package admin

import (
	"net/http"
	"strconv"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/shopspring/decimal"
	"go.uber.org/zap"
	"gorm.io/gorm"

	"openteam/server/internal/billing"
	"openteam/server/internal/pkg/httpx"
	"openteam/server/internal/store"
	"openteam/server/internal/user"
)

type usageHandler struct {
	db   *gorm.DB
	bill *billing.Service
	log  *zap.Logger
}

// Overview handles GET /api/v1/admin/stats/overview.
func (h *usageHandler) Overview(c *gin.Context) {
	now := time.Now()
	today := now.Format("2006-01-02")
	month := now.Format("2006-01-02")

	var totals struct {
		Requests int
		Cost     decimal.Decimal
	}
	h.db.Model(&store.UsageDaily{}).
		Select("COALESCE(SUM(requests),0) as requests, COALESCE(SUM(cost),0) as cost").
		Scan(&totals)

	var todayAgg struct {
		Requests    int
		Cost        decimal.Decimal
		InputTokens int64
		OutputTokens int64
	}
	h.db.Model(&store.UsageDaily{}).Where("date = ?", today).
		Select("COALESCE(SUM(requests),0) as requests, COALESCE(SUM(cost),0) as cost, COALESCE(SUM(input_tokens),0) as input_tokens, COALESCE(SUM(output_tokens),0) as output_tokens").
		Scan(&todayAgg)

	var monthAgg struct {
		Requests int
		Cost     decimal.Decimal
	}
	h.db.Model(&store.UsageDaily{}).Where("date >= ? AND date <= ?", month[:7]+"-01", today).
		Select("COALESCE(SUM(requests),0) as requests, COALESCE(SUM(cost),0) as cost").
		Scan(&monthAgg)

	var userCount, channelCount, modelCount int64
	h.db.Model(&store.User{}).Count(&userCount)
	h.db.Model(&store.Channel{}).Count(&channelCount)
	h.db.Model(&store.Model{}).Count(&modelCount)

	httpx.OK(c, gin.H{
		"total": gin.H{
			"requests": totals.Requests,
			"cost":     totals.Cost.String(),
			"users":    userCount,
			"channels": channelCount,
			"models":   modelCount,
		},
		"today": gin.H{
			"requests":     todayAgg.Requests,
			"cost":         todayAgg.Cost.String(),
			"inputTokens":  todayAgg.InputTokens,
			"outputTokens": todayAgg.OutputTokens,
		},
		"month": gin.H{
			"requests": monthAgg.Requests,
			"cost":     monthAgg.Cost.String(),
		},
	})
}

// Usage handles GET /api/v1/admin/usage?from&to&userId&model&group=day|model|user.
func (h *usageHandler) Usage(c *gin.Context) {
	from := c.Query("from")
	to := c.Query("to")
	group := c.DefaultQuery("group", "day")

	q := h.db.Model(&store.UsageDaily{})
	if from != "" {
		q = q.Where("date >= ?", from)
	}
	if to != "" {
		q = q.Where("date <= ?", to)
	}
	if uid := c.Query("userId"); uid != "" {
		q = q.Where("user_id = ?", uid)
	}
	if m := c.Query("model"); m != "" {
		q = q.Where("model_id = ?", m)
	}

	var rows []struct {
		Key          string `gorm:"column:g"`
		Requests     int
		InputTokens  int64
		OutputTokens int64
		Cost         decimal.Decimal
	}
	switch group {
	case "model":
		q = q.Joins("JOIN models ON models.id = usage_dailies.model_id").
			Select("models.name as g, COALESCE(SUM(requests),0) as requests, COALESCE(SUM(input_tokens),0) as input_tokens, COALESCE(SUM(output_tokens),0) as output_tokens, COALESCE(SUM(cost),0) as cost").
			Group("models.name")
	case "user":
		q = q.Joins("JOIN users ON users.id = usage_dailies.user_id").
			Select("users.username as g, COALESCE(SUM(requests),0) as requests, COALESCE(SUM(input_tokens),0) as input_tokens, COALESCE(SUM(output_tokens),0) as output_tokens, COALESCE(SUM(cost),0) as cost").
			Group("users.username")
	default:
		q = q.Select("date as g, COALESCE(SUM(requests),0) as requests, COALESCE(SUM(input_tokens),0) as input_tokens, COALESCE(SUM(output_tokens),0) as output_tokens, COALESCE(SUM(cost),0) as cost").
			Group("date").Order("date ASC")
	}
	if err := q.Scan(&rows).Error; err != nil {
		h.log.Warn("admin usage query failed", zap.Error(err))
		httpx.Fail(c, http.StatusInternalServerError, "usage query failed")
		return
	}
	out := make([]gin.H, 0, len(rows))
	for _, r := range rows {
		out = append(out, gin.H{
			"key": r.Key, "requests": r.Requests,
			"inputTokens": r.InputTokens, "outputTokens": r.OutputTokens,
			"cost": r.Cost.String(),
		})
	}
	httpx.OK(c, out)
}

// Recharges handles GET /api/v1/admin/recharges.
func (h *usageHandler) Recharges(c *gin.Context) {
	status := c.Query("status")
	q := h.db.Preload("User").Model(&store.RechargeOrder{})
	if status != "" {
		q = q.Where("status = ?", status)
	}
	var orders []store.RechargeOrder
	if err := q.Order("id DESC").Limit(100).Find(&orders).Error; err != nil {
		h.log.Warn("list recharges failed", zap.Error(err))
		httpx.Fail(c, http.StatusInternalServerError, "list recharges failed")
		return
	}
	out := make([]gin.H, 0, len(orders))
	for i := range orders {
		o := &orders[i]
		out = append(out, gin.H{
			"id": o.ID, "userId": o.UserID, "username": o.User.Username,
			"amount": o.Amount.String(), "status": o.Status, "method": o.Method,
			"remark": o.Remark, "createdAt": o.CreatedAt,
		})
	}
	httpx.OK(c, out)
}

// ApproveRecharge handles POST /api/v1/admin/recharges/:id/approve.
func (h *usageHandler) ApproveRecharge(c *gin.Context) {
	h.decideRecharge(c, "approve")
}

// RejectRecharge handles POST /api/v1/admin/recharges/:id/reject.
func (h *usageHandler) RejectRecharge(c *gin.Context) {
	h.decideRecharge(c, "reject")
}

func (h *usageHandler) decideRecharge(c *gin.Context, action string) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		httpx.Fail(c, http.StatusBadRequest, "invalid order id")
		return
	}
	admin := user.Current(c)

	var order store.RechargeOrder
	if err := h.db.First(&order, id).Error; err != nil {
		httpx.Fail(c, http.StatusNotFound, "order not found")
		return
	}
	if order.Status != "pending" {
		httpx.Fail(c, http.StatusBadRequest, "order already processed")
		return
	}

	var in struct {
		Remark string `json:"remark"`
	}
	_ = c.ShouldBindJSON(&in)

	now := time.Now()
	if action == "approve" {
		err = h.db.Transaction(func(tx *gorm.DB) error {
			if _, cerr := h.bill.Credit(order.UserID, order.Amount, "recharge", orderIDStr(order.ID)); cerr != nil {
				return cerr
			}
			return tx.Model(&order).Updates(map[string]any{
				"status": "credited", "reviewed_by": admin.ID, "reviewed_at": now, "remark": in.Remark,
			}).Error
		})
	} else {
		err = h.db.Model(&order).Updates(map[string]any{
			"status": "rejected", "reviewed_by": admin.ID, "reviewed_at": now, "remark": in.Remark,
		}).Error
	}
	if err != nil {
		h.log.Warn("recharge decision failed", zap.Error(err))
		httpx.Fail(c, http.StatusInternalServerError, "recharge decision failed")
		return
	}
	httpx.OK(c, gin.H{"ok": true, "status": order.Status})
}

func orderIDStr(id int64) string {
	return strconv.FormatInt(id, 10)
}