package app

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

// Refunds for feeding tasks. Three things make this different from the
// membership refund next door: it can happen more than once on the same order
// (part now, part later), it has to say which way the money went when no
// channel is connected, and it must refuse to quietly reverse a payout that has
// already reached a sitter.

type feedRefundRequest struct {
	AmountCent    int64  `json:"amountCent"` // 0 表示退全部剩余
	Reason        string `json:"reason"`
	Offline       bool   `json:"offline"`       // 渠道没接通时，登记为线下已退
	PlatformBears bool   `json:"platformBears"` // 已结算的任务由平台承担
}

func (a *App) adminRefundFeedTask(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r)
	if err != nil {
		fail(w, http.StatusBadRequest, 20001, "编号无效")
		return
	}
	var req feedRefundRequest
	if decode(r, &req) != nil {
		fail(w, http.StatusBadRequest, 20001, "参数错误")
		return
	}
	req.Reason = strings.TrimSpace(req.Reason)
	if len([]rune(req.Reason)) < 5 {
		fail(w, http.StatusBadRequest, 20001, "请写明退款原因，双方都会收到")
		return
	}

	var owner, sitter int64
	var orderID sql.NullInt64
	var gross, refunded int64
	var status string
	if a.db.QueryRowContext(r.Context(), `SELECT owner_user_id,COALESCE(sitter_user_id,0),order_id,gross_cent,refunded_cent,status
		FROM pet_feed_tasks WHERE id=?`, id).Scan(&owner, &sitter, &orderID, &gross, &refunded, &status) != nil {
		fail(w, http.StatusNotFound, 30001, "任务不存在")
		return
	}
	remaining := gross - refunded
	if remaining <= 0 {
		fail(w, http.StatusBadRequest, 20001, "这笔任务已经退完了")
		return
	}
	amount := req.AmountCent
	if amount <= 0 {
		amount = remaining
	}
	if amount > remaining {
		fail(w, http.StatusBadRequest, 20001, fmt.Sprintf("最多还能退 %.2f 元", float64(remaining)/100))
		return
	}

	// 已结算意味着钱在喂养者账上，退给主人的那份只能由平台承担 —— 这是一次
	// 支出决定，不能顺手做掉，所以要显式勾选。
	settled := status == "SETTLED" || status == "ARBITRATED"
	if settled && !req.PlatformBears {
		fail(w, http.StatusBadRequest, 20001, "任务已结算，报酬在喂养者账上。要退给主人只能由平台承担，请勾选后再提交")
		return
	}
	if status == "CREATED" {
		fail(w, http.StatusBadRequest, 20001, "任务还没有支付，直接取消即可")
		return
	}

	var orderNo, providerOrderNo, orderStatus string
	if orderID.Valid && orderID.Int64 > 0 {
		_ = a.db.QueryRowContext(r.Context(), `SELECT order_no,provider_order_no,status FROM orders WHERE id=?`, orderID.Int64).
			Scan(&orderNo, &providerOrderNo, &orderStatus)
	}
	// 只有真实支付过的订单才谈得上原路退回：手工托管进来的没有渠道流水号，
	// 沙箱支付的流水号是假的，这两种都只能登记为线下已退。
	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("feed:%d:%d", id, time.Now().UnixMilli())

	if channel == "gateway" {
		if err = a.createGatewayRefund(r.Context(), orderNo, providerOrderNo, refundNo, int(amount)); err != nil {
			a.audit(r, "feed_refund_failed", "pet_feed_task", id, map[string]any{"amountCent": amount, "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 pet_feed_refunds
		(task_id,order_id,refund_no,user_id,amount_cent,channel,platform_bears,reason,handled_by)
		VALUES(?,?,?,?,?,?,?,?,?)`, id, orderID, refundNo, owner, amount, channel, settled, req.Reason, current(r).ID); err != nil {
		fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
		return
	}
	if _, err = tx.ExecContext(r.Context(), `UPDATE pet_feed_tasks SET refunded_cent=refunded_cent+? WHERE id=?`, amount, id); err != nil {
		fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
		return
	}
	if orderID.Valid && orderID.Int64 > 0 {
		if _, err = tx.ExecContext(r.Context(), `UPDATE orders SET refunded_cent=refunded_cent+?,
			status=IF(refunded_cent+?>=amount_cent,'REFUNDED',status) WHERE id=?`, amount, amount, orderID.Int64); err != nil {
			fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
			return
		}
	}
	// 退完并且还没结算的任务就此关闭；部分退款保留原状态，服务还得继续。
	if refunded+amount >= gross && !settled {
		if _, err = tx.ExecContext(r.Context(), `UPDATE pet_feed_tasks SET status='REFUNDED',confirm_due_at=NULL WHERE id=?`, id); err != nil {
			fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
			return
		}
	}
	if tx.Commit() != nil {
		fail(w, http.StatusInternalServerError, 50001, "退款记账失败")
		return
	}

	a.audit(r, "feed_refund", "pet_feed_task", id, map[string]any{
		"amountCent": amount, "channel": channel, "platformBears": settled, "reason": req.Reason, "refundNo": refundNo,
	})
	body := fmt.Sprintf("已退款 %.2f 元：%s", float64(amount)/100, req.Reason)
	a.notifyUser(r.Context(), owner, "system", "代喂任务已退款", body, "feed_task", id)
	if sitter > 0 {
		a.notifyUser(r.Context(), sitter, "system", "代喂任务已退款", req.Reason, "feed_task", id)
	}
	reply(w, map[string]any{
		"success": true, "amountCent": amount, "channel": channel,
		"refundedCent": refunded + amount, "remainingCent": remaining - amount,
	})
}

func (a *App) adminFeedRefunds(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.platform_bears,f.reason,
		f.created_at,COALESCE(admin.username,'') FROM pet_feed_refunds f
		LEFT JOIN admin_users admin ON admin.id=f.handled_by WHERE f.task_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 platformBears bool
		var created time.Time
		if rows.Scan(&refundID, &amount, &channel, &platformBears, &reason, &created, &operator) != nil {
			continue
		}
		items = append(items, map[string]any{
			"id": refundID, "amountCent": amount, "channel": channel, "platformBears": platformBears,
			"reason": reason, "operator": operator, "createdAt": created.Format(time.RFC3339),
		})
	}
	reply(w, map[string]any{"items": items})
}