import sys
import os
import re
import argparse
import errno
import time
from PIL import Image
from multiprocessing import Pool
from multiprocessing import Value


class State(object):
    def __init__(self):
        self.counter = Value('i', 0)
        self.start_ticks = Value('d', time.process_time())

    def increment(self, n=1):
        with self.counter.get_lock():
            self.counter.value += n

    @property
    def value(self):
        return self.counter.value

    @property
    def start(self):
        return self.start_ticks.value


def init(args):
    global state
    state = args


def main():
    args = parse_args()
    state = State()

    files = find_files(args.directory)

    with Pool(processes=4, initializer=init, initargs=(state, )) as pool:
        pool.map(process_file, files)

    print("{0} files processed in total.".format(state.value))


def parse_args():
    parser = argparse.ArgumentParser(
        description="Create thumbnails for Synology Photo Station.")
    parser.add_argument("--directory", required=True,
                        help="Directory to generate thumbnails for. "
                             "Subdirectories will always be processed.")

    return parser.parse_args()


def find_files(dir):
    valid_exts = ('jpeg', 'jpg', 'bmp', 'gif')
    valid_exts_re = "|".join(
        map((lambda ext: ".*\\.{0}$".format(ext)), valid_exts))

    for root, dirs, files in os.walk(dir):
        for name in files:
            if re.match(valid_exts_re, name, re.IGNORECASE) \
                    and not name.startswith('SYNOPHOTO_THUMB'):
                yield os.path.join(root, name)


def print_progress():
    global state
    state.increment(1)
    processed = state.value
    if processed % 10 == 0:
        print("{0} files processed so far, averaging {1:.2f} files per second."
              .format(processed, float(processed) /
                                 (float(time.process_time() - state.start))))


def process_file(file_path):
    print(file_path)

    (dir, filename) = os.path.split(file_path)
    thumb_dir = os.path.join(dir, 'eaDir_tmp', filename)
    ensure_directory_exists(thumb_dir)

    create_thumbnails(file_path, thumb_dir)

    print_progress()


def ensure_directory_exists(path):
    try:
        os.makedirs(path)
    except OSError as exception:
        if exception.errno != errno.EEXIST:
            raise


def create_thumbnails(source_path, dest_dir):
    im = Image.open(source_path)

    to_generate = (('SYNOPHOTO_THUMB_XL.jpg', 1280),
                   ('SYNOPHOTO_THUMB_B.jpg', 640),
                   ('SYNOPHOTO_THUMB_M.jpg', 320),
                   ('SYNOPHOTO_THUMB_PREVIEW.jpg', 160),
                   ('SYNOPHOTO_THUMB_S.jpg', 120))

    for thumb in to_generate:
        if os.path.exists(os.path.join(dest_dir, thumb[0])):
            continue

        im.thumbnail((thumb[1], thumb[1]), Image.ANTIALIAS)
        im.save(os.path.join(dest_dir, thumb[0]))


if __name__ == "__main__":
    sys.exit(main())