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"""Class containing the Alias class."""

import re

class Alias:

    """An alias object.

    In a MUD client terminology, an alias is here to speed up command
    inputs by associating a certain (short) command with a desired
    input.  For instance, "co" could be associated with "crew order".

    """

    def __init__(self, sharp, alias, action):
        self.sharp_engine = sharp
        self.alias = alias
        self.re_alias = self.find_regex(alias)
        self.action = action

        # Set the alias's level
        self.level = sharp.engine.level

    def __repr__(self):
        return "<Alias for {} (level={})>".format(
                repr(self.alias), self.level.name)

    def find_regex(self, alias):
        """Find and compile the alias given as argument.

        If the alias begins with '^', the alias is already a
        regular expression that just needs to be compiled.  Otherwise,
        some automatic actions will be performed on it.

        """
        if alias.startswith("^"):
            return re.compile(alias)

        alias = re.escape(alias)

        # The '*' sign will be replaced by a group
        alias = alias.replace("\\*", "(.*?)")
        alias = "^" + alias + "$"

        return re.compile(alias, re.IGNORECASE)

    def test(self, command):
        """Should the alias be triggered by the text?"""
        if self.re_alias.search(command):
            self.execute()
            return True

        return False

    def execute(self):
        """Execute the alias."""
        self.sharp_engine.execute(self.action)