fix: エラーハンドリング・ログ・環境変数・DeleteListの改善

handler.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"html/template"
+	"log/slog"
 	"net/http"
 	"strings"
 )
@@ -30,14 +31,18 @@ func registerRoutes(mux *http.ServeMux, store *Store) {
 	mux.HandleFunc("POST /lists/{token}/items/{id}/toggle-required", handleToggleRequired(store))
 	mux.HandleFunc("POST /lists/{token}/items/{id}/assignee", handleUpdateAssignee(store))
 	mux.HandleFunc("POST /lists/{token}/items/{id}/delete", handleDeleteItem(store))
+	mux.HandleFunc("POST /lists/{token}/delete", handleDeleteList(store))
 }
 
 func handleIndex(w http.ResponseWriter, r *http.Request) {
 	if r.URL.Path != "/" {
 		http.NotFound(w, r)
 		return
 	}
-	tmpl.ExecuteTemplate(w, "index.html", nil)
+	if err := tmpl.ExecuteTemplate(w, "index.html", nil); err != nil {
+		slog.Error("テンプレート描画エラー", "template", "index.html", "error", err)
+		http.Error(w, "テンプレートの描画に失敗しました", http.StatusInternalServerError)
+	}
 }
 
 func handleCreateList(store *Store) http.HandlerFunc {
@@ -65,7 +70,10 @@ func handleShowList(store *Store) http.HandlerFunc {
 			"List":     l,
 			"ShareURL": "http://" + r.Host + "/lists/" + l.ShareToken,
 		}
-		tmpl.ExecuteTemplate(w, "list.html", data)
+		if err := tmpl.ExecuteTemplate(w, "list.html", data); err != nil {
+			slog.Error("テンプレート描画エラー", "template", "list.html", "error", err)
+			http.Error(w, "テンプレートの描画に失敗しました", http.StatusInternalServerError)
+		}
 	}
 }
 
@@ -120,3 +128,14 @@ func handleDeleteItem(store *Store) http.HandlerFunc {
 		http.Redirect(w, r, "/lists/"+token, http.StatusSeeOther)
 	}
 }
+
+func handleDeleteList(store *Store) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		token := r.PathValue("token")
+		if !store.DeleteList(token) {
+			http.NotFound(w, r)
+			return
+		}
+		http.Redirect(w, r, "/", http.StatusSeeOther)
+	}
+}

main.go

@@ -1,17 +1,28 @@
 package main
 
 import (
-	"fmt"
-	"log"
+	"log/slog"
 	"net/http"
+	"os"
 )
 
+// getEnv は環境変数を取得し、未設定の場合はデフォルト値を返す。
+func getEnv(key, defaultVal string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return defaultVal
+}
+
 func main() {
 	store := NewStore()
 	mux := http.NewServeMux()
 	registerRoutes(mux, store)
 
-	addr := ":8080"
-	fmt.Println("BringIt server started on http://localhost" + addr)
-	log.Fatal(http.ListenAndServe(addr, mux))
+	addr := ":" + getEnv("PORT", "8080")
+	slog.Info("BringItサーバーを起動しました", "addr", "http://localhost"+addr)
+	if err := http.ListenAndServe(addr, mux); err != nil {
+		slog.Error("サーバーの起動に失敗しました", "error", err)
+		os.Exit(1)
+	}
 }

model.go

@@ -14,9 +14,10 @@ type List struct {
 
 // Item represents a single item in a packing list.
 type Item struct {
-	ID       string
-	Name     string
-	Assignee string
-	Required bool
-	Prepared bool
+	ID        string
+	Name      string
+	Assignee  string
+	Required  bool
+	Prepared  bool
+	UpdatedAt time.Time // アイテムの最終更新日時
 }

store.go

@@ -26,7 +26,9 @@ func (s *Store) genID() string {
 
 func generateToken() string {
 	b := make([]byte, 8)
-	rand.Read(b)
+	if _, err := rand.Read(b); err != nil {
+		panic("乱数生成に失敗しました: " + err.Error())
+	}
 	return hex.EncodeToString(b)
 }
 
@@ -61,10 +63,11 @@ func (s *Store) AddItem(token, name, assignee string, required bool) *Item {
 		return nil
 	}
 	item := &Item{
-		ID:       s.genID(),
-		Name:     name,
-		Assignee: assignee,
-		Required: required,
+		ID:        s.genID(),
+		Name:      name,
+		Assignee:  assignee,
+		Required:  required,
+		UpdatedAt: time.Now(),
 	}
 	l.Items = append(l.Items, item)
 	return item
@@ -88,6 +91,7 @@ func (s *Store) TogglePrepared(token, itemID string) {
 	defer s.mu.Unlock()
 	if it := s.findItem(token, itemID); it != nil {
 		it.Prepared = !it.Prepared
+		it.UpdatedAt = time.Now()
 	}
 }
 
@@ -96,6 +100,7 @@ func (s *Store) ToggleRequired(token, itemID string) {
 	defer s.mu.Unlock()
 	if it := s.findItem(token, itemID); it != nil {
 		it.Required = !it.Required
+		it.UpdatedAt = time.Now()
 	}
 }
 
@@ -104,7 +109,19 @@ func (s *Store) UpdateAssignee(token, itemID, assignee string) {
 	defer s.mu.Unlock()
 	if it := s.findItem(token, itemID); it != nil {
 		it.Assignee = assignee
+		it.UpdatedAt = time.Now()
+	}
+}
+
+// DeleteList はトークンに対応するリストを削除する。削除に成功した場合は true を返す。
+func (s *Store) DeleteList(token string) bool {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if _, ok := s.lists[token]; !ok {
+		return false
 	}
+	delete(s.lists, token)
+	return true
 }
 
 func (s *Store) DeleteItem(token, itemID string) {