package store

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

// Briefing 每日简报模型
type Briefing struct {
	ID            string           `json:"id"`
	UserID        string           `json:"user_id"`
	Date          string           `json:"date"` // YYYY-MM-DD
	Weather       *WeatherData     `json:"weather"`
	News          []NewsItem       `json:"news"`
	Reminders     []BriefReminder  `json:"reminders"`
	Summary       string           `json:"summary"`
	SummarySource string           `json:"summary_source"` // "ai" | "fallback"
	Status        string           `json:"status"`          // pending, generated, delivered
	GeneratedAt   *time.Time       `json:"generated_at,omitempty"`
	DeliveredAt   *time.Time       `json:"delivered_at,omitempty"`
	CreatedAt     time.Time        `json:"created_at"`
}

// WeatherData 天气数据
type WeatherData struct {
	Location  string  `json:"location"`
	Temp      float64 `json:"temp"`
	Condition string  `json:"condition"`
	Icon      string  `json:"icon"`
}

// NewsItem 新闻条目
type NewsItem struct {
	Title   string `json:"title"`
	URL     string `json:"url"`
	Source  string `json:"source"`
	Summary string `json:"summary"`
}

// BriefReminder 简报中的提醒摘要
type BriefReminder struct {
	ID       string `json:"id"`
	Title    string `json:"title"`
	RemindAt string `json:"remind_at"`
}

// BriefingStore 每日简报持久化存储
type BriefingStore struct {
	db *sql.DB
}

// NewBriefingStore 使用已有数据库连接初始化简报存储并自动建表
func NewBriefingStore(db *sql.DB) (*BriefingStore, error) {
	store := &BriefingStore{db: db}

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

	log.Println("[BriefingStore] 简报持久化存储已初始化")
	return store, nil
}

// migrate 自动创建简报表结构
func (s *BriefingStore) migrate() error {
	queries := []string{
		`CREATE TABLE IF NOT EXISTS daily_briefings (
			id VARCHAR(36) PRIMARY KEY,
			user_id VARCHAR(255) NOT NULL,
			date DATE NOT NULL,
			weather JSONB DEFAULT '{}',
			news JSONB DEFAULT '[]',
			reminders JSONB DEFAULT '[]',
			summary TEXT DEFAULT '',
			summary_source VARCHAR(20) DEFAULT 'ai',
			status VARCHAR(20) DEFAULT 'pending',
			generated_at TIMESTAMPTZ,
			delivered_at TIMESTAMPTZ,
			created_at TIMESTAMPTZ DEFAULT NOW(),
			UNIQUE(user_id, date)
		)`,
		`ALTER TABLE daily_briefings ADD COLUMN IF NOT EXISTS summary_source VARCHAR(20) DEFAULT 'ai'`,
		`CREATE INDEX IF NOT EXISTS idx_briefings_user_id ON daily_briefings(user_id)`,
		`CREATE INDEX IF NOT EXISTS idx_briefings_date ON daily_briefings(date)`,
		`CREATE INDEX IF NOT EXISTS idx_briefings_user_date ON daily_briefings(user_id, date)`,
	}

	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
}

// CreateOrUpdateBriefing upsert 简报
func (s *BriefingStore) CreateOrUpdateBriefing(b *Briefing) error {
	weatherJSON, err := json.Marshal(b.Weather)
	if err != nil {
		return fmt.Errorf("序列化天气数据失败: %w", err)
	}
	newsJSON, err := json.Marshal(b.News)
	if err != nil {
		return fmt.Errorf("序列化新闻数据失败: %w", err)
	}
	remindersJSON, err := json.Marshal(b.Reminders)
	if err != nil {
		return fmt.Errorf("序列化提醒数据失败: %w", err)
	}

	if b.SummarySource == "" {
		b.SummarySource = "ai"
	}

	_, err = s.db.Exec(
		`INSERT INTO daily_briefings (id, user_id, date, weather, news, reminders, summary, summary_source, status, generated_at, delivered_at)
		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
		 ON CONFLICT (user_id, date) DO UPDATE SET
		   weather = EXCLUDED.weather,
		   news = EXCLUDED.news,
		   reminders = EXCLUDED.reminders,
		   summary = EXCLUDED.summary,
		   summary_source = EXCLUDED.summary_source,
		   status = EXCLUDED.status,
		   generated_at = EXCLUDED.generated_at,
		   delivered_at = EXCLUDED.delivered_at`,
		b.ID, b.UserID, b.Date, string(weatherJSON), string(newsJSON), string(remindersJSON),
		b.Summary, b.SummarySource, b.Status, b.GeneratedAt, b.DeliveredAt,
	)
	if err != nil {
		return fmt.Errorf("upsert 简报失败: %w", err)
	}
	return nil
}

// GetBriefingByDate 获取指定日期简报
func (s *BriefingStore) GetBriefingByDate(userID, date string) (*Briefing, error) {
	row := s.db.QueryRow(
		`SELECT id, user_id, date::TEXT, weather, news, reminders, summary, COALESCE(summary_source, 'ai'), status, generated_at, delivered_at, created_at
		 FROM daily_briefings WHERE user_id = $1 AND date = $2::DATE`,
		userID, date,
	)

	b, err := s.scanBriefing(row)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, nil
		}
		return nil, fmt.Errorf("查询简报失败: %w", err)
	}
	return b, nil
}

// GetLatestBriefings 获取最近简报列表
func (s *BriefingStore) GetLatestBriefings(userID string, limit int) ([]Briefing, error) {
	if limit <= 0 {
		limit = 7
	}

	rows, err := s.db.Query(
		`SELECT id, user_id, date::TEXT, weather, news, reminders, summary, COALESCE(summary_source, 'ai'), status, generated_at, delivered_at, created_at
		 FROM daily_briefings WHERE user_id = $1
		 ORDER BY date DESC LIMIT $2`,
		userID, limit,
	)
	if err != nil {
		return nil, fmt.Errorf("查询简报列表失败: %w", err)
	}
	defer rows.Close()

	var briefings []Briefing
	for rows.Next() {
		var (
			id, uid, date, summary, summarySource, status string
			weatherRaw, newsRaw, remindersRaw []byte
			generatedAt, deliveredAt, createdAt sql.NullTime
		)
		if err := rows.Scan(&id, &uid, &date, &weatherRaw, &newsRaw, &remindersRaw,
			&summary, &summarySource, &status, &generatedAt, &deliveredAt, &createdAt); err != nil {
			return nil, fmt.Errorf("扫描简报行失败: %w", err)
		}

		b := Briefing{
			ID:            id,
			UserID:        uid,
			Date:          date,
			Summary:       summary,
			SummarySource: summarySource,
			Status:        status,
		}

		if weatherRaw != nil {
			var w WeatherData
			if err := json.Unmarshal(weatherRaw, &w); err == nil {
				b.Weather = &w
			}
		}
		if newsRaw != nil {
			json.Unmarshal(newsRaw, &b.News)
		}
		if remindersRaw != nil {
			json.Unmarshal(remindersRaw, &b.Reminders)
		}
		if generatedAt.Valid {
			b.GeneratedAt = &generatedAt.Time
		}
		if deliveredAt.Valid {
			b.DeliveredAt = &deliveredAt.Time
		}
		b.CreatedAt = createdAt.Time

		// 确保切片不为 nil
		if b.News == nil {
			b.News = []NewsItem{}
		}
		if b.Reminders == nil {
			b.Reminders = []BriefReminder{}
		}
		if b.Weather == nil {
			b.Weather = &WeatherData{}
		}

		briefings = append(briefings, b)
	}

	if briefings == nil {
		briefings = []Briefing{}
	}
	return briefings, rows.Err()
}

// GetUsersWithBriefings 获取拥有简报的所有用户 ID 列表（用于调度器）
func (s *BriefingStore) GetUsersWithBriefings() ([]string, error) {
	rows, err := s.db.Query(`SELECT DISTINCT user_id FROM daily_briefings`)
	if err != nil {
		return nil, fmt.Errorf("查询简报用户列表失败: %w", err)
	}
	defer rows.Close()

	var userIDs []string
	for rows.Next() {
		var uid string
		if err := rows.Scan(&uid); err != nil {
			return nil, fmt.Errorf("扫描用户ID失败: %w", err)
		}
		userIDs = append(userIDs, uid)
	}
	if userIDs == nil {
		userIDs = []string{}
	}
	return userIDs, rows.Err()
}

// GetAllUsers 获取所有用户 ID（从 reminders 表获取，作为降级方案）
func (s *BriefingStore) GetAllUsers() ([]string, error) {
	rows, err := s.db.Query(`SELECT DISTINCT user_id FROM reminders`)
	if err != nil {
		return nil, fmt.Errorf("查询用户列表失败: %w", err)
	}
	defer rows.Close()

	var userIDs []string
	for rows.Next() {
		var uid string
		if err := rows.Scan(&uid); err != nil {
			return nil, fmt.Errorf("扫描用户ID失败: %w", err)
		}
		userIDs = append(userIDs, uid)
	}
	if userIDs == nil {
		userIDs = []string{}
	}
	return userIDs, rows.Err()
}

// scanBriefing 扫描单行简报
func (s *BriefingStore) scanBriefing(row *sql.Row) (*Briefing, error) {
	var (
		id, uid, date, summary, summarySource, status string
		weatherRaw, newsRaw, remindersRaw []byte
		generatedAt, deliveredAt, createdAt sql.NullTime
	)

	if err := row.Scan(&id, &uid, &date, &weatherRaw, &newsRaw, &remindersRaw,
		&summary, &summarySource, &status, &generatedAt, &deliveredAt, &createdAt); err != nil {
		return nil, err
	}

	b := &Briefing{
		ID:            id,
		UserID:        uid,
		Date:          date,
		Summary:       summary,
		SummarySource: summarySource,
		Status:        status,
	}

	if weatherRaw != nil {
		var w WeatherData
		if err := json.Unmarshal(weatherRaw, &w); err == nil {
			b.Weather = &w
		}
	}
	if b.Weather == nil {
		b.Weather = &WeatherData{}
	}
	if newsRaw != nil {
		json.Unmarshal(newsRaw, &b.News)
	}
	if b.News == nil {
		b.News = []NewsItem{}
	}
	if remindersRaw != nil {
		json.Unmarshal(remindersRaw, &b.Reminders)
	}
	if b.Reminders == nil {
		b.Reminders = []BriefReminder{}
	}
	if generatedAt.Valid {
		b.GeneratedAt = &generatedAt.Time
	}
	if deliveredAt.Valid {
		b.DeliveredAt = &deliveredAt.Time
	}
	b.CreatedAt = createdAt.Time

	return b, nil
}