package app

import (
	"fmt"
	"net/http"
	"strings"
	"time"
)

// The money view operations actually needs: what has been taken in, what is
// still held on someone's behalf, what has been paid out, and whether the two
// sides of the book still agree. Split across four pages it was impossible to
// answer "how much of our balance is other people's money" — that is the
// number this page exists for.

func (a *App) adminFinanceOverview(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	days := 14
	if value := strings.TrimSpace(r.URL.Query().Get("days")); value != "" {
		if parsed, err := fmt.Sscanf(value, "%d", &days); parsed != 1 || err != nil || days < 1 || days > 90 {
			days = 14
		}
	}

	money := map[string]int64{
		// 托管中 = 已经从主人那里收到、还没结算也没退的钱。这是平台账上"别人的钱"。
		"escrowedCent": a.countOne(ctx, `SELECT COALESCE(SUM(gross_cent-refunded_cent),0) FROM pet_feed_tasks
			WHERE status IN ('ESCROWED','ASSIGNED','SERVING','COMPLETED','DISPUTED')`),
		"settledCent":       a.countOne(ctx, `SELECT COALESCE(SUM(payout_cent),0) FROM pet_feed_tasks WHERE status='SETTLED'`),
		"platformFeeCent":   a.countOne(ctx, `SELECT COALESCE(SUM(platform_fee_cent),0) FROM pet_feed_tasks WHERE status='SETTLED'`),
		"tipCent":           a.countOne(ctx, `SELECT COALESCE(SUM(tip_cent),0) FROM pet_feed_tasks WHERE status IN ('SETTLED','COMPLETED','SERVING','ASSIGNED','ESCROWED')`),
		"walletBalanceCent": a.countOne(ctx, `SELECT COALESCE(SUM(available_cent),0) FROM wallet_accounts`),
		"pendingPayoutCent": a.countOne(ctx, `SELECT COALESCE(SUM(amount_cent),0) FROM withdrawals WHERE status IN ('PENDING','APPROVED')`),
		"paidPayoutCent":    a.countOne(ctx, `SELECT COALESCE(SUM(payout_cent),0) FROM withdrawals WHERE status='PAID'`),
		"orderPaidCent":     a.countOne(ctx, `SELECT COALESCE(SUM(amount_cent),0) FROM orders WHERE status IN ('PAID','REFUNDING') AND deleted_at IS NULL`),
		"orderRefundedCent": a.countOne(ctx, `SELECT COALESCE(SUM(refunded_cent),0) FROM orders WHERE deleted_at IS NULL`),
		"feedRefundedCent":  a.countOne(ctx, `SELECT COALESCE(SUM(refunded_cent),0) FROM pet_feed_tasks`),
		"unpaidOrderCent":   a.countOne(ctx, `SELECT COALESCE(SUM(amount_cent),0) FROM orders WHERE status='CREATED' AND deleted_at IS NULL`),
		"platformOwesCent":  a.countOne(ctx, `SELECT COALESCE(SUM(available_cent),0) FROM wallet_accounts`),
		"disputeHeldCent":   a.countOne(ctx, `SELECT COALESCE(SUM(gross_cent-refunded_cent),0) FROM pet_feed_tasks WHERE status='DISPUTED'`),
		"ledgerMismatchUser": a.countOne(ctx, `SELECT COUNT(*) FROM (SELECT a.user_id FROM wallet_accounts a
			LEFT JOIN wallet_transactions t ON t.user_id=a.user_id GROUP BY a.user_id,a.available_cent
			HAVING a.available_cent<>COALESCE(SUM(t.amount_cent*t.direction),0)) AS drift`),
	}

	// 按产品看收入：会员、代喂、保证金各自多少，退了多少。
	products := []map[string]any{}
	rows, err := a.db.QueryContext(ctx, `SELECT product_type,COUNT(*),COALESCE(SUM(amount_cent),0),COALESCE(SUM(refunded_cent),0)
		FROM orders WHERE status IN ('PAID','REFUNDING','REFUNDED') AND deleted_at IS NULL GROUP BY product_type`)
	if err == nil {
		defer rows.Close()
		for rows.Next() {
			var productType string
			var count, amount, refunded int64
			if rows.Scan(&productType, &count, &amount, &refunded) == nil {
				products = append(products, map[string]any{
					"productType": productType, "orderCount": count,
					"amountCent": amount, "refundedCent": refunded,
				})
			}
		}
	}

	// 按日趋势：收进来的和退出去的放在一起看，才能看出某天是不是在净流出。
	trend := []map[string]any{}
	trendRows, err := a.db.QueryContext(ctx, `SELECT DATE(paid_at) AS day,COALESCE(SUM(amount_cent),0),COUNT(*)
		FROM orders WHERE paid_at IS NOT NULL AND paid_at>=DATE_SUB(CURDATE(),INTERVAL ? DAY) AND deleted_at IS NULL
		GROUP BY DATE(paid_at) ORDER BY day`, days)
	if err == nil {
		defer trendRows.Close()
		for trendRows.Next() {
			var day time.Time
			var amount, count int64
			if trendRows.Scan(&day, &amount, &count) == nil {
				trend = append(trend, map[string]any{
					"date": day.Format("2006-01-02"), "amountCent": amount, "orderCount": count,
				})
			}
		}
	}

	reply(w, map[string]any{
		"money": money, "products": products, "trend": trend, "days": days,
		"withdrawEnabled": a.configBool(ctx, "pet.withdraw_enabled", false),
		"paymentMode":     a.configPlain(ctx, "payment.mode", "sandbox"),
	})
}

// adminOrderRefunds lists what has already been sent back on one order.
func (a *App) adminOrderRefunds(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r)
	if err != nil {
		fail(w, http.StatusBadRequest, 20001, "编号无效")
		return
	}
	rows, queryErr := a.db.QueryContext(r.Context(), `SELECT f.id,f.amount_cent,f.channel,f.reason,f.created_at,
		COALESCE(admin.username,'') FROM order_refunds f LEFT JOIN admin_users admin ON admin.id=f.handled_by
		WHERE f.order_id=? ORDER BY f.id DESC`, id)
	if queryErr != nil {
		fail(w, http.StatusInternalServerError, 50001, "查询退款记录失败")
		return
	}
	defer rows.Close()
	items := []map[string]any{}
	for rows.Next() {
		var refundID, amount int64
		var channel, reason, operator string
		var created time.Time
		if rows.Scan(&refundID, &amount, &channel, &reason, &created, &operator) != nil {
			continue
		}
		items = append(items, map[string]any{
			"id": refundID, "amountCent": amount, "channel": channel, "reason": reason,
			"operator": operator, "createdAt": created.Format(time.RFC3339),
		})
	}
	reply(w, map[string]any{"items": items})
}

// adminRefundOrder is the one refund entry point for every product. A partial
// refund leaves what it bought alone; only refunding the last cent revokes it,
// because half a membership is still a membership.
func (a *App) adminRefundOrder(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r)
	if err != nil {
		fail(w, http.StatusBadRequest, 20001, "订单编号无效")
		return
	}
	var req struct {
		AmountCent int64  `json:"amountCent"`
		Reason     string `json:"reason"`
		Offline    bool   `json:"offline"`
	}
	if r.ContentLength > 0 && decode(r, &req) != nil {
		fail(w, http.StatusBadRequest, 20001, "参数错误")
		return
	}
	req.Reason = strings.TrimSpace(req.Reason)
	if req.Reason == "" {
		req.Reason = "客服操作退款"
	}

	var userID, productID int64
	var amount, refunded int
	var orderNo, providerOrderNo, status, productType string
	if a.db.QueryRowContext(r.Context(), `SELECT user_id,product_type,product_id,amount_cent,COALESCE(refunded_cent,0),
		order_no,provider_order_no,status FROM orders WHERE id=? AND deleted_at IS NULL`, id).
		Scan(&userID, &productType, &productID, &amount, &refunded, &orderNo, &providerOrderNo, &status) != nil {
		fail(w, http.StatusNotFound, 30001, "订单不存在")
		return
	}
	if status != "PAID" && status != "REFUND_REQUESTED" && status != "REFUNDING" && status != "REFUNDED" {
		fail(w, http.StatusBadRequest, 20001, "只有已支付的订单可以退款")
		return
	}
	remaining := int64(amount - refunded)
	if remaining <= 0 {
		fail(w, http.StatusBadRequest, 20001, "这笔订单已经退完了")
		return
	}
	refundAmount := req.AmountCent
	if refundAmount <= 0 {
		refundAmount = remaining
	}
	if refundAmount > remaining {
		fail(w, http.StatusBadRequest, 20001, fmt.Sprintf("最多还能退 %.2f 元", float64(remaining)/100))
		return
	}

	live := a.configPlain(r.Context(), "payment.mode", "sandbox") == "live"
	channel := "gateway"
	if req.Offline || providerOrderNo == "" || strings.HasPrefix(providerOrderNo, "sandbox:") || !live {
		channel = "offline"
	}
	refundNo := fmt.Sprintf("order:%d:%d", id, time.Now().UnixMilli())
	if channel == "gateway" {
		if err = a.createGatewayRefund(r.Context(), orderNo, providerOrderNo, refundNo, int(refundAmount)); err != nil {
			a.audit(r, "refund_failed", "order", id, map[string]any{"amountCent": refundAmount, "error": err.Error()})
			fail(w, http.StatusBadGateway, 50003, "退款网关请求失败，未记账，可以重试或改为线下退款登记")
			return
		}
	}

	tx, err := a.db.BeginTx(r.Context(), nil)
	if err != nil {
		fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
		return
	}
	defer func() { _ = tx.Rollback() }()
	if _, err = tx.ExecContext(r.Context(), `INSERT INTO order_refunds(order_id,refund_no,user_id,amount_cent,channel,reason,handled_by)
		VALUES(?,?,?,?,?,?,?)`, id, refundNo, userID, refundAmount, channel, req.Reason, current(r).ID); err != nil {
		fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
		return
	}
	full := int64(refunded)+refundAmount >= int64(amount)
	newStatus := status
	if full {
		newStatus = "REFUNDED"
	}
	if _, err = tx.ExecContext(r.Context(), `UPDATE orders SET refunded_cent=refunded_cent+?,status=? WHERE id=?`,
		refundAmount, newStatus, id); err != nil {
		fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
		return
	}
	// 退完才收回买到的东西：半份会员仍然是会员，代喂任务同理。
	if full {
		if err = a.revokePaidOrderTx(r.Context(), tx, id, userID, productType, productID, int(refundAmount)); err != nil {
			fail(w, http.StatusBadRequest, 20001, err.Error())
			return
		}
	}
	if tx.Commit() != nil {
		fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
		return
	}

	a.audit(r, "refund", "order", id, map[string]any{
		"amountCent": refundAmount, "channel": channel, "full": full, "reason": req.Reason, "refundNo": refundNo,
	})
	a.notifyUser(r.Context(), userID, "system", "订单已退款",
		fmt.Sprintf("订单 %s 已退款 %.2f 元：%s", orderNo, float64(refundAmount)/100, req.Reason), "order", id)
	reply(w, map[string]any{
		"success": true, "amountCent": refundAmount, "channel": channel,
		"refundedCent": int64(refunded) + refundAmount, "remainingCent": remaining - refundAmount, "full": full,
	})
}