feat: handle errors

Signed-off-by: Carlos Alexandro Becker <caarlos0@gmail.com>

controller/index.go

@@ -2,22 +2,26 @@ package controller
 
 import (
 	"html/template"
+	"io"
 	"io/fs"
 	"net/http"
+
+	"github.com/caarlos0/httperr"
 )
 
-func Index(fsys fs.FS) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		err := template.Must(template.ParseFS(fsys, "static/templates/index.html")).
-			Execute(w, nil)
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-		}
-	}
+func Index(fsys fs.FS) http.Handler {
+	return httperr.NewF(func(w http.ResponseWriter, r *http.Request) error {
+		return executeTemplate(fsys, w, nil)
+	})
 }
 
 func HandleForm(fsys fs.FS) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "/"+r.FormValue("repository"), http.StatusSeeOther)
 	}
 }
+
+func executeTemplate(fsys fs.FS, w io.Writer, data interface{}) error {
+	return template.Must(template.ParseFS(fsys, "static/templates/index.html")).
+		Execute(w, data)
+}

controller/repositories.go

@@ -1,14 +1,13 @@
 package controller
 
 import (
-	"errors"
 	"fmt"
-	"html/template"
 	"io/fs"
 	"net/http"
 	"time"
 
 	"github.com/apex/log"
+	"github.com/caarlos0/httperr"
 	"github.com/caarlos0/starcharts/internal/cache"
 	"github.com/caarlos0/starcharts/internal/github"
 	"github.com/gorilla/mux"
@@ -17,24 +16,21 @@ import (
 )
 
 // GetRepo shows the given repo chart.
-func GetRepo(fsys fs.FS, github *github.GitHub, cache *cache.Redis) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
+func GetRepo(fsys fs.FS, github *github.GitHub, cache *cache.Redis) http.Handler {
+	return httperr.NewF(func(w http.ResponseWriter, r *http.Request) error {
 		name := fmt.Sprintf(
 			"%s/%s",
 			mux.Vars(r)["owner"],
 			mux.Vars(r)["repo"],
 		)
 		details, err := github.RepoDetails(r.Context(), name)
 		if err != nil {
-			http.Error(w, err.Error(), http.StatusBadRequest)
-			return
+			return executeTemplate(fsys, w, map[string]error{
+				"Error": err,
+			})
 		}
-		err = template.Must(template.ParseFS(fsys, "static/templates/index.html")).
-			Execute(w, details)
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-		}
-	}
+		return executeTemplate(fsys, w, details)
+	})
 }
 
 // IntValueFormatter is a ValueFormatter for int.
@@ -46,8 +42,8 @@ func IntValueFormatter(v interface{}) string {
 //
 // nolint: funlen
 // TODO: refactor.
-func GetRepoChart(gh *github.GitHub, cache *cache.Redis) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
+func GetRepoChart(gh *github.GitHub, cache *cache.Redis) http.Handler {
+	return httperr.NewF(func(w http.ResponseWriter, r *http.Request) error {
 		name := fmt.Sprintf(
 			"%s/%s",
 			mux.Vars(r)["owner"],
@@ -57,8 +53,7 @@ func GetRepoChart(gh *github.GitHub, cache *cache.Redis) http.HandlerFunc {
 		defer log.Trace("collect_stars").Stop(nil)
 		repo, err := gh.RepoDetails(r.Context(), name)
 		if err != nil {
-			http.Error(w, err.Error(), http.StatusBadRequest)
-			return
+			return httperr.Wrap(err, http.StatusBadRequest)
 		}
 
 		w.Header().Add("content-type", "image/svg+xml;charset=utf-8")
@@ -67,14 +62,10 @@ func GetRepoChart(gh *github.GitHub, cache *cache.Redis) http.HandlerFunc {
 		w.Header().Add("expires", time.Now().Format(time.RFC1123))
 
 		stargazers, err := gh.Stargazers(r.Context(), repo)
-		if errors.Is(err, github.ErrTooManyStars) {
-			_, _ = w.Write([]byte(errSvg(err)))
-			return
-		}
 		if err != nil {
 			log.WithError(err).Error("failed to get stars")
-			http.Error(w, err.Error(), http.StatusServiceUnavailable)
-			return
+			_, err = w.Write([]byte(errSvg(err)))
+			return err
 		}
 		series := chart.TimeSeries{
 			Style: chart.Style{
@@ -133,8 +124,10 @@ func GetRepoChart(gh *github.GitHub, cache *cache.Redis) http.HandlerFunc {
 		defer log.Trace("chart").Stop(&err)
 		if err := graph.Render(chart.SVG, w); err != nil {
 			log.WithError(err).Error("failed to render graph")
+			return err
 		}
-	}
+		return nil
+	})
 }
 
 func errSvg(err error) string {

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/apex/log v1.9.0
 	github.com/blend/go-sdk v1.1.1 // indirect
 	github.com/caarlos0/env/v6 v6.6.2
+	github.com/caarlos0/httperr v1.1.0
 	github.com/go-redis/cache v6.4.0+incompatible
 	github.com/go-redis/redis v6.15.9+incompatible
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect

go.sum

@@ -46,6 +46,8 @@ github.com/blend/go-sdk v1.1.1 h1:R7PcwuIxYvrGc/r9TLLfMpajIboTjqs/HyQouzgJ7mQ=
 github.com/blend/go-sdk v1.1.1/go.mod h1:IP1XHXFveOXHRnojRJO7XvqWGqyzevtXND9AdSztAe8=
 github.com/caarlos0/env/v6 v6.6.2 h1:BypLXDWQTA32rS4UM7pBz+/0BOuvs6C7LSeQAxMwyvI=
 github.com/caarlos0/env/v6 v6.6.2/go.mod h1:P0BVSgU9zfkxfSpFUs6KsO3uWR4k3Ac0P66ibAGTybM=
+github.com/caarlos0/httperr v1.1.0 h1:bvzM4cmFFd5IX6IowjjDvyvB3n2ARRlCwjwZsfVEY7E=
+github.com/caarlos0/httperr v1.1.0/go.mod h1:eN09jvBHHXvCHUGwBDm3rcgNqdqmBXvcsZvSn0cWAFo=
 github.com/casbin/casbin/v2 v2.1.2/go.mod h1:YcPU1XXisHhLzuxH9coDNf2FbKpjGlbCg3n9yuLkIJQ=
 github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=

main.go

@@ -40,7 +40,7 @@ func main() {
 	r := mux.NewRouter()
 	r.Path("/").
 		Methods(http.MethodGet).
-		HandlerFunc(controller.Index(static))
+		Handler(controller.Index(static))
 	r.Path("/").
 		Methods(http.MethodPost).
 		HandlerFunc(controller.HandleForm(static))
@@ -49,10 +49,10 @@ func main() {
 		Handler(http.FileServer(http.FS(static)))
 	r.Path("/{owner}/{repo}.svg").
 		Methods(http.MethodGet).
-		HandlerFunc(controller.GetRepoChart(github, cache))
+		Handler(controller.GetRepoChart(github, cache))
 	r.Path("/{owner}/{repo}").
 		Methods(http.MethodGet).
-		HandlerFunc(controller.GetRepo(static, github, cache))
+		Handler(controller.GetRepo(static, github, cache))
 
 	// generic metrics
 	requestCounter := promauto.NewCounterVec(prometheus.CounterOpts{
@@ -80,7 +80,7 @@ func main() {
 				),
 			),
 		),
-		Addr:         "0.0.0.0:" + config.Port,
+		Addr:         "127.0.0.1:" + config.Port,
 		WriteTimeout: 30 * time.Second,
 		ReadTimeout:  30 * time.Second,
 	}

static/styles.css

@@ -94,7 +94,7 @@ div.code {
 	border-top: 1px solid #eee;
 }
 
-div.main>form>input[type=text] { 
+div.main>form>input[type=text] {
 	width: 100%;
 	padding: 12px 20px;
 	margin: 8px 0;
@@ -107,7 +107,7 @@ div.main>form>input[type=text] {
 	color: #555;
 }
 
-div.main>form>input[type=submit] { 
+div.main>form>input[type=submit] {
 	width: 100%;
 	background-color: #3F3D56;
 	color: white;
@@ -119,4 +119,11 @@ div.main>form>input[type=submit] {
 	font-family: inherit;
     font-size: 1rem;
     font-weight: 450;
-}
+}
+
+p.error {
+	color: #e76060;
+	font-weight: bold;
+	margin-top: 1em;
+	margin-bottom: 1em;
+}

static/templates/index.html

@@ -65,9 +65,11 @@
 	{{ end }}
 	{{ else }}
 	<div class="main">
+		{{ with .Error }}<p class="error">{{ . }}</p>{{ end }}
 		<form method="POST">
 			<label for="repo">Repository:</label><br>
-			<input type="text" id="repository" name="repository" placeholder="caarlos0/starcharts"><br><br>
+			<input type="text" id="repository" name="repository" value="caarlos0/starcharts" placeholder="caarlos0/starcharts"
+				autofocus="true"><br>
 			<input type="submit" value="Submit">
 		</form>
 	</div>