Refactor to JSON API with Chi router and interface-based design

- Add pkg/greet/api_v1.go with ApiV1Greet interface and handler
- Implement Greeter interface for dependency injection
- Return JSON responses with proper Content-Type headers
- Move greet service instantiation to server package
- Separate v1 route registration into registerApiV1Routes function
- Health endpoint at /api level, greet endpoints at /api/v1/greet
- Simplify server entrypoint by removing external dependencies

cmd/greet/main.go

@@ -8,10 +8,11 @@ import (
 )
 
 func main() {
+	service := greet.NewService()
 	name := ""
 	if len(os.Args) > 1 {
 		name = os.Args[1]
 	}
 	
-	fmt.Println(greet.Greet(name))
+	fmt.Println(service.Greet(name))
 }

cmd/server/main.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+
+	"DanceLessonsCoach/pkg/server"
+)
+
+func main() {
+	server := server.NewServer()
+
+	fmt.Println("Server running on :8080")
+	http.ListenAndServe(":8080", server.Router())
+}

go.mod

@@ -1,3 +1,5 @@
 module DanceLessonsCoach
 
 go 1.26.1
+
+require github.com/go-chi/chi/v5 v5.2.5 // indirect

go.sum

@@ -0,0 +1,2 @@
+github.com/go-chi/chi/v5 v5.2.5 h1:Eg4myHZBjyvJmAFjFvWgrqDTXFyOzjj7YIm3L3mu6Ug=
+github.com/go-chi/chi/v5 v5.2.5/go.mod h1:X7Gx4mteadT3eDOMTsXzmI4/rwUpOwBHLpAfupzFJP0=

pkg/greet/api_v1.go

@@ -0,0 +1,44 @@
+package greet
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+)
+
+type Greeter interface {
+	Greet(name string) string
+}
+
+type ApiV1Greet interface {
+	RegisterRoutes(router chi.Router)
+}
+
+type apiV1GreetHandler struct {
+	greeter Greeter
+}
+
+func NewApiV1GreetHandler(greeter Greeter) ApiV1Greet {
+	return &apiV1GreetHandler{greeter: greeter}
+}
+
+func (h *apiV1GreetHandler) RegisterRoutes(router chi.Router) {
+	router.Get("/", h.handleGreetQuery)
+	router.Get("/{name}", h.handleGreetPath)
+}
+
+func (h *apiV1GreetHandler) handleGreetQuery(w http.ResponseWriter, r *http.Request) {
+	name := r.URL.Query().Get("name")
+	h.writeJSONResponse(w, h.greeter.Greet(name))
+}
+
+func (h *apiV1GreetHandler) handleGreetPath(w http.ResponseWriter, r *http.Request) {
+	name := chi.URLParam(r, "name")
+	h.writeJSONResponse(w, h.greeter.Greet(name))
+}
+
+func (h *apiV1GreetHandler) writeJSONResponse(w http.ResponseWriter, message string) {
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(map[string]string{"message": message})
+}

pkg/greet/greet.go

@@ -1,8 +1,15 @@
 package greet
 
+type Service struct{}
+
+func NewService() *Service {
+	return &Service{}
+}
+
 // Greet returns a greeting message for the given name.
 // If name is empty, it defaults to "world".
-func Greet(name string) string {
+// Implements the Greeter interface.
+func (s *Service) Greet(name string) string {
 	if name == "" {
 		return "Hello world!"
 	}

pkg/greet/greet_test.go

@@ -2,7 +2,8 @@ package greet
 
 import "testing"
 
-func TestGreet(t *testing.T) {
+func TestService_Greet(t *testing.T) {
+	service := NewService()
 	tests := []struct {
 		name     string
 		expected string
@@ -15,7 +16,7 @@ func TestGreet(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			result := Greet(tt.name)
+			result := service.Greet(tt.name)
 			if result != tt.expected {
 				t.Errorf("Greet(%q) = %q, want %q", tt.name, result, tt.expected)
 			}

pkg/server/server.go

@@ -0,0 +1,58 @@
+package server
+
+import (
+	"net/http"
+
+	"DanceLessonsCoach/pkg/greet"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+)
+
+type Server struct {
+	router *chi.Mux
+}
+
+func NewServer() *Server {
+	s := &Server{
+		router: chi.NewRouter(),
+	}
+	s.setupRoutes()
+	return s
+}
+
+func (s *Server) setupRoutes() {
+	s.router.Use(middleware.Logger)
+	s.router.Route("/api", func(r chi.Router) {
+		r.Use(s.apiMiddlewares()...)
+		r.Get("/health", s.handleHealth)
+		s.registerApiV1Routes(r)
+	})
+}
+
+func (s *Server) registerApiV1Routes(r chi.Router) {
+	r.Route("/v1", func(r chi.Router) {
+
+		greetService := greet.NewService()
+		greetHandler := greet.NewApiV1GreetHandler(greetService)
+		r.Route("/greet", func(r chi.Router) {
+			greetHandler.RegisterRoutes(r)
+		})
+
+	})
+}
+
+func (s *Server) apiMiddlewares() []func(http.Handler) http.Handler {
+	return []func(http.Handler) http.Handler{
+		middleware.StripSlashes,
+		middleware.Recoverer,
+	}
+}
+
+func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
+	w.Write([]byte(`{"status":"healthy"}`))
+}
+
+func (s *Server) Router() http.Handler {
+	return s.router
+}