// Package store 保存应用自身的数据（设置、会话）。笔记内容不在这里，见 vault。
package store

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

	_ "modernc.org/sqlite"
)

type Store struct{ db *sql.DB }

const schema = `
CREATE TABLE IF NOT EXISTS settings (
  key   TEXT PRIMARY KEY,
  value TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS sessions (
  token_hash TEXT PRIMARY KEY,
  created_at INTEGER NOT NULL,
  expires_at INTEGER NOT NULL
);
`

func Open(path string) (*Store, error) {
	db, err := sql.Open("sqlite", "file:"+path+"?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)&_pragma=foreign_keys(1)")
	if err != nil {
		return nil, err
	}
	if _, err := db.Exec(schema); err != nil {
		db.Close()
		return nil, fmt.Errorf("初始化数据库失败: %w", err)
	}
	return &Store{db: db}, nil
}

func (s *Store) Close() error { return s.db.Close() }

// Setting 读取设置项；不存在时 ok 为 false
func (s *Store) Setting(key string) (value string, ok bool, err error) {
	err = s.db.QueryRow(`SELECT value FROM settings WHERE key = ?`, key).Scan(&value)
	if errors.Is(err, sql.ErrNoRows) {
		return "", false, nil
	}
	return value, err == nil, err
}

func (s *Store) SetSetting(key, value string) error {
	_, err := s.db.Exec(`INSERT INTO settings (key, value) VALUES (?, ?) ON CONFLICT(key) DO UPDATE SET value = excluded.value`, key, value)
	return err
}

// SetSettingIfAbsent 仅在设置项不存在时写入，返回是否写入成功（用于首次初始化，防止并发重复设置）
func (s *Store) SetSettingIfAbsent(key, value string) (bool, error) {
	res, err := s.db.Exec(`INSERT INTO settings (key, value) VALUES (?, ?) ON CONFLICT(key) DO NOTHING`, key, value)
	if err != nil {
		return false, err
	}
	n, err := res.RowsAffected()
	return n == 1, err
}

func (s *Store) CreateSession(tokenHash string, expires time.Time) error {
	_, err := s.db.Exec(`INSERT INTO sessions (token_hash, created_at, expires_at) VALUES (?, ?, ?)`,
		tokenHash, time.Now().Unix(), expires.Unix())
	return err
}

// SessionValid 校验会话未过期，并顺延有效期（滑动过期）
func (s *Store) SessionValid(tokenHash string, extendTo time.Time) (bool, error) {
	res, err := s.db.Exec(`UPDATE sessions SET expires_at = ? WHERE token_hash = ? AND expires_at > ?`,
		extendTo.Unix(), tokenHash, time.Now().Unix())
	if err != nil {
		return false, err
	}
	n, err := res.RowsAffected()
	return n == 1, err
}

func (s *Store) DeleteSession(tokenHash string) error {
	_, err := s.db.Exec(`DELETE FROM sessions WHERE token_hash = ?`, tokenHash)
	return err
}

func (s *Store) DeleteAllSessions() error {
	_, err := s.db.Exec(`DELETE FROM sessions`)
	return err
}

func (s *Store) DeleteExpiredSessions() error {
	_, err := s.db.Exec(`DELETE FROM sessions WHERE expires_at <= ?`, time.Now().Unix())
	return err
}