module main

import os

// this is a example script to show you stdin can be used and keep a process open

fn exec(cmd string) (string, int) {
    mut cmd2 := cmd
    mut out := ''
    mut line := ''
    mut rc := 0
    mut p := os.new_process('/bin/bash')

    // there are methods missing to know if stderr/stdout has data as such its better to redirect bot on same FD
    // not so nice trick to run bash in bash and redirect stderr, maybe someone has a better solution
    p.set_args(['-c', 'bash 2>&1'])
    p.set_redirect_stdio()
    p.run()

    p.stdin_write('${cmd2} && echo **OK**')
    os.fd_close(p.stdio_fd[0]) // important: close stdin so cmd can end by itself

    for p.is_alive() {
        line = p.stdout_read()
        println(line)
        // line_err = p.stderr_read() //IF WE CALL STDERR_READ will block
        // we need a mechanism which allows us to check if stderr/stdout has data or it should never block
        // is not a good way, need to use a string buffer, is slow like this
        out += line
        if line.ends_with('**OK**\n') {
            out = out[0..(out.len - 7)]
            break
        }
    }

    // println("read from stdout, should not block")
    // is not really needed but good test to see behaviour
    out += p.stdout_read()
    println('read done')

    println(p.stderr_read())
    p.close()
    p.wait()
    if p.code > 0 {
        rc = 1
        println('ERROR:')
        println(cmd2)
        print(out)
    }

    return out, rc
}

fn main() {
    mut out := ''
    mut rc := 0

    // find files from /tmp excluding files unlistable by current user

    out, rc = exec("find /tmp/ -user \$UID; echo '******'")
    println(out)
    assert out.ends_with('******\n')

    out, rc = exec('echo to stdout')
    assert out.contains('to stdout')

    out, rc = exec('echo to stderr 1>&2')
    assert out.contains('to stderr')

    out, rc = exec('ls /sssss')
    assert rc > 0 // THIS STILL GIVES AN ERROR !

    println('test ok stderr & stdout is indeed redirected')
}