init

internal/handler/refund_handler.go

@@ -0,0 +1,96 @@
+package handler
+
+import (
+	"errors"
+	"strconv"
+
+	"accounting-app/pkg/api"
+	"accounting-app/internal/models"
+	"accounting-app/internal/service"
+
+	"github.com/gin-gonic/gin"
+)
+
+// RefundServiceInterface defines the interface for refund operations
+type RefundServiceInterface interface {
+	ProcessRefund(userID uint, transactionID uint, amount float64) (*models.Transaction, error)
+}
+
+// RefundHandler handles HTTP requests for refund operations
+// Feature: accounting-feature-upgrade
+// Validates: Requirements 8.10-8.18
+type RefundHandler struct {
+	refundService RefundServiceInterface
+}
+
+// NewRefundHandler creates a new RefundHandler instance
+func NewRefundHandler(refundService RefundServiceInterface) *RefundHandler {
+	return &RefundHandler{
+		refundService: refundService,
+	}
+}
+
+// ProcessRefundInput represents the input for processing a refund
+type ProcessRefundInput struct {
+	Amount float64 `json:"amount" binding:"required,gt=0"`
+}
+
+// ProcessRefund handles PUT /api/v1/transactions/:id/refund
+// Processes a refund on an expense transaction, automatically creating a refund income record
+// Feature: accounting-feature-upgrade
+// Validates: Requirements 8.10-8.18, 8.28
+func (h *RefundHandler) ProcessRefund(c *gin.Context) {
+	userId, exists := c.Get("user_id")
+	if !exists {
+		api.Unauthorized(c, "User not authenticated")
+		return
+	}
+
+	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
+	if err != nil {
+		api.BadRequest(c, "Invalid transaction ID")
+		return
+	}
+
+	var input ProcessRefundInput
+	if err := c.ShouldBindJSON(&input); err != nil {
+		api.ValidationError(c, "Invalid request body: "+err.Error())
+		return
+	}
+
+	refundIncome, err := h.refundService.ProcessRefund(userId.(uint), uint(id), input.Amount)
+	if err != nil {
+		if errors.Is(err, service.ErrTransactionNotFound) {
+			api.NotFound(c, "Transaction not found")
+			return
+		}
+		if errors.Is(err, service.ErrNotExpenseTransaction) {
+			api.BadRequest(c, "Only expense transactions can be refunded")
+			return
+		}
+		if errors.Is(err, service.ErrAlreadyRefunded) {
+			api.BadRequest(c, "Transaction already refunded")
+			return
+		}
+		if errors.Is(err, service.ErrInvalidRefundAmount) {
+			api.BadRequest(c, "Refund amount must be greater than 0 and not exceed original amount")
+			return
+		}
+		if errors.Is(err, service.ErrRefundCategoryNotFound) {
+			api.InternalError(c, "Refund system category not found. Please run database migrations.")
+			return
+		}
+		api.InternalError(c, "Failed to process refund: "+err.Error())
+		return
+	}
+
+	api.Success(c, refundIncome)
+}
+
+// RegisterRoutes registers all refund routes to the given router group
+func (h *RefundHandler) RegisterRoutes(rg *gin.RouterGroup) {
+	transactions := rg.Group("/transactions")
+	{
+		transactions.PUT("/:id/refund", h.ProcessRefund)
+	}
+}