#################################################################################
# The Institute for the Design of Advanced Energy Systems Integrated Platform
# Framework (IDAES IP) was produced under the DOE Institute for the
# Design of Advanced Energy Systems (IDAES).
#
# Copyright (c) 2018-2023 by the software owners: The Regents of the
# University of California, through Lawrence Berkeley National Laboratory,
# National Technology & Engineering Solutions of Sandia, LLC, Carnegie Mellon
# University, West Virginia University Research Corporation, et al.
# All rights reserved.  Please see the files COPYRIGHT.md and LICENSE.md
# for full copyright and license information.
#################################################################################
"""Transformation to replace variables with other variables."""
# TODO: Missing docstrings
# pylint: disable=missing-function-docstring

from pyomo.core.base.transformation import TransformationFactory
from pyomo.core.plugins.transform.hierarchy import NonIsomorphicTransformation
from pyomo.core.expr import current as EXPR
from pyomo.common.config import (
    ConfigBlock,
    ConfigValue,
    document_kwargs_from_configdict,
)
from pyomo.core.base.var import _GeneralVarData, Var
from pyomo.core.base.constraint import Constraint
from pyomo.core.base.expression import Expression
from pyomo.core.base.objective import Objective


__author__ = "John Eslick"


def _is_var(v):
    return isinstance(v, (_GeneralVarData, Var))


@TransformationFactory.register(
    "replace_variables", doc="Replace variables with other variables."
)
@document_kwargs_from_configdict("CONFIG")
class ReplaceVariables(NonIsomorphicTransformation):
    """Replace variables in a model or block with other variables.

    Keyword arguments below are specified for the ``apply_to(instance, **kwargs)``
    method.

    """

    CONFIG = ConfigBlock()
    CONFIG.declare(
        "substitute",
        ConfigValue(
            default=[],
            description="List-like of tuples where the first item in a tuple is a "
            "Pyomo variable to be replaced and the second item in the "
            "tuple is a Pyomo variable to replace it with. This "
            "transformation is not reversible.",
        ),
    )

    @staticmethod
    def replace(instance, substitute):
        # Create the replacement dict. Do some argument validation and indexed
        # var handling
        d = {}
        for r in substitute:
            if not (_is_var(r[0]) and _is_var(r[1])):
                raise TypeError(
                    "Replace only allows variables to be replaced, {} is type {}"
                    " and {} is type {}".format(r[0], type(r[0]), r[1], type(r[1]))
                )
            if r[0].is_indexed() != r[1].is_indexed():
                raise TypeError(
                    "IndexedVars must be replaced by IndexedVars, {} is type {}"
                    " and {} is type {}".format(r[0], type(r[0]), r[1], type(r[1]))
                )
            if r[0].is_indexed() and r[1].is_indexed():
                if not r[0].index_set().issubset(r[1].index_set()):
                    raise ValueError(
                        "The index set of {} must be a subset of"
                        " {}.".format(r[0], r[1])
                    )
                for i in r[0]:
                    d[id(r[0][i])] = r[1][i]
            else:
                # scalar replace
                d[id(r[0])] = r[1]

        # Replacement Visitor
        vis = EXPR.ExpressionReplacementVisitor(
            substitute=d,
            descend_into_named_expressions=True,
            remove_named_expressions=False,
        )

        # Do replacements in Expressions, Constraints, and Objectives
        for c in instance.component_data_objects(
            (Constraint, Expression, Objective), descend_into=True, active=True
        ):
            c.set_value(expr=vis.walk_expression(c.expr))

    def _apply_to(self, instance, **kwds):
        """
        Apply the transformation.  This is called by ``apply_to`` in the
        superclass, and should not be called directly.  ``apply_to`` takes the
        same arguments.

        Args:
            instance: A block or model to apply the transformation to
            substitute: A list-like of two-element list-likes.  Each two element
                list-like specifies a replacement of the first variable by the
                second.  SimpleVar, IndexedVar, _GeneralVarData, and Reference are
                all accepted types.

        Returns:
            None
        """
        config = self.CONFIG(kwds)
        self.replace(instance, config.substitute)
