gohrl/main.go

package main

import (
	"bytes"
	"fmt"
	"hash/fnv"
	"io"
	"io/fs"
	"log"
	"os"
	"os/exec"
	"os/signal"
	"path/filepath"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/mqu/go-notify"
)

const iconpath = "/data/drive/jan/hotreload/icon.png"

var enableNotify = os.Getenv("GOHRL_NO_NOTIFY") == ""

func logg(v ...any) {
	spr := fmt.Sprintln(v...)
	fmt.Print("\x1B[32m", time.Now().Format("15:04:05.000"), " \x1B[93m", spr[:len(spr)-1], "\x1B[0m\n")
}

func main() {
	notify.Init("gohrl")

	name := os.Args[1]
	args := os.Args[2:]

	cont := true

	sc := make(chan os.Signal, 1)
	exit := make(chan struct{}, 1)
	change := make(chan struct{}, 1)
	updated := make(chan struct{}, 1)

	signal.Notify(sc, syscall.SIGINT, syscall.SIGTERM, os.Interrupt, os.Kill)

	tdir, err := os.MkdirTemp("", "gohrl-build-*")
	if err != nil {
		log.Fatalln(err)
	}
	defer func() {
		logg(os.RemoveAll(tdir))
	}()

	var changes []string
	go func() {
		hash()
		var ok bool

		for {
			time.Sleep(time.Second)

			changes, ok = hash()
			if !ok {
				continue
			}

			change <- struct{}{}
		}
	}()

	// build loop
	go func() {
		//var not = notify.NotificationNew("updating", strings.Join(changes, "\n"), iconpath)

		change <- struct{}{} // make sure it builds once off the bat

		for cont {
			<-change
			logg("change detected", changes, "building")
			//not.Update("updating", strings.Join(changes, "\n"), iconpath)
			//not.SetTimeout(500)
			//not.Show()

			cmd := exec.Command("go", "build", "-o", tdir+"/build", name)
			cmd.Stdout = os.Stdout
			cmd.Stderr = os.Stderr
			cmd.Stdin = os.Stdin
			err := cmd.Run()

			if err != nil {
				logg("possible error, waiting for next update")
				continue
			}

			updated <- struct{}{}
		}
	}()

	select {
	case <-sc:
		return
	case <-updated:
	}

	var wg sync.WaitGroup
	wg.Add(1)

	// application run loop
	go func() {
		var not = notify.NotificationNew("app running", "", iconpath)

		var rapid = 0

		for cont {
			logg("starting:", name, args)

			cmd := exec.Command(tdir+"/build", args...)
			cmd.Stdout = os.Stdout
			cmd.Stderr = os.Stderr
			cmd.Stdin = os.Stdin

			kill := func() {
				syscall.Kill(cmd.Process.Pid, syscall.SIGINT)

				t := time.NewTimer(time.Second * 10)

				select {
				case <-exit:
					return
				case <-t.C:
					logg("program didn't exit: killing")
					syscall.Kill(cmd.Process.Pid, syscall.SIGTERM)
				}
			}

			startedAt := time.Now()
			cmd.Start()
			go func() {
				cmd.Wait()
				exit <- struct{}{}
			}()

			if not != nil && enableNotify {
				not.Update("update applied", strings.Join(changes, "\n"), iconpath)
				not.SetTimeout(1000)
				not.Show()
			}

			select {
			case <-sc:
				logg("inturrupting")
				cont = false
				kill()
			case <-updated:
				logg("restarting to apply update")
				//not.Update("restarting to apply updates", strings.Join(changes, "\n"), iconpath)
				//not.SetTimeout(1000)
				//not.Show()

				kill()
			case <-exit:
				logg("program exited on its own...")

				switch t := time.Since(startedAt); {
				case t < time.Second*3:
					rapid++
				case t > time.Minute:
					rapid = 0
				default:
					rapid--
				}

				if rapid > 2 {
					multip := rapid * (rapid / 2)
					if enableNotify {
						not.Update("delaying restart due to rapid exiting", fmt.Sprint(time.Second*time.Duration(multip)), iconpath)
						not.Show()
					}

					timer := time.NewTimer(time.Second * time.Duration(multip))
					select {
					case <-timer.C:
					case <-updated:
					case <-sc:
						os.Exit(1)
					}
				}
			}

			time.Sleep(time.Second)
			logg("releasing")
			cmd.Process.Release()
		}

		wg.Done()
	}()

	wg.Wait()
}

var hashes = make(map[string][]byte)

var pt = false

func hash() ([]string, bool) {
	dif := false
	var changes = []string{}

	err := filepath.WalkDir(".", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			logg(err)
		}
		if !strings.HasSuffix(d.Name(), ".go") {
			return nil
		}

		dat, err := os.Open(filepath.Join(path))
		if err != nil {
			return err
		}
		defer dat.Close()

		h := fnv.New128()
		_, err = io.Copy(h, dat)
		if err != nil {
			return err
		}

		var b []byte
		b = h.Sum(b)

		if !bytes.Equal(hashes[dat.Name()], b) {
			if pt {
				logg(dat.Name(), "changed, recompiling and reloading")
				changes = append(changes, dat.Name())
			}
			dif = true
		}
		hashes[dat.Name()] = b

		return nil
	})
	if err != nil {
		log.Fatalln(err)
	}
	pt = true

	return changes, dif
}