v0.2.0 transitioned to api-only, extended and improved features, docs and tests added

internal/http/validator.go

@@ -0,0 +1,103 @@
+// FILE: internal/http/handler.go
+package http
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"chess/internal/core"
+
+	"github.com/go-playground/validator/v10"
+	"github.com/gofiber/fiber/v2"
+	"github.com/google/uuid"
+)
+
+// Add validator instance near top of file
+var validate = validator.New()
+
+// Add custom validation middleware function
+func validationMiddleware(c *fiber.Ctx) error {
+	// Skip validation for GET, DELETE, OPTIONS
+	method := c.Method()
+	if method == fiber.MethodGet || method == fiber.MethodDelete || method == fiber.MethodOptions {
+		return c.Next()
+	}
+
+	// Determine request type based on path
+	path := c.Path()
+	var requestType interface{}
+
+	switch {
+	case strings.HasSuffix(path, "/games") && method == fiber.MethodPost:
+		requestType = &core.CreateGameRequest{}
+	case strings.HasSuffix(path, "/players") && method == fiber.MethodPut:
+		requestType = &core.ConfigurePlayersRequest{}
+	case strings.HasSuffix(path, "/moves") && method == fiber.MethodPost:
+		requestType = &core.MoveRequest{}
+	case strings.HasSuffix(path, "/undo") && method == fiber.MethodPost:
+		requestType = &core.UndoRequest{}
+	default:
+		return c.Next() // No validation for unknown endpoints
+	}
+
+	// Parse body
+	if err := c.BodyParser(requestType); err != nil {
+		return c.Status(fiber.StatusBadRequest).JSON(core.ErrorResponse{
+			Error:   "invalid request body",
+			Code:    core.ErrInvalidRequest,
+			Details: err.Error(),
+		})
+	}
+
+	// Validate
+	if errs := validate.Struct(requestType); errs != nil {
+		var details strings.Builder
+		for _, err := range errs.(validator.ValidationErrors) {
+			if details.Len() > 0 {
+				details.WriteString("; ")
+			}
+			switch err.Tag() {
+			case "required":
+				details.WriteString(fmt.Sprintf("%s is required", err.Field()))
+			case "oneof":
+				details.WriteString(fmt.Sprintf("%s must be one of [%s]", err.Field(), err.Param()))
+			case "min":
+				if err.Type().Kind() == reflect.String {
+					details.WriteString(fmt.Sprintf("%s must be at least %s characters", err.Field(), err.Param()))
+				} else {
+					details.WriteString(fmt.Sprintf("%s must be at least %s", err.Field(), err.Param()))
+				}
+			case "max":
+				if err.Type().Kind() == reflect.String {
+					details.WriteString(fmt.Sprintf("%s must be at most %s characters", err.Field(), err.Param()))
+				} else {
+					details.WriteString(fmt.Sprintf("%s must be at most %s", err.Field(), err.Param()))
+				}
+			case "omitempty": // Skip, a control tag that doesn't error
+				continue
+			case "dive": // Skip, panics on wrong type, no error handling since current code does not call validator on slice or map
+				continue
+			default:
+				details.WriteString(fmt.Sprintf("%s failed %s validation", err.Field(), err.Tag()))
+			}
+		}
+
+		return c.Status(fiber.StatusBadRequest).JSON(core.ErrorResponse{
+			Error:   "validation failed",
+			Code:    core.ErrInvalidRequest,
+			Details: details.String(),
+		})
+	}
+
+	// Store validated body for handler use
+	c.Locals("validatedBody", requestType)
+	c.Locals("validated", true)
+
+	return c.Next()
+}
+
+func isValidUUID(s string) bool {
+	_, err := uuid.Parse(s)
+	return err == nil
+}