package agent

import (
	"context"
	"crypto/tls"
	"fmt"
	"log"
	"net/http"
	"net/url"
	"os"
	"time"

	"github.com/hashicorp/yamux"
)

func Handle(ctx context.Context, agentURL, agentToken string, h http.Handler) error {
	u, err := url.Parse(agentURL)
	if err != nil {
		return fmt.Errorf("error parsing URL: %w", err)
	}

	if u.Scheme != "iconia" {
		return fmt.Errorf("wanted scheme %s, got: %s", "iconia", u.Scheme)
	}

	if u.Path == "" {
		return fmt.Errorf("put the domain you want to forward in the path")
	}

	tc := &tls.Config{
		ServerName:         u.Path[1:],
		InsecureSkipVerify: true, // TODO(Cadey): FIX THIS OMG
		NextProtos:         []string{agentToken},
	}

	log.Println("dialing", u.Host)

	conn, err := tls.Dial("tcp", u.Host, tc)
	if err != nil {
		return fmt.Errorf("error dialing remote host %s: %w", u.Host, err)
	}
	defer conn.Close()

	log.Println("connection established")

	sesh, err := yamux.Client(conn, &yamux.Config{
		AcceptBacklog:          1,
		EnableKeepAlive:        true,
		KeepAliveInterval:      time.Minute,
		ConnectionWriteTimeout: 100 * time.Millisecond,
		MaxStreamWindowSize:    262144 * 16,
		Logger:                 log.New(os.Stderr, u.Path+"(yamux): ", log.LstdFlags),
	})
	if err != nil {
		return fmt.Errorf("error connecting to iconia: %w", err)
	}
	defer sesh.Close()

	s := &http.Server{
		Handler: h,
	}

	log.Println("listening for traffic from iconia")

	err = s.Serve(sesh)
	if err != nil {
		return fmt.Errorf("error serving http: %w", err)
	}

	go func() {
		<-ctx.Done()
		s.Shutdown(context.Background())
		sesh.GoAway()
	}()

	return nil
}