✨ feat(server): add GET /api/v1/uptime endpoint (#67)

Co-authored-by: Gabriel Radureau <arcodange@gmail.com>
Co-committed-by: Gabriel Radureau <arcodange@gmail.com>

pkg/server/server.go

@@ -246,6 +246,9 @@ func (s *Server) registerApiV1Routes(r chi.Router) {
 		r.Get("/{name}", s.handleGreetPath)
 	})
 
+	// Uptime endpoint
+	r.Get("/uptime", s.handleUptime)
+
 	// Register user authentication routes
 	if s.userService != nil && s.userRepo != nil {
 		// Use unified user service - much simpler!
@@ -583,6 +586,30 @@ func (s *Server) handleInfo(w http.ResponseWriter, r *http.Request) {
 	w.Write(data)
 }
 
+// UptimeResponse represents the JSON response for /api/v1/uptime
+type UptimeResponse struct {
+	StartTime     string `json:"start_time"`
+	UptimeSeconds int    `json:"uptime_seconds"`
+}
+
+// handleUptime godoc
+//
+//	@Summary		Get server uptime
+//	@Description	Returns server start time and uptime duration
+//	@Tags			System/Info
+//	@Produce		json
+//	@Success		200	{object}	UptimeResponse
+//	@Router			/v1/uptime [get]
+func (s *Server) handleUptime(w http.ResponseWriter, r *http.Request) {
+	log.Trace().Msg("Uptime check requested")
+	resp := UptimeResponse{
+		StartTime:     s.startedAt.Format(time.RFC3339),
+		UptimeSeconds: int(time.Since(s.startedAt).Seconds()),
+	}
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(resp)
+}
+
 // handleGreetQuery godoc
 //
 //	@Summary		Get greeting with cache

pkg/server/uptime_test.go

@@ -0,0 +1,81 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"dance-lessons-coach/pkg/config"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHandleUptime(t *testing.T) {
+	// Setup with a known start time
+	cfg := &config.Config{}
+	// We need to create a server and then set its startedAt to a known time
+	// Since NewServer sets startedAt to time.Now(), we'll create the server
+	// and then use reflection or we can use NewServerWithUserRepo which also sets startedAt
+	s := NewServer(cfg, context.Background())
+
+	// Set a fixed start time for deterministic testing
+	// We can't directly set s.startedAt since it's unexported, but we can test
+	// that the handler uses the server's startedAt
+	// The test will verify the structure and that uptime_seconds is >= 0
+
+	// Create request
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/uptime", nil)
+	w := httptest.NewRecorder()
+
+	// Call handler
+	s.handleUptime(w, req)
+
+	// Check status code
+	assert.Equal(t, http.StatusOK, w.Code)
+
+	// Check content type
+	assert.Equal(t, "application/json", w.Header().Get("Content-Type"))
+
+	// Decode response
+	var resp UptimeResponse
+	err := json.NewDecoder(w.Body).Decode(&resp)
+	assert.NoError(t, err)
+
+	// Assert fields
+	assert.NotEmpty(t, resp.StartTime)
+	// Verify start_time is in RFC3339 format
+	_, err = time.Parse(time.RFC3339, resp.StartTime)
+	assert.NoError(t, err)
+	assert.GreaterOrEqual(t, resp.UptimeSeconds, 0)
+}
+
+func TestHandleUptime_Deterministic(t *testing.T) {
+	// For a more deterministic test, we would need to be able to set startedAt
+	// Since startedAt is unexported, we test the behavior with a known server
+	// that was just created (uptime should be very small)
+	cfg := &config.Config{}
+	s := NewServer(cfg, context.Background())
+
+	// Small delay to ensure uptime is at least 0 seconds
+	time.Sleep(10 * time.Millisecond)
+
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/uptime", nil)
+	w := httptest.NewRecorder()
+
+	s.handleUptime(w, req)
+
+	assert.Equal(t, http.StatusOK, w.Code)
+
+	var resp UptimeResponse
+	err := json.NewDecoder(w.Body).Decode(&resp)
+	assert.NoError(t, err)
+
+	// Uptime should be at least 0 (it's int() of seconds, so minimum is 0)
+	assert.GreaterOrEqual(t, resp.UptimeSeconds, 0)
+	// Start time should be parseable
+	_, err = time.Parse(time.RFC3339, resp.StartTime)
+	assert.NoError(t, err)
+}