import os

from ctypes import c_ulong
from collections import namedtuple

from binascii import crc32

FileInfo = namedtuple("FileRecord", "path, crc32, size, mtime")

def os_walkf(root, filterDir=None, filterName=None, filterExt=None):
    for base, dirs, names in os.walk(root):
        if filterDir:
            dirs[:] = [dir for dir in dirs if filterDir(dir)]

        if filterName:
            if filterExt:
                for name in names:
                    if filterName(name) and filterExt(os.path.splitext(name)[1]):
                        yield os.path.join(base, name)
            else:
                for name in names:
                    if filterName(name):
                        yield os.path.join(base, name)
        else:
            if filterExt:
                for name in names:
                    if filterExt(os.path.splitext(name)[1]):
                        yield os.path.join(base, name)
            else:
                for name in names:
                    yield os.path.join(base, name)

def os_resetdirs(root):
    if os.access(root, os.R_OK):
        for base, dirs, names in os.walk(root):
            for name in names:
                os.remove(os.path.join(base, name))
    else:
        os.makedirs(root)

def os_savefile(path, data, mode="wb"):
    branch, leaf = os.path.split(path)
    if not os.access(branch, os.R_OK):
        os.makedirs(branch)
    open(path, mode).write(data)

def os_fileinfo(path):
    data = open(path, "rb").read()
    return FileInfo(path, crc32(data), len(data), os.stat(path).st_mtime)