#
# This file is part of pyperplan.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>
#

from heuristics.heuristic_base import Heuristic
from task import Operator, Task


class GoalcountHeuristic(Heuristic):
    """
    Implements a goalcount heuristic.
    It counts the number of goal atoms that are unsatisfied in the
    evaluated state.
    """

    def __init__(self, task):
        super().__init__()
        self.goals = task.goals

    def __call__(self, node):
        state = node.state
        goalcount = len([g for g in self.goals if g not in state])
        return goalcount
