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package main
import (
"bytes"
"encoding/json"
"flag"
"fmt"
"html/template"
"log"
"net/http"
"os"
"path/filepath"
"strings"
"time"
)
type Website struct {
Attrs map[string]interface{}
StaticDir string
homepage *template.Template
article []byte
}
// Serve a single file
func (web *Website) IconHandler(w http.ResponseWriter, r *http.Request) {
// TODO No reason to perform this join on every request
http.ServeFile(w, r, filepath.Join(web.StaticDir, "favicon.ico"))
}
// Execute the template for each request
func (web *Website) HomepageHandler(w http.ResponseWriter, r *http.Request) {
// Make a copy of the attrs map to prevent a race condition
// TODO Is making a copy of attrs necessary?
attrs := make(map[string]interface{})
for k, v := range web.Attrs {
attrs[k] = v
}
// Add the attrs for this request to the map
attrs["IP"] = strings.SplitN(r.RemoteAddr, ":", 2)[0]
// Execute the template
web.homepage.ExecuteTemplate(w, "foundation", attrs)
// Log the request
Log(r)
}
// Write the pre-executed template as a response
func (web *Website) ArticleHandler(w http.ResponseWriter, r *http.Request) {
w.Write(web.article)
// Log the request
Log(r)
}
type Resource struct {
IP string `json:"ip"`
Agent string `json:"agent"`
}
func (web *Website) JSONHandler(w http.ResponseWriter, r *http.Request) {
// Always write the content type before any content!
w.Header().Set("Content-Type", "application/json")
resource := &Resource{
IP: strings.SplitN(r.RemoteAddr, ":", 2)[0],
Agent: r.Header.Get("User-Agent"),
}
output, err := json.Marshal(resource)
if err != nil {
// You may not want to expose your errors to the public
http.Error(w, err.Error(), 500)
return
}
w.Write(output)
}
func (web *Website) Status404Handler(w http.ResponseWriter, r *http.Request) {
http.NotFound(w, r)
}
func Create(staticDir, templateDir string) (*Website, error) {
// Parse the nested templates
homepage, err := template.New("homepage").ParseFiles(filepath.Join(templateDir, "homepage.html"), filepath.Join(templateDir, "foundation.html"))
if err != nil {
return nil, err
}
// Create the attrs that will be passed to templates during execution
attrs := map[string]interface{}{
"Title": "A Website in Go",
"StaticURL": "/static/",
"Time": time.Now(),
}
// Execute a template and save its result
articleTemplate, err := template.ParseFiles(filepath.Join(templateDir, "article.html"))
if err != nil {
return nil, err
}
buffer := &bytes.Buffer{}
articleTemplate.Execute(buffer, attrs)
website := &Website{
Attrs: attrs,
StaticDir: staticDir,
homepage: homepage,
article: buffer.Bytes(),
}
// TODO named return types?
return website, nil
}
func Log(r *http.Request) {
// By default, a timestamp will be written by the logger
log.Printf(`"%s %s" %s "%s"`, r.Method, r.URL, strings.SplitN(r.RemoteAddr, ":", 2)[0], r.Header.Get("User-Agent"))
}
func main() {
// Declare the flags and parse
port := flag.Int("port", 8000, "Server Port")
// If no log is specified it will use stdout
path := flag.String("log", "", "Log File")
staticDir := flag.String("static", "./_static", "Static Files")
templateDir := flag.String("templates", ".", "Templates")
flag.Parse()
// If a path was set, tell the logger to write to a file rather than stdout
if len(*path) > 0 {
flags := os.O_APPEND | os.O_WRONLY | os.O_CREATE
logf, err := os.OpenFile(*path, flags, 0644)
if err != nil {
panic(err)
}
defer logf.Close()
log.SetOutput(logf)
}
// Create the website, which loads the templates
website, err := Create(*staticDir, *templateDir)
if err != nil {
panic(err)
}
// Add the pages to the multiplexer (this could be done in Create)
http.HandleFunc("/", website.HomepageHandler)
http.HandleFunc("/api", website.JSONHandler)
http.HandleFunc("/article", website.ArticleHandler)
http.HandleFunc("/404", website.Status404Handler)
http.HandleFunc("/favicon.ico", website.IconHandler)
// Serve static files
http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir(*staticDir))))
// Start the site and server forever
address := fmt.Sprintf(":%d", *port)
log.Println("Running on address:", address)
err = http.ListenAndServe(address, nil)
if err != nil {
panic(err)
}
}