feat: impl requests handllers for contacts and healthcheck

internal/handler/base_handler.go

@@ -0,0 +1,47 @@
+package handler
+
+import (
+	"net/http"
+	"sync"
+)
+
+type Route struct {
+	pattern string
+	handler func(w http.ResponseWriter, r *http.Request)
+}
+
+type baseHandler struct {
+	mux              *http.ServeMux
+	registeredRoutes map[string]bool
+	Routes           []Route
+}
+
+var (
+	bh     *baseHandler
+	bhOnce sync.Once
+	bhMu   sync.RWMutex
+)
+
+func NewBaseHandler(mux *http.ServeMux, routes []Route) *baseHandler {
+	bhOnce.Do(func() {
+		bh = &baseHandler{
+			mux:              mux,
+			registeredRoutes: make(map[string]bool),
+			Routes:           routes,
+		}
+	})
+
+	bhMu.Lock()
+	defer bhMu.Unlock()
+	bh.registerRoutes(routes)
+	return bh
+}
+
+func (b *baseHandler) registerRoutes(routes []Route) {
+	for _, route := range routes {
+		if !bh.registeredRoutes[route.pattern] {
+			b.mux.HandleFunc(route.pattern, route.handler)
+			bh.registeredRoutes[route.pattern] = true
+		}
+	}
+}