package db

import (
	"database/sql"
	"fmt"
)

func scanUser(row interface {
	Scan(dest ...any) error
}) (User, error) {
	var user User
	var uid, gid sql.NullInt64
	var groups, createdAt, updatedAt string
	var smbEnabled, disabled int
	if err := row.Scan(
		&user.ID,
		&user.Username,
		&uid,
		&gid,
		&groups,
		&smbEnabled,
		&disabled,
		&user.PendingPassword,
		&createdAt,
		&updatedAt,
	); err != nil {
		return User{}, err
	}
	if uid.Valid {
		user.UID = &uid.Int64
	}
	if gid.Valid {
		user.GID = &gid.Int64
	}
	user.SMBEnabled = smbEnabled != 0
	user.Disabled = disabled != 0
	var err error
	user.Groups, err = decodeJSONStrings(groups)
	if err != nil {
		return User{}, err
	}
	user.CreatedAt = parseTime(createdAt)
	user.UpdatedAt = parseTime(updatedAt)
	return user, nil
}

const userColumns = `id, username, uid, gid, groups, smb_enabled, disabled, pending_password, created_at, updated_at`

func (d *DB) ListUsers() ([]User, error) {
	rows, err := d.conn.Query(`SELECT ` + userColumns + ` FROM system_users ORDER BY username ASC`)
	if err != nil {
		return nil, fmt.Errorf("list users: %w", err)
	}
	defer rows.Close()

	var users []User
	for rows.Next() {
		user, err := scanUser(rows)
		if err != nil {
			return nil, fmt.Errorf("scan user: %w", err)
		}
		users = append(users, user)
	}
	return users, rows.Err()
}

func (d *DB) GetUser(id int64) (User, error) {
	row := d.conn.QueryRow(`SELECT `+userColumns+` FROM system_users WHERE id = ?`, id)
	user, err := scanUser(row)
	if err == sql.ErrNoRows {
		return User{}, fmt.Errorf("user not found")
	}
	if err != nil {
		return User{}, fmt.Errorf("get user: %w", err)
	}
	return user, nil
}

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

func (d *DB) CreateUser(user User) (User, error) {
	groups, err := encodeJSONStrings(user.Groups)
	if err != nil {
		return User{}, err
	}
	result, err := d.conn.Exec(`
		INSERT INTO system_users (username, groups, smb_enabled, disabled, pending_password)
		VALUES (?, ?, ?, ?, ?)`,
		user.Username, groups, boolToInt(user.SMBEnabled), boolToInt(user.Disabled), user.PendingPassword,
	)
	if err != nil {
		return User{}, fmt.Errorf("create user: %w", err)
	}
	id, err := result.LastInsertId()
	if err != nil {
		return User{}, fmt.Errorf("last insert id: %w", err)
	}
	return d.GetUser(id)
}

func (d *DB) UpdateUser(id int64, user User) (User, error) {
	groups, err := encodeJSONStrings(user.Groups)
	if err != nil {
		return User{}, err
	}
	result, err := d.conn.Exec(`
		UPDATE system_users
		SET groups = ?, smb_enabled = ?, disabled = ?, pending_password = ?, updated_at = datetime('now')
		WHERE id = ?`,
		groups, boolToInt(user.SMBEnabled), boolToInt(user.Disabled), user.PendingPassword, id,
	)
	if err != nil {
		return User{}, fmt.Errorf("update user: %w", err)
	}
	rows, err := result.RowsAffected()
	if err != nil {
		return User{}, err
	}
	if rows == 0 {
		return User{}, fmt.Errorf("user not found")
	}
	return d.GetUser(id)
}

func (d *DB) SetUserPendingPassword(id int64, password string) error {
	_, err := d.conn.Exec(
		`UPDATE system_users SET pending_password = ?, updated_at = datetime('now') WHERE id = ?`,
		password, id,
	)
	if err != nil {
		return fmt.Errorf("set pending password: %w", err)
	}
	return nil
}

// ClearUserPendingPassword removes the stored password once it has been applied.
func (d *DB) ClearUserPendingPassword(id int64) error {
	_, err := d.conn.Exec(
		`UPDATE system_users SET pending_password = '' WHERE id = ?`, id,
	)
	if err != nil {
		return fmt.Errorf("clear pending password: %w", err)
	}
	return nil
}

// DeleteUser removes the user row and records a tombstone so the users module
// can run userdel on the next apply.
func (d *DB) DeleteUser(id int64) error {
	user, err := d.GetUser(id)
	if err != nil {
		return err
	}
	tx, err := d.conn.Begin()
	if err != nil {
		return fmt.Errorf("begin tx: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	if _, err := tx.Exec(`DELETE FROM system_users WHERE id = ?`, id); err != nil {
		return fmt.Errorf("delete user: %w", err)
	}
	if _, err := tx.Exec(
		`INSERT INTO deleted_system_users (username, marked_at) VALUES (?, datetime('now'))
		 ON CONFLICT(username) DO UPDATE SET marked_at = datetime('now')`,
		user.Username,
	); err != nil {
		return fmt.Errorf("record deleted user: %w", err)
	}
	return tx.Commit()
}

func (d *DB) ListDeletedUsers() ([]string, error) {
	rows, err := d.conn.Query(`SELECT username FROM deleted_system_users ORDER BY username ASC`)
	if err != nil {
		return nil, fmt.Errorf("list deleted users: %w", err)
	}
	defer rows.Close()

	var usernames []string
	for rows.Next() {
		var username string
		if err := rows.Scan(&username); err != nil {
			return nil, err
		}
		usernames = append(usernames, username)
	}
	return usernames, rows.Err()
}

func (d *DB) ClearDeletedUser(username string) error {
	_, err := d.conn.Exec(`DELETE FROM deleted_system_users WHERE username = ?`, username)
	if err != nil {
		return fmt.Errorf("clear deleted user: %w", err)
	}
	return nil
}

func (d *DB) GetAdminByUsername(username string) (Admin, error) {
	row := d.conn.QueryRow(
		`SELECT id, username, password_hash, created_at, updated_at FROM admins WHERE username = ?`,
		username,
	)
	var admin Admin
	var createdAt, updatedAt string
	err := row.Scan(&admin.ID, &admin.Username, &admin.PasswordHash, &createdAt, &updatedAt)
	if err == sql.ErrNoRows {
		return Admin{}, fmt.Errorf("admin not found")
	}
	if err != nil {
		return Admin{}, fmt.Errorf("get admin: %w", err)
	}
	admin.CreatedAt = parseTime(createdAt)
	admin.UpdatedAt = parseTime(updatedAt)
	return admin, nil
}

func (d *DB) CountAdmins() (int, error) {
	var count int
	if err := d.conn.QueryRow(`SELECT COUNT(1) FROM admins`).Scan(&count); err != nil {
		return 0, fmt.Errorf("count admins: %w", err)
	}
	return count, nil
}

func (d *DB) CreateAdmin(username, passwordHash string) (Admin, error) {
	if _, err := d.conn.Exec(
		`INSERT INTO admins (username, password_hash) VALUES (?, ?)`,
		username, passwordHash,
	); err != nil {
		return Admin{}, fmt.Errorf("create admin: %w", err)
	}
	return d.GetAdminByUsername(username)
}

func (d *DB) GetSetting(key string) (string, bool, error) {
	var value string
	err := d.conn.QueryRow(`SELECT value FROM settings WHERE key = ?`, key).Scan(&value)
	if err == sql.ErrNoRows {
		return "", false, nil
	}
	if err != nil {
		return "", false, fmt.Errorf("get setting %q: %w", key, err)
	}
	return value, true, nil
}

func (d *DB) SetSetting(key, value string) error {
	_, err := d.conn.Exec(
		`INSERT INTO settings (key, value) VALUES (?, ?)
		 ON CONFLICT(key) DO UPDATE SET value = excluded.value`,
		key, value,
	)
	if err != nil {
		return fmt.Errorf("set setting %q: %w", key, err)
	}
	return nil
}