from __future__ import print_function
import subprocess
import os
import argparse
import ast
import multiprocessing
import sys
import threading


FIND_KEYS = {
    'inode': '%i',
    'name': '"%p"',
    'size_B': '%s',
    'disk_kB': '%k',
    'a_time': '%A@',
    'c_time': '%C@',
    'm_time': '%T@',
    'type': '"%Y"',
    'uid': '%U',
    'gid': '%G',
    'perm': '%m',
}


DEFAULT_KEYS = ('name', 'inode', 'size_B', 'm_time')


class SearchDir(object):
    """
    A directory to search for file metadata
    """
    def __init__(self, path, recurse=True):
        self.path = path
        self.recurse = recurse

    def search(self, find_keys=None):
        find_keys = find_keys if find_keys is not None else DEFAULT_KEYS
        cmd = [
            'find' if sys.platform != 'darwin' else 'gfind',
            '-L', self.path,
        ]
        if not self.recurse:
            cmd += ['-maxdepth', '0']
        cmd += [
            '-type', 'f',
            '-printf', '\t'.join(FIND_KEYS[key] for key in find_keys) + '\n'
        ]
        finder = subprocess.Popen(
            cmd,
            stdout=subprocess.PIPE,
        )
        # print('"' + '" "'.join(cmd) + '"')
        try:
            for line in finder.stdout:
                line = line.decode()
                values = line.split('\t')
                yield [ast.literal_eval(val.strip()) for val in values]
        finally:
            finder.terminate()

    def __repr__(self):
        return '%s(%r, recurse=%s)' % (self.__class__.__name__, self.path, self.recurse)


def find_searchdirs(basepath, max_recurse=1):
    """Find all sub-directories to search inside a basepath"""
    basepath = basepath.rstrip(os.sep)
    dirs = []
    for dirpath, dirnames, filenames in os.walk(basepath):
        relpath = os.path.relpath(dirpath, basepath)
        if relpath == '.':
            depth = 0
        else:
            depth = relpath.count(os.sep) + 1
        print('inspecting %r, depth %d, files %d, dirs %d' % (dirpath, depth, len(filenames), len(dirnames)), file=sys.stderr)
        # once we have recursed deeply enough, have the entire directory searched as a task
        if depth >= max_recurse:
            # add all leaf directories for searching
            dirs.extend(
                SearchDir(os.path.join(dirpath, subdirpath), True) for subdirpath in dirnames
            )
            dirnames[:] = []
        # if there are files at intermediate levels, reap them without recursion
        if filenames:
            dirs.append(SearchDir(dirpath, False))
    return dirs


def search_dir(target, push_every=100, find_keys=None):
    """Search all paths inside target"""
    if find_keys is not None:
        dir_iter = target.search(find_keys=find_keys)
    else:
        dir_iter = target.search()
    file_buffer = []
    for file_data in dir_iter:
        file_buffer.append(file_data)
        if len(file_buffer) >= push_every:
            search_dir.queue.put(file_buffer)
            file_buffer = []
    if file_buffer:
        search_dir.queue.put(file_buffer)


def pmap(args):
    return search_dir(*args)


def pinit(queue):
    search_dir.queue = queue


def preduce(queue, find_keys):
    find_keys = find_keys if find_keys is not None else DEFAULT_KEYS
    print(','.join(find_keys))
    while True:
        file_buffer = queue.get()
        if file_buffer is None:
            return
        for file_data in file_buffer:
            line = ','.join(str(item) for item in file_data)
            print(line)


def reap_from_path(path, max_recurse=1, nprocesses=None, push_every=100, find_keys=None):
    dirs = find_searchdirs(path, max_recurse=max_recurse)
    print('Searching %d directories...' % len(dirs), file=sys.stderr)
    queue = multiprocessing.Queue()
    pool = multiprocessing.Pool(processes=nprocesses, initializer=pinit, initargs=(queue,))
    procs = pool.imap_unordered(
        pmap, [
            (target, push_every, find_keys) for target in dirs
        ],
        chunksize=1,
    )
    reaper_thread = threading.Thread(target=preduce, args=(queue, find_keys))
    reaper_thread.daemon = True
    reaper_thread.start()
    for count, _ in enumerate(procs):
        print('%d/%d' % (count + 1, len(dirs)), file=sys.stderr)
    queue.put(None)
    try:
        reaper_thread.join()
    except KeyboardInterrupt:
        pass

if __name__ == '__main__':
    CLI = argparse.ArgumentParser()
    CLI.add_argument(
        '--path',
        default='.',
        help='Path from which to start searching files'
    )
    CLI.add_argument(
        '-r',
        '--max-recurse',
        default=2,
        type=int,
        help='Maximum recursion depth for parallelization'
    )
    CLI.add_argument(
        '--max-output',
        default=float('inf'),
        type=int,
        help='Maximum output to produce, in bytes'
    )
    options = CLI.parse_args()
    reap_from_path(path=options.path, max_recurse=options.max_recurse)