package handler

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

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

	"github.com/wangjia/jiu/backend/internal/middleware"
	"github.com/wangjia/jiu/backend/internal/model"
	"github.com/wangjia/jiu/backend/internal/util"
)

type FinanceHandler struct {
	db *gorm.DB
}

func NewFinanceHandler(db *gorm.DB) *FinanceHandler {
	return &FinanceHandler{db: db}
}

// ListRecords GET /api/v1/finance/records
func (h *FinanceHandler) ListRecords(c *gin.Context) {
	shopID := middleware.GetShopID(c)

	var q struct {
		Type      string `form:"type"`
		Month     string `form:"month"`      // e.g. "2026-04"
		StartDate string `form:"start_date"` // YYYY-MM-DD（区间过滤，优先于 month）
		EndDate   string `form:"end_date"`
		PartnerID uint64 `form:"partner_id"`
		Page      int    `form:"page,default=1"`
		PageSize  int    `form:"page_size,default=50"`
	}
	if err := c.ShouldBindQuery(&q); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	q.PageSize = util.ValidatePageSize(q.PageSize, 50, 500)
	if q.Page <= 0 {
		q.Page = 1
	}

	base := h.db.Model(&model.FinanceRecord{}).Where("shop_id = ?", shopID)
	if q.Type != "" {
		base = base.Where("type = ?", q.Type)
	}
	if q.PartnerID != 0 {
		base = base.Where("partner_id = ?", q.PartnerID)
	}
	// 日期过滤：区间（本季/自定义）优先；否则按单月。日期串比较跨 MySQL/SQLite 可移植。
	if q.StartDate != "" || q.EndDate != "" {
		if q.StartDate != "" {
			base = base.Where("record_date >= ?", q.StartDate)
		}
		if q.EndDate != "" {
			base = base.Where("record_date <= ?", q.EndDate)
		}
	} else if q.Month != "" {
		base = base.Where("DATE_FORMAT(record_date, '%Y-%m') = ?", q.Month)
	}

	var total int64
	base.Count(&total)

	records := make([]model.FinanceRecord, 0)
	offset := (q.Page - 1) * q.PageSize
	base.Preload("Partner", "shop_id = ?", shopID).Order("record_date DESC, id DESC").Offset(offset).Limit(q.PageSize).Find(&records)

	c.JSON(http.StatusOK, gin.H{
		"data":      records,
		"total":     total,
		"page":      q.Page,
		"page_size": q.PageSize,
	})
}

// Create POST /api/v1/finance/records — 手动录入付款/收款
func (h *FinanceHandler) Create(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	userID := middleware.GetUserID(c)

	var req struct {
		PartnerID  *uint64 `json:"partner_id"`
		Type       string  `json:"type" binding:"required"`
		Amount     float64 `json:"amount" binding:"required,gt=0"`
		RecordDate string  `json:"record_date" binding:"required"`
		Remark     string  `json:"remark"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	// SEC-001：往来单位必须属于当前店（防跨租户引用泄露）
	if err := ensureShopRefOpt(h.db, "partners", req.PartnerID, shopID); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if req.Type != "payment" && req.Type != "receipt" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "type must be payment or receipt"})
		return
	}

	date, err := time.Parse("2006-01-02", req.RecordDate)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid record_date, use YYYY-MM-DD"})
		return
	}

	// 付款/收款 均为减少余额（抵消应付/应收）
	prevBalance := partnerLastBalance(h.db, shopID, req.PartnerID)
	bal := prevBalance - req.Amount

	rec := model.FinanceRecord{
		ShopID:     shopID,
		PartnerID:  req.PartnerID,
		Type:       req.Type,
		Amount:     req.Amount,
		Balance:    bal,
		Status:     "closed",
		OperatorID: userID,
		RecordDate: date,
		Remark:     req.Remark,
	}
	if err := h.db.Create(&rec).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, rec)
}

// Close PUT /api/v1/finance/records/:id/close — 标记结清
func (h *FinanceHandler) Close(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	id := c.Param("id")

	var rec model.FinanceRecord
	if err := h.db.Where("id = ? AND shop_id = ? AND deleted_at IS NULL", id, shopID).
		First(&rec).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "record not found"})
		return
	}
	if rec.Type != "payable" && rec.Type != "receivable" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "only payable/receivable can be closed"})
		return
	}
	if rec.Status == "closed" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "already closed"})
		return
	}
	if err := h.db.Model(&rec).Update("status", "closed").Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

// CloseByRef PUT /api/v1/finance/records/close-by-ref?ref_type=stock_in&ref_id=123
func (h *FinanceHandler) CloseByRef(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	refType := c.Query("ref_type")
	refID := c.Query("ref_id")
	if refType == "" || refID == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "ref_type and ref_id are required"})
		return
	}

	var rec model.FinanceRecord
	err := h.db.Where("shop_id = ? AND ref_type = ? AND ref_id = ? AND status = 'open' AND deleted_at IS NULL",
		shopID, refType, refID).First(&rec).Error
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "no open finance record found"})
		return
	}
	if err := h.db.Model(&rec).Update("status", "closed").Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

// Trend GET /api/v1/finance/trend?months=6 — 近 N 个自然月收支趋势
// in=当月出库(销售)额、out=当月入库(采购)额；与 stock Summary 同口径
// （按 order_date、不筛状态、deleted_at IS NULL），日期串比较跨 MySQL/SQLite 可移植。
func (h *FinanceHandler) Trend(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	months := 6
	if v := c.Query("months"); v != "" {
		if n, err := strconv.Atoi(v); err == nil && n >= 1 && n <= 24 {
			months = n
		}
	}

	now := time.Now()
	first := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
	type point struct {
		Month string  `json:"month"`
		In    float64 `json:"in"`
		Out   float64 `json:"out"`
	}
	// 出库=应收合计(sale_total)，入库=应付合计(cost_total)——2026-07 定价字段消歧后分列
	sum := func(table, col, from, to string) float64 {
		var v float64
		h.db.Table(table).
			Where("shop_id = ? AND deleted_at IS NULL AND order_date >= ? AND order_date < ?",
				shopID, from, to).
			Select("COALESCE(SUM(" + col + "),0)").Scan(&v)
		return v
	}
	const f = "2006-01-02"
	points := make([]point, 0, months)
	for i := months - 1; i >= 0; i-- {
		mStart := first.AddDate(0, -i, 0)
		mEnd := mStart.AddDate(0, 1, 0)
		points = append(points, point{
			Month: mStart.Format("2006-01"),
			In:    sum("stock_out_orders", "sale_total", mStart.Format(f), mEnd.Format(f)),
			Out:   sum("stock_in_orders", "cost_total", mStart.Format(f), mEnd.Format(f)),
		})
	}
	c.JSON(http.StatusOK, gin.H{"data": points})
}

// Summary GET /api/v1/finance/summary — 按往来单位汇总未结清
func (h *FinanceHandler) Summary(c *gin.Context) {
	shopID := middleware.GetShopID(c)

	type row struct {
		PartnerID   *uint64 `json:"partner_id"`
		PartnerName string  `json:"partner_name"`
		Type        string  `json:"type"`
		RecordCount int     `json:"record_count"`
		TotalAmount float64 `json:"total_amount"`
	}
	var rows []row
	if err := h.db.Raw(`
		SELECT f.partner_id,
		       COALESCE(p.name, '') AS partner_name,
		       f.type,
		       COUNT(*) AS record_count,
		       SUM(f.amount) AS total_amount
		FROM finance_records f
		LEFT JOIN partners p ON p.id = f.partner_id AND p.shop_id = f.shop_id
		WHERE f.shop_id = ? AND f.deleted_at IS NULL
		  AND f.type IN ('payable','receivable')
		  AND f.status = 'open'
		GROUP BY f.partner_id, f.type
		ORDER BY total_amount DESC
	`, shopID).Scan(&rows).Error; err != nil {
		util.RespondError(c, http.StatusInternalServerError, "QUERY_ERROR", "查询失败")
		return
	}

	util.RespondSuccess(c, rows)
}

// partnerLastBalance 查询该往来单位最后一条财务记录的余额
func partnerLastBalance(db *gorm.DB, shopID uint64, partnerID *uint64) float64 {
	var last model.FinanceRecord
	q := db.Where("shop_id = ? AND deleted_at IS NULL", shopID)
	if partnerID != nil {
		q = q.Where("partner_id = ?", *partnerID)
	} else {
		q = q.Where("partner_id IS NULL")
	}
	q.Order("id DESC").First(&last)
	return last.Balance
}