private/apigen: Panic types defined in main package

The API generator was generating invalid code when types were defined in
a main package because the generated Go code was defining in import from
it.

This commit update the Go generator to panic with a explicit error
message if that situation happens.

The commit also add a new endpoint to the example with a named types
(i.e. no anonymous) to show that the Generator works fine with them.

Change-Id: Ieddd89c67048de50516f7ac7787d602660dc4a54

private/apigen/example/api.gen.go

@@ -16,6 +16,7 @@ import (
 
 	"storj.io/common/uuid"
 	"storj.io/storj/private/api"
+	"storj.io/storj/private/apigen/example/myapi"
 )
 
 const dateLayout = "2006-01-02T15:04:05.999Z"
@@ -23,6 +24,7 @@ const dateLayout = "2006-01-02T15:04:05.999Z"
 var ErrDocsAPI = errs.Class("example docs api")
 
 type DocumentsService interface {
+	GetOne(ctx context.Context, path string) (*myapi.Document, api.HTTPError)
 	UpdateContent(ctx context.Context, path string, id uuid.UUID, date time.Time, request struct {
 		Content string "json:\"content\""
 	}) (*struct {
@@ -50,11 +52,44 @@ func NewDocuments(log *zap.Logger, mon *monkit.Scope, service DocumentsService,
 	}
 
 	docsRouter := router.PathPrefix("/api/v0/docs").Subrouter()
+	docsRouter.HandleFunc("/{path}", handler.handleGetOne).Methods("GET")
 	docsRouter.HandleFunc("/{path}", handler.handleUpdateContent).Methods("POST")
 
 	return handler
 }
 
+func (h *DocumentsHandler) handleGetOne(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	var err error
+	defer h.mon.Task()(&ctx)(&err)
+
+	w.Header().Set("Content-Type", "application/json")
+
+	path, ok := mux.Vars(r)["path"]
+	if !ok {
+		api.ServeError(h.log, w, http.StatusBadRequest, errs.New("missing path route param"))
+		return
+	}
+
+	ctx, err = h.auth.IsAuthenticated(ctx, r, true, true)
+	if err != nil {
+		h.auth.RemoveAuthCookie(w)
+		api.ServeError(h.log, w, http.StatusUnauthorized, err)
+		return
+	}
+
+	retVal, httpErr := h.service.GetOne(ctx, path)
+	if httpErr.Err != nil {
+		api.ServeError(h.log, w, httpErr.Status, httpErr.Err)
+		return
+	}
+
+	err = json.NewEncoder(w).Encode(retVal)
+	if err != nil {
+		h.log.Debug("failed to write json GetOne response", zap.Error(ErrDocsAPI.Wrap(err)))
+	}
+}
+
 func (h *DocumentsHandler) handleUpdateContent(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
 	var err error

private/apigen/example/apidocs.gen.md

@@ -7,8 +7,34 @@
 <h2 id='list-of-endpoints'>List of Endpoints</h2>
 
 * Documents
+  * [Get One](#documents-get-one)
   * [Update Content](#documents-update-content)
 
+<h3 id='documents-get-one'>Get One (<a href='#list-of-endpoints'>go to full list</a>)</h3>
+
+Get one document with the specified version
+
+`GET /api/v0/docs/{path}`
+
+**Path Params:**
+
+| name | type | elaboration |
+|---|---|---|
+| `path` | `string` |  |
+
+**Response body:**
+
+```typescript
+{
+	id: string // UUID formatted as `00000000-0000-0000-0000-000000000000`
+	date: string // Date timestamp formatted as `2006-01-02T15:00:00Z`
+	pathParam: string
+	body: string
+	version: number
+}
+
+```
+
 <h3 id='documents-update-content'>Update Content (<a href='#list-of-endpoints'>go to full list</a>)</h3>
 
 Update the content of the document with the specified path and ID if the last update is before the indicated date

private/apigen/example/client-api.gen.ts

@@ -4,6 +4,14 @@
 import { HttpClient } from '@/utils/httpClient';
 import { Time, UUID } from '@/types/common';
 
+export class Document {
+    id: UUID;
+    date: Time;
+    pathParam: string;
+    body: string;
+    version: number;
+}
+
 export class UpdateContentRequest {
     content: string;
 }
@@ -19,6 +27,16 @@ export class docsHttpApiV0 {
     private readonly http: HttpClient = new HttpClient();
     private readonly ROOT_PATH: string = '/api/v0/docs';
 
+    public async GetOne(path: string): Promise<Document> {
+        const fullPath = `${this.ROOT_PATH}/${path}`;
+        const response = await this.http.get(fullPath);
+        if (response.ok) {
+            return response.json().then((body) => body as Document);
+        }
+        const err = await response.json();
+        throw new Error(err.error);
+    }
+
     public async UpdateContent(request: UpdateContentRequest, path: string, id: UUID, date: Time): Promise<UpdateContentResponse> {
         const u = new URL(`${this.ROOT_PATH}/${path}`);
         u.searchParams.set('id', id);

private/apigen/example/gen.go

@@ -11,6 +11,7 @@ import (
 
 	"storj.io/common/uuid"
 	"storj.io/storj/private/apigen"
+	"storj.io/storj/private/apigen/example/myapi"
 )
 
 func main() {
@@ -18,6 +19,16 @@ func main() {
 
 	g := a.Group("Documents", "docs")
 
+	g.Get("/{path}", &apigen.Endpoint{
+		Name:        "Get One",
+		Description: "Get one document with the specified version",
+		MethodName:  "GetOne",
+		Response:    myapi.Document{},
+		PathParams: []apigen.Param{
+			apigen.NewParam("path", ""),
+		},
+	})
+
 	g.Post("/{path}", &apigen.Endpoint{
 		Name:        "Update Content",
 		Description: "Update the content of the document with the specified path and ID if the last update is before the indicated date",

private/apigen/example/myapi/types.go

@@ -0,0 +1,19 @@
+// Copyright (C) 2023 Storj Labs, Inc.
+// See LICENSE for copying information.
+
+package myapi
+
+import (
+	"time"
+
+	"storj.io/common/uuid"
+)
+
+// Document is a retrieved document.
+type Document struct {
+	ID        uuid.UUID `json:"id"`
+	Date      time.Time `json:"date"`
+	PathParam string    `json:"pathParam"`
+	Body      string    `json:"body"`
+	Version   uint      `json:"version"`
+}

private/apigen/gogen.go

@@ -42,7 +42,12 @@ func (a *API) generateGo() ([]byte, error) {
 
 	getPackageName := func(path string) string {
 		pathPackages := strings.Split(path, "/")
-		return pathPackages[len(pathPackages)-1]
+		name := pathPackages[len(pathPackages)-1]
+		if name == "main" {
+			panic(errs.New(`invalid package name. Your types cannot be defined in a package named "main"`))
+		}
+
+		return name
 	}
 
 	imports := struct {

private/apigen/gogen_test.go

@@ -25,6 +25,7 @@ import (
 	"storj.io/storj/private/api"
 	"storj.io/storj/private/apigen"
 	"storj.io/storj/private/apigen/example"
+	"storj.io/storj/private/apigen/example/myapi"
 )
 
 type (
@@ -44,6 +45,13 @@ func (a auth) IsAuthenticated(ctx context.Context, r *http.Request, isCookieAuth
 
 func (a auth) RemoveAuthCookie(w http.ResponseWriter) {}
 
+func (s service) GetOne(
+	ctx context.Context,
+	pathParam string,
+) (*myapi.Document, api.HTTPError) {
+	return &myapi.Document{}, api.HTTPError{}
+}
+
 func (s service) UpdateContent(
 	ctx context.Context,
 	pathParam string,