package server

import (
	"encoding/json"
	"errors"
	"fmt"
	"net"
	"net/http"

	"github.com/charmbracelet/log"
)

type WebServer struct {
	server     *Server
	listener   net.Listener
	logger     *log.Logger
	httpServer *http.Server
}

func NewWebServer(server *Server) (*WebServer, error) {
	listener, err := net.Listen("tcp", fmt.Sprintf(":%d", server.Config.Web.Port))
	if err != nil {
		return nil, fmt.Errorf("cannot create listener: %w", err)
	}

	ws := &WebServer{
		server:   server,
		listener: listener,
		logger:   server.Logger,
	}

	mux := http.NewServeMux()
	mux.HandleFunc("/health", ws.healthHandler)
	mux.HandleFunc("/next_birthdays", ws.nextBirthdayHandler)

	ws.httpServer = &http.Server{Handler: mux}

	return ws, nil
}

func (ws *WebServer) Start() error {
	ws.logger.Debug("starting web server")

	go func() {
		if err := ws.httpServer.Serve(ws.listener); err != nil && !errors.Is(err, http.ErrServerClosed) {
			ws.logger.Fatal("cannot start web server", "error", err)
		}
	}()

	return nil
}

func (ws *WebServer) Stop() error {
	ws.logger.Debug("stopping web server")

	if err := ws.httpServer.Close(); err != nil {
		return fmt.Errorf("cannot stop web server: %w", err)
	}

	return nil
}

func (ws *WebServer) Port() int {
	return ws.listener.Addr().(*net.TCPAddr).Port
}

func (ws *WebServer) healthHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprint(w, "OK")
}

func (ws *WebServer) nextBirthdayHandler(w http.ResponseWriter, r *http.Request) {
	ws.JSON(w, http.StatusOK, ws.server.NextBirthdays())
}

func (ws *WebServer) JSON(w http.ResponseWriter, statusCode int, data any) {
	b, err := json.Marshal(data)
	if err != nil {
		ws.logger.Error("cannot marshal data", "error", err)
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
		return
	}

	w.WriteHeader(statusCode)
	if _, err := w.Write(b); err != nil {
		ws.logger.Error("cannot write to response writer", "error", err)
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
	}
}