New dosasite.go with templates

dosasite.go

package main

import (
        "fmt"
        "html/template"
        "log"
        "net/http"
        "os"
        "path"
)

func main() {
        fs := http.FileServer(http.Dir("public"))
        http.Handle("/public/", http.StripPrefix("/public/", fs))

        http.HandleFunc("/", ServeTemplate)
        
        fmt.Println("Listening...")
        err := http.ListenAndServe(GetPort(), nil)
        if err != nil {
                log.Fatal("ListenAndServe: ", err)
                return
        }
}

// Get the Port from the environment so we can run on Heroku
func GetPort() string {
        var port = os.Getenv("PORT")
	// Set a default port if there is nothing in the environment
	if port == "" {
		port = "4747"
		fmt.Println("INFO: No PORT environment variable detected, defaulting to " + port)
	}
	return ":" + port
}

func ServeTemplate(w http.ResponseWriter, r *http.Request) {
        lp := path.Join("templates", "layout.html")
        fp := path.Join("templates", r.URL.Path)

        // Return a 404 if the template doesn't exist
        info, err := os.Stat(fp)
        if err != nil {
                if os.IsNotExist(err) {
                        http.NotFound(w, r)
                        return
                }
        }

        // Return a 404 if the request is for a directory
        if info.IsDir() {
                http.NotFound(w, r)
                return
        }

        templates, err := template.ParseFiles(lp, fp)
        if err != nil {
                fmt.Println(err)
                http.Error(w, "500 Internal Server Error", 500)
                return
        }
  
        templates.ExecuteTemplate(w, "layout", nil)
}