feat: Add REST API handlers for exercises, plans, and sessions

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/internal/api/router.go

@@ -0,0 +1,55 @@
+package api
+
+import (
+	"net/http"
+	"strings"
+	"training-tracker/internal/storage"
+)
+
+// Router sets up and returns the HTTP router
+type Router struct {
+	exerciseHandler *ExerciseHandler
+	planHandler     *PlanHandler
+	sessionHandler  *SessionHandler
+}
+
+// NewRouter creates a new router with all handlers
+func NewRouter(db *storage.DB) *Router {
+	exerciseRepo := storage.NewExerciseRepository(db)
+	planRepo := storage.NewPlanRepository(db)
+	sessionRepo := storage.NewSessionRepository(db)
+
+	return &Router{
+		exerciseHandler: NewExerciseHandler(exerciseRepo),
+		planHandler:     NewPlanHandler(planRepo),
+		sessionHandler:  NewSessionHandler(sessionRepo),
+	}
+}
+
+// ServeHTTP implements http.Handler
+func (router *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// Enable CORS
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
+	w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
+
+	if r.Method == http.MethodOptions {
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	path := r.URL.Path
+
+	switch {
+	case strings.HasPrefix(path, "/api/exercises"):
+		router.exerciseHandler.ServeHTTP(w, r)
+	case strings.HasPrefix(path, "/api/plans"):
+		router.planHandler.ServeHTTP(w, r)
+	case strings.HasPrefix(path, "/api/sessions"):
+		router.sessionHandler.ServeHTTP(w, r)
+	case path == "/api/health":
+		respondJSON(w, http.StatusOK, map[string]string{"status": "ok"})
+	default:
+		respondError(w, http.StatusNotFound, "not found")
+	}
+}