initial commit

main.go

@@ -0,0 +1,200 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+	"github.com/go-chi/render"
+)
+
+//var routes = flag.Bool("routes", false, "Generate router documentation")
+
+func main() {
+	flag.Parse()
+
+	r := chi.NewRouter()
+
+	r.Use(middleware.RequestID)
+	r.Use(middleware.Logger)
+	r.Use(middleware.Recoverer)
+	r.Use(middleware.URLFormat)
+	r.Use(render.SetContentType(render.ContentTypeJSON))
+
+	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("hello world"))
+	})
+
+	r.Get("/ping", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("pong"))
+	})
+
+	r.Get("/panic", func(w http.ResponseWriter, r *http.Request) {
+		panic("oh no")
+	})
+
+	r.Route("/messages", func(r chi.Router) {
+		r.Route("/{messageID}", func(r chi.Router) {
+			r.Use(MessageCtx) // Load message
+			r.Get("/", GetMessage)
+		})
+	})
+
+	http.ListenAndServe(":3000", r)
+
+}
+
+type ErrResponse struct {
+	Err            error `json:"-"` // low-level runtime error
+	HTTPStatusCode int   `json:"-"` // http response status code
+
+	StatusText string `json:"status"`          // user-level status message
+	AppCode    int64  `json:"code,omitempty"`  // application-specific error code
+	ErrorText  string `json:"error,omitempty"` // application-level error message, for debugging
+}
+
+func (e *ErrResponse) Render(w http.ResponseWriter, r *http.Request) error {
+	render.Status(r, e.HTTPStatusCode)
+	return nil
+}
+
+func ErrInvalidRequest(err error) render.Renderer {
+	return &ErrResponse{
+		Err:            err,
+		HTTPStatusCode: 400,
+		StatusText:     "Invalid request.",
+		ErrorText:      err.Error(),
+	}
+}
+
+func ErrRender(err error) render.Renderer {
+	return &ErrResponse{
+		Err:            err,
+		HTTPStatusCode: 422,
+		StatusText:     "Error rendering response.",
+		ErrorText:      err.Error(),
+	}
+}
+
+var ErrNotFound = &ErrResponse{HTTPStatusCode: 404, StatusText: "Resource not found."}
+
+type messageKey struct{}
+
+func MessageCtx(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var message *Message
+		var err error
+
+		if messageID := chi.URLParam(r, "messageID"); messageID != "" {
+			message, err = dbGetMessage(messageID)
+		} else {
+			render.Render(w, r, ErrNotFound)
+			return
+		}
+		if err != nil {
+			render.Render(w, r, ErrNotFound)
+			return
+		}
+
+		ctx := context.WithValue(r.Context(), messageKey{}, message)
+		next.ServeHTTP(w, r.WithContext(ctx))
+	})
+}
+func GetMessage(w http.ResponseWriter, r *http.Request) {
+	message, ok := r.Context().Value(messageKey{}).(*Message)
+	if !ok || message == nil {
+		render.Render(w, r, ErrNotFound)
+		return
+	}
+
+	if err := render.Render(w, r, NewMessageResponse(message)); err != nil {
+		render.Render(w, r, ErrRender(err))
+		return
+	}
+
+}
+
+func NewMessageResponse(message *Message) *MessageResponse {
+	resp := &MessageResponse{Message: message}
+
+	if resp.User == nil {
+		if user, _ := dbGetUser(resp.UserID); user != nil {
+			resp.User = NewUserPayloadResponse(user)
+		}
+	}
+
+	return resp
+}
+
+func NewUserPayloadResponse(user *User) *UserPayload {
+	return &UserPayload{User: user}
+}
+
+type User struct {
+	ID   int64  `json:"id"`
+	Name string `json:"name"`
+}
+
+type Message struct {
+	ID        string `json:"id"`
+	UserID    int64  `json:"user_id"`
+	Body      string `json:"body"`
+	Timestamp int64  `json:"timestamp"`
+}
+
+var users = []*User{
+	{ID: 1, Name: "duby"},
+	{ID: 2, Name: "astolfo"},
+}
+
+var messages = []*Message{
+	{ID: "1", UserID: 1, Body: "hello", Timestamp: 1234567890},
+	{ID: "2", UserID: 2, Body: "world", Timestamp: 1234567890},
+	{ID: "3", UserID: 1, Body: "abababa", Timestamp: 1234567890},
+	{ID: "4", UserID: 2, Body: "bitch", Timestamp: 1234567890},
+}
+
+type UserPayload struct {
+	*User
+}
+
+type MessageRequest struct {
+	*Message
+
+	User *UserPayload `json:"user"`
+
+	ProtectedID string `json:"id"`
+}
+
+type MessageResponse struct {
+	*Message
+
+	User *UserPayload `json:"user,omitempty"`
+
+	Elapsed int64 `json:"elapsed"`
+}
+
+func (mr *MessageResponse) Render(w http.ResponseWriter, r *http.Request) error {
+	return nil
+}
+
+func dbGetUser(id int64) (*User, error) {
+	for _, u := range users {
+		if u.ID == id {
+			return u, nil
+		}
+	}
+	return nil, errors.New("User not found")
+}
+
+func dbGetMessage(id string) (*Message, error) {
+	for _, a := range messages {
+		if a.ID == id {
+			return a, nil
+		}
+	}
+	return nil, errors.New("Message not found")
+}