package web

import (
	"billit/internal/database"
	"net/http"
	"strconv"

	"github.com/labstack/echo/v4"
)

// ProductHandlers holds db reference for product operations
type ProductHandlers struct {
	db database.Service
}

// NewProductHandlers creates handlers with db access
func NewProductHandlers(db database.Service) *ProductHandlers {
	return &ProductHandlers{db: db}
}

// getUserID extracts user ID from context (set by auth middleware)
func getUserID(c echo.Context) string {
	if uid, ok := c.Get("user_id").(string); ok {
		return uid
	}
	return ""
}

// ProductListHandler renders the /product page with all products
func (h *ProductHandlers) ProductListHandler(c echo.Context) error {
	userID := getUserID(c)
	products, err := h.db.GetAllProducts(userID)
	if err != nil {
		return RenderServerError(c, "Failed to load products. Please try again.")
	}
	return Render(c, ProductListPage(products))
}

// ProductCreatePageHandler renders the /product/create form page
func (h *ProductHandlers) ProductCreatePageHandler(c echo.Context) error {
	return Render(c, ProductCreatePage())
}

// ProductEditPageHandler renders the /product/edit/:sku form page
func (h *ProductHandlers) ProductEditPageHandler(c echo.Context) error {
	sku := c.Param("sku")
	userID := getUserID(c)

	product, err := h.db.GetProductBySKU(sku, userID)
	if err != nil || product == nil {
		return RenderNotFound(c, "Product not found or you don't have access to it.")
	}
	return Render(c, ProductEditPage(*product))
}

// ProductCreateHandler handles POST /product/create
func (h *ProductHandlers) ProductCreateHandler(c echo.Context) error {
	userID := getUserID(c)
	if userID == "" {
		return c.Redirect(http.StatusFound, "/")
	}

	sku := c.FormValue("sku")
	if sku == "" {
		return c.String(http.StatusBadRequest, "SKU is required")
	}

	name := c.FormValue("name")
	if name == "" {
		return c.String(http.StatusBadRequest, "Name is required")
	}

	// Check if SKU already exists for this user
	existing, _ := h.db.GetProductBySKU(sku, userID)
	if existing != nil {
		return c.String(http.StatusBadRequest, "A product with this SKU already exists")
	}

	hsn := c.FormValue("hsn")
	baseStr := c.FormValue("base_price")
	wholesaleStr := c.FormValue("wholesale_price")
	gstStr := c.FormValue("gst_rate")
	smallQtyStr := c.FormValue("small_order_qty")

	base, _ := strconv.ParseFloat(baseStr, 64)
	wholesale, _ := strconv.ParseFloat(wholesaleStr, 64)
	if wholesale == 0 {
		wholesale = base // default wholesale to base price
	}

	gstRate := 0.18 // default 18%
	switch gstStr {
	case "0":
		gstRate = 0.0
	case "5":
		gstRate = 0.05
	case "12":
		gstRate = 0.12
	case "18":
		gstRate = 0.18
	case "28":
		gstRate = 0.28
	}

	smallQty := 1
	if v, err := strconv.Atoi(smallQtyStr); err == nil && v > 0 {
		smallQty = v
	}

	smallFeeStr := c.FormValue("small_order_fee")
	smallFee, _ := strconv.ParseFloat(smallFeeStr, 64)

	unit := c.FormValue("unit")
	if unit == "" {
		unit = "pcs"
	}

	product := database.Product{
		SKU:            sku,
		Name:           name,
		HSNCode:        hsn,
		BasePrice:      base,
		WholesalePrice: wholesale,
		GSTRate:        gstRate,
		SmallOrderQty:  smallQty,
		SmallOrderFee:  smallFee,
		Unit:           unit,
	}

	if err := h.db.CreateProduct(product, userID); err != nil {
		return c.String(http.StatusInternalServerError, "failed to create product")
	}

	// Redirect to product list
	return c.Redirect(http.StatusSeeOther, "/product")
}

// ProductUpdateHandler handles POST /product/edit/:sku
func (h *ProductHandlers) ProductUpdateHandler(c echo.Context) error {
	userID := getUserID(c)
	if userID == "" {
		return c.Redirect(http.StatusFound, "/")
	}

	sku := c.Param("sku")

	// Verify product belongs to user
	existing, _ := h.db.GetProductBySKU(sku, userID)
	if existing == nil {
		return c.String(http.StatusNotFound, "Product not found")
	}

	name := c.FormValue("name")
	if name == "" {
		return c.String(http.StatusBadRequest, "Name is required")
	}

	hsn := c.FormValue("hsn")
	baseStr := c.FormValue("base_price")
	wholesaleStr := c.FormValue("wholesale_price")
	gstStr := c.FormValue("gst_rate")
	smallQtyStr := c.FormValue("small_order_qty")

	base, _ := strconv.ParseFloat(baseStr, 64)
	wholesale, _ := strconv.ParseFloat(wholesaleStr, 64)
	if wholesale == 0 {
		wholesale = base
	}

	gstRate := 0.18
	switch gstStr {
	case "0":
		gstRate = 0.0
	case "5":
		gstRate = 0.05
	case "12":
		gstRate = 0.12
	case "18":
		gstRate = 0.18
	case "28":
		gstRate = 0.28
	}

	smallQty := 1
	if v, err := strconv.Atoi(smallQtyStr); err == nil && v > 0 {
		smallQty = v
	}

	smallFeeStr := c.FormValue("small_order_fee")
	smallFee, _ := strconv.ParseFloat(smallFeeStr, 64)

	unit := c.FormValue("unit")
	if unit == "" {
		unit = "pcs"
	}

	product := database.Product{
		SKU:            sku,
		Name:           name,
		HSNCode:        hsn,
		BasePrice:      base,
		WholesalePrice: wholesale,
		GSTRate:        gstRate,
		SmallOrderQty:  smallQty,
		SmallOrderFee:  smallFee,
		Unit:           unit,
	}

	if err := h.db.UpdateProduct(product, userID); err != nil {
		return c.String(http.StatusInternalServerError, "failed to update product")
	}

	return c.Redirect(http.StatusSeeOther, "/product")
}

// ProductDeleteHandler handles DELETE /product/:sku
func (h *ProductHandlers) ProductDeleteHandler(c echo.Context) error {
	userID := getUserID(c)
	sku := c.Param("sku")

	if err := h.db.DeleteProduct(sku, userID); err != nil {
		return c.String(http.StatusInternalServerError, "failed to delete product")
	}

	// For HTMX, return empty to remove the row
	if c.Request().Header.Get("HX-Request") == "true" {
		return c.NoContent(http.StatusOK)
	}

	return c.Redirect(http.StatusSeeOther, "/product")
}