#!/usr/bin/python

import itertools
import optparse
import os
import shlex
import subprocess
import sys
import time


def run(running_jobs, cmd):
    p = subprocess.Popen(cmd, stdin=subprocess.DEVNULL)
    running_jobs.append(p)

def wait_for_completion(max_jobs, running_jobs):
    while len(running_jobs) >= max_jobs:
        time.sleep(1)
        for job in running_jobs:
            if job.poll() is not None:
                running_jobs.remove(job)
                job.wait()

def parse_file(fd):
    def count_indent(s):
        level = 0
        for ch in s:
            if ch == "\t":
                level += 1
            else:
                break
        return level

    for line in fd:
        if not line.strip():
            continue # Ignore blank lines
        level = count_indent(line)
        line = line[level:] # Slice off the indentation
        yield level, line
    yield 0, None

def batch_process(opts, lines):
    running_jobs = []
    cmd = []

    for level, line in lines:
        old_level = len(cmd) - 1
        if level <= old_level:
            run(running_jobs, itertools.chain(*cmd))
            wait_for_completion(opts.jobs, running_jobs)

        # Delete all options that belong to groups that are indented more than
        # this one
        cmd = cmd[:level]
        assert len(cmd) == level

        if line:
            cmd.append(shlex.split(line))

    # Wait for remaining jobs to finish
    wait_for_completion(1, running_jobs)

def make_and_chdir(filename):
    dirname = os.path.splitext(filename)[0] + ".out"
    try:
        os.makedirs(dirname)
    except FileExistsError:
        pass
    os.chdir(dirname)

def parse_args():
    parser = optparse.OptionParser(usage="%prog batchfile1 [batchfile2] ...")
    parser.add_option("-j", "--jobs",
        action="store", dest="jobs", default=1, type="int",
        help="The number of concurrent jobs to run")
    opts, args = parser.parse_args(sys.argv[1:])
    opts.running_jobs = []
    args = map(os.path.abspath, args)
    return opts, args

def main():
    opts, args = parse_args()
    filenames = list(map(os.path.abspath, args))
    for filename in filenames:
        print("Processing", filename)
        make_and_chdir(filename)
        with open(filename) as fd:
            batch_process(opts, parse_file(fd))

if __name__ == "__main__":
    main()