feat: add new handler for GET admin orders

backend/handlers/item_handlers.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net/http"
 	"path/filepath"
+	"time"
 
 	"github.com/disintegration/imaging"
 	"github.com/gin-gonic/gin"
@@ -169,3 +170,66 @@ func UploadItemAvatar(c *gin.Context) {
 
 	c.JSON(http.StatusOK, gin.H{"avatar_url": item.AvatarURL})
 }
+
+func GetAdminOrder(c *gin.Context) {
+	orderID := c.Param("id")
+
+	type OrderItemDetail struct {
+		ItemID   uint    `json:"item_id"`
+		Name     string  `json:"name"`
+		Quantity float64 `json:"quantity"`
+		Price    float64 `json:"price"`
+		Unit     string  `json:"unit"`
+	}
+	type OrderHeader struct {
+		OrderID   uint      `json:"order_id"`
+		Address   string    `json:"address"`
+		Status    string    `json:"status"`
+		CreatedAt time.Time `json:"created_at"`
+	}
+
+	type OrderDetail struct {
+		OrderHeader
+		Items []OrderItemDetail `json:"items"`
+		Total float64           `json:"total"`
+	}
+
+	var header OrderHeader
+
+	err := database.DB.Table("orders").
+		Select("orders.id as order_id, orders.status, orders.created_at").
+		Where("orders.id = ?", orderID).
+		Scan(&header).Error
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	if header.OrderID == 0 {
+		c.JSON(http.StatusNotFound, gin.H{"error": "заказ не найден"})
+		return
+	}
+
+	var items []OrderItemDetail
+
+	err = database.DB.Table("order_items").
+		Select("order_items.item_id, items.name, order_items.quantity, order_items.price, items.unit").
+		Joins("JOIN items ON items.id = order_items.item_id").
+		Where("order_items.order_id = ?", orderID).
+		Scan(&items).Error
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	order := OrderDetail{
+		OrderHeader: header,
+		Items:       items,
+	}
+
+	for _, it := range items {
+		order.Total += it.Price * it.Quantity
+	}
+
+	c.JSON(http.StatusOK, order)
+}