# Each rule will append its hint message to the following dictionary. The
# function pointer to the apply function of the rule is used as key. The
# corresponding value is a string, which will be used to produce the hint
# message. The string will be processed using string.format().
MESSAGES = {}


class Possibility(object):
    def __init__(self, root, handler, args=()):
        self.root = root
        self.handler = handler
        self.args = args

    def __str__(self):
        if self.handler in MESSAGES:
            return MESSAGES[self.handler].format(self.root, *self.args)

        return '<Possibility root="%s" handler=%s args=%s>' \
                % (self.root, self.handler.func_name, self.args)

    def __repr__(self):
        return '<Possibility root="%s" handler=%s args=%s>' \
                % (self.root, self.handler.func_name, self.args)

    # TODO: Add unit tests
    def __eq__(self, other):
        return self.handler == other.handler \
               and hash(self.root) == hash(other.root) \
               and self.args == other.args


def filter_duplicates(items):
    unique = []

    for item in items:
        found = False

        for compare in unique:
            if item == compare:
                found = True
                break

        if not found:
            unique.append(item)

    return unique


def pick_suggestion(possibilities):
    # TODO: pick the best suggestion.
    suggestion = 0
    return possibilities[suggestion]


def apply_suggestion(suggestion):
    return suggestion.handler(suggestion.root, suggestion.args)