Implement Dummy API for Project Understanding (#445)

* Add hello api types

* Implement dummy api

* Apply comments

* Fix lint

* Apply comments

* Fix lint errors

---------

Co-authored-by: kokodak <[email protected]>

Author: devleejb

api/backend-openapi-spec.json

@@ -0,0 +1,14 @@
+package models
+
+import (
+	"errors"
+	"fmt"
+)
+
+func RequiredFieldError(field string) error {
+	return errors.New(field + " is required")
+}
+
+func MinLengthError(field string, min int) error {
+	return errors.New(fmt.Sprintf("%s must be at least %d characters", field, min))
+}

backend-go/api/codepair/v1/models/errors.go

@@ -0,0 +1,7 @@
+package models
+
+type HelloRequest struct {
+
+	// New nickname to say hello
+	Nickname string `json:"nickname"`
+}

backend-go/api/codepair/v1/models/model_hello_request.go

@@ -0,0 +1,7 @@
+package models
+
+type HelloResponse struct {
+
+	// Welcome message
+	Message string `json:"message"`
+}

backend-go/api/codepair/v1/models/model_hello_response.go

@@ -3,7 +3,7 @@ package models
 type HttpExceptionResponse struct {
 
 	// HTTP status code
-	StatusCode float32 `json:"statusCode"`
+	StatusCode int `json:"statusCode"`
 
 	// Description of the error
 	Message string `json:"message"`

backend-go/api/codepair/v1/models/model_http_exception_response.go

@@ -0,0 +1,13 @@
+package models
+
+func (r *HelloRequest) Validate() error {
+	if r.Nickname == "" {
+		return RequiredFieldError("nickname")
+	}
+
+	if len(r.Nickname) < 2 {
+		return MinLengthError("nickname", 2)
+	}
+
+	return nil
+}

backend-go/api/codepair/v1/models/validators.go

@@ -0,0 +1,26 @@
+package core
+
+import (
+	"github.com/yorkie-team/codepair/backend/internal/core/hello"
+	"github.com/yorkie-team/codepair/backend/internal/infra/database/mongo"
+)
+
+type Handlers struct {
+	Hello *hello.Handler
+}
+
+// NewHandlers creates a new handlers.
+func NewHandlers() *Handlers {
+	// Repositories
+	helloRepository := mongo.NewHelloRepository()
+
+	// Services
+	helloService := hello.NewService(helloRepository)
+
+	// Handlers
+	helloHandler := hello.NewHandler(helloService)
+
+	return &Handlers{
+		Hello: helloHandler,
+	}
+}

backend-go/internal/core/handlers.go

@@ -0,0 +1,41 @@
+package hello
+
+import (
+	"fmt"
+
+	"github.com/labstack/echo/v4"
+
+	"github.com/yorkie-team/codepair/backend/api/codepair/v1/models"
+	"github.com/yorkie-team/codepair/backend/internal/transport/http"
+)
+
+type Handler struct {
+	helloService *Service
+}
+
+// NewHandler creates a new handler for hello.
+func NewHandler(service *Service) *Handler {
+	return &Handler{
+		helloService: service,
+	}
+}
+
+// HelloCodePair returns a hello message for a given CodePairVisitor.
+func (h *Handler) HelloCodePair(e echo.Context) error {
+	req := new(models.HelloRequest)
+
+	if err := http.BindAndValidateRequest(e, req); err != nil {
+		return fmt.Errorf("%w", err)
+	}
+
+	helloMessage, err := h.helloService.HelloCodePair(e, CodePairVisitor{
+		Nickname: req.Nickname,
+	})
+	if err != nil {
+		return fmt.Errorf("%w", http.NewErrorResponse(e, err))
+	}
+
+	return fmt.Errorf("%w", http.NewOkResponse(e, models.HelloResponse{
+		Message: helloMessage,
+	}))
+}

backend-go/internal/core/hello/handler.go

@@ -0,0 +1,7 @@
+package hello
+
+// CodePairVisitor is a visitor for CodePair
+type CodePairVisitor struct {
+	// Nickname is the nickname of the visitor
+	Nickname string
+}

backend-go/internal/core/hello/model.go

@@ -0,0 +1,6 @@
+package hello
+
+type Repository interface {
+	// ReadHelloMessageFor reads a hello message for a given CodePairVisitor
+	ReadHelloMessageFor(codePairVisitor CodePairVisitor) (string, error)
+}

backend-go/internal/core/hello/repository.go

@@ -0,0 +1,28 @@
+package hello
+
+import (
+	"github.com/labstack/echo/v4"
+	"github.com/yorkie-team/codepair/backend/internal/transport/http"
+)
+
+type Service struct {
+	helloRepository Repository
+}
+
+// NewService creates a new service for hello.
+func NewService(repository Repository) *Service {
+	return &Service{
+		helloRepository: repository,
+	}
+}
+
+// HelloCodePair returns a hello message for a given CodePairVisitor
+func (s *Service) HelloCodePair(e echo.Context, codePairVisitor CodePairVisitor) (string, error) {
+	helloMessage, err := s.helloRepository.ReadHelloMessageFor(codePairVisitor)
+	if err != nil {
+		e.Logger().Fatal(err)
+		return "", http.ErrInternalServerError
+	}
+
+	return helloMessage, nil
+}

backend-go/internal/core/hello/service.go

@@ -0,0 +1,14 @@
+package mongo
+
+import "github.com/yorkie-team/codepair/backend/internal/core/hello"
+
+type HelloRepository struct{}
+
+// NewHelloRepository creates a new HelloRepository.
+func NewHelloRepository() HelloRepository {
+	return HelloRepository{}
+}
+
+func (h HelloRepository) ReadHelloMessageFor(codePairVisitor hello.CodePairVisitor) (string, error) {
+	return "Hello, " + codePairVisitor.Nickname + "!", nil
+}

backend-go/internal/infra/database/mongo/hello.go

@@ -1,15 +1,11 @@
 package server
 
 import (
-	"fmt"
-	"net/http"
-
 	"github.com/labstack/echo/v4"
+	"github.com/yorkie-team/codepair/backend/internal/core"
 )
 
-func RegisterRoutes(e *echo.Echo) {
-	e.GET("/", func(c echo.Context) error {
-		err := c.String(http.StatusOK, "Hello, World!")
-		return fmt.Errorf("error: %w", err)
-	})
+// RegisterRoutes registers routes for the server.
+func RegisterRoutes(e *echo.Echo, handlers *core.Handlers) {
+	e.POST("/hello", handlers.Hello.HelloCodePair)
 }

backend-go/internal/server/routes.go

@@ -8,15 +8,18 @@ import (
 	"github.com/labstack/echo/v4"
 
 	"github.com/yorkie-team/codepair/backend/internal/config"
+	"github.com/yorkie-team/codepair/backend/internal/core"
 )
 
 type CodePair struct {
 	config *config.Config
 	echo   *echo.Echo
 }
 
+// New creates a new CodePair server.
 func New(e *echo.Echo, conf *config.Config) *CodePair {
-	RegisterRoutes(e)
+	handlers := core.NewHandlers()
+	RegisterRoutes(e, handlers)
 
 	cp := &CodePair{
 		config: conf,
@@ -25,6 +28,7 @@ func New(e *echo.Echo, conf *config.Config) *CodePair {
 	return cp
 }
 
+// Start starts the server.
 func (c *CodePair) Start() error {
 	addr := fmt.Sprintf(":%d", c.config.Server.Port)
 	if err := c.echo.Start(addr); !errors.Is(err, http.ErrServerClosed) {

backend-go/internal/server/server.go

@@ -0,0 +1,17 @@
+package http
+
+import (
+	"errors"
+
+	"github.com/yorkie-team/codepair/backend/api/codepair/v1/models"
+)
+
+// ConvertErrorToResponse converts an error to a response.
+func ConvertErrorToResponse(err error) models.HttpExceptionResponse {
+	switch {
+	case errors.Is(err, ErrInternalServerError):
+		return NewInternalServerErrorResponse()
+	default:
+		return NewInvalidJSONErrorResponse()
+	}
+}

backend-go/internal/transport/http/converter.go

@@ -0,0 +1,29 @@
+package http
+
+import (
+	nethttp "net/http"
+
+	"github.com/yorkie-team/codepair/backend/api/codepair/v1/models"
+)
+
+func newHTTPExceptionResponse(statusCode int, message string) models.HttpExceptionResponse {
+	return models.HttpExceptionResponse{
+		StatusCode: statusCode,
+		Message:    message,
+	}
+}
+
+// NewInvalidJSONErrorResponse creates a HttpExceptionResponse that represents an invalid JSON error.
+func NewInvalidJSONErrorResponse() models.HttpExceptionResponse {
+	return newHTTPExceptionResponse(nethttp.StatusBadRequest, "Invalid JSON")
+}
+
+// NewValidationErrorResponse creates a HttpExceptionResponse that represents a validation error.
+func NewValidationErrorResponse(reason string) models.HttpExceptionResponse {
+	return newHTTPExceptionResponse(nethttp.StatusBadRequest, reason)
+}
+
+// NewInternalServerErrorResponse creates a HttpExceptionResponse that represents a internal server error.
+func NewInternalServerErrorResponse() models.HttpExceptionResponse {
+	return newHTTPExceptionResponse(nethttp.StatusInternalServerError, "Internal Server Error")
+}

backend-go/internal/transport/http/error_responses.go

@@ -0,0 +1,8 @@
+package http
+
+import "errors"
+
+var (
+	// ErrInternalServerError is an internal server error
+	ErrInternalServerError = errors.New("internal server error")
+)

backend-go/internal/transport/http/errors.go

@@ -0,0 +1,37 @@
+package http
+
+import (
+	"fmt"
+	nethttp "net/http"
+
+	"github.com/labstack/echo/v4"
+)
+
+type request interface {
+	Validate() error
+}
+
+// BindAndValidateRequest binds and validates the request.
+// If the request is invalid, it returns an error response.
+func BindAndValidateRequest(e echo.Context, req request) error {
+	if err := e.Bind(req); err != nil {
+		return fmt.Errorf("failed to bind request: %w", e.JSON(nethttp.StatusBadRequest, NewInvalidJSONErrorResponse()))
+	}
+	if err := req.Validate(); err != nil {
+		return fmt.Errorf("validation failed: %w", e.JSON(nethttp.StatusBadRequest, NewValidationErrorResponse(err.Error())))
+	}
+	return nil
+}
+
+// NewErrorResponse handles the creation and response of an error.
+// It converts the provided error into a response structure and sends it as a JSON response.
+// The response status code is determined by the error's associated status.
+func NewErrorResponse(e echo.Context, err error) error {
+	resp := ConvertErrorToResponse(err)
+	return fmt.Errorf("returning error response as JSON: %w", e.JSON(resp.StatusCode, ConvertErrorToResponse(err)))
+}
+
+// NewOkResponse sends a JSON response with a status code of 200.
+func NewOkResponse(e echo.Context, resp interface{}) error {
+	return fmt.Errorf("returning success response as JSON: %w", e.JSON(nethttp.StatusOK, resp))
+}

backend-go/internal/transport/http/handler_utils.go

@@ -15,7 +15,7 @@
     "lint:check": "pnpm run --parallel lint:check",
     "format": "pnpm run --parallel format",
     "format:check": "pnpm run --parallel format:check",
-    "generate:backend": "openapi-generator-cli generate -i ./api/backend-openapi-spec.json -g go-echo-server -o ./backend-go/api/codepair/v1 --global-property models",
+    "generate:backend": "openapi-generator-cli generate -i ./api/backend-openapi-spec.json -g go-echo-server -o ./backend-go/api/codepair/v1 --global-property models --type-mappings int32=int",
     "generate:frontend": "openapi-generator-cli generate -i ./api/backend-openapi-spec.json -g typescript-axios -o ./frontend/src/api"
   },
   "devDependencies": {