From 9495f5ec9f5bfd5eed2ec77fb1fb1a9549023c11 Mon Sep 17 00:00:00 2001
From: Exsors <huliokevin7@gmail.com>
Date: Tue, 1 Sep 2026 14:43:06 +0700
Subject: [PATCH] first commit

---
 go.mod  |   3 +
 main.go | 183 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 186 insertions(+)
 create mode 100644 go.mod
 create mode 100644 main.go

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..88779ec
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module task-manager
+
+go 1.21
\ No newline at end of file
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..be0f48e
--- /dev/null
+++ b/main.go
@@ -0,0 +1,183 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+)
+
+type Task struct {
+	ID   string `json:"id"`
+	Name string `json:"name"`
+}
+
+type createUpdateRequest struct {
+	Name string `json:"name"`
+}
+
+var (
+	store = make(map[string]Task)
+	mu    sync.RWMutex
+	idSeq int64
+)
+
+func main() {
+	mux := http.NewServeMux()
+
+	mux.HandleFunc("/tasks", handleTasks)     // GET list + POST create
+	mux.HandleFunc("/tasks/", handleTaskByID) // GET/PUT/DELETE by id
+
+	fmt.Println("Server running on http://localhost:8080")
+	if err := http.ListenAndServe(":8080", mux); err != nil {
+		panic(err)
+	}
+}
+
+func handleTasks(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodGet:
+		listTasks(w, r)
+	case http.MethodPost:
+		createTask(w, r)
+	default:
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+	}
+}
+
+func handleTaskByID(w http.ResponseWriter, r *http.Request) {
+	// Path: /tasks/{id}
+	id := strings.TrimPrefix(r.URL.Path, "/tasks/")
+	if id == "" || strings.Contains(id, "/") {
+		writeJSONError(w, "Invalid ID", http.StatusBadRequest)
+		return
+	}
+
+	switch r.Method {
+	case http.MethodGet:
+		getTask(w, r, id)
+	case http.MethodPut:
+		updateTask(w, r, id)
+	case http.MethodDelete:
+		deleteTask(w, r, id)
+	default:
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+	}
+}
+
+// ---------- Handlers ----------
+
+func listTasks(w http.ResponseWriter, r *http.Request) {
+	mu.RLock()
+	defer mu.RUnlock()
+
+	// PENTING: selalu kembalikan slice kosong, bukan nil
+	tasks := make([]Task, 0, len(store))
+	for _, t := range store {
+		tasks = append(tasks, t)
+	}
+
+	writeJSON(w, tasks, http.StatusOK)
+}
+
+func createTask(w http.ResponseWriter, r *http.Request) {
+	var req createUpdateRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeJSONError(w, "Invalid JSON body", http.StatusBadRequest)
+		return
+	}
+
+	if strings.TrimSpace(req.Name) == "" {
+		writeJSONError(w, "name is required and cannot be empty", http.StatusBadRequest)
+		return
+	}
+
+	// Generate ID (server-side only)
+	newID := strconv.FormatInt(atomic.AddInt64(&idSeq, 1), 10)
+
+	task := Task{
+		ID:   newID,
+		Name: req.Name,
+	}
+
+	mu.Lock()
+	store[newID] = task
+	mu.Unlock()
+
+	writeJSON(w, task, http.StatusCreated)
+}
+
+func getTask(w http.ResponseWriter, r *http.Request, id string) {
+	mu.RLock()
+	task, exists := store[id]
+	mu.RUnlock()
+
+	if !exists {
+		writeJSONError(w, "Task not found", http.StatusNotFound)
+		return
+	}
+
+	writeJSON(w, task, http.StatusOK)
+}
+
+func updateTask(w http.ResponseWriter, r *http.Request, id string) {
+	var req createUpdateRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeJSONError(w, "Invalid JSON body", http.StatusBadRequest)
+		return
+	}
+
+	if strings.TrimSpace(req.Name) == "" {
+		writeJSONError(w, "name is required and cannot be empty", http.StatusBadRequest)
+		return
+	}
+
+	mu.Lock()
+	defer mu.Unlock()
+
+	task, exists := store[id]
+	if !exists {
+		writeJSONError(w, "Task not found", http.StatusNotFound)
+		return
+	}
+
+	// Full replacement of name, ID remains the same
+	task.Name = req.Name
+	store[id] = task
+
+	writeJSON(w, task, http.StatusOK)
+}
+
+func deleteTask(w http.ResponseWriter, r *http.Request, id string) {
+	mu.Lock()
+	defer mu.Unlock()
+
+	if _, exists := store[id]; !exists {
+		writeJSONError(w, "Task not found", http.StatusNotFound)
+		return
+	}
+
+	delete(store, id)
+
+	// 204 No Content — JANGAN tulis body apapun
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// ---------- Helper ----------
+
+func writeJSON(w http.ResponseWriter, data interface{}, status int) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(data)
+}
+
+func writeJSONError(w http.ResponseWriter, message string, status int) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(map[string]string{
+		"error": message,
+	})
+}