package radio

import (
	"sundynix-go/global"
	"sundynix-go/model/radio/response"
	"time"
)

type AnalyticsService struct{}

// parseDateRange 解析日期范围，未传则默认最近30天
func parseDateRange(startDate, endDate string) (time.Time, time.Time) {
	now := time.Now()
	layout := "2006-01-02"

	end, err := time.ParseInLocation(layout, endDate, now.Location())
	if err != nil {
		end = now
	}
	// 结束日期取当天 23:59:59
	end = time.Date(end.Year(), end.Month(), end.Day(), 23, 59, 59, 0, end.Location())

	start, err := time.ParseInLocation(layout, startDate, now.Location())
	if err != nil {
		start = end.AddDate(0, 0, -29) // 默认30天
	}
	// 开始日期取当天 00:00:00
	start = time.Date(start.Year(), start.Month(), start.Day(), 0, 0, 0, 0, start.Location())

	return start, end
}

// GetListeningTrend 获取收听趋势 (使用持久化的 ListenLog)
func (s *AnalyticsService) GetListeningTrend(startDate, endDate, channelId string) (response.ListeningTrendResponse, error) {
	var resp response.ListeningTrendResponse
	start, end := parseDateRange(startDate, endDate)

	db := global.DB.Table("sundynix_radio_listen_log")
	if channelId != "" {
		db = db.Where("channel_id = ?", channelId)
	}

	// 按天聚合收听次数 (即便用户删除了 history，日志依然存在)
	err := db.Select("DATE(created_at) AS date, COUNT(*) AS count").
		Where("created_at BETWEEN ? AND ?", start, end).
		Where("deleted_at IS NULL").
		Group("DATE(created_at)").
		Order("date ASC").
		Scan(&resp.Trend).Error
	if err != nil {
		return resp, err
	}

	for _, p := range resp.Trend {
		resp.TotalCount += p.Count
	}
	return resp, nil
}

// GetSubscriptionTrend 获取新增订阅趋势 (使用永久 Order 记录)
func (s *AnalyticsService) GetSubscriptionTrend(startDate, endDate, channelId string) (response.SubscriptionTrendResponse, error) {
	var resp response.SubscriptionTrendResponse
	start, end := parseDateRange(startDate, endDate)

	// 订阅趋势 = 首次购买该频道成功的订单
	// 通过子查询找到每个 (user_id, channel_id) 的最小成功订单日期
	subQuery := global.DB.Table("sundynix_order").
		Select("MIN(updated_at) as first_pay").
		Where("type = 1 AND status = 1 AND deleted_at IS NULL").
		Group("user_id, channel_id")

	db := global.DB.Table("(?) as first_orders", subQuery).
		Where("first_pay BETWEEN ? AND ?", start, end)

	err := db.Select("DATE(first_pay) AS date, COUNT(*) AS count").
		Group("DATE(first_pay)").
		Order("date ASC").
		Scan(&resp.Trend).Error
	if err != nil {
		return resp, err
	}

	for _, p := range resp.Trend {
		resp.TotalNewSubs += p.Count
	}
	return resp, nil
}

// GetRenewalTrend 获取续费趋势 (使用永久 Order 记录)
func (s *AnalyticsService) GetRenewalTrend(startDate, endDate, channelId string) (response.RenewalTrendResponse, error) {
	var resp response.RenewalTrendResponse
	start, end := parseDateRange(startDate, endDate)

	// 续费 = 成功支付的订阅订单，且不是该用户对该频道的首笔订单
	db := global.DB.Table("sundynix_order AS o").
		Where("o.type = 1 AND o.status = 1 AND o.deleted_at IS NULL").
		Where("o.updated_at BETWEEN ? AND ?", start, end).
		Where("EXISTS (SELECT 1 FROM sundynix_order AS o2 WHERE o2.user_id = o.user_id AND o2.channel_id = o.channel_id AND o2.updated_at < o.updated_at AND o2.status = 1)")

	if channelId != "" {
		db = db.Where("o.channel_id = ?", channelId)
	}

	err := db.Select("DATE(o.updated_at) AS date, COUNT(*) AS count").
		Group("DATE(o.updated_at)").
		Order("date ASC").
		Scan(&resp.Trend).Error
	if err != nil {
		return resp, err
	}

	for _, p := range resp.Trend {
		resp.TotalRenewals += p.Count
	}
	return resp, nil
}

// GetSubscriberStats 获取订阅用户统计 (混合实时 Subscription 与历史 Order)
func (s *AnalyticsService) GetSubscriberStats(startDate, endDate, channelId string) (response.SubscriberStatsResponse, error) {
	var resp response.SubscriberStatsResponse
	start, end := parseDateRange(startDate, endDate)
	now := time.Now()

	// 1. 当前有效订阅用户数 (实时表)
	activeQuery := global.DB.Table("sundynix_radio_subscription").
		Where("deleted_at IS NULL AND status = 1 AND expired_at > ?", now)
	if channelId != "" {
		activeQuery = activeQuery.Where("channel_id = ?", channelId)
	}
	activeQuery.Select("COUNT(DISTINCT user_id)").Scan(&resp.ActiveSubscribers)

	// 2. 累积总订阅人数 (从历史 Order 表统计全量真实去重用户)
	totalUserQuery := global.DB.Table("sundynix_order").
		Where("type = 1 AND status = 1 AND deleted_at IS NULL")
	if channelId != "" {
		totalUserQuery = totalUserQuery.Where("channel_id = ?", channelId)
	}
	totalUserQuery.Select("COUNT(DISTINCT user_id)").Scan(&resp.TotalSubscribers)

	// 3. 已流失/过期用户 = 历史总计 - 当前有效
	resp.ExpiredSubscribers = resp.TotalSubscribers - resp.ActiveSubscribers
	if resp.ExpiredSubscribers < 0 {
		resp.ExpiredSubscribers = 0
	}

	// 4. 每日新增转化用户趋势 (从 Order 表提取)
	trendQuery := global.DB.Table("sundynix_order").
		Where("type = 1 AND status = 1 AND updated_at BETWEEN ? AND ? AND deleted_at IS NULL", start, end)
	if channelId != "" {
		trendQuery = trendQuery.Where("channel_id = ?", channelId)
	}

	err := trendQuery.Select("DATE(updated_at) AS date, COUNT(DISTINCT user_id) AS count").
		Group("DATE(updated_at)").
		Order("date ASC").
		Scan(&resp.ActiveTrend).Error

	return resp, err
}

// GetContentQuality 内容质量分析：完播率
func (s *AnalyticsService) GetContentQuality(channelId string) ([]response.CompletionRateResponse, error) {
	var results []response.CompletionRateResponse

	// 使用更具韧性的 SQL 计算完播率：
	// 1. 优先使用 program 表中的 duration (得益于“贪婪学习”，它会越来越准)
	// 2. 如果 program.duration 为 0，则动态使用该节目在日志中的 MAX(progress) 作为推定时长
	// 3. 过滤掉完全没有任何播放深度记录的异常数据

	baseQuery := global.DB.Table("sundynix_radio_program AS p").
		Select("p.id as program_id, p.title, " +
			"AVG(CAST(h.progress AS DECIMAL) / " +
			"NULLIF(COALESCE(NULLIF(p.duration, 0), (SELECT MAX(progress) FROM sundynix_radio_listen_log WHERE program_id = p.id)), 0)) as avg_completion, " +
			"COUNT(DISTINCT h.user_id) as play_count").
		Joins("INNER JOIN sundynix_radio_history AS h ON h.program_id = p.id")

	if channelId != "" {
		baseQuery = baseQuery.Where("p.channel_id = ?", channelId)
	}

	err := baseQuery.Group("p.id, p.title").
		Having("avg_completion >= 0").
		Order("avg_completion DESC").
		Limit(20).
		Scan(&results).Error

	return results, err
}

// GetUserStickiness 用户黏性分析：留存分析 (Cohort Analysis)
func (s *AnalyticsService) GetUserStickiness(startDate, endDate string) ([]response.RetentionResponse, error) {
	var list []response.RetentionResponse
	start, end := parseDateRange(startDate, endDate)

	// 获取时间范围内的每日新增活跃用户
	var dailyNewUsers []struct {
		Date  string
		Count int64
	}
	global.DB.Table("sundynix_radio_listen_log").
		Select("DATE(created_at) as date, COUNT(DISTINCT user_id) as count").
		Where("created_at BETWEEN ? AND ?", start, end).
		Group("DATE(created_at)").
		Scan(&dailyNewUsers)

	for _, day := range dailyNewUsers {
		dayTime, _ := time.Parse("2006-01-02", day.Date)
		res := response.RetentionResponse{
			Date:     day.Date,
			NewUsers: day.Count,
		}

		// 计算 1, 3, 7, 30 天后的留存率
		intervals := []int{1, 3, 7, 30}
		for _, dayDelta := range intervals {
			checkDayStart := dayTime.AddDate(0, 0, dayDelta)
			checkDayEnd := checkDayStart.AddDate(0, 0, 1)

			var retainedCount int64
			// 统计在 day.Date 活跃过的用户中，有多少在 checkDay 再次出现了
			global.DB.Table("sundynix_radio_listen_log").
				Where("user_id IN (SELECT DISTINCT user_id FROM sundynix_radio_listen_log WHERE DATE(created_at) = ?)", day.Date).
				Where("created_at BETWEEN ? AND ?", checkDayStart, checkDayEnd).
				Distinct("user_id").
				Count(&retainedCount)

			rate := 0.0
			if day.Count > 0 {
				rate = float64(retainedCount) / float64(day.Count)
			}
			res.Retention = append(res.Retention, rate)
		}
		list = append(list, res)
	}

	return list, nil
}

// GetBusinessConversion 商业转化分析：漏斗与 LTV
func (s *AnalyticsService) GetBusinessConversion(startDate, endDate string) (response.FunnelResponse, error) {
	var resp response.FunnelResponse
	start, end := parseDateRange(startDate, endDate)

	// 1. 活跃收听用户数 (Top of Funnel)
	global.DB.Table("sundynix_radio_listen_log").
		Where("created_at BETWEEN ? AND ?", start, end).
		Distinct("user_id").Count(&resp.ListenUsers)

	// 2. 尝试下单用户数 (Middle of Funnel) - 只要创建过订单就算
	global.DB.Table("sundynix_order").
		Where("created_at BETWEEN ? AND ?", start, end).
		Distinct("user_id").Count(&resp.OrderUsers)

	// 3. 支付成功用户数 (Bottom of Funnel)
	global.DB.Table("sundynix_order").
		Where("updated_at BETWEEN ? AND ? AND status = 1", start, end).
		Distinct("user_id").Count(&resp.PayUsers)

	// 4. LTV 计算 (活跃期内总营收 / 总活跃用户数)
	var totalRevenue int64
	global.DB.Table("sundynix_order").
		Where("updated_at BETWEEN ? AND ? AND status = 1", start, end).
		Select("SUM(amount)").Scan(&totalRevenue)

	if resp.ListenUsers > 0 {
		resp.LTV = float64(totalRevenue) / float64(resp.ListenUsers)
	}

	return resp, nil
}

// GetPreferenceAnalysis 品类偏好分析
func (s *AnalyticsService) GetPreferenceAnalysis() (response.PreferenceAnalysisResponse, error) {
	var resp response.PreferenceAnalysisResponse
	var totalRevenue int64

	// 获取总营收用于计算占比
	global.DB.Table("sundynix_order").Where("status = 1").Select("SUM(amount)").Scan(&totalRevenue)

	// 按分类聚合播放量与营收
	err := global.DB.Table("sundynix_radio_category AS cat").
		Select("cat.id as category_id, cat.name as category_name, " +
			"COUNT(DISTINCT l.id) as listen_count, " +
			"COALESCE(SUM(DISTINCT o.amount), 0) as revenue").
		Joins("LEFT JOIN sundynix_radio_channel AS ch ON ch.category_id = cat.id").
		Joins("LEFT JOIN sundynix_radio_listen_log AS l ON l.channel_id = ch.id").
		Joins("LEFT JOIN sundynix_order AS o ON o.channel_id = ch.id AND o.status = 1").
		Group("cat.id, cat.name").
		Order("revenue DESC").
		Scan(&resp.List).Error

	if totalRevenue > 0 {
		for i := range resp.List {
			resp.List[i].Share = float64(resp.List[i].Revenue) / float64(totalRevenue)
		}
	}

	return resp, err
}