// 功能：向当前用户返回本人设备的可追溯用气统计；版本：1.0.0。
package user

import (
	"math"
	"strings"
	"time"

	"git.apinb.com/bsm-sdk/core/errcode"
	"git.apinb.com/bsm-sdk/core/infra"
	"git.apinb.com/heqiapp/platforms/backend/api/internal/impl"
	"git.apinb.com/heqiapp/platforms/backend/api/internal/logic/common"
	"git.apinb.com/heqiapp/platforms/backend/api/internal/models"
	"github.com/gin-gonic/gin"
)

// GetUsageStatistics 严格限定当前归属设备，没有计量数据时返回明确不可用状态。
func GetUsageStatistics(ctx *gin.Context) {
	account, ok := common.UserAccount(ctx)
	if !ok {
		return
	}
	identity := strings.TrimSpace(ctx.Query("device_identity"))
	if identity == "" {
		infra.Response.Error(ctx, errcode.ErrInvalidArgument)
		return
	}
	var device models.ProductInfo
	if err := ownedProductQuery(account.ID).Where("identity = ? AND device_kind IN ?", identity, []string{"valve", "alarm"}).First(&device).Error; err != nil {
		common.RespondRecordError(ctx, err)
		return
	}
	period := strings.TrimSpace(ctx.DefaultQuery("period", "month"))
	anchor := time.Now()
	if raw := strings.TrimSpace(ctx.Query("anchor")); raw != "" {
		parsed, err := time.Parse("2006-01-02", raw)
		if err != nil {
			infra.Response.Error(ctx, errcode.ErrInvalidArgument)
			return
		}
		anchor = parsed
	}
	start, end, valid := usagePeriod(period, anchor)
	if !valid {
		infra.Response.Error(ctx, errcode.ErrInvalidArgument)
		return
	}
	var rows []models.DevUsageStat
	if err := impl.DBService.Where("product_info_id = ? AND stat_date >= ? AND stat_date < ? AND status = ?", device.ID, start, end, common.StatusEnable).
		Order("stat_date").Find(&rows).Error; err != nil {
		infra.Response.Error(ctx, err)
		return
	}
	details := gin.H{"available": len(rows) > 0, "device": gin.H{"identity": device.Identity, "name": device.Name, "code": device.Code},
		"period": period, "period_start": start.Format("2006-01-02"), "period_end": end.AddDate(0, 0, -1).Format("2006-01-02"), "unit": "kg", "points": []gin.H{}}
	if len(rows) == 0 {
		details["unavailable_reason"] = "该设备尚无可用计量数据"
		infra.Response.Success(ctx, details)
		return
	}
	points := make([]gin.H, 0, len(rows))
	total, breakfast, lunch, dinner := 0.0, 0.0, 0.0, 0.0
	latest := rows[0]
	for _, row := range rows {
		total += row.UsageKg
		breakfast += row.BreakfastKg
		lunch += row.LunchKg
		dinner += row.DinnerKg
		points = append(points, gin.H{"date": row.StatDate.Format("2006-01-02"), "usage": roundUsage(row.UsageKg)})
		if row.CalculatedAt.After(latest.CalculatedAt) {
			latest = row
		}
	}
	details["total_usage"] = roundUsage(total)
	details["average_usage"] = roundUsage(total / float64(len(rows)))
	details["composition"] = gin.H{"breakfast": roundUsage(breakfast), "lunch": roundUsage(lunch), "dinner": roundUsage(dinner)}
	details["points"] = points
	details["source"] = latest.Source
	details["calc_version"] = latest.CalcVersion
	details["updated_at"] = latest.CalculatedAt
	infra.Response.Success(ctx, details)
}

// usagePeriod 返回左闭右开的统计时间范围。
func usagePeriod(period string, anchor time.Time) (time.Time, time.Time, bool) {
	day := time.Date(anchor.Year(), anchor.Month(), anchor.Day(), 0, 0, 0, 0, anchor.Location())
	switch period {
	case "day":
		return day, day.AddDate(0, 0, 1), true
	case "week":
		offset := (int(day.Weekday()) + 6) % 7
		start := day.AddDate(0, 0, -offset)
		return start, start.AddDate(0, 0, 7), true
	case "month":
		start := time.Date(day.Year(), day.Month(), 1, 0, 0, 0, 0, day.Location())
		return start, start.AddDate(0, 1, 0), true
	case "year":
		start := time.Date(day.Year(), 1, 1, 0, 0, 0, 0, day.Location())
		return start, start.AddDate(1, 0, 0), true
	default:
		return time.Time{}, time.Time{}, false
	}
}

func roundUsage(value float64) float64 { return math.Round(value*1000) / 1000 }