package handler

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

	"bj_power_wms/ent/ordermaterialledger"
	"bj_power_wms/internal/svc"

	"github.com/zeromicro/go-zero/core/logx"
)

// backflushRequest 报工反冲核销请求（MES 报工完成时调用，X-API-TOKEN 内部接口）
//
// 口径（2026-09-19 定稿 · 方案 A「出库扣减，反冲只核销」）：
// 一次物理位移 = 一次库存账变。备料出库时库存已经扣过，报工消耗**不再动库存、不再生成出库单**，
// 只把台账「已消耗(consumed_qty)」累加，供 已发出 / 已接料 / 已消耗 三方对账。
//
// 核销上限 = net_out_qty − consumed_qty，其中 net_out_qty = out_qty − returned_qty。
// 上限的意义：没走出库的料（工位自取辅料、现场替换）不会被核销成负数，
// 避免出现「库存从未扣过、台账却记了消耗」的漏扣假象。
type backflushRequest struct {
	OrderNo     string          `json:"orderNo"`     // 关联工单号（空=不做核销）
	StationNo   int             `json:"stationNo"`   // 当前工位号（记录用）
	ProcessCode int             `json:"processCode"` // 当前工序号（记录用）
	Operator    string          `json:"operator"`
	Items       []backflushItem `json:"items"` // 本次消耗的物料明细
}

type backflushItem struct {
	MaterialCode string `json:"materialCode"`
	Qty          int    `json:"qty"` // 该工序单件消耗（已含损耗）* 完成件数
}

// backflushInternalHandler 报工反冲核销：只累加台账 consumed_qty。
// 不扣库存、不写出库单、不写 out_qty。库存不足/无台账不阻塞产线，只记 shortfall 供对账。
func backflushInternalHandler(ctx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var req backflushRequest
		if err := parseJSON(r, &req); err != nil {
			fail(w, http.StatusBadRequest, "参数错误: "+err.Error())
			return
		}
		if len(req.Items) == 0 {
			ok(w, map[string]any{"consumed": 0, "shortfall": false, "note": "无反冲物料"})
			return
		}
		if req.OrderNo == "" {
			// 不挂工单的消耗没有台账可承载，不阻塞产线
			logx.Infof("backflush skipped: no orderNo, station=%d", req.StationNo)
			ok(w, map[string]any{"consumed": 0, "shortfall": false, "note": "未挂工单，不做核销"})
			return
		}

		tx, err := ctx.EntClient.Tx(ctx0())
		if err != nil {
			fail(w, http.StatusInternalServerError, "开启事务失败: "+err.Error())
			return
		}
		committed := false
		defer func() {
			if !committed {
				_ = tx.Rollback()
			}
		}()

		totalConsumed := 0
		shortfall := false
		notes := make([]string, 0, 4)
		for _, it := range req.Items {
			if it.MaterialCode == "" || it.Qty <= 0 {
				continue
			}
			ledger, lerr := tx.OrderMaterialLedger.Query().
				Where(
					ordermaterialledger.OrderNoEQ(req.OrderNo),
					ordermaterialledger.MaterialCodeEQ(it.MaterialCode),
				).Only(ctx0())
			if lerr != nil || ledger == nil {
				shortfall = true
				notes = append(notes, it.MaterialCode+" 无台账")
				continue
			}
			// 可核销量 = 净领用 − 已消耗（负数归零：退料后可能出现「已消耗 > 净领用」）
			capa := (ledger.OutQty - ledger.ReturnedQty) - ledger.ConsumedQty
			if capa < 0 {
				capa = 0
			}
			take := it.Qty
			if take > capa {
				take = capa
				shortfall = true
				notes = append(notes, fmt.Sprintf("%s 超出可核销量(需%d/可%d)", it.MaterialCode, it.Qty, capa))
			}
			if take <= 0 {
				continue
			}
			if _, uerr := tx.OrderMaterialLedger.UpdateOneID(ledger.ID).
				AddConsumedQty(take).
				SetUpdatedAt(time.Now().Unix()).
				Save(ctx0()); uerr != nil {
				fail(w, http.StatusInternalServerError, "更新台账失败: "+uerr.Error())
				return
			}
			totalConsumed += take
		}

		if err = tx.Commit(); err != nil {
			fail(w, http.StatusInternalServerError, "提交事务失败: "+err.Error())
			return
		}
		committed = true

		ctx.EventLog.Write(ctx0(), "material.backflush", req.Operator, "order_material_ledger", req.OrderNo,
			"报工消耗核销 工单 "+req.OrderNo+" 工序"+strconv.Itoa(req.ProcessCode)+" 共核销 ×"+strconv.Itoa(totalConsumed),
			map[string]any{"orderNo": req.OrderNo, "stationNo": req.StationNo, "consumed": totalConsumed, "shortfall": shortfall, "notes": notes})
		logx.Infof("backflush(consume-only): order=%s station=%d consumed=%d shortfall=%v", req.OrderNo, req.StationNo, totalConsumed, shortfall)
		ok(w, map[string]any{
			"consumed":  totalConsumed,
			"shortfall": shortfall,
			"notes":     notes,
		})
	}
}