package interfaces

import (
	"time"

	"mengstack/internal/kernel/response"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

type Handler struct {
	db *gorm.DB
}

func NewHandler(db *gorm.DB) *Handler {
	return &Handler{db: db}
}

type StatsResponse struct {
	TenantCount      int64   `json:"tenantCount"`
	UserCount        int64   `json:"userCount"`
	RoleCount        int64   `json:"roleCount"`
	OnlineCount      int64   `json:"onlineCount"`
	TenantGrowth     float64 `json:"tenantGrowth"`
	UserGrowth       float64 `json:"userGrowth"`
	RoleGrowth       float64 `json:"roleGrowth"`
	TodayActiveUsers int64   `json:"todayActiveUsers"`
}

// GetStats godoc
// @Summary      仪表盘统计
// @Description  返回平台核心指标的统计数据
// @Tags         Dashboard
// @Produce      json
// @Success      200  {object}  response.Response{data=StatsResponse}
// @Security     Bearer
// @Security     TenantID
// @Router       /dashboard/stats [get]
func (h *Handler) GetStats(c *gin.Context) {
	tenantID, _ := c.Get("tenant_id")
	isSuperAdmin := tenantID == ""

	var tenantCount, userCount, roleCount int64
	var tenantPrev, userPrev, rolePrev int64

	now := time.Now()
	thirtyDaysAgo := now.AddDate(0, 0, -30)
	sixtyDaysAgo := now.AddDate(0, 0, -60)

	if isSuperAdmin {
		h.db.Table("tenants").Count(&tenantCount)
		h.db.Table("users").Count(&userCount)
		h.db.Table("roles").Count(&roleCount)

		h.db.Table("tenants").Where("created_at < ? AND created_at >= ?", thirtyDaysAgo, sixtyDaysAgo).Count(&tenantPrev)
		h.db.Table("users").Where("created_at < ? AND created_at >= ?", thirtyDaysAgo, sixtyDaysAgo).Count(&userPrev)
		h.db.Table("roles").Where("created_at < ? AND created_at >= ?", thirtyDaysAgo, sixtyDaysAgo).Count(&rolePrev)
	} else {
		h.db.Table("users").Where("tenant_id = ?", tenantID).Count(&userCount)
		h.db.Table("roles").Where("tenant_id = ?", tenantID).Count(&roleCount)

		h.db.Table("users").Where("tenant_id = ? AND created_at < ? AND created_at >= ?", tenantID, thirtyDaysAgo, sixtyDaysAgo).Count(&userPrev)
		h.db.Table("roles").Where("tenant_id = ? AND created_at < ? AND created_at >= ?", tenantID, thirtyDaysAgo, sixtyDaysAgo).Count(&rolePrev)
	}

	var todayActiveUsers int64
	todayStart := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	if isSuperAdmin {
		h.db.Table("users").Where("last_login >= ?", todayStart).Count(&todayActiveUsers)
	} else {
		h.db.Table("users").Where("tenant_id = ? AND last_login >= ?", tenantID, todayStart).Count(&todayActiveUsers)
	}

	stats := StatsResponse{
		TenantCount:      tenantCount,
		UserCount:        userCount,
		RoleCount:        roleCount,
		OnlineCount:      0,
		TenantGrowth:     calcGrowth(tenantCount, tenantPrev),
		UserGrowth:       calcGrowth(userCount, userPrev),
		RoleGrowth:       calcGrowth(roleCount, rolePrev),
		TodayActiveUsers: todayActiveUsers,
	}

	response.Success(c, stats)
}

func calcGrowth(current, previous int64) float64 {
	if previous == 0 {
		if current > 0 {
			return 100
		}
		return 0
	}
	return float64(current-previous) / float64(previous) * 100
}