initial commit

Change-Id: Ied1b5f2137f2b5f803d5411235607bd27c5e57ba

main.go

@@ -0,0 +1,163 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// ---------------------------------------------------------------------------
+// Domain model
+// ---------------------------------------------------------------------------
+
+type Item struct {
+	ID          int    `json:"id"`
+	Name        string `json:"name"`
+	Description string `json:"description"`
+}
+
+type ItemRequest struct {
+	Name        string `json:"name"`
+	Description string `json:"description"`
+}
+
+// ---------------------------------------------------------------------------
+// In-memory store
+// ---------------------------------------------------------------------------
+
+var (
+	store   sync.Map
+	counter atomic.Int64
+)
+
+func nextID() int {
+	return int(counter.Add(1))
+}
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+func writeJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(v)
+}
+
+func itemIDFromPath(path string) (int, bool) {
+	parts := strings.Split(strings.TrimSuffix(path, "/"), "/")
+	if len(parts) < 3 {
+		return 0, false
+	}
+	id, err := strconv.Atoi(parts[len(parts)-1])
+	return id, err == nil
+}
+
+// ---------------------------------------------------------------------------
+// Handlers
+// ---------------------------------------------------------------------------
+
+func healthHandler(w http.ResponseWriter, _ *http.Request) {
+	writeJSON(w, http.StatusOK, map[string]string{"status": "UP"})
+}
+
+func itemsHandler(w http.ResponseWriter, r *http.Request) {
+	// Route: /api/items  or  /api/items/{id}
+	hasSub := strings.Count(strings.TrimSuffix(r.URL.Path, "/"), "/") >= 3
+
+	if hasSub {
+		id, ok := itemIDFromPath(r.URL.Path)
+		if !ok {
+			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
+			return
+		}
+		switch r.Method {
+		case http.MethodGet:
+			v, exists := store.Load(id)
+			if !exists {
+				writeJSON(w, http.StatusNotFound, map[string]string{"error": "not found"})
+				return
+			}
+			writeJSON(w, http.StatusOK, v)
+		case http.MethodPut:
+			var req ItemRequest
+			if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+				writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
+				return
+			}
+			existingRaw, exists := store.Load(id)
+			if !exists {
+				writeJSON(w, http.StatusNotFound, map[string]string{"error": "not found"})
+				return
+			}
+			existing := existingRaw.(Item)
+			if req.Name == "" {
+				req.Name = existing.Name
+			}
+			if req.Description == "" {
+				req.Description = existing.Description
+			}
+			updated := Item{ID: id, Name: req.Name, Description: req.Description}
+			store.Store(id, updated)
+			writeJSON(w, http.StatusOK, updated)
+		case http.MethodDelete:
+			store.Delete(id)
+			writeJSON(w, http.StatusOK, map[string]int{"deleted": id})
+		default:
+			w.WriteHeader(http.StatusMethodNotAllowed)
+		}
+		return
+	}
+
+	// /api/items — list or create
+	switch r.Method {
+	case http.MethodGet:
+		var items []Item
+		store.Range(func(_, v any) bool {
+			items = append(items, v.(Item))
+			return true
+		})
+		if items == nil {
+			items = []Item{}
+		}
+		writeJSON(w, http.StatusOK, items)
+	case http.MethodPost:
+		var req ItemRequest
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+			writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
+			return
+		}
+		if req.Name == "" {
+			req.Name = "unnamed"
+		}
+		item := Item{ID: nextID(), Name: req.Name, Description: req.Description}
+		store.Store(item.ID, item)
+		writeJSON(w, http.StatusCreated, item)
+	default:
+		w.WriteHeader(http.StatusMethodNotAllowed)
+	}
+}
+
+// ---------------------------------------------------------------------------
+// Main
+// ---------------------------------------------------------------------------
+
+func main() {
+	mux := http.NewServeMux()
+
+	mux.HandleFunc("/health", healthHandler)
+	mux.Handle("/metrics", promhttp.Handler())
+	mux.HandleFunc("/api/items/", itemsHandler)
+	mux.HandleFunc("/api/items", itemsHandler)
+
+	addr := ":8080"
+	fmt.Printf("tmpl-test-go listening on %s\n", addr)
+	log.Fatal(http.ListenAndServe(addr, mux))
+}