package main

import (
	"crypto/rand"
	"embed"
	"encoding/base64"
	"flag"
	"fmt"
	"io/fs"
	"log"
	"net"
	"net/http"
	"os"
	"os/exec"
	"runtime"
	"time"
)

//go:embed web/*
var embeddedWeb embed.FS

var version = "dev"

func main() {
	noOpen := flag.Bool("no-open", false, "do not open the browser automatically")
	publicMode := flag.Bool("public", false, "run the public web service")
	listenAddress := flag.String("listen", "0.0.0.0:8080", "public web service listen address")
	publicOrigin := flag.String("origin", "https://lrc.flechazo.xin", "allowed public browser origin")
	downloadDirectory := flag.String("downloads", "", "directory containing optional local-app downloads")
	healthcheckURL := flag.String("healthcheck", "", "check a running service and exit")
	showVersion := flag.Bool("version", false, "print version and exit")
	flag.Parse()
	if *showVersion {
		fmt.Println(version)
		return
	}
	if *healthcheckURL != "" {
		client := &http.Client{Timeout: 3 * time.Second}
		response, err := client.Get(*healthcheckURL)
		if err != nil {
			log.Fatal(err)
		}
		_ = response.Body.Close()
		if response.StatusCode != http.StatusOK {
			log.Fatalf("healthcheck returned HTTP %d", response.StatusCode)
		}
		return
	}
	if *publicMode {
		runPublic(*listenAddress, *publicOrigin, *downloadDirectory)
		return
	}
	runLocal(*noOpen)
}

func runLocal(noOpen bool) {

	listener, err := net.Listen("tcp4", "127.0.0.1:0")
	if err != nil {
		log.Fatal(err)
	}
	token, err := randomToken()
	if err != nil {
		log.Fatal(err)
	}
	webFS, err := fs.Sub(embeddedWeb, "web")
	if err != nil {
		log.Fatal(err)
	}

	baseURL := "http://" + listener.Addr().String()
	app := newApp(baseURL, token, webFS, newQQClient())
	server := &http.Server{
		Handler:           app.routes(),
		ReadHeaderTimeout: 5 * time.Second,
		ReadTimeout:       15 * time.Second,
		WriteTimeout:      30 * time.Second,
		IdleTimeout:       60 * time.Second,
		MaxHeaderBytes:    16 * 1024,
	}

	launchURL := baseURL + "/start?t=" + token
	fmt.Printf("LRC Local %s\n仅监听本机：%s\n关闭此窗口即可停止。\n", version, baseURL)
	if !noOpen {
		go func() {
			time.Sleep(150 * time.Millisecond)
			if err := openBrowser(launchURL); err != nil {
				log.Printf("无法自动打开浏览器，请手动访问：%s", launchURL)
			}
		}()
	} else {
		fmt.Printf("请访问：%s\n", launchURL)
	}
	if err := server.Serve(listener); err != nil && err != http.ErrServerClosed {
		log.Fatal(err)
	}
}

func runPublic(listenAddress, origin, downloadDirectory string) {
	listener, err := net.Listen("tcp4", listenAddress)
	if err != nil {
		log.Fatal(err)
	}
	webFS, err := fs.Sub(embeddedWeb, "web")
	if err != nil {
		log.Fatal(err)
	}
	app, err := newPublicApp(origin, downloadDirectory, webFS, newQQClient())
	if err != nil {
		log.Fatal(err)
	}
	server := &http.Server{
		Handler:           app.routes(),
		ReadHeaderTimeout: 5 * time.Second,
		ReadTimeout:       15 * time.Second,
		WriteTimeout:      5 * time.Minute,
		IdleTimeout:       60 * time.Second,
		MaxHeaderBytes:    16 * 1024,
	}
	log.Printf("LRC Local %s public service listening on %s", version, listener.Addr())
	if err := server.Serve(listener); err != nil && err != http.ErrServerClosed {
		log.Fatal(err)
	}
}

func randomToken() (string, error) {
	buf := make([]byte, 32)
	if _, err := rand.Read(buf); err != nil {
		return "", err
	}
	return base64.RawURLEncoding.EncodeToString(buf), nil
}

func openBrowser(url string) error {
	var command *exec.Cmd
	switch runtime.GOOS {
	case "windows":
		command = exec.Command("rundll32", "url.dll,FileProtocolHandler", url)
	case "darwin":
		command = exec.Command("open", url)
	default:
		command = exec.Command("xdg-open", url)
	}
	command.Stdout = os.Stdout
	command.Stderr = os.Stderr
	return command.Start()
}