package handler

import (
	"fmt"
	"io"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/extrame/xls"
	"github.com/gin-gonic/gin"
	"github.com/xuri/excelize/v2"
	"gorm.io/gorm"

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

type ImportHandler struct {
	db *gorm.DB
}

func NewImportHandler(db *gorm.DB) *ImportHandler {
	return &ImportHandler{db: db}
}

// ImportProducts POST /api/v1/import/products
// 支持 .xlsx / .csv，列顺序：名称,系列,规格,单位,品牌,最低库存,备注
func (h *ImportHandler) ImportProducts(c *gin.Context) {
	shopID := middleware.GetShopID(c)

	file, err := c.FormFile("file")
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "file required"})
		return
	}

	f, err := file.Open()
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	defer f.Close()

	xl, err := excelize.OpenReader(f)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid excel file: " + err.Error()})
		return
	}

	sheetName := xl.GetSheetName(0)
	rows, err := xl.GetRows(sheetName)
	if err != nil || len(rows) < 2 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "empty or invalid sheet"})
		return
	}

	var products []model.Product
	var errRows []map[string]interface{}

	for i, row := range rows[1:] { // 跳过表头
		if len(row) < 1 || strings.TrimSpace(row[0]) == "" {
			continue
		}
		p := model.Product{
			TenantBase: model.TenantBase{ShopID: shopID},
		}
		p.Name = cell(row, 0)
		p.Series = cell(row, 1)
		p.Spec = cell(row, 2)
		p.Unit = cell(row, 3)
		p.Brand = cell(row, 4)
		p.Remark = cell(row, 6)

		if p.Name == "" {
			errRows = append(errRows, map[string]interface{}{"row": i + 2, "error": "name is empty"})
			continue
		}
		products = append(products, p)
	}

	if len(products) == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "no valid rows", "errors": errRows})
		return
	}

	if err := h.db.CreateInBatches(&products, 100).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"imported": len(products),
		"errors":   errRows,
	})
}

// ImportPartners POST /api/v1/import/partners
// 列顺序（来往单位.xls）：编号,类型,状态,名称,电话,卡号,初始金额,单位,地址,...,备注
func (h *ImportHandler) ImportPartners(c *gin.Context) {
	shopID := middleware.GetShopID(c)

	rows, err := parseUploadedExcel(c)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	total, imported, skipped := 0, 0, 0
	for _, row := range rows[1:] {
		name := cell(row, 3)
		if name == "" {
			continue
		}
		total++
		var existing model.Partner
		if h.db.Where("shop_id = ? AND name = ? AND deleted_at IS NULL", shopID, name).First(&existing).Error == nil {
			skipped++
			continue
		}
		balance, _ := strconv.ParseFloat(cell(row, 6), 64)
		status := "enabled"
		if cell(row, 2) == "禁用" {
			status = "disabled"
		}
		p := model.Partner{
			TenantBase:  model.TenantBase{ShopID: shopID},
			Code:        cell(row, 0),
			Type:        parsePartnerType(cell(row, 1)),
			Status:      status,
			Name:        name,
			Phone:       cell(row, 4),
			BankAccount: cell(row, 5),
			Balance:     balance,
			Address:     cell(row, 8),
			Remark:      cell(row, 11),
		}
		if h.db.Create(&p).Error == nil {
			imported++
		}
	}

	c.JSON(http.StatusOK, gin.H{"total": total, "imported": imported, "skipped": skipped})
}

// ImportProductNames POST /api/v1/import/product-names
// 列顺序（商品名称.xls）：选项编号,选项名称,备注
func (h *ImportHandler) ImportProductNames(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	rows, err := parseUploadedExcel(c)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	total, imported, skipped := 0, 0, 0
	for _, row := range rows[1:] {
		name := cell(row, 1)
		if name == "" {
			continue
		}
		total++
		var existing model.ProductNameOption
		if h.db.Where("shop_id = ? AND name = ? AND deleted_at IS NULL", shopID, name).First(&existing).Error == nil {
			skipped++
			continue
		}
		opt := model.ProductNameOption{
			TenantBase: model.TenantBase{ShopID: shopID},
			Code:       cell(row, 0),
			Name:       name,
			Remark:     cell(row, 2),
		}
		if h.db.Create(&opt).Error == nil {
			imported++
		}
	}
	c.JSON(http.StatusOK, gin.H{"total": total, "imported": imported, "skipped": skipped})
}

// ImportProductSeries POST /api/v1/import/product-series
// 列顺序（商品系列.xls）：选项编号,选项名称,备注
func (h *ImportHandler) ImportProductSeries(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	rows, err := parseUploadedExcel(c)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	total, imported, skipped := 0, 0, 0
	for _, row := range rows[1:] {
		name := cell(row, 1)
		if name == "" {
			continue
		}
		total++
		var existing model.ProductSeriesOption
		if h.db.Where("shop_id = ? AND name = ? AND deleted_at IS NULL", shopID, name).First(&existing).Error == nil {
			skipped++
			continue
		}
		opt := model.ProductSeriesOption{
			TenantBase: model.TenantBase{ShopID: shopID},
			Code:       cell(row, 0),
			Name:       name,
			Remark:     cell(row, 2),
		}
		if h.db.Create(&opt).Error == nil {
			imported++
		}
	}
	c.JSON(http.StatusOK, gin.H{"total": total, "imported": imported, "skipped": skipped})
}

// ImportProductSpecs POST /api/v1/import/product-specs
// 列顺序（商品规格.xls）：选项编号,选项名称,单品数量,备注
func (h *ImportHandler) ImportProductSpecs(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	rows, err := parseUploadedExcel(c)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	total, imported, skipped := 0, 0, 0
	for _, row := range rows[1:] {
		name := cell(row, 1)
		if name == "" {
			continue
		}
		total++
		var existing model.ProductSpecOption
		if h.db.Where("shop_id = ? AND name = ? AND deleted_at IS NULL", shopID, name).First(&existing).Error == nil {
			skipped++
			continue
		}
		qty, _ := strconv.Atoi(strings.TrimSuffix(cell(row, 2), ".0")) // "12" 或 "12.0"
		if qty == 0 {
			qtyF, _ := strconv.ParseFloat(cell(row, 2), 64)
			qty = int(qtyF)
		}
		opt := model.ProductSpecOption{
			TenantBase: model.TenantBase{ShopID: shopID},
			Code:       cell(row, 0),
			Name:       name,
			Quantity:   qty,
			Remark:     cell(row, 3),
		}
		if h.db.Create(&opt).Error == nil {
			imported++
		}
	}
	c.JSON(http.StatusOK, gin.H{"total": total, "imported": imported, "skipped": skipped})
}

// ImportStockIn POST /api/v1/import/stock-in
// 支持老系统打印格式（每文件一张入库单）
func (h *ImportHandler) ImportStockIn(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	userID := middleware.GetUserID(c)
	rows, err := parseUploadedExcel(c)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if len(rows) < 7 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "文件行数不足，请检查格式"})
		return
	}

	// 解析单据头
	partnerName := strings.TrimPrefix(cell(rows[3], 0), "来往单位名称：")
	dateStr := strings.TrimPrefix(cell(rows[3], 7), "单据日期：")
	orderNo := strings.TrimPrefix(cell(rows[3], 18), "NO.")

	if orderNo == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "未找到单据号，请检查文件格式"})
		return
	}

	// 检查重复
	var existing model.StockInOrder
	if h.db.Where("shop_id = ? AND order_no = ?", shopID, orderNo).First(&existing).Error == nil {
		c.JSON(http.StatusOK, gin.H{"order_no": orderNo, "skipped": true, "message": "单据已存在，已跳过"})
		return
	}

	// 解析日期
	orderDate := parseDate(dateStr)

	// 往来单位
	partnerID := findOrCreatePartner(h.db, shopID, partnerName, "supplier")

	// 默认仓库
	var wh model.Warehouse
	if h.db.Where("shop_id = ? AND is_default = 1", shopID).First(&wh).Error != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请先在系统设置中设置默认仓库"})
		return
	}

	// 解析明细
	var items []model.StockInItem
	var totalAmount float64
	for _, row := range rows[6:] {
		if cell(row, 0) == "" || strings.HasPrefix(cell(row, 0), "单据总计") {
			break
		}
		productName := cell(row, 1)
		if productName == "" {
			continue
		}
		series := cell(row, 5)
		spec := cell(row, 6)
		qty, _ := strconv.ParseFloat(cell(row, 9), 64)
		price, _ := strconv.ParseFloat(cell(row, 11), 64)
		batchNo := cell(row, 16)

		prod, err := findOrCreateProductFn(h.db, shopID, productName, series, spec)
		if err != nil {
			continue
		}
		total := qty * price
		totalAmount += total
		items = append(items, model.StockInItem{
			ShopID:    shopID,
			ProductID: prod.ID,
			Quantity:  qty,
			UnitPrice: price,
			TotalPrice: total,
			BatchNo:   batchNo,
		})
	}

	if len(items) == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "未解析到有效明细行"})
		return
	}

	order := model.StockInOrder{
		TenantBase:  model.TenantBase{ShopID: shopID},
		OrderNo:     orderNo,
		Type:        "purchase",
		WarehouseID: wh.ID,
		PartnerID:   partnerID,
		OperatorID:  userID,
		Status:      "draft",
		OrderDate:   orderDate,
		TotalAmount: totalAmount,
	}

	if err := h.db.Create(&order).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	for i := range items {
		items[i].OrderID = order.ID
	}
	if err := h.db.CreateInBatches(&items, 50).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{"order_no": orderNo, "items": len(items)})
}

// ImportStockOut POST /api/v1/import/stock-out
// 支持老系统打印格式（每文件一张出库单）
func (h *ImportHandler) ImportStockOut(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	userID := middleware.GetUserID(c)
	rows, err := parseUploadedExcel(c)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if len(rows) < 7 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "文件行数不足，请检查格式"})
		return
	}

	// 出库单日期在 col8（比入库单多一个空列）
	partnerName := strings.TrimPrefix(cell(rows[3], 0), "来往单位名称：")
	dateStr := strings.TrimPrefix(cell(rows[3], 8), "单据日期：")
	orderNo := strings.TrimPrefix(cell(rows[3], 18), "NO.")

	if orderNo == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "未找到单据号，请检查文件格式"})
		return
	}

	var existing model.StockOutOrder
	if h.db.Where("shop_id = ? AND order_no = ?", shopID, orderNo).First(&existing).Error == nil {
		c.JSON(http.StatusOK, gin.H{"order_no": orderNo, "skipped": true, "message": "单据已存在，已跳过"})
		return
	}

	orderDate := parseDate(dateStr)
	partnerID := findOrCreatePartner(h.db, shopID, partnerName, "customer")

	var wh model.Warehouse
	if h.db.Where("shop_id = ? AND is_default = 1", shopID).First(&wh).Error != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请先在系统设置中设置默认仓库"})
		return
	}

	var items []model.StockOutItem
	var totalAmount float64
	for _, row := range rows[6:] {
		if cell(row, 0) == "" || strings.HasPrefix(cell(row, 0), "单据总计") {
			break
		}
		productName := cell(row, 1)
		if productName == "" {
			continue
		}
		series := cell(row, 5)
		spec := cell(row, 6)
		qty, _ := strconv.ParseFloat(cell(row, 9), 64)
		price, _ := strconv.ParseFloat(cell(row, 11), 64)

		prod, err := findOrCreateProductFn(h.db, shopID, productName, series, spec)
		if err != nil {
			continue
		}
		total := qty * price
		totalAmount += total
		items = append(items, model.StockOutItem{
			ShopID:    shopID,
			ProductID: prod.ID,
			Quantity:  qty,
			UnitPrice: price,
			TotalPrice: total,
		})
	}

	if len(items) == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "未解析到有效明细行"})
		return
	}

	order := model.StockOutOrder{
		TenantBase:  model.TenantBase{ShopID: shopID},
		OrderNo:     orderNo,
		Type:        "sale",
		WarehouseID: wh.ID,
		PartnerID:   partnerID,
		OperatorID:  userID,
		Status:      "draft",
		OrderDate:   orderDate,
		TotalAmount: totalAmount,
	}

	if err := h.db.Create(&order).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	for i := range items {
		items[i].OrderID = order.ID
	}
	if err := h.db.CreateInBatches(&items, 50).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{"order_no": orderNo, "items": len(items)})
}

// ── 内部辅助函数 ─────────────────────────────────────────────

func parseUploadedExcel(c *gin.Context) ([][]string, error) {
	file, err := c.FormFile("file")
	if err != nil {
		return nil, fmt.Errorf("file required")
	}
	f, err := file.Open()
	if err != nil {
		return nil, err
	}
	defer f.Close()

	// 读取前 4 字节检测 OLE2 格式（D0 CF 11 E0 = 老式 .xls BIFF）
	var magic [4]byte
	f.Read(magic[:])
	f.Seek(0, 0)
	isOLE := magic[0] == 0xD0 && magic[1] == 0xCF && magic[2] == 0x11 && magic[3] == 0xE0

	var rows [][]string

	if isOLE {
		// 老格式 BIFF — extrame/xls 需要文件路径，写入临时文件
		tmp, tmpErr := os.CreateTemp("", "import_*.xls")
		if tmpErr != nil {
			return nil, fmt.Errorf("cannot create temp file: %s", tmpErr.Error())
		}
		defer os.Remove(tmp.Name())
		if _, cpErr := io.Copy(tmp, f); cpErr != nil {
			tmp.Close()
			return nil, fmt.Errorf("cannot write temp file: %s", cpErr.Error())
		}
		tmp.Close()

		wb, xlErr := xls.Open(tmp.Name(), "utf-8")
		if xlErr != nil {
			return nil, fmt.Errorf("invalid xls file: %s", xlErr.Error())
		}
		sheet := wb.GetSheet(0)
		if sheet == nil {
			return nil, fmt.Errorf("no sheet found")
		}
		// LastCol() returns 0 for many data rows in extrame/xls; derive column
		// count from the header row instead.
		numCols := 0
		headerRow := sheet.Row(0)
		for c := 0; c < headerRow.LastCol(); c++ {
			if strings.TrimSpace(headerRow.Col(c)) != "" {
				numCols = c + 1
			}
		}
		if numCols == 0 {
			numCols = 20
		}
		for r := 0; r <= int(sheet.MaxRow); r++ {
			row := sheet.Row(r)
			cells := make([]string, numCols)
			for c := 0; c < numCols; c++ {
				cells[c] = strings.TrimSpace(row.Col(c))
			}
			rows = append(rows, cells)
		}
	} else {
		// xlsx / xlsm（ZIP 格式）
		xl, xlErr := excelize.OpenReader(f)
		if xlErr != nil {
			return nil, fmt.Errorf("invalid xlsx file: %s", xlErr.Error())
		}
		rows, err = xl.GetRows(xl.GetSheetName(0))
		if err != nil {
			return nil, fmt.Errorf("cannot read sheet: %s", err.Error())
		}
	}

	if len(rows) < 2 {
		return nil, fmt.Errorf("empty or invalid sheet")
	}
	return rows, nil
}

func findOrCreateProductFn(db *gorm.DB, shopID uint64, name, series, spec string) (model.Product, error) {
	var p model.Product
	if db.Where("shop_id = ? AND name = ? AND series = ? AND spec = ? AND deleted_at IS NULL",
		shopID, name, series, spec).First(&p).Error == nil {
		return p, nil
	}
	p = model.Product{
		TenantBase: model.TenantBase{ShopID: shopID},
		Name:       name,
		Series:     series,
		Spec:       spec,
		Unit:       "瓶",
	}
	return p, db.Create(&p).Error
}

func findOrCreatePartner(db *gorm.DB, shopID uint64, name, ptype string) *uint64 {
	if name == "" {
		return nil
	}
	var p model.Partner
	if db.Where("shop_id = ? AND name = ? AND deleted_at IS NULL", shopID, name).First(&p).Error == nil {
		id := p.ID
		return &id
	}
	p = model.Partner{
		TenantBase: model.TenantBase{ShopID: shopID},
		Name:       name,
		Type:       ptype,
		Status:     "enabled",
	}
	if db.Create(&p).Error != nil {
		return nil
	}
	id := p.ID
	return &id
}

func parseDate(s string) model.Date {
	t, err := time.ParseInLocation("2006-01-02", s, time.Local)
	if err != nil {
		return model.Date{Time: time.Now()}
	}
	return model.Date{Time: t}
}

func parsePartnerType(raw string) string {
	hasCust := strings.Contains(raw, "客户")
	hasSupp := strings.Contains(raw, "供应商")
	switch {
	case hasCust && hasSupp:
		return "supplier,customer"
	case hasCust:
		return "customer"
	default:
		return "supplier"
	}
}

func cell(row []string, idx int) string {
	if idx >= len(row) {
		return ""
	}
	return strings.TrimSpace(row[idx])
}