use std.runtime;
use std.os;
use std.io;
use std.unix;

use std.subprocess;

runtime.windows.set_utf8_output();

var os_time = func() {
    return "\e[33;1m[" ~ os.time() ~ "]\e[0m ";
}

var err_hd = func() {
    return "\e[91;1m[error]\e[0m ";
}

var info_hd = func() {
    return "\e[96;1m[info]\e[0m ";
}

var modified_hd = func() {
    return "\e[92;1m[modified]\e[0m ";
}

var usage = func() {
    println(
        os_time(),
        info_hd(),
        "\e[1musage: nasal watchdog.nas <filename> [\"argv\"]\e[0m"
    );
}

var argv = runtime.argv();
if (size(argv)<1) {
    println(
        os_time(),
        err_hd(),
        "\e[1mneed correct file path to watch\e[0m"
    );
    usage();
    exit(-1);
}

var filename = argv[0];
if (!io.exists(filename)) {
    println(
        os_time(),
        err_hd(),
        "\e[1mfile <",
        filename,
        "> does not exist\e[0m"
    );
    usage();
    exit(-1);
}

var args = [];
if (size(argv)==2) {
    println(
        os_time(),
        info_hd(),
        "\e[1mwith argument(s) ",
        argv[1],
        "\e[0m"
    );
    args = split(" ", argv[1]);
}

var modified_time = io.fstat(filename).st_mtime;
println(os_time(), info_hd(), "\e[1mwatching ", filename, " ..\e[0m");
while(1) {
    unix.sleep(1);
    if (!io.exists(filename)) {
        println(
            os_time(),
            err_hd(),
            "\e[1mfile <",
            filename,
            "> does not exist\e[0m"
        );
        break;
    }

    var latest_modified_time = io.fstat(filename).st_mtime;
    if (latest_modified_time!=modified_time) {
        modified_time = latest_modified_time;
        println(os_time(), modified_hd(), "\e[1m", filename, "\e[0m");

        var cmd = (os.platform()=="windows"?"":"./") ~ "nasal " ~ filename;
        foreach(var i; args) {
            cmd ~= " " ~ i;
        }
        println(
            os_time(),
            info_hd(),
            "\e[1mexecuting command \"",
            cmd,
            "\"\e[0m"
        );

        var subproc = subprocess.create(["nasal", filename]~args);

        unix.sleep(2);
        var ret = subprocess.terminate(subproc);

        println(
            os_time(),
            ret!=0? err_hd():info_hd(),
            "\e[1mprocess returned " ~ ret ~ "\e[0m"
        );
    }
}