package api

import (
	"log/slog"
	"net/http"
	"strings"
	"time"

	"messenger/internal/auth"
	"messenger/internal/media"
	"messenger/internal/platform/config"
	"messenger/internal/platform/ratelimit"
	"messenger/internal/realtime"
	"messenger/internal/store"
)

type apiHandler struct {
	store    *store.Store
	tokens   *auth.TokenManager
	hub      *realtime.Hub
	log      *slog.Logger
	secure   bool
	media    media.Storage
	notifier *pushNotifier
}

// NewHandler builds the /api/v1 route tree with all middleware applied.
// static, when non-nil, serves the built frontend for non-API paths.
func NewHandler(st *store.Store, tm *auth.TokenManager, hub *realtime.Hub, log *slog.Logger, cfg *config.Config, ms media.Storage, static http.Handler) http.Handler {
	h := &apiHandler{
		store:    st,
		tokens:   tm,
		hub:      hub,
		log:      log,
		secure:   cfg.Environment == "production",
		media:    ms,
		notifier: newPushNotifier(st, hub, log, cfg.VAPIDPublicKey, cfg.VAPIDPrivateKey, cfg.VAPIDSubject),
	}

	mux := http.NewServeMux()
	authHandler := requireAuth(tm, http.HandlerFunc(h.websocket))

	authLimiter := ratelimit.New(20, time.Minute)
	limited := func(inner http.HandlerFunc) http.HandlerFunc {
		return func(w http.ResponseWriter, r *http.Request) {
			if !authLimiter.Allow(r) {
				w.Header().Set("Retry-After", "60")
				writeError(w, http.StatusTooManyRequests, "too many requests")
				return
			}
			inner(w, r)
		}
	}

	mux.HandleFunc("GET /api/v1/ping", func(w http.ResponseWriter, r *http.Request) {
		writeJSON(w, http.StatusOK, map[string]string{"message": "pong"})
	})

	mux.HandleFunc("POST /api/v1/auth/register", limited(h.register))
	mux.HandleFunc("POST /api/v1/auth/login", limited(h.login))
	mux.HandleFunc("POST /api/v1/auth/refresh", limited(h.refresh))
	mux.HandleFunc("POST /api/v1/auth/logout", h.logout)

	mux.Handle("GET /api/v1/users/me", requireAuth(tm, h.me))
	mux.Handle("GET /api/v1/users", requireAuth(tm, h.searchUsers))
	mux.Handle("GET /api/v1/search/messages", requireAuth(tm, h.searchMessages))

	mux.Handle("GET /api/v1/contacts", requireAuth(tm, h.listContacts))
	mux.Handle("POST /api/v1/contacts", requireAuth(tm, h.addContact))
	mux.Handle("DELETE /api/v1/contacts/{user_id}", requireAuth(tm, h.removeContact))

	mux.Handle("GET /api/v1/conversations", requireAuth(tm, h.listConversations))
	mux.Handle("POST /api/v1/conversations", requireAuth(tm, h.createConversation))
	mux.Handle("GET /api/v1/conversations/{id}/members", requireAuth(tm, h.listMembers))
	mux.Handle("POST /api/v1/conversations/{id}/members", requireAuth(tm, h.addMember))
	mux.Handle("DELETE /api/v1/conversations/{id}/members/{user_id}", requireAuth(tm, h.removeMember))
	mux.Handle("GET /api/v1/conversations/{id}/messages", requireAuth(tm, h.listMessages))
	mux.Handle("POST /api/v1/conversations/{id}/messages", requireAuth(tm, h.sendMessage))
	mux.Handle("PUT /api/v1/conversations/{id}/messages/{msg_id}/reactions", requireAuth(tm, h.addReaction))
	mux.Handle("DELETE /api/v1/conversations/{id}/messages/{msg_id}/reactions/{emoji}", requireAuth(tm, h.removeReaction))

	mux.Handle("POST /api/v1/media", requireAuth(tm, h.uploadMedia))
	mux.Handle("GET /api/v1/media/{id}", requireAuth(tm, h.downloadMedia))
	mux.Handle("GET /api/v1/media/{id}/thumb", requireAuth(tm, h.downloadThumb))

	mux.Handle("POST /api/v1/push/subscribe", requireAuth(tm, h.subscribePush))
	mux.Handle("DELETE /api/v1/push/subscribe", requireAuth(tm, h.unsubscribePush))

	mux.Handle("GET /ws", authHandler)

	if static != nil {
		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
			if strings.HasPrefix(r.URL.Path, "/api/") {
				writeError(w, http.StatusNotFound, "not found")
				return
			}
			static.ServeHTTP(w, r)
		})
	}

	return mux
}

func (h *apiHandler) websocket(w http.ResponseWriter, r *http.Request) {
	userID, ok := userIDFrom(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthenticated")
		return
	}
	h.hub.HandleWS(w, r, userID)
}