# Copyright (c) 2009 Tim Freeman
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# (This is the standard MIT License, copied from
# http://www.opensource.org/licenses/mit-license.php on 24 Apr 2007.)
#desc Various ways to combine together the utilities of all of the agents other
#desc than the AI to get the AI's utility.

# Selfless_utility_combiner simply adds up all the utilities, so the
# AI is completely fair.
class Selfless_utility_combiner(object):
    def ai_utility(self, utility_dict, do_nothing_utility_dict):
        total_utility = 0.0
        for A in utility_dict:
            total_utility += utility_dict[A]
        return total_utility

# Variable_compassion_uc combines utilities based on a compassion table.
# The compassion table maps person-id's to how much the AI cares about
# that person.
class Compassionate_utility_combiner(object):
    def __init__(self, compassion_table):
        self.compassion_table = compassion_table
    def ai_utility(self, utility_dict, do_nothing_utility_dict):
        total_utility = 0.0
        for A in utility_dict:
            total_utility += self.compassion_table[A] * utility_dict[A]
        return total_utility

# Respectful_utility_combiner is like Compassionate_utility_combiner,
# except we get to say that reducing the other agent's utility (as compared to
# the alternative of doing nothing) reduces the AI's computed utility.
# respect_table gives the ratio between their reduced utility and our
# reduced utility.  If the AI has both compassion and respect for
# an agent, and the AI is considering a plan that reduces their
# utility, then the dysutilities add.
#
# Typically the values in respect_table will be nonnegative.  Negative
# respect or negative compassion can plausibly be called "spite".
class Respectful_utility_combiner(object):
    def __init__(self, compassion_table, respect_table):
        self.compassion_table = compassion_table
        self.respect_table = respect_table
    def ai_utility(self, utility_dict, do_nothing_utility_dict):
        total_utility = 0.0
        for A in utility_dict:
            increment = utility_dict[A] - do_nothing_utility_dict[A]
            if increment > 0:
                total_utility += self.compassion_table[A] * increment
            if increment < 0:
                # increment is negative, self.respect_table[A] is
                # typically positive, so if we get here we'll decrease
                # total_utility.
                total_utility += self.respect_table[A] * increment
        return total_utility