package httpserver

import (
	"context"
	"errors"
	"fmt"
	"net"
	"net/http"
	"os"
	"time"

	"bunker/server/internal/services/core"

	"github.com/coder/websocket"
)

const httpServerAddrEnvVar = "BUNKERD_HTTP_ADDRESS"

var (
	errHTTPServerAddrInvalid = errors.New("BUNKERD_HTTP_ADDRESS environment variable contains invalid address to " +
		"listen, should be 'host:port'")
	errHTTPServerAddrNotFound = errors.New("BUNKERD_HTTP_ADDRESS environment variable empty")
)

func (h *httpServer) configureHTTPServer() error {
	httpSrvAddr, found := os.LookupEnv(httpServerAddrEnvVar)
	if !found {
		return fmt.Errorf("configure HTTP server: get address from environment variable: %w", errHTTPServerAddrNotFound)
	}

	host, port, err := net.SplitHostPort(httpSrvAddr)
	if err != nil {
		return fmt.Errorf("configure HTTP server: validate HTTP server address: %w", err)
	}

	if httpSrvAddr != host+":"+port {
		return fmt.Errorf("configure HTTP server: validate HTTP server address: %w", errHTTPServerAddrInvalid)
	}

	h.httpMux = new(http.ServeMux)

	// Default catch-all handler.
	h.RegisterHandler("", "/", h.defaultHandler)
	h.RegisterHandler(http.MethodGet, "/api/v1/socket", h.handleWebsocketRequest)

	h.httpSrv = &http.Server{
		Addr:              httpSrvAddr,
		Handler:           h.httpMux,
		ReadHeaderTimeout: time.Second * 3,
	}

	return nil
}

func (h *httpServer) handleWebsocketRequest(w http.ResponseWriter, r *http.Request) {
	wsConn, err := websocket.Accept(w, r, &websocket.AcceptOptions{
		OnPingReceived: func(_ context.Context, _ []byte) bool {
			return true
		},
	})
	if err != nil {
		h.logger.Error("Failed to accept WS connection!", "error", err.Error())

		return
	}

	defer func() {
		if err := wsConn.CloseNow(); err != nil {
			h.logger.Warn("Failed to close WS connection in defer!", "error", err.Error())
		}
	}()
}

func (h *httpServer) RegisterHandler(method, path string, handler http.HandlerFunc) {
	h.httpMux.HandleFunc(fmt.Sprintf("%s %s", method, path), func(w http.ResponseWriter, r *http.Request) {
		for i := len(h.middlewares) - 1; i >= 0; i-- {
			handler = h.middlewares[i](handler)
		}

		handler(w, r)
	})
}

func (h *httpServer) RegisterMiddleware(middleware core.HTTPMiddlewareFunc) {
	h.middlewares = append(h.middlewares, middleware)
}

func (h *httpServer) startHTTPServer() {
	h.logger.Info("Starting listening for HTTP requests.", "address", h.httpSrv.Addr)

	if err := h.httpSrv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		h.logger.Warn("Error when listening to ", "error", err.Error())
	}
}

func (h *httpServer) stopHTTPServer() error {
	h.logger.Info("Stopping HTTP server...")

	if err := h.httpSrv.Shutdown(h.app.ContextWithTimeout(time.Second * 3)); err != nil {
		return fmt.Errorf("stopping HTTP server: %w", err)
	}

	return nil
}