocks
		WHERE is_permanent=1 OR expires_at IS NULL OR expires_at > datetime('now')
		ORDER BY blocked_at DESC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var result []IPBlock
	for rows.Next() {
		var b IPBlock
		var expiresAt sql.NullTime
		rows.Scan(&b.ID, &b.IP, &b.Reason, &b.Country, &b.CountryCode,
			&b.Attempts, &b.BlockedAt, &expiresAt, &b.IsPermanent)
		if expiresAt.Valid {
			t := expiresAt.Time
			b.ExpiresAt = &t
		}
		result = append(result, b)
	}
	return result, rows.Err()
}

// ListLoginAttemptStats returns per-IP attempt summaries for display.
func (d *DB) ListLoginAttemptStats(limitHours int) ([]LoginAttemptStat, error) {
	rows, err := d.sql.Query(`
		SELECT ip, country, country_code,
		       COUNT(*) as total,
		       SUM(CASE WHEN success=0 THEN 1 ELSE 0 END) as failures,
		       MAX(created_at) as last_seen
		FROM login_attempts
		WHERE created_at >= datetime('now', ? || ' hours')
		GROUP BY ip ORDER BY failures DESC LIMIT 100`,
		fmt.Sprintf("-%d", limitHours),
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var result []LoginAttemptStat
	for rows.Next() {
		var s LoginAttemptStat
		rows.Scan(&s.IP, &s.Country, &s.CountryCode, &s.Total, &s.Failures, &s.LastSeen)
		result = append(result, s)
	}
	return result, rows.Err()
}

// PurgeExpiredBlocks removes expired (non-permanent) blocks from the table.
func (d *DB) PurgeExpiredBlocks() {
	d.sql.Exec(`DELETE FROM ip_blocks WHERE is_permanent=0 AND expires_at IS NOT NULL AND expires_at <= datetime('now')`)
}

// LookupIPCountry returns cached country info for an IP from recent login_attempts.
func (d *DB) LookupCachedCountry(ip string) (country, countryCode string) {
	d.sql.QueryRow(`
		SELECT country, country_code FROM login_attempts
		WHERE ip=? AND country != '' ORDER BY created_at DESC LIMIT 1`, ip,
	).Scan(&country, &countryCode)
	return
}

// ---- Profile Updates ----

// UpdateUserEmail changes a user's email address. Returns error if already taken.
func (d *DB) UpdateUserEmail(userID int64, newEmail string) error {
	_, err := d.sql.Exec(
		`UPDATE users SET email=?, updated_at=datetime('now') WHERE id=?`,
		newEmail, userID)
	return err
}

// UpdateUserUsername changes a user's display username. Returns error if already taken.
func (d *DB) UpdateUserUsername(userID int64, newUsername string) error {
	_, err := d.sql.Exec(
		`UPDATE users SET username=?, updated_at=datetime('now') WHERE id=?`,
		newUsername, userID)
	return err
}

// ---- Per-User IP Rules ----

// UserIPRule holds per-user IP access settings.
type UserIPRule struct {
	UserID int64  `json:"user_id"`
	Mode   string `json:"mode"`    // "brute_skip" | "allow_only" | "disabled"
	IPList string `json:"ip_list"` // comma-separated IPs
}

// GetUserIPRule returns the IP rule for a user, or nil if none set.
func (d *DB) GetUserIPRule(userID int64) (*UserIPRule, error) {
	row := d.sql.QueryRow(`SELECT user_id, mode, ip_list FROM user_ip_rules WHERE user_id=?`, userID)
	r := &UserIPRule{}
	if err := row.Scan(&r.UserID, &r.Mode, &r.IPList); err == sql.ErrNoRows {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return r, nil
}

// SetUserIPRule upserts the IP rule for a user.
func (d *DB) SetUserIPRule(userID int64, mode, ipList string) error {
	_, err := d.sql.Exec(`
		INSERT INTO user_ip_rules (user_id, mode, ip_list, updated_at)
		VALUES (?, ?, ?, datetime('now'))
		ON CONFLICT(user_id) DO UPDATE SET
			mode=excluded.mode,
			ip_list=excluded.ip_list,
			updated_at=datetime('now')`,
		userID, mode, ipList)
	return err
}

// DeleteUserIPRule removes IP rules for a user (disables the feature).
func (d *DB) DeleteUserIPRule(userID int64) error {
	_, err := d.sql.Exec(`DELETE FROM user_ip_rules WHERE user_id=?`, userID)
	return err
}

// CheckUserIPAccess evaluates per-user IP rules against a connecting IP.
// Returns:
//   "allow"      — rule says allow (brute_skip match or allow_only match)
//   "deny"       — allow_only mode and IP is not in list
//   "skip_brute" — brute_skip mode and IP is in list (skip brute force check)
//   "default"    — no rule exists, fall through to global rules
func (d *DB) CheckUserIPAccess(userID int64, ip string) string {
	rule, err := d.GetUserIPRule(userID)
	if err != nil || rule == nil || rule.Mode == "disabled" || rule.IPList == "" {
		return "default"
	}
	for _, listed := range splitIPs(rule.IPList) {
		if listed == ip {
			if rule.Mode == "allow_only" {
				return "allow"
			}
			return "skip_brute"
		}
	}
	// IP not in list
	if rule.Mode == "allow_only" {
		return "deny"
	}
	return "default"
}

// SplitIPList splits a comma-separated IP string into trimmed, non-empty entries.
func SplitIPList(s string) []string {
	return splitIPs(s)
}

func splitIPs(s string) []string {
	var result []string
	for _, p := range strings.Split(s, ",") {
		p = strings.TrimSpace(p)
		if p != "" {
			result = append(result, p)
		}
	}
	return result
}

// IPBlockWithUsername extends IPBlock with the last username attempted from that IP.
type IPBlockWithUsername struct {
	IPBlock
	LastUsername string
}

// ListIPBlocksWithUsername returns active blocks enriched with the most recent
// username that was attempted from each IP (from login_attempts history).
func (d *DB) ListIPBlocksWithUsername() ([]IPBlockWithUsername, error) {
	rows, err := d.sql.Query(`
		SELECT
			b.id, b.ip, b.reason, b.country, b.country_code,
			b.attempts, b.blocked_at, b.expires_at, b.is_permanent,
			COALESCE(
				(SELECT username FROM login_attempts
				 WHERE ip=b.ip AND username != ''
				 ORDER BY created_at DESC LIMIT 1),
				''
			) AS last_username
		FROM ip_blocks b
		WHERE b.is_permanent=1 OR b.expires_at IS NULL OR b.expires_at > datetime('now')
		ORDER BY b.blocked_at DESC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var result []IPBlockWithUsername
	for rows.Next() {
		var b IPBlockWithUsername
		var expiresAt sql.NullTime
		err := rows.Scan(
			&b.ID, &b.IP, &b.Reason, &b.Country, &b.CountryCode,
			&b.Attempts, &b.BlockedAt, &expiresAt, &b.IsPermanent,
			&b.LastUsername,
		)
		if err != nil {
			return nil, err
		}
		if expiresAt.Valid {
			t := expiresAt.Time
			b.ExpiresAt = &t
		}
		result = append(result, b)
	}
	return result, rows.Err()
}