#!/usr/bin/env python3
# Apache License, Version 2.0

"""
This tool optimizes images if their size can be improved.
Currently only performs lossless compression on PNG images using 'pngcrush'.
"""

import multiprocessing
import os

BASEDIR = os.path.abspath(os.path.dirname(__file__))

VERBOSE = False

# Ignore result unless it's at least 5% improvement
FACTOR = 0.05


def find_vcs_root(test, dirs=(".svn", ".git"), default=None):
    import os
    prev, test = None, os.path.abspath(test)
    while prev != test:
        if any(os.path.isdir(os.path.join(test, d)) for d in dirs):
            return test
        prev, test = test, os.path.abspath(os.path.join(test, os.pardir))
    return default


def run(cmd):
    if VERBOSE:
        print(">>> ", cmd)

    import subprocess
    proc = subprocess.Popen(cmd, shell=False)
    proc.wait()
    return proc.returncode


def files_recursive(path, ext_test):
    for dirpath, dirnames, filenames in os.walk(path):
        if dirpath.startswith((".", "_")):
            continue

        for filename in filenames:
            ext = os.path.splitext(filename)[1]
            if ext.lower().endswith(ext_test):
                yield os.path.join(dirpath, filename)


def exec(f):
    # ensure we never used a stale file
    TMP_NAME = f + ".tmp"

    if os.path.exists(TMP_NAME):
        os.remove(TMP_NAME)

    if os.path.exists(TMP_NAME):
        print("Error removing %r" % TMP_NAME)

    cmd = [
        "pngcrush",
        "-brute",
        "-reduce",
        "-m", "7",
        f,
        TMP_NAME,
    ]

    run(cmd)

    if os.path.exists(TMP_NAME):
        s = os.path.getsize(f)
        d = os.path.getsize(TMP_NAME)

        if d != 0:
            fac = d / s
            if fac < (1.0 - FACTOR):
                print("Replacing: %r" % f)
                os.remove(f)
                os.rename(TMP_NAME, f)
            else:
                os.remove(TMP_NAME)


def main():
    vcs_dir = find_vcs_root(BASEDIR)
    if vcs_dir is None:
        print("Can't find version directory, aborting!")
        return

    images = os.path.join(vcs_dir, "manual", "images")

    pool = multiprocessing.Pool()
    pool.map_async(exec, files_recursive(images, ".png"))
    pool.close()
    pool.join()


if __name__ == "__main__":
    main()