#  ___________________________________________________________________________
#
#  Pyomo: Python Optimization Modeling Objects
#  Copyright 2017 National Technology and Engineering Solutions of Sandia, LLC
#  Under the terms of Contract DE-NA0003525 with National Technology and 
#  Engineering Solutions of Sandia, LLC, the U.S. Government retains certain 
#  rights in this software.
#  This software is distributed under the 3-clause BSD License.
#  ___________________________________________________________________________

import pyomo.kernel as pmo
from pyomo.core import ConcreteModel, Var, Objective, Constraint, Binary
from pyomo.opt import TerminationCondition
from pyomo.solvers.tests.models.base import _BaseTestModel, register_model

@register_model
class MILP_infeasible1(_BaseTestModel):
    """
    An infeasible mixed-integer linear program
    """

    description = "MILP_infeasible1"
    capabilities = set(['linear', 'integer'])

    def __init__(self):
        _BaseTestModel.__init__(self)
        self.solve_should_fail = True
        self.add_results(self.description+".json")

    def _generate_model(self):
        self.model = ConcreteModel()
        model = self.model
        model._name = self.description

        model.x = Var(within=Binary)
        model.y = Var(within=Binary)
        model.z = Var(within=Binary)

        model.o = Objective(expr=-model.x-model.y-model.z)

        model.c1 = Constraint(expr=model.x+model.y <= 1)
        model.c2 = Constraint(expr=model.x+model.z <= 1)
        model.c3 = Constraint(expr=model.y+model.z <= 1)
        model.c4 = Constraint(expr=model.x+model.y+model.z >= 1.5)

    def warmstart_model(self):
        assert self.model is not None
        model = self.model
        model.x.value = None
        model.y.value = None
        model.z.value = None

    def post_solve_test_validation(self, tester, results):
        if tester is None:
            assert results['Solver'][0]['termination condition'] == \
                TerminationCondition.infeasible
        else:
            tester.assertEqual(results['Solver'][0]['termination condition'],
                               TerminationCondition.infeasible)

@register_model
class MILP_infeasible1_kernel(MILP_infeasible1):

    def _generate_model(self):
        self.model = pmo.block()
        model = self.model
        model._name = self.description

        model.x = pmo.variable(domain=Binary)
        model.y = pmo.variable(domain=Binary)
        model.z = pmo.variable(domain=Binary)

        model.o = pmo.objective(-model.x-model.y-model.z)

        model.c1 = pmo.constraint(model.x+model.y <= 1)
        model.c2 = pmo.constraint(model.x+model.z <= 1)
        model.c3 = pmo.constraint(model.y+model.z <= 1)
        model.c4 = pmo.constraint(model.x+model.y+model.z >= 1.5)