argus.go

package main

import (
	"html/template"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"regexp"
)

var templates = template.Must(template.ParseFiles("edit.html", "view.html"))

var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$")

// Page struct
type Page struct {
	Title string
	Body  []byte
}

func (p *Page) save() error {
	filename := p.Title + ".txt"
	return ioutil.WriteFile(filename, p.Body, 0600)
}

func loadPage(title string) (*Page, error) {
	filename := title + ".txt"
	body, err := ioutil.ReadFile(filename)
	if err != nil {
		return nil, err
	}
	log.Printf("Loaded Page - %s", filename)
	return &Page{Title: title, Body: body}, nil
}

func viewHandler(w http.ResponseWriter, r *http.Request, title string) {

	p, err := loadPage(title)
	if err != nil {
		http.Redirect(w, r, "/edit/"+title, http.StatusFound)
		return
	}
	renderTemplate(w, "view", p)
}
func editHandler(w http.ResponseWriter, r *http.Request, title string) {

	p, err := loadPage(title)
	if err != nil {
		p = &Page{Title: title}

	}
	renderTemplate(w, "edit", p)

}
func saveHandler(w http.ResponseWriter, r *http.Request, title string) {

	body := r.FormValue("body")
	p := &Page{Title: title, Body: []byte(body)}
	err := p.save()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	http.Redirect(w, r, "/view/"+title, http.StatusFound)
}

func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
	err := templates.ExecuteTemplate(w, tmpl+".html", p)

	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)

	}
	log.Printf("Rendered html template %s", tmpl+".html")

}
func makeHandler(fn func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		m := validPath.FindStringSubmatch(r.URL.Path)
		if m == nil {
			http.NotFound(w, r)
			return
		}
		fn(w, r, m[2])

	}
}

func main() {
	http.HandleFunc("/view/", makeHandler(viewHandler))
	http.HandleFunc("/edit/", makeHandler(editHandler))
	http.HandleFunc("/save/", makeHandler(saveHandler))
	hostname, _ := os.Hostname()
    log.Printf("Serving on host: %s & port: %d", hostname, 8080)
	log.Fatal(http.ListenAndServe(":8080", nil))
}