Refactor app, add support for service hooks

app.go

@@ -0,0 +1,132 @@
+package main
+
+import (
+	"bytes"
+	"crypto/sha1"
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+	"text/template"
+
+	"github.com/Luzifer/rconfig"
+	"github.com/gorilla/mux"
+	"github.com/tdewolff/minify"
+	"github.com/tdewolff/minify/svg"
+)
+
+const (
+	xSpacing     = 8
+	defaultColor = "4c1"
+)
+
+var (
+	cfg = struct {
+		Port   int64  `env:"PORT"`
+		Listen string `flag:"listen" default:":3000" description:"Port/IP to listen on"`
+	}{}
+	serviceHandlers = map[string]serviceHandlerFunction{}
+)
+
+type serviceHandlerFunction func(params []string) (title, text, color string, err error)
+
+func registerServiceHandler(service string, f serviceHandlerFunction) error {
+	if _, ok := serviceHandlers[service]; ok {
+		return errors.New("Duplicate service handler")
+	}
+	serviceHandlers[service] = f
+	return nil
+}
+
+func main() {
+	rconfig.Parse(&cfg)
+	if cfg.Port != 0 {
+		cfg.Listen = fmt.Sprintf(":%d", cfg.Port)
+	}
+
+	r := mux.NewRouter()
+	r.HandleFunc("/v1/badge", generateBadge).Methods("GET")
+	r.HandleFunc("/{service}/{parameters:.*}", generateServiceBadge).Methods("GET")
+
+	http.ListenAndServe(cfg.Listen, r)
+}
+
+func generateServiceBadge(res http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	service := vars["service"]
+	params := strings.Split(vars["parameters"], "/")
+
+	handler, ok := serviceHandlers[service]
+	if !ok {
+		http.Error(res, "Service not found: "+service, http.StatusNotFound)
+		return
+	}
+
+	title, text, color, err := handler(params)
+	if err != nil {
+		http.Error(res, "Error while executing service: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	renderBadgeToResponse(res, title, text, color)
+}
+
+func generateBadge(res http.ResponseWriter, r *http.Request) {
+	title := r.URL.Query().Get("title")
+	text := r.URL.Query().Get("text")
+	color := r.URL.Query().Get("color")
+
+	if title == "" || text == "" {
+		http.Error(res, "You must specify parameters 'title' and 'text'.", http.StatusInternalServerError)
+		return
+	}
+
+	if color == "" {
+		color = defaultColor
+	}
+
+	renderBadgeToResponse(res, title, text, color)
+}
+
+func renderBadgeToResponse(res http.ResponseWriter, title, text, color string) {
+	badge, eTag := createBadge(title, text, color)
+
+	res.Header().Add("Content-Type", "image/svg+xml")
+	res.Header().Add("Cache-Control", "public, max-age=31536000")
+	res.Header().Add("ETag", eTag)
+
+	m := minify.New()
+	m.AddFunc("image/svg+xml", svg.Minify)
+
+	badge, _ = m.Bytes("image/svg+xml", badge)
+
+	res.Write(badge)
+}
+
+func createBadge(title, text, color string) ([]byte, string) {
+	var buf bytes.Buffer
+
+	titleW, _ := calculateTextWidth(title)
+	textW, _ := calculateTextWidth(text)
+
+	width := titleW + textW + 4*xSpacing
+
+	t, _ := Asset("assets/badgeTemplate.tpl")
+	tpl, _ := template.New("svg").Parse(string(t))
+
+	tpl.Execute(&buf, map[string]interface{}{
+		"Width":       width,
+		"TitleWidth":  titleW + 2*xSpacing,
+		"Title":       title,
+		"Text":        text,
+		"TitleAnchor": titleW/2 + xSpacing,
+		"TextAnchor":  titleW + textW/2 + 3*xSpacing,
+		"Color":       color,
+	})
+
+	return buf.Bytes(), generateETag(buf.Bytes())
+}
+
+func generateETag(in []byte) string {
+	return fmt.Sprintf("%x", sha1.Sum(in))
+}

font.go

@@ -5,7 +5,10 @@
 // Copyright 2010 The Freetype-Go Authors. All rights reserved.
 package main
 
-import "code.google.com/p/freetype-go/freetype/truetype"
+import (
+	"github.com/golang/freetype/truetype"
+	"golang.org/x/image/math/fixed"
+)
 
 const (
 	fontSize = 11
@@ -23,11 +26,12 @@ func calculateTextWidth(text string) (int, error) {
 	width := 0
 	prev, hasPrev := truetype.Index(0), false
 	for _, rune := range text {
+		fUnitsPerEm := fixed.Int26_6(font.FUnitsPerEm())
 		index := font.Index(rune)
 		if hasPrev {
-			width += int(font.Kerning(font.FUnitsPerEm(), prev, index))
+			width += int(font.Kern(fUnitsPerEm, prev, index))
 		}
-		width += int(font.HMetric(font.FUnitsPerEm(), index).AdvanceWidth)
+		width += int(font.HMetric(fUnitsPerEm, index).AdvanceWidth)
 		prev, hasPrev = index, true
 	}
 

main.go

@@ -1,88 +0,0 @@
-package main
-
-import (
-	"bufio"
-	"bytes"
-	"fmt"
-	"net/http"
-	"os"
-
-	"github.com/alecthomas/template"
-	"github.com/gorilla/mux"
-	"github.com/tdewolff/minify"
-	"github.com/tdewolff/minify/svg"
-)
-
-const (
-	xSpacing = 8
-)
-
-func main() {
-	port := fmt.Sprintf(":%s", os.Getenv("PORT"))
-	if port == ":" {
-		port = ":3000"
-	}
-
-	http.Handle("/", generateMux())
-	http.ListenAndServe(port, nil)
-}
-
-func generateMux() *mux.Router {
-	r := mux.NewRouter()
-	r.HandleFunc("/v1/badge", generateBadge).Methods("GET")
-
-	return r
-}
-
-func generateBadge(res http.ResponseWriter, r *http.Request) {
-	title := r.URL.Query().Get("title")
-	text := r.URL.Query().Get("text")
-	color := r.URL.Query().Get("color")
-
-	if title == "" || text == "" {
-		http.Error(res, "You must specify parameters 'title' and 'text'.", http.StatusInternalServerError)
-		return
-	}
-
-	if color == "" {
-		color = "4c1"
-	}
-
-	badge := createBadge(title, text, color)
-
-	res.Header().Add("Content-Type", "image/svg+xml")
-	res.Header().Add("Cache-Control", "public, max-age=31536000")
-
-	m := minify.New()
-	m.AddFunc("image/svg+xml", svg.Minify)
-
-	badge, _ = minify.Bytes(m, "image/svg+xml", badge)
-
-	res.Write(badge)
-}
-
-func createBadge(title, text, color string) []byte {
-	var buf bytes.Buffer
-	bufw := bufio.NewWriter(&buf)
-
-	titleW, _ := calculateTextWidth(title)
-	textW, _ := calculateTextWidth(text)
-
-	width := titleW + textW + 4*xSpacing
-
-	t, _ := Asset("assets/badgeTemplate.tpl")
-	tpl, _ := template.New("svg").Parse(string(t))
-
-	tpl.Execute(bufw, map[string]interface{}{
-		"Width":       width,
-		"TitleWidth":  titleW + 2*xSpacing,
-		"Title":       title,
-		"Text":        text,
-		"TitleAnchor": titleW/2 + xSpacing,
-		"TextAnchor":  titleW + textW/2 + 3*xSpacing,
-		"Color":       color,
-	})
-
-	bufw.Flush()
-	return buf.Bytes()
-}