import re


def cssmin(path):

    with open(path, "r") as f:
        css = f.read()

    # remove comments - this will break a lot of hacks :-P
    css = re.sub(r"\s*/\*\s*\*/", "$$HACK1$$", css)  # preserve IE<6 comment hack
    css = re.sub(r"/\*[\s\S]*?\*/", "", css)
    css = css.replace("$$HACK1$$", "/**/")  # preserve IE<6 comment hack

    # url() doesn't need quotes
    css = re.sub(r'url\((["\'])([^)]*)\1\)', r"url(\2)", css)

    # spaces may be safely collapsed as generated content will collapse them anyway
    css = re.sub(r"\s+", " ", css)

    # shorten collapsable colors: #aabbcc to #abc
    css = re.sub(r"#([0-9a-f])\1([0-9a-f])\2([0-9a-f])\3(\s|;)", r"#\1\2\3\4", css)

    # fragment values can loose zeros
    css = re.sub(r":\s*0(\.\d+([cm]m|e[mx]|in|p[ctx]))\s*;", r":\1;", css)

    return_string = ""
    for rule in re.findall(r"([^{]+){([^}]*)}", css):

        # we don't need spaces around operators
        selectors = [
            re.sub(r"(?<=[\[\(>+=])\s+|\s+(?=[=~^$*|>+\]\)])", r"", selector.strip())
            for selector in rule[0].split(",")
        ]

        # order is important, but we still want to discard repetitions
        properties = {}
        porder = []
        for prop in re.findall("(.*?):(.*?)(;|$)", rule[1]):
            key = prop[0].strip().lower()
            if key not in porder:
                porder.append(key)
            properties[key] = prop[1].strip()

        # output rule if it contains any declarations
        if properties:
            return_string += "%s{%s}" % (
                ",".join(selectors),
                "".join(["%s:%s;" % (key, properties[key]) for key in porder])[:-1],
            )

    return return_string
