htmx-demo/contactsapp/app.go

package main

import (
	"errors"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"sync"

	"github.com/masterminds/sprig"
)

const (
	addr = ":8080"
)

type data map[string]any

var (
	flashMessage string
	flashMX      sync.Mutex
)

/*
@app.route("/")
def index():
*/
func index(w http.ResponseWriter, r *http.Request) {
	http.Redirect(w, r, "/contacts", http.StatusSeeOther)
}

/*
@app.route("/contacts")
*/
func contacts(cs *ContactsStore) http.HandlerFunc {
	tpl := makeTemplate(
		"layout",
		"index",
	)
	return func(w http.ResponseWriter, r *http.Request) {
		search := r.URL.Query().Get("q")
		var contacts_set []*Contact
		if search == "" {
			contacts_set = cs.GetAll()
		} else {
			contacts_set = cs.Get(search)
		}
		if err := tpl.ExecuteTemplate(w, "layout.html", data{
			"contacts": contacts_set,
			"search":   search,
		}); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
	}
}

/*
@app.route("/contacts/new", methods=['GET']) (1)
*/
func contactsNewGet(cs *ContactsStore) http.HandlerFunc {
	tpl := makeTemplate(
		"layout",
		"new",
	)
	return func(w http.ResponseWriter, r *http.Request) {
		contact := cs.New(nil)
		if err := tpl.ExecuteTemplate(w, "layout.html", contact); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
	}
}

/*
@app.route("/contacts/new", methods=['POST'])
*/
func contactsNew(cs *ContactsStore) http.HandlerFunc {
	tpl := makeTemplate(
		"layout",
		"new",
	)
	return func(w http.ResponseWriter, r *http.Request) {
		contact := cs.New(map[string]string{
			"first": r.PostFormValue("first_name"),
			"last":  r.PostFormValue("last_name"),
			"phone": r.PostFormValue("phone"),
			"email": r.PostFormValue("email"),
		})
		if err := cs.Save(contact); err != nil {
			flash(fmt.Sprintf("Error saving contact: %v", err))
			if err := tpl.ExecuteTemplate(w, "layout.html", contact); err != nil {
				http.Error(w, err.Error(), http.StatusInternalServerError)
			}
		}
		flash("Created New Contact!")
		http.Redirect(w, r, "/contacts", http.StatusSeeOther)
		return
	}
}

// flash implements a public flash: the first handler asking for a flash gets it.
//
// Not a good system in the general case, but it avoids using a session.
func flash(newFlash string) {
	flashMX.Lock()
	defer flashMX.Unlock()
	flashMessage += newFlash
}

func getFlash() string {
	flashMX.Lock()
	defer flashMX.Unlock()
	previousFlash := flashMessage
	flashMessage = ""
	return previousFlash
}

func makeTemplate(first string, others ...string) *template.Template {
	paths := append([]string{first}, others...)
	for i, path := range paths {
		paths[i] = "./templates/" + path + ".gohtml"
	}
	tpl := template.Must(
		template.New(first).
			Funcs(sprig.FuncMap()).
			Funcs(template.FuncMap{"flash": getFlash}).
			ParseFiles(paths...))
	return tpl
}

func setupRoutes(mux *http.ServeMux, cs *ContactsStore) {
	mux.HandleFunc("/", index)
	mux.HandleFunc("/favicon.ico", func(w http.ResponseWriter, r *http.Request) {
		http.ServeFile(w, r, "./static/img/favicon.ico")
	})
	mux.Handle("GET /static/", http.StripPrefix("/static/", http.FileServer(http.Dir("./static"))))
	mux.Handle("GET /contacts", contacts(cs))
	mux.Handle("GET /contacts/new", contactsNewGet(cs))
	mux.Handle("POST /contacts/new", contactsNew(cs))
}

func main() {
	cs, err := NewContactsStore()
	if err != nil {
		log.Fatalf("initializing contacts: %v\n", err)
	}
	mux := http.NewServeMux()
	setupRoutes(mux, cs)
	log.Printf("Listening on http://localhost%s", addr)
	if err := http.ListenAndServe(addr, mux); err != nil {
		if !errors.Is(err, http.ErrServerClosed) {
			log.Printf("Server error: %v\n", err)
			return
		}
	}
	log.Println("Server shutdown")
}