package store

import (
	"database/sql"
	"fmt"
	"log"
	"time"
)

// Reminder 提醒模型
type Reminder struct {
	ID          string     `json:"id"`
	UserID      string     `json:"user_id"`
	Title       string     `json:"title"`
	Description string     `json:"description"`
	RemindAt    time.Time  `json:"remind_at"`
	Status      string     `json:"status"` // pending, completed, cancelled
	CreatedAt   time.Time  `json:"created_at"`
	CompletedAt *time.Time `json:"completed_at,omitempty"`
	RepeatType  string     `json:"repeat_type"` // none, daily, weekly, monthly
	SessionID   string     `json:"session_id"`
	Notified    bool       `json:"notified"`
}

// ReminderStore 提醒持久化存储
type ReminderStore struct {
	db *sql.DB
}

// NewReminderStore 使用已有数据库连接初始化提醒存储并自动建表
func NewReminderStore(db *sql.DB) (*ReminderStore, error) {
	store := &ReminderStore{db: db}

	if err := store.migrate(); err != nil {
		return nil, fmt.Errorf("提醒表迁移失败: %w", err)
	}

	log.Println("[ReminderStore] 提醒持久化存储已初始化")
	return store, nil
}

// migrate 自动创建提醒表结构
func (s *ReminderStore) migrate() error {
	queries := []string{
		`CREATE TABLE IF NOT EXISTS reminders (
			id VARCHAR(36) PRIMARY KEY,
			user_id VARCHAR(255) NOT NULL,
			title VARCHAR(500) NOT NULL,
			description TEXT DEFAULT '',
			remind_at TIMESTAMPTZ NOT NULL,
			status VARCHAR(20) DEFAULT 'pending',
			created_at TIMESTAMPTZ DEFAULT NOW(),
			completed_at TIMESTAMPTZ,
			repeat_type VARCHAR(20) DEFAULT '',
			session_id VARCHAR(36) DEFAULT '',
			notified BOOLEAN DEFAULT FALSE
		)`,
		`CREATE INDEX IF NOT EXISTS idx_reminders_user_id ON reminders(user_id)`,
		`CREATE INDEX IF NOT EXISTS idx_reminders_remind_at ON reminders(remind_at)`,
		`CREATE INDEX IF NOT EXISTS idx_reminders_status ON reminders(status)`,
		`CREATE INDEX IF NOT EXISTS idx_reminders_due ON reminders(remind_at, status, notified)`,
	}

	for _, q := range queries {
		if _, err := s.db.Exec(q); err != nil {
			return fmt.Errorf("迁移SQL执行失败: %w\nSQL: %s", err, q)
		}
	}
	return nil
}

// CreateReminder 创建新提醒
func (s *ReminderStore) CreateReminder(r *Reminder) error {
	_, err := s.db.Exec(
		`INSERT INTO reminders (id, user_id, title, description, remind_at, status, repeat_type, session_id)
		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8)`,
		r.ID, r.UserID, r.Title, r.Description, r.RemindAt, r.Status, r.RepeatType, r.SessionID,
	)
	if err != nil {
		return fmt.Errorf("创建提醒失败: %w", err)
	}
	return nil
}

// GetRemindersByUser 获取用户的提醒列表（可按状态筛选，按 remind_at 升序）
func (s *ReminderStore) GetRemindersByUser(userID, status string, limit, offset int) ([]Reminder, error) {
	if limit <= 0 {
		limit = 50
	}
	if offset < 0 {
		offset = 0
	}

	var rows *sql.Rows
	var err error

	if status != "" {
		rows, err = s.db.Query(
			`SELECT id, user_id, title, description, remind_at, status, created_at, completed_at, repeat_type, session_id, notified
			 FROM reminders WHERE user_id = $1 AND status = $2
			 ORDER BY remind_at ASC LIMIT $3 OFFSET $4`,
			userID, status, limit, offset,
		)
	} else {
		rows, err = s.db.Query(
			`SELECT id, user_id, title, description, remind_at, status, created_at, completed_at, repeat_type, session_id, notified
			 FROM reminders WHERE user_id = $1
			 ORDER BY remind_at ASC LIMIT $2 OFFSET $3`,
			userID, limit, offset,
		)
	}
	if err != nil {
		return nil, fmt.Errorf("查询提醒列表失败: %w", err)
	}
	defer rows.Close()

	var reminders []Reminder
	for rows.Next() {
		var r Reminder
		if err := rows.Scan(&r.ID, &r.UserID, &r.Title, &r.Description, &r.RemindAt,
			&r.Status, &r.CreatedAt, &r.CompletedAt, &r.RepeatType, &r.SessionID, &r.Notified); err != nil {
			return nil, fmt.Errorf("扫描提醒行失败: %w", err)
		}
		reminders = append(reminders, r)
	}

	if reminders == nil {
		reminders = []Reminder{}
	}
	return reminders, rows.Err()
}

// GetDueReminders 获取所有到期且未通知的提醒
func (s *ReminderStore) GetDueReminders() ([]Reminder, error) {
	rows, err := s.db.Query(
		`SELECT id, user_id, title, description, remind_at, status, created_at, completed_at, repeat_type, session_id, notified
		 FROM reminders
		 WHERE remind_at <= NOW() AND status = 'pending' AND notified = FALSE
		 ORDER BY remind_at ASC`,
	)
	if err != nil {
		return nil, fmt.Errorf("查询到期提醒失败: %w", err)
	}
	defer rows.Close()

	var reminders []Reminder
	for rows.Next() {
		var r Reminder
		if err := rows.Scan(&r.ID, &r.UserID, &r.Title, &r.Description, &r.RemindAt,
			&r.Status, &r.CreatedAt, &r.CompletedAt, &r.RepeatType, &r.SessionID, &r.Notified); err != nil {
			return nil, fmt.Errorf("扫描到期提醒行失败: %w", err)
		}
		reminders = append(reminders, r)
	}

	if reminders == nil {
		reminders = []Reminder{}
	}
	return reminders, rows.Err()
}

// MarkNotified 标记提醒为已通知
func (s *ReminderStore) MarkNotified(id string) error {
	_, err := s.db.Exec(
		`UPDATE reminders SET notified = TRUE WHERE id = $1`,
		id,
	)
	if err != nil {
		return fmt.Errorf("标记提醒已通知失败: %w", err)
	}
	return nil
}

// UpdateReminder 更新提醒字段
func (s *ReminderStore) UpdateReminder(id string, r *Reminder) error {
	_, err := s.db.Exec(
		`UPDATE reminders SET title = $1, description = $2, remind_at = $3, status = $4,
		 completed_at = $5, repeat_type = $6, session_id = $7, notified = $8
		 WHERE id = $9`,
		r.Title, r.Description, r.RemindAt, r.Status, r.CompletedAt, r.RepeatType, r.SessionID, r.Notified, id,
	)
	if err != nil {
		return fmt.Errorf("更新提醒失败: %w", err)
	}
	return nil
}

// DeleteReminder 删除提醒
func (s *ReminderStore) DeleteReminder(id string) error {
	_, err := s.db.Exec(`DELETE FROM reminders WHERE id = $1`, id)
	if err != nil {
		return fmt.Errorf("删除提醒失败: %w", err)
	}
	return nil
}