// Command tinygit serves signed repository metadata and native Git smart HTTP.
package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"io"
	"net"
	"net/http"
	"os"
	"os/exec"
	"os/signal"
	"syscall"
	"time"

	"github.com/FelineStateMachine/tinyrelay/tinygit"
)

func main() {
	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()
	if err := run(ctx, os.Args[1:], os.Stdout, os.Stderr); err != nil {
		fmt.Fprintln(os.Stderr, "tinygit:", err)
		os.Exit(1)
	}
}

func run(ctx context.Context, args []string, stdout, stderr io.Writer) error {
	flags := flag.NewFlagSet("tinygit", flag.ContinueOnError)
	flags.SetOutput(stderr)
	listen := flags.String("listen", "127.0.0.1:8082", "HTTP listen address (put TLS and request limits in front for public hosting)")
	data := flags.String("data", "./tinygit-data", "dedicated data directory for events.db and bare Git repositories")
	owner := flags.String("owner", "", "required repository owner's lowercase hex Nostr public key")
	publicURL := flags.String("public-url", "", "canonical public HTTP(S) URL")
	if err := flags.Parse(args); err != nil {
		if errors.Is(err, flag.ErrHelp) {
			return nil
		}
		return err
	}
	if flags.NArg() != 0 {
		return errors.New("unexpected positional arguments")
	}
	if _, err := exec.LookPath("git"); err != nil {
		return fmt.Errorf("native Git is required: %w", err)
	}
	handler, err := tinygit.OpenServer(ctx, tinygit.ServerConfig{DataDir: *data, Owner: *owner, PublicURL: *publicURL})
	if err != nil {
		return err
	}
	defer handler.Close()
	listener, err := net.Listen("tcp", *listen)
	if err != nil {
		return err
	}
	defer listener.Close()
	server := &http.Server{
		Handler:           handler,
		ReadHeaderTimeout: 10 * time.Second,
		IdleTimeout:       60 * time.Second,
		MaxHeaderBytes:    1 << 20,
		BaseContext:       func(net.Listener) context.Context { return ctx },
	}
	done := make(chan error, 1)
	go func() { done <- server.Serve(listener) }()
	fmt.Fprintln(stdout, "tinygit listening on http://"+listener.Addr().String())
	select {
	case err := <-done:
		if errors.Is(err, http.ErrServerClosed) {
			return nil
		}
		return err
	case <-ctx.Done():
		shutdown, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		err := server.Shutdown(shutdown)
		if err != nil {
			_ = server.Close()
		}
		serveErr := <-done
		if errors.Is(serveErr, http.ErrServerClosed) {
			serveErr = nil
		}
		return errors.Join(err, serveErr)
	}
}