http response tooling written

internal/site/accounts.go

@@ -3,25 +3,24 @@ package site
 import (
 	"fmt"
 	"net/http"
+
+	"ruben/inventory2/internal/site/response"
 )
 
 // POST /accounts
-func (s *Server) createAccount(w http.ResponseWriter, r *http.Request) {
+func (s *Server) createAccount(r *http.Request) (response.Response, error) {
 	ctx := r.Context()
 	email := r.FormValue("email")
 	if email == "" {
-		http.Error(w, "no email provided", http.StatusBadRequest)
-		return
+		return nil, response.BadRequest().Msg("no email provided")
 	}
 
 	userID := getAccessTokenClaims(ctx).Subject
 
 	acct, err := s.accts.CreateAccount(ctx, userID, email)
 	if err != nil {
-		http.Error(w, fmt.Sprintf("failed to create account: %v", err), http.StatusInternalServerError)
-		return
+		return nil, response.Errorf("failed to create account: %w", err)
 	}
 
-	//http.Redirect(w, r, fmt.Sprintf("/site/accounts/%d", acct.ID), http.StatusSeeOther)
-	http.Redirect(w, r, fmt.Sprintf("/accounts/%d", acct.ID), http.StatusSeeOther)
+	return response.SeeOther(fmt.Sprintf("/accounts/%d", acct.ID)), nil
 }

internal/site/auth.go

@@ -9,24 +9,24 @@ import (
 
 	"ruben/inventory2/internal/consts"
 	"ruben/inventory2/internal/domains/authentication"
+	"ruben/inventory2/internal/site/response"
 )
 
 // just keep this around long enough for testing auth middleware..
-func (s *Server) testAuthEndpoint(w http.ResponseWriter, r *http.Request) {
-	fmt.Println("SUCCESS:", getAccessTokenClaims(r.Context()))
+func (s *Server) testAuthEndpoint(r *http.Request) (response.Response, error) {
+	fmt.Println("AUTH TEST SUCCESS:", getAccessTokenClaims(r.Context()))
 
-	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+	return response.TemporaryRedirect("/"), nil
 }
 
 type customClaimsKey struct{}
 
 // auth middleware to verify access_token cookie and set custom claims in the request context
-func (s *Server) authenticate(h http.Handler) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+func (s *Server) authenticate(f response.HandlerFunc) response.HandlerFunc {
+	return func(r *http.Request) (response.Response, error) {
 		ck, err := r.Cookie("access_token")
 		if err != nil {
-			http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
-			return
+			return response.TemporaryRedirect("/"), nil
 		}
 
 		ctx := r.Context()
@@ -34,22 +34,18 @@ func (s *Server) authenticate(h http.Handler) http.Handler {
 		claims, expiration, err := s.auth.GetAccessTokenClaimsAndExpiration(ctx, ck.Value)
 		if err != nil {
 			if errors.Is(err, consts.ErrNotFound) {
-				http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
-				return
+				return response.TemporaryRedirect("/"), nil
 			}
 
-			http.Error(w, fmt.Sprintf("failed to authenticate: %v", err), http.StatusInternalServerError)
-			return
+			return nil, response.Errorf("failed to authenticate: %w", err)
 		}
 
 		if expiration.Before(time.Now()) {
-			deleteCookieInResponse(w, "access_token")
-			http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
-			return
+			return response.TemporaryRedirect("/").Cookie(getExpiredCookie("access_token")), nil
 		}
 
-		h.ServeHTTP(w, r.WithContext(setAccessTokenClaims(ctx, claims)))
-	})
+		return f(r.WithContext(setAccessTokenClaims(ctx, claims)))
+	}
 }
 
 func (s *Server) getAccessTokenClaims(r *http.Request) (authentication.AccessTokenClaims, bool) {

internal/site/cookie.go

@@ -2,10 +2,10 @@ package site
 
 import "net/http"
 
-func deleteCookieInResponse(w http.ResponseWriter, name string) {
-	w.Header().Set("Set-Cookie", (&http.Cookie{
+func getExpiredCookie(name string) http.Cookie {
+	return http.Cookie{
 		Name:   name,
 		Path:   "/",
 		MaxAge: -1, // expire the cookie
-	}).String())
+	}
 }

internal/site/login.go

@@ -3,44 +3,41 @@ package site
 import (
 	"fmt"
 	"net/http"
+	"ruben/inventory2/internal/site/response"
 )
 
 // GET /login
-func (s *Server) loginPage(w http.ResponseWriter, r *http.Request) {
+func (s *Server) loginPage(r *http.Request) (response.Response, error) {
 	ctx := r.Context()
 
 	state, err := s.auth.NewState(ctx)
 	if err != nil {
-		http.Error(w, fmt.Sprintf("failed to generate random state: %v", err), http.StatusInternalServerError)
-		return
+		return nil, response.Errorf("failed to generate random state: %w", err)
 	}
 
 	base64EncodedState := fmt.Sprintf("%x", state[:])
 
-	http.Redirect(w, r, s.auth.AuthCodeURL(base64EncodedState), http.StatusTemporaryRedirect)
+	return response.TemporaryRedirect(s.auth.AuthCodeURL(base64EncodedState)), nil
 }
 
 // POST /login
-func (s *Server) login(w http.ResponseWriter, r *http.Request) {
+func (s *Server) login(r *http.Request) (response.Response, error) {
 	ctx := r.Context()
 	email := r.FormValue("email")
 	if email == "" {
-		http.Error(w, "no email provided", http.StatusBadRequest)
-		return
+		return nil, response.BadRequest().Msg("no email provided")
 	}
 
 	acct, err := s.accts.GetAccountByEmail(ctx, email)
 	if err != nil {
-		http.Error(w, fmt.Sprintf("failed to create account: %v", err), http.StatusInternalServerError)
-		return
+		return nil, response.Errorf("failed to create account: %w", err)
 	}
 
-	//http.Redirect(w, r, fmt.Sprintf("/site/accounts/%d", acct.ID), http.StatusSeeOther)
-	http.Redirect(w, r, fmt.Sprintf("/accounts/%d", acct.ID), http.StatusSeeOther)
+	return response.SeeOther(fmt.Sprintf("/accounts/%d", acct.ID)), nil
 }
 
 // GET /login/callback
-func (s *Server) loginCallback(w http.ResponseWriter, r *http.Request) {
+func (s *Server) loginCallback(r *http.Request) (response.Response, error) {
 	ctx := r.Context()
 	q := r.URL.Query()
 
@@ -48,38 +45,37 @@ func (s *Server) loginCallback(w http.ResponseWriter, r *http.Request) {
 
 	accessToken, expiration, err := s.auth.Exchange(ctx, q.Get("state"), q.Get("code"))
 	if err != nil {
-		http.Error(w, fmt.Sprintf("Failed to exchange an authorization code for a token: %v", err), http.StatusUnauthorized)
-		return
+		return nil, response.Unauthorized().
+			Msg(fmt.Sprintf("Failed to exchange an authorization code for a token")).
+			Wrap(err)
 	}
 
 	// set access_token cookie and redirect to a reasonable place
 
-	w.Header().Set("Set-Cookie", (&http.Cookie{
+	return response.TemporaryRedirect("/").
+		Cookie(http.Cookie{
 			Name:    "access_token",
 			Value:   accessToken,
 			Path:    "/",
 			Expires: expiration,
 			MaxAge:  0, // using Expiration instead
 			Secure:  true,
-	}).String())
-
-	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
+		}), nil
 }
 
 // GET /logout
-func (s *Server) logoutPage(w http.ResponseWriter, r *http.Request) {
+func (s *Server) logoutPage(r *http.Request) (response.Response, error) {
 	host := r.Header.Get("X-Forwarded-Host")
 	if host == "" {
 		host = r.Host
 	}
 
-	deleteCookieInResponse(w, "access_token")
-
 	if ck, err := r.Cookie("access_token"); err == nil && ck != nil {
 		if err := s.auth.DeleteOAuthTokens(r.Context(), ck.Value); err != nil {
 			fmt.Println("[ERROR] failed to delete auth token:", err)
 		}
 	}
 
-	http.Redirect(w, r, s.auth.GetLogoutURL(host).String(), http.StatusTemporaryRedirect)
+	return response.TemporaryRedirect(s.auth.GetLogoutURL(host).String()).
+		Cookie(getExpiredCookie("access_token")), nil
 }

internal/site/redirect/code.go

@@ -0,0 +1,19 @@
+package redirect
+
+import "net/http"
+
+type (
+	Code int
+)
+
+var (
+	MovedPermanently  = Code(http.StatusMovedPermanently)
+	Found             = Code(http.StatusFound)
+	SeeOther          = Code(http.StatusSeeOther)
+	TemporaryRedirect = Code(http.StatusTemporaryRedirect)
+	PermanentRedirect = Code(http.StatusPermanentRedirect)
+)
+
+func (c Code) Int() int {
+	return int(c)
+}

internal/site/response/cookie.go

@@ -0,0 +1,83 @@
+package response
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"ruben/inventory2/internal/site/redirect"
+)
+
+type (
+	cookieRes struct {
+		cookie http.Cookie
+		res    Response
+	}
+)
+
+var _ Response = cookieRes{}
+
+func Cookie(c http.Cookie) Response {
+	return cookieRes{
+		cookie: c,
+	}
+}
+
+func (c cookieRes) String() string {
+	if c.res != nil {
+		return fmt.Sprintf(`{"cookie": %q, "nested": %s}`, c.cookie, c.res)
+	}
+	return fmt.Sprintf(`{"cookie": %q}`, c.cookie)
+}
+
+func (c cookieRes) wrap(res Response) Response {
+	c.res = res
+	return c
+}
+
+func (c cookieRes) Status(code int) Response {
+	return Status(code).wrap(c)
+}
+
+func (c cookieRes) Redirect(code redirect.Code, to string) Response {
+	return Redirect(code, to).wrap(c)
+}
+
+func (c cookieRes) JSON(body any) Response {
+	return JSON(body).wrap(c)
+}
+
+func (c cookieRes) Cookie(ck http.Cookie) Response {
+	return Cookie(ck).wrap(c)
+}
+
+func (c cookieRes) getStatus() (int, bool) {
+	if c.res == nil {
+		return 0, false
+	}
+
+	return c.res.getStatus()
+}
+
+func (c cookieRes) getRedirect() (code redirect.Code, to string, ok bool) {
+	if c.res == nil {
+		return 0, "", false
+	}
+
+	return c.res.getRedirect()
+}
+
+func (c cookieRes) getBody() (body io.ReadCloser, ok bool, err error) {
+	if c.res == nil {
+		return nil, false, nil
+	}
+
+	return c.res.getBody()
+}
+
+func (c cookieRes) getCookies() []http.Cookie {
+	if c.res != nil {
+		return append(c.res.getCookies(), c.cookie)
+	}
+
+	return []http.Cookie{c.cookie}
+}

internal/site/response/error.go

@@ -0,0 +1,124 @@
+package response
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+)
+
+type (
+	// ErrorResponse is an error
+	ErrorResponse struct {
+		err    error
+		msg    string
+		status int
+	}
+)
+
+// Constructors
+
+func Errorf(format string, args ...any) ErrorResponse {
+	return ErrorResponse{
+		err: fmt.Errorf(format, args...),
+	}
+}
+
+func BadRequest() ErrorResponse {
+	return ErrorResponse{
+		status: http.StatusBadRequest,
+	}
+}
+
+func NotFound() ErrorResponse {
+	return ErrorResponse{
+		status: http.StatusNotFound,
+	}
+}
+
+func Unauthorized() ErrorResponse {
+	return ErrorResponse{
+		status: http.StatusUnauthorized,
+	}
+}
+
+func Forbidden() ErrorResponse {
+	return ErrorResponse{
+		status: http.StatusForbidden,
+	}
+}
+
+// builder pattern implementation
+
+func (e ErrorResponse) Msg(msg string) ErrorResponse {
+	e.msg = msg
+	return e
+}
+
+func (e ErrorResponse) Status(status int) ErrorResponse {
+	e.status = status
+	return e
+}
+
+func (e ErrorResponse) Wrap(err error) ErrorResponse {
+	e.err = err
+	return e
+}
+
+// error implementation
+
+func (e ErrorResponse) Error() string {
+	parts := make([]string, 0, 3)
+
+	if e.msg != "" {
+		parts = append(parts, e.msg)
+	} else if e.status != 0 {
+		parts = append(parts, fmt.Sprintf("status = %d", e.status))
+	}
+	if e.err != nil {
+		parts = append(parts, e.err.Error())
+	}
+
+	if len(parts) == 0 {
+		return "status = 500"
+	}
+
+	return strings.Join(parts, ": ")
+}
+
+func (e ErrorResponse) Unwrap() error {
+	return e.err
+}
+
+// nested response value resolution
+
+func (e ErrorResponse) getStatus() (int, bool) {
+	if e.status != 0 {
+		return e.status, true
+	}
+
+	ce, ok := getError(e.err)
+	if ok {
+		return ce.getStatus()
+	}
+
+	return 0, false
+}
+
+func (e ErrorResponse) getMsg() (string, bool) {
+	if e.msg != "" {
+		return e.msg, true
+	}
+
+	ce, ok := getError(e.err)
+	if ok {
+		return ce.getMsg()
+	}
+
+	return "", false
+}
+
+func getError(err error) (e ErrorResponse, ok bool) {
+	ok = errors.As(err, &e)
+	return e, ok
+}

internal/site/response/handler.go

@@ -0,0 +1,18 @@
+package response
+
+import (
+	"net/http"
+)
+
+type HandlerFunc = func(r *http.Request) (Response, error)
+
+func Handler(f HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		res, err := f(r)
+		if err != nil {
+			WriteError(w, err)
+		} else {
+			Write(w, r, res)
+		}
+	}
+}

internal/site/response/json.go

@@ -0,0 +1,83 @@
+package response
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"ruben/inventory2/internal/site/redirect"
+)
+
+type (
+	jsonRes struct {
+		body any
+		res  Response
+	}
+)
+
+var _ Response = jsonRes{}
+
+func JSON(body any) Response {
+	return jsonRes{
+		body: body,
+	}
+}
+
+func (j jsonRes) String() string {
+	if j.res != nil {
+		return fmt.Sprintf(`{"body": %q, "nested": %s}`, j.body, j.res)
+	}
+	return fmt.Sprintf(`{"body": %q}`, j.body)
+}
+
+func (j jsonRes) wrap(res Response) Response {
+	j.res = res
+	return j
+}
+
+func (j jsonRes) Status(code int) Response {
+	return Status(code).wrap(j)
+}
+
+func (j jsonRes) Redirect(code redirect.Code, to string) Response {
+	return Redirect(code, to).wrap(j)
+}
+
+func (j jsonRes) JSON(body any) Response {
+	j.body = body
+	return j
+}
+
+func (j jsonRes) Cookie(ck http.Cookie) Response {
+	return Cookie(ck).wrap(j)
+}
+
+func (j jsonRes) getStatus() (int, bool) {
+	if j.res == nil {
+		return 0, false
+	}
+
+	return j.res.getStatus()
+}
+
+func (j jsonRes) getRedirect() (code redirect.Code, to string, ok bool) {
+	if j.res == nil {
+		return 0, "", false
+	}
+
+	return j.res.getRedirect()
+}
+
+func (j jsonRes) getBody() (body io.ReadCloser, ok bool, err error) {
+	buf := new(bytes.Buffer)
+	return io.NopCloser(buf), true, json.NewEncoder(buf).Encode(j.body)
+}
+
+func (j jsonRes) getCookies() []http.Cookie {
+	if j.res != nil {
+		return j.res.getCookies()
+	}
+
+	return nil
+}

internal/site/response/redirect.go

@@ -0,0 +1,120 @@
+package response
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"ruben/inventory2/internal/site/redirect"
+)
+
+type (
+	redirectRes struct {
+		code redirect.Code
+		to   string
+		res  Response
+	}
+)
+
+var _ Response = redirectRes{}
+
+// convenience constructors
+
+func MovedPermanently(to string) Response {
+	return redirectRes{
+		code: redirect.MovedPermanently,
+		to:   to,
+	}
+}
+
+func Found(to string) Response {
+	return redirectRes{
+		code: redirect.Found,
+		to:   to,
+	}
+}
+
+func SeeOther(to string) Response {
+	return redirectRes{
+		code: redirect.SeeOther,
+		to:   to,
+	}
+}
+
+func TemporaryRedirect(to string) Response {
+	return redirectRes{
+		code: redirect.TemporaryRedirect,
+		to:   to,
+	}
+}
+
+func PermanentRedirect(to string) Response {
+	return redirectRes{
+		code: redirect.PermanentRedirect,
+		to:   to,
+	}
+}
+
+func Redirect(code redirect.Code, to string) Response {
+	return redirectRes{
+		code: code,
+		to:   to,
+	}
+}
+
+func (r redirectRes) String() string {
+	if r.res != nil {
+		return fmt.Sprintf(`{"redirect": {"code": %d, "to": %q}, "nested": %s}`, r.code, r.to, r.res)
+	}
+	return fmt.Sprintf(`{"redirect": {"code": %d, "to": %q}}`, r.code, r.to)
+}
+
+func (r redirectRes) wrap(res Response) Response {
+	r.res = res
+	return r
+}
+
+func (r redirectRes) Status(code int) Response {
+	return Status(code).wrap(r)
+}
+
+func (r redirectRes) Redirect(code redirect.Code, to string) Response {
+	r.code = code
+	r.to = to
+	return r
+}
+
+func (r redirectRes) JSON(body any) Response {
+	return JSON(body).wrap(r)
+}
+
+func (r redirectRes) Cookie(ck http.Cookie) Response {
+	return Cookie(ck).wrap(r)
+}
+
+func (r redirectRes) getStatus() (int, bool) {
+	if r.res == nil {
+		return 0, false
+	}
+
+	return r.res.getStatus()
+}
+
+func (r redirectRes) getRedirect() (code redirect.Code, to string, ok bool) {
+	return r.code, r.to, true
+}
+
+func (r redirectRes) getBody() (body io.ReadCloser, ok bool, err error) {
+	if r.res == nil {
+		return nil, false, nil
+	}
+
+	return r.res.getBody()
+}
+
+func (r redirectRes) getCookies() []http.Cookie {
+	if r.res != nil {
+		return r.res.getCookies()
+	}
+
+	return nil
+}

internal/site/response/response.go

@@ -0,0 +1,24 @@
+package response
+
+import (
+	"io"
+	"net/http"
+
+	"ruben/inventory2/internal/site/redirect"
+)
+
+type (
+	Response interface {
+		Status(int) Response
+		Redirect(code redirect.Code, to string) Response
+		JSON(any) Response
+		Cookie(http.Cookie) Response
+
+		getStatus() (code int, ok bool)
+		getBody() (body io.ReadCloser, ok bool, err error)
+		getRedirect() (code redirect.Code, to string, ok bool)
+		getCookies() []http.Cookie
+
+		wrap(Response) Response
+	}
+)

internal/site/response/status.go

@@ -0,0 +1,81 @@
+package response
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+
+	"ruben/inventory2/internal/site/redirect"
+)
+
+type (
+	statusRes struct {
+		code int
+		res  Response
+	}
+)
+
+var _ Response = statusRes{}
+
+func Status(code int) Response {
+	return statusRes{
+		code: code,
+	}
+}
+
+func (s statusRes) String() string {
+	if s.res != nil {
+		return fmt.Sprintf(`{"status": %d, "nested": %s}`, s.code, s.res)
+	}
+	return fmt.Sprintf(`{"status": %d}`, s.code)
+}
+
+func (s statusRes) wrap(res Response) Response {
+	s.res = res
+	return s
+}
+
+func (s statusRes) Status(code int) Response {
+	s.code = code
+	return s
+}
+
+func (s statusRes) Redirect(code redirect.Code, to string) Response {
+	return Redirect(code, to).wrap(s)
+}
+
+func (s statusRes) JSON(body any) Response {
+	return JSON(body).wrap(s)
+}
+
+func (s statusRes) Cookie(ck http.Cookie) Response {
+	return Cookie(ck).wrap(s)
+}
+
+func (s statusRes) getStatus() (int, bool) {
+	return s.code, true
+}
+
+func (s statusRes) getRedirect() (code redirect.Code, to string, ok bool) {
+	if s.res == nil {
+		return 0, "", false
+	}
+
+	return s.res.getRedirect()
+}
+
+func (s statusRes) getBody() (body io.ReadCloser, ok bool, err error) {
+	if s.res == nil {
+		return nil, false, nil
+	}
+
+	return s.res.getBody()
+}
+
+func (s statusRes) getCookies() []http.Cookie {
+	if s.res != nil {
+		return s.res.getCookies()
+	}
+
+	return nil
+}

internal/site/response/write.go

@@ -0,0 +1,56 @@
+package response
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+)
+
+func Write(w http.ResponseWriter, r *http.Request, res Response) {
+	// w.Header() must be set before ResponseWriter.WriteHeader is called
+	// or redirect is attempted
+	hdrs := w.Header()
+	for _, ck := range res.getCookies() {
+		hdrs.Add("Set-Cookie", ck.String())
+	}
+
+	if code, to, ok := res.getRedirect(); ok {
+		http.Redirect(w, r, to, code.Int())
+		return
+	}
+
+	// the body is written after the status header, but it's read here
+	// first, because if an error is incurred, an error status header will
+	// need to be written.
+	body, bodySet, err := res.getBody()
+	if err != nil {
+		http.Error(
+			w,
+			fmt.Sprintf("Failed to construct response body: %v", err.Error()),
+			http.StatusInternalServerError,
+		)
+		return
+	}
+
+	if status, ok := res.getStatus(); ok {
+		w.WriteHeader(status)
+	}
+	if bodySet {
+		// will automatically set the status header,
+		// if w.WriteHeader wasn't already called
+		io.Copy(w, body)
+	}
+
+}
+
+func WriteError(w http.ResponseWriter, err error) {
+	var status int
+
+	if e, ok := getError(err); ok {
+		if status, ok = e.getStatus(); !ok {
+			status = http.StatusInternalServerError
+		}
+	}
+
+	http.Error(w, err.Error(), status)
+}

internal/site/site.go

@@ -15,6 +15,7 @@ import (
 	"ruben/inventory2/internal/domains/authentication"
 	etsy_platform "ruben/inventory2/internal/domains/platforms/etsy"
 	"ruben/inventory2/internal/domains/raw_events"
+	"ruben/inventory2/internal/site/response"
 )
 
 type Server struct {
@@ -90,16 +91,16 @@ func NewServer(
 
 	// api routes
 
-	s.mux.HandleFunc("GET /login", s.loginPage)
-	s.mux.HandleFunc("GET /login/callback", s.loginCallback)
-	s.mux.HandleFunc("GET /logout", s.logoutPage)
-	s.mux.Handle("POST /accounts", s.authenticate(http.HandlerFunc(s.createAccount)))
+	s.mux.HandleFunc("GET /login", response.Handler(s.loginPage))
+	s.mux.HandleFunc("GET /login/callback", response.Handler(s.loginCallback))
+	s.mux.HandleFunc("GET /logout", response.Handler(s.logoutPage))
+	s.mux.Handle("POST /accounts", response.Handler(s.authenticate(s.createAccount)))
 
 	// TODO: eliminate once no longer used.
-	s.mux.HandleFunc("POST /login", s.login)
+	s.mux.HandleFunc("POST /login", response.Handler(s.login))
 
 	// TODO: get rid of this, once we're confident this isn't needed...
-	s.mux.Handle("GET /test-auth", s.authenticate(http.HandlerFunc(s.testAuthEndpoint)))
+	s.mux.Handle("GET /test-auth", response.Handler(s.authenticate(s.testAuthEndpoint)))
 
 	// webpage content