package main

import (
    "flag"
    "fmt"
    "log"
    "os"
    "os/exec"
    "strconv"
    "sync"
    "time"
)

type Color string

const (
    Version = "0.1"

    ColorGreen  = "2"
    ColorYellow = "3"
    ColorGray   = "7"
)

var (
    roIndex int
)

func printLog(color Color, args ...interface{}) {
    format := []interface{}{"- \x1b[3" + color + "m[godemon]"}
    format = append(format, args...)
    format = append(format, "\x1b[0m")
    log.Println(format...)
}

func startGo(file string, args []string, gwg *sync.WaitGroup, kill *chan bool) {
    params := []string{"run", file}
    params = append(params, args...)
    params = append(params, strconv.Itoa(roIndex))
    roIndex += 1

    printLog(ColorGreen, "starting `"+file+"`")

    cmd := exec.Command("go", params...)
    cmd.Stdout, cmd.Stderr = os.Stdout, os.Stderr
    cmd.Start()

    var wg sync.WaitGroup
    wg.Add(1)

    go func() {
        <-*kill
        cmd.Process.Kill()    // - убийство
        wg.Done()
    }()

    cmd.Wait()
    close(*kill)
    wg.Wait()

    printLog(ColorGreen, "clean exit - waiting for changes before restart")

    gwg.Done()
}

func init() {
    flag.Parse()
    log.SetPrefix("\x1b[3" + ColorGray + "m")
}

func main() {
    pattern := *flag.String("w", "**/*.*", "watching glob pattern")

    if len(flag.Args()) == 0 {
        fmt.Println("Usage: godemon gofile [args]\n\n" +
            "See \"godemon --help\" for more.")
        os.Exit(0)
    }

    printLog(ColorYellow, "v"+Version)
    printLog(ColorYellow, "watching:", pattern)

    file := flag.Arg(0) + ".go"
    args := flag.Args()[1:]

    for {
        var wg sync.WaitGroup
        kill := make(chan bool)

        wg.Add(1)
        go startGo(file, args, &wg, &kill)
        time.Sleep(time.Second)
        kill <- true
        wg.Wait()
    }
}