refactor(handler): extract DTOs and helpers to dto.go

- Move 18 request/response structs to dto.go
- Move utility functions (writeJSON, decodeJSON, parseUUID, etc)
- Reduce handler.go from 1471 to 1254 lines (~15% reduction)
- All tests passing

backend/internal/http/handler/dto.go

@@ -0,0 +1,233 @@
+package handler
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/gofrs/uuid/v5"
+	"github.com/saveinmed/backend-go/internal/domain"
+	"github.com/saveinmed/backend-go/internal/http/middleware"
+)
+
+// --- Request DTOs ---
+
+type createUserRequest struct {
+	CompanyID uuid.UUID `json:"company_id"`
+	Role      string    `json:"role"`
+	Name      string    `json:"name"`
+	Email     string    `json:"email"`
+	Password  string    `json:"password"`
+}
+
+type registerAuthRequest struct {
+	CompanyID *uuid.UUID             `json:"company_id,omitempty"`
+	Company   *registerCompanyTarget `json:"company,omitempty"`
+	Role      string                 `json:"role"`
+	Name      string                 `json:"name"`
+	Email     string                 `json:"email"`
+	Password  string                 `json:"password"`
+}
+
+type registerCompanyTarget struct {
+	ID            uuid.UUID `json:"id,omitempty"`
+	Role          string    `json:"role"`
+	CNPJ          string    `json:"cnpj"`
+	CorporateName string    `json:"corporate_name"`
+	LicenseNumber string    `json:"license_number"`
+}
+
+type loginRequest struct {
+	Email    string `json:"email"`
+	Password string `json:"password"`
+}
+
+type authResponse struct {
+	Token     string    `json:"token"`
+	ExpiresAt time.Time `json:"expires_at"`
+}
+
+type inventoryAdjustRequest struct {
+	ProductID uuid.UUID `json:"product_id"`
+	Delta     int64     `json:"delta"`
+	Reason    string    `json:"reason"`
+}
+
+type addCartItemRequest struct {
+	ProductID uuid.UUID `json:"product_id"`
+	Quantity  int64     `json:"quantity"`
+}
+
+type createReviewRequest struct {
+	OrderID uuid.UUID `json:"order_id"`
+	Rating  int       `json:"rating"`
+	Comment string    `json:"comment"`
+}
+
+type updateUserRequest struct {
+	CompanyID *uuid.UUID `json:"company_id,omitempty"`
+	Role      *string    `json:"role,omitempty"`
+	Name      *string    `json:"name,omitempty"`
+	Email     *string    `json:"email,omitempty"`
+	Password  *string    `json:"password,omitempty"`
+}
+
+type requester struct {
+	Role      string
+	CompanyID *uuid.UUID
+}
+
+type registerCompanyRequest struct {
+	Role          string `json:"role"`
+	CNPJ          string `json:"cnpj"`
+	CorporateName string `json:"corporate_name"`
+	LicenseNumber string `json:"license_number"`
+}
+
+type updateCompanyRequest struct {
+	Role          *string `json:"role,omitempty"`
+	CNPJ          *string `json:"cnpj,omitempty"`
+	CorporateName *string `json:"corporate_name,omitempty"`
+	LicenseNumber *string `json:"license_number,omitempty"`
+	IsVerified    *bool   `json:"is_verified,omitempty"`
+}
+
+type registerProductRequest struct {
+	SellerID    uuid.UUID `json:"seller_id"`
+	Name        string    `json:"name"`
+	Description string    `json:"description"`
+	Batch       string    `json:"batch"`
+	ExpiresAt   time.Time `json:"expires_at"`
+	PriceCents  int64     `json:"price_cents"`
+	Stock       int64     `json:"stock"`
+}
+
+type updateProductRequest struct {
+	SellerID    *uuid.UUID `json:"seller_id,omitempty"`
+	Name        *string    `json:"name,omitempty"`
+	Description *string    `json:"description,omitempty"`
+	Batch       *string    `json:"batch,omitempty"`
+	ExpiresAt   *time.Time `json:"expires_at,omitempty"`
+	PriceCents  *int64     `json:"price_cents,omitempty"`
+	Stock       *int64     `json:"stock,omitempty"`
+}
+
+type createOrderRequest struct {
+	BuyerID  uuid.UUID              `json:"buyer_id"`
+	SellerID uuid.UUID              `json:"seller_id"`
+	Items    []domain.OrderItem     `json:"items"`
+	Shipping domain.ShippingAddress `json:"shipping"`
+}
+
+type createShipmentRequest struct {
+	OrderID          uuid.UUID `json:"order_id"`
+	Carrier          string    `json:"carrier"`
+	TrackingCode     string    `json:"tracking_code"`
+	ExternalTracking string    `json:"external_tracking"`
+}
+
+type updateStatusRequest struct {
+	Status string `json:"status"`
+}
+
+// --- Utility Functions ---
+
+func writeJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(v)
+}
+
+func writeError(w http.ResponseWriter, status int, err error) {
+	writeJSON(w, status, map[string]string{"error": err.Error()})
+}
+
+func decodeJSON(ctx context.Context, r *http.Request, v any) error {
+	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+
+	dec := json.NewDecoder(r.Body)
+	dec.DisallowUnknownFields()
+	if err := dec.Decode(v); err != nil {
+		return err
+	}
+	return ctx.Err()
+}
+
+func parseUUIDFromPath(path string) (uuid.UUID, error) {
+	parts := splitPath(path)
+	for i := len(parts) - 1; i >= 0; i-- {
+		if id, err := uuid.FromString(parts[i]); err == nil {
+			return id, nil
+		}
+	}
+	return uuid.UUID{}, errors.New("missing resource id")
+}
+
+func splitPath(p string) []string {
+	var parts []string
+	start := 0
+	for i := 0; i < len(p); i++ {
+		if p[i] == '/' {
+			if i > start {
+				parts = append(parts, p[start:i])
+			}
+			start = i + 1
+		}
+	}
+	if start < len(p) {
+		parts = append(parts, p[start:])
+	}
+	return parts
+}
+
+func isValidStatus(status string) bool {
+	switch domain.OrderStatus(status) {
+	case domain.OrderStatusPending, domain.OrderStatusPaid, domain.OrderStatusInvoiced, domain.OrderStatusDelivered:
+		return true
+	default:
+		return false
+	}
+}
+
+func parsePagination(r *http.Request) (int, int) {
+	page := 1
+	pageSize := 20
+
+	if v := r.URL.Query().Get("page"); v != "" {
+		if p, err := strconv.Atoi(v); err == nil && p > 0 {
+			page = p
+		}
+	}
+
+	if v := r.URL.Query().Get("page_size"); v != "" {
+		if ps, err := strconv.Atoi(v); err == nil && ps > 0 {
+			pageSize = ps
+		}
+	}
+
+	return page, pageSize
+}
+
+func getRequester(r *http.Request) (requester, error) {
+	if claims, ok := middleware.GetClaims(r.Context()); ok {
+		return requester{Role: claims.Role, CompanyID: claims.CompanyID}, nil
+	}
+	role := r.Header.Get("X-User-Role")
+	if role == "" {
+		role = "Admin"
+	}
+
+	var companyID *uuid.UUID
+	if cid := r.Header.Get("X-Company-ID"); cid != "" {
+		id, err := uuid.FromString(cid)
+		if err != nil {
+			return requester{}, errors.New("invalid X-Company-ID header")
+		}
+		companyID = &id
+	}
+
+	return requester{Role: role, CompanyID: companyID}, nil
+}

backend/internal/http/handler/handler.go

@@ -1,7 +1,6 @@
 package handler
 
 import (
-	"context"
 	"errors"
 	"net/http"
 	"strconv"
@@ -1252,219 +1251,3 @@ func (h *Handler) DeleteUser(w http.ResponseWriter, r *http.Request) {
 
 	w.WriteHeader(http.StatusNoContent)
 }
-
-type createUserRequest struct {
-	CompanyID uuid.UUID `json:"company_id"`
-	Role      string    `json:"role"`
-	Name      string    `json:"name"`
-	Email     string    `json:"email"`
-	Password  string    `json:"password"`
-}
-
-type registerAuthRequest struct {
-	CompanyID *uuid.UUID             `json:"company_id,omitempty"`
-	Company   *registerCompanyTarget `json:"company,omitempty"`
-	Role      string                 `json:"role"`
-	Name      string                 `json:"name"`
-	Email     string                 `json:"email"`
-	Password  string                 `json:"password"`
-}
-
-type registerCompanyTarget struct {
-	ID            uuid.UUID `json:"id,omitempty"`
-	Role          string    `json:"role"`
-	CNPJ          string    `json:"cnpj"`
-	CorporateName string    `json:"corporate_name"`
-	LicenseNumber string    `json:"license_number"`
-}
-
-type loginRequest struct {
-	Email    string `json:"email"`
-	Password string `json:"password"`
-}
-
-type authResponse struct {
-	Token     string    `json:"token"`
-	ExpiresAt time.Time `json:"expires_at"`
-}
-
-type inventoryAdjustRequest struct {
-	ProductID uuid.UUID `json:"product_id"`
-	Delta     int64     `json:"delta"`
-	Reason    string    `json:"reason"`
-}
-
-type addCartItemRequest struct {
-	ProductID uuid.UUID `json:"product_id"`
-	Quantity  int64     `json:"quantity"`
-}
-
-type createReviewRequest struct {
-	OrderID uuid.UUID `json:"order_id"`
-	Rating  int       `json:"rating"`
-	Comment string    `json:"comment"`
-}
-
-type updateUserRequest struct {
-	CompanyID *uuid.UUID `json:"company_id,omitempty"`
-	Role      *string    `json:"role,omitempty"`
-	Name      *string    `json:"name,omitempty"`
-	Email     *string    `json:"email,omitempty"`
-	Password  *string    `json:"password,omitempty"`
-}
-
-type requester struct {
-	Role      string
-	CompanyID *uuid.UUID
-}
-
-func parsePagination(r *http.Request) (int, int) {
-	page := 1
-	pageSize := 20
-
-	if v := r.URL.Query().Get("page"); v != "" {
-		if p, err := strconv.Atoi(v); err == nil && p > 0 {
-			page = p
-		}
-	}
-
-	if v := r.URL.Query().Get("page_size"); v != "" {
-		if ps, err := strconv.Atoi(v); err == nil && ps > 0 {
-			pageSize = ps
-		}
-	}
-
-	return page, pageSize
-}
-
-func getRequester(r *http.Request) (requester, error) {
-	if claims, ok := middleware.GetClaims(r.Context()); ok {
-		return requester{Role: claims.Role, CompanyID: claims.CompanyID}, nil
-	}
-	role := r.Header.Get("X-User-Role")
-	if role == "" {
-		role = "Admin"
-	}
-
-	var companyID *uuid.UUID
-	if cid := r.Header.Get("X-Company-ID"); cid != "" {
-		id, err := uuid.FromString(cid)
-		if err != nil {
-			return requester{}, errors.New("invalid X-Company-ID header")
-		}
-		companyID = &id
-	}
-
-	return requester{Role: role, CompanyID: companyID}, nil
-}
-
-type registerCompanyRequest struct {
-	Role          string `json:"role"`
-	CNPJ          string `json:"cnpj"`
-	CorporateName string `json:"corporate_name"`
-	LicenseNumber string `json:"license_number"`
-}
-
-type updateCompanyRequest struct {
-	Role          *string `json:"role,omitempty"`
-	CNPJ          *string `json:"cnpj,omitempty"`
-	CorporateName *string `json:"corporate_name,omitempty"`
-	LicenseNumber *string `json:"license_number,omitempty"`
-	IsVerified    *bool   `json:"is_verified,omitempty"`
-}
-
-type registerProductRequest struct {
-	SellerID    uuid.UUID `json:"seller_id"`
-	Name        string    `json:"name"`
-	Description string    `json:"description"`
-	Batch       string    `json:"batch"`
-	ExpiresAt   time.Time `json:"expires_at"`
-	PriceCents  int64     `json:"price_cents"`
-	Stock       int64     `json:"stock"`
-}
-
-type updateProductRequest struct {
-	SellerID    *uuid.UUID `json:"seller_id,omitempty"`
-	Name        *string    `json:"name,omitempty"`
-	Description *string    `json:"description,omitempty"`
-	Batch       *string    `json:"batch,omitempty"`
-	ExpiresAt   *time.Time `json:"expires_at,omitempty"`
-	PriceCents  *int64     `json:"price_cents,omitempty"`
-	Stock       *int64     `json:"stock,omitempty"`
-}
-
-type createOrderRequest struct {
-	BuyerID  uuid.UUID              `json:"buyer_id"`
-	SellerID uuid.UUID              `json:"seller_id"`
-	Items    []domain.OrderItem     `json:"items"`
-	Shipping domain.ShippingAddress `json:"shipping"`
-}
-
-type createShipmentRequest struct {
-	OrderID          uuid.UUID `json:"order_id"`
-	Carrier          string    `json:"carrier"`
-	TrackingCode     string    `json:"tracking_code"`
-	ExternalTracking string    `json:"external_tracking"`
-}
-
-type updateStatusRequest struct {
-	Status string `json:"status"`
-}
-
-func writeJSON(w http.ResponseWriter, status int, v any) {
-	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(status)
-	_ = json.NewEncoder(w).Encode(v)
-}
-
-func writeError(w http.ResponseWriter, status int, err error) {
-	writeJSON(w, status, map[string]string{"error": err.Error()})
-}
-
-func decodeJSON(ctx context.Context, r *http.Request, v any) error {
-	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
-	defer cancel()
-
-	dec := json.NewDecoder(r.Body)
-	dec.DisallowUnknownFields()
-	if err := dec.Decode(v); err != nil {
-		return err
-	}
-	return ctx.Err()
-}
-
-func parseUUIDFromPath(path string) (uuid.UUID, error) {
-	parts := splitPath(path)
-	for i := len(parts) - 1; i >= 0; i-- {
-		if id, err := uuid.FromString(parts[i]); err == nil {
-			return id, nil
-		}
-	}
-	return uuid.UUID{}, errors.New("missing resource id")
-}
-
-func splitPath(p string) []string {
-	var parts []string
-	start := 0
-	for i := 0; i < len(p); i++ {
-		if p[i] == '/' {
-			if i > start {
-				parts = append(parts, p[start:i])
-			}
-			start = i + 1
-		}
-	}
-	if start < len(p) {
-		parts = append(parts, p[start:])
-	}
-	return parts
-}
-
-func isValidStatus(status string) bool {
-	switch domain.OrderStatus(status) {
-	case domain.OrderStatusPending, domain.OrderStatusPaid, domain.OrderStatusInvoiced, domain.OrderStatusDelivered:
-		return true
-	default:
-		return false
-	}
-}