import re


def parse_tags(app_tags):
    """
    Parse given tags value, standardize, and remove duplicates.
    """
    app_tags = [_f for _f in re.split("[,]+ *", app_tags) if _f]
    tags = []

    for tag in app_tags:
        tag = tag.replace('"', '')
        tag = tag.replace("'", '')
        tag = re.sub(r"\s+", '-', tag)
        tag = tag.lower()
        tags.append(tag)

    tags = list(set(tags))
    return tags