// Command warp-web serves the Warp web client. It is optional: a Warp
// server runs without it, and anyone who wants the client in the browser
// runs this next to it.
//
//	warp-web -homeserver http://localhost:8008 -listen :8080
package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"log/slog"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"github.com/dariuszjaniak/warp/apps/web/internal/client"
	"github.com/dariuszjaniak/warp/apps/web/internal/host"
)

// Set with -ldflags "-X main.version=...".
var version = "0.0.0-dev"

func main() {
	if err := run(); err != nil {
		fmt.Fprintln(os.Stderr, "warp-web:", err)
		os.Exit(1)
	}
}

func env(key, def string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return def
}

func parseURL(name, raw string) (*url.URL, error) {
	u, err := url.Parse(strings.TrimRight(raw, "/"))
	if err != nil {
		return nil, fmt.Errorf("%s: %w", name, err)
	}
	return u, nil
}

func run() error {
	listen := flag.String("listen", env("WARP_WEB_LISTEN", ":8080"), "address to listen on (WARP_WEB_LISTEN)")
	homeserver := flag.String("homeserver", env("WARP_WEB_HOMESERVER", "http://localhost:8008"),
		"base URL of the homeserver, proxied for the client (WARP_WEB_HOMESERVER)")
	public := flag.String("public-homeserver", env("WARP_WEB_PUBLIC_HOMESERVER", ""),
		"public URL of the homeserver; when set, the browser calls it directly and nothing is proxied (WARP_WEB_PUBLIC_HOMESERVER)")
	logFormat := flag.String("log-format", env("WARP_WEB_LOG_FORMAT", "text"), "text or json (WARP_WEB_LOG_FORMAT)")
	showVersion := flag.Bool("version", false, "print the version and exit")
	flag.Parse()

	if *showVersion {
		fmt.Println("warp-web", version)
		return nil
	}

	var logger *slog.Logger
	switch *logFormat {
	case "json":
		logger = slog.New(slog.NewJSONHandler(os.Stderr, nil))
	case "text":
		logger = slog.New(slog.NewTextHandler(os.Stderr, nil))
	default:
		return fmt.Errorf("unknown log format %q", *logFormat)
	}
	slog.SetDefault(logger)

	opts := host.Options{Logger: logger, Version: version}
	mode, target := "proxy", *homeserver
	if *public != "" {
		u, err := parseURL("public-homeserver", *public)
		if err != nil {
			return err
		}
		opts.PublicHomeserver = u
		mode, target = "direct", *public
	} else {
		u, err := parseURL("homeserver", *homeserver)
		if err != nil {
			return err
		}
		opts.Homeserver = u
	}

	files, built := client.FS()
	if !built {
		logger.Warn("the web client was not built into this binary; serving a placeholder page")
		files = nil
	}
	opts.Client = files

	h, err := host.New(opts)
	if err != nil {
		return err
	}

	srv := &http.Server{
		Addr:              *listen,
		Handler:           h,
		ReadHeaderTimeout: 10 * time.Second,
		// Uploads and downloads of large media pass through here.
		ReadTimeout:    15 * time.Minute,
		WriteTimeout:   15 * time.Minute,
		IdleTimeout:    2 * time.Minute,
		MaxHeaderBytes: 64 << 10,
	}

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	errc := make(chan error, 1)
	go func() {
		logger.Info("warp-web listening", "addr", *listen, "homeserver", target, "mode", mode, "version", version)
		errc <- srv.ListenAndServe()
	}()

	select {
	case err := <-errc:
		if !errors.Is(err, http.ErrServerClosed) {
			return err
		}
		return nil
	case <-ctx.Done():
	}

	logger.Info("shutting down")
	shutdownCtx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
	defer cancel()
	return srv.Shutdown(shutdownCtx)
}