#     Copyright 2021, Kay Hayen, mailto:kay.hayen@gmail.com
#
#     Part of "Nuitka", an optimizing Python compiler that is compatible and
#     integrates with CPython, but also works on its own.
#
#     Licensed under the Apache License, Version 2.0 (the "License");
#     you may not use this file except in compliance with the License.
#     You may obtain a copy of the License at
#
#        http://www.apache.org/licenses/LICENSE-2.0
#
#     Unless required by applicable law or agreed to in writing, software
#     distributed under the License is distributed on an "AS IS" BASIS,
#     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#     See the License for the specific language governing permissions and
#     limitations under the License.
#
""" Reformulation of assignment statements.

Consult the developer manual for information. TODO: Add ability to sync
source code comments with developer manual sections.

"""

from nuitka.nodes.AssignNodes import (
    StatementAssignmentVariable,
    StatementAssignmentVariableName,
    StatementDelVariable,
    StatementDelVariableName,
    StatementReleaseVariable,
)
from nuitka.nodes.AttributeNodes import (
    ExpressionAttributeLookup,
    StatementAssignmentAttribute,
    StatementDelAttribute,
)
from nuitka.nodes.BuiltinIteratorNodes import (
    ExpressionBuiltinIter1,
    ExpressionBuiltinIterForUnpack,
    StatementSpecialUnpackCheck,
)
from nuitka.nodes.BuiltinLenNodes import ExpressionBuiltinLen
from nuitka.nodes.BuiltinNextNodes import ExpressionSpecialUnpack
from nuitka.nodes.BuiltinTypeNodes import ExpressionBuiltinList
from nuitka.nodes.ComparisonNodes import makeComparisonExpression
from nuitka.nodes.ConditionalNodes import makeStatementConditional
from nuitka.nodes.ConstantRefNodes import (
    ExpressionConstantEllipsisRef,
    makeConstantRefNode,
)
from nuitka.nodes.ContainerMakingNodes import makeExpressionMakeTupleOrConstant
from nuitka.nodes.ContainerOperationNodes import ExpressionListOperationPop
from nuitka.nodes.NodeMakingHelpers import (
    makeRaiseExceptionExpressionFromTemplate,
)
from nuitka.nodes.OperatorNodes import (
    makeBinaryOperationNode,
    makeExpressionOperationBinaryInplace,
)
from nuitka.nodes.OutlineNodes import ExpressionOutlineBody
from nuitka.nodes.ReturnNodes import StatementReturn
from nuitka.nodes.SliceNodes import (
    ExpressionSliceLookup,
    StatementAssignmentSlice,
    StatementDelSlice,
    makeExpressionBuiltinSlice,
)
from nuitka.nodes.SubscriptNodes import (
    ExpressionSubscriptLookup,
    StatementAssignmentSubscript,
    StatementDelSubscript,
)
from nuitka.nodes.VariableRefNodes import (
    ExpressionTempVariableRef,
    ExpressionVariableLocalNameRef,
    ExpressionVariableNameRef,
)
from nuitka.PythonVersions import python_version

from .ReformulationImportStatements import getFutureSpec
from .ReformulationTryFinallyStatements import makeTryFinallyStatement
from .SyntaxErrors import raiseSyntaxError
from .TreeHelpers import (
    buildAnnotationNode,
    buildNode,
    getKind,
    makeStatementsSequence,
    makeStatementsSequenceFromStatement,
    makeStatementsSequenceFromStatements,
    makeStatementsSequenceOrStatement,
    mangleName,
)


def buildExtSliceNode(provider, node, source_ref):
    elements = []

    for dim in node.slice.dims:
        dim_kind = getKind(dim)

        if dim_kind == "Slice":
            lower = buildNode(provider, dim.lower, source_ref, True)
            upper = buildNode(provider, dim.upper, source_ref, True)
            step = buildNode(provider, dim.step, source_ref, True)

            element = makeExpressionBuiltinSlice(
                start=lower, stop=upper, step=step, source_ref=source_ref
            )
        elif dim_kind == "Ellipsis":
            element = ExpressionConstantEllipsisRef(source_ref=source_ref)
        elif dim_kind == "Index":
            element = buildNode(
                provider=provider, node=dim.value, source_ref=source_ref
            )
        else:
            assert False, dim

        elements.append(element)

    return makeExpressionMakeTupleOrConstant(
        elements=elements, user_provided=True, source_ref=source_ref
    )


def buildAssignmentStatementsFromDecoded(provider, kind, detail, source, source_ref):
    # This is using many variable names on purpose, so as to give names to the
    # unpacked detail values, and has many branches due to the many cases
    # dealt with, pylint: disable=too-many-branches,too-many-locals,too-many-statements

    if kind == "Name":
        return StatementAssignmentVariableName(
            provider=provider,
            variable_name=detail,
            source=source,
            source_ref=source_ref,
        )
    elif kind == "Attribute":
        lookup_source, attribute_name = detail

        return StatementAssignmentAttribute(
            expression=lookup_source,
            attribute_name=mangleName(attribute_name, provider),
            source=source,
            source_ref=source_ref,
        )
    elif kind == "Subscript":
        subscribed, subscript = detail

        return StatementAssignmentSubscript(
            subscribed=subscribed,
            subscript=subscript,
            source=source,
            source_ref=source_ref,
        )
    elif kind == "Slice":
        lookup_source, lower, upper = detail

        # For Python3 there is no slicing operation, this is always done
        # with subscript using a slice object. For Python2, it is only done
        # if no "step" is provided.
        use_sliceobj = python_version >= 0x300

        if use_sliceobj:
            return StatementAssignmentSubscript(
                subscribed=lookup_source,
                source=source,
                subscript=makeExpressionBuiltinSlice(
                    start=lower, stop=upper, step=None, source_ref=source_ref
                ),
                source_ref=source_ref,
            )

        else:
            return StatementAssignmentSlice(
                expression=lookup_source,
                lower=lower,
                upper=upper,
                source=source,
                source_ref=source_ref,
            )
    elif kind == "Tuple":
        temp_scope = provider.allocateTempScope("tuple_unpack")

        source_iter_var = provider.allocateTempVariable(
            temp_scope=temp_scope, name="source_iter"
        )

        element_vars = [
            provider.allocateTempVariable(
                temp_scope=temp_scope, name="element_%d" % (element_index + 1)
            )
            for element_index in range(len(detail))
        ]

        starred_list_var = None
        starred_index = None

        statements = []

        for element_index, element in enumerate(detail):
            if element[0] == "Starred":
                if starred_index is not None:
                    raiseSyntaxError(
                        "two starred expressions in assignment"
                        if python_version < 0x390
                        else "multiple starred expressions in assignment",
                        source_ref.atColumnNumber(0),
                    )

                starred_index = element_index

        for element_index, element in enumerate(detail):
            element_var = element_vars[element_index]

            if starred_list_var is not None:
                statements.insert(
                    starred_index + 1,
                    StatementAssignmentVariable(
                        variable=element_var,
                        source=ExpressionListOperationPop(
                            list_arg=ExpressionTempVariableRef(
                                variable=starred_list_var, source_ref=source_ref
                            ),
                            source_ref=source_ref,
                        ),
                        source_ref=source_ref,
                    ),
                )
            elif element[0] != "Starred":
                statements.append(
                    StatementAssignmentVariable(
                        variable=element_var,
                        source=ExpressionSpecialUnpack(
                            value=ExpressionTempVariableRef(
                                variable=source_iter_var, source_ref=source_ref
                            ),
                            count=element_index + 1,
                            expected=starred_index or len(detail),
                            starred=starred_index is not None,
                            source_ref=source_ref,
                        ),
                        source_ref=source_ref,
                    )
                )
            else:
                assert starred_index == element_index
                starred_list_var = element_var

                statements.append(
                    StatementAssignmentVariable(
                        variable=element_var,
                        source=ExpressionBuiltinList(
                            value=ExpressionTempVariableRef(
                                variable=source_iter_var, source_ref=source_ref
                            ),
                            source_ref=source_ref,
                        ),
                        source_ref=source_ref,
                    )
                )

        if starred_list_var is None:
            statements.append(
                StatementSpecialUnpackCheck(
                    iterator=ExpressionTempVariableRef(
                        variable=source_iter_var, source_ref=source_ref
                    ),
                    count=len(detail),
                    source_ref=source_ref,
                )
            )
        else:
            statements.insert(
                starred_index + 1,
                makeStatementConditional(
                    condition=makeComparisonExpression(
                        comparator="Lt",
                        left=ExpressionBuiltinLen(
                            value=ExpressionTempVariableRef(
                                variable=starred_list_var, source_ref=source_ref
                            ),
                            source_ref=source_ref,
                        ),
                        right=makeConstantRefNode(
                            constant=len(statements) - starred_index - 1,
                            source_ref=source_ref,
                        ),
                        source_ref=source_ref,
                    ),
                    yes_branch=makeRaiseExceptionExpressionFromTemplate(
                        exception_type="ValueError",
                        template="""\
not enough values to unpack (expected at least %d, got %%d)"""
                        % (len(statements) - 1),
                        template_args=makeBinaryOperationNode(
                            operator="Add",
                            left=ExpressionBuiltinLen(
                                value=ExpressionTempVariableRef(
                                    variable=starred_list_var, source_ref=source_ref
                                ),
                                source_ref=source_ref,
                            ),
                            right=makeConstantRefNode(
                                constant=starred_index, source_ref=source_ref
                            ),
                            source_ref=source_ref,
                        ),
                        source_ref=source_ref,
                    ).asStatement(),
                    no_branch=None,
                    source_ref=source_ref,
                ),
            )

        if python_version >= 0x370:
            iter_creation_class = ExpressionBuiltinIterForUnpack
        else:
            iter_creation_class = ExpressionBuiltinIter1

        statements = [
            StatementAssignmentVariable(
                variable=source_iter_var,
                source=iter_creation_class(value=source, source_ref=source_ref),
                source_ref=source_ref,
            ),
            makeTryFinallyStatement(
                provider=provider,
                tried=statements,
                final=(
                    StatementReleaseVariable(
                        variable=source_iter_var, source_ref=source_ref
                    ),
                ),
                source_ref=source_ref,
            ),
        ]

        # When all is done, copy over to the actual assignment targets, starred
        # or not makes no difference here anymore.
        for element_index, element in enumerate(detail):
            if element[0] == "Starred":
                element = element[1]

            element_var = element_vars[element_index]

            statements.append(
                buildAssignmentStatementsFromDecoded(
                    provider=provider,
                    kind=element[0],
                    detail=element[1],
                    source=ExpressionTempVariableRef(
                        variable=element_var, source_ref=source_ref
                    ),
                    source_ref=source_ref,
                )
            )

            # Need to release temporary variables right after successful
            # usage.
            statements.append(
                StatementDelVariable(
                    variable=element_var, tolerant=True, source_ref=source_ref
                )
            )

        final_statements = []

        for element_var in element_vars:
            final_statements.append(
                StatementReleaseVariable(variable=element_var, source_ref=source_ref)
            )

        return makeTryFinallyStatement(
            provider=provider,
            tried=statements,
            final=final_statements,
            source_ref=source_ref,
        )
    elif kind == "Starred":
        raiseSyntaxError(
            "starred assignment target must be in a list or tuple",
            source_ref.atColumnNumber(0),
        )
    else:
        assert False, (kind, source_ref, detail)


def buildAssignmentStatements(
    provider, node, source, source_ref, allow_none=False, temp_provider=None
):
    if node is None and allow_none:
        return None

    if temp_provider is None:
        temp_provider = provider

    kind, detail = decodeAssignTarget(
        provider=provider, node=node, source_ref=source_ref
    )

    return buildAssignmentStatementsFromDecoded(
        provider=provider,
        kind=kind,
        detail=detail,
        source=source,
        source_ref=source_ref,
    )


def decodeAssignTarget(provider, node, source_ref, allow_none=False):
    # Many cases to deal with, because of the different assign targets,
    # pylint: disable=too-many-branches,too-many-return-statements

    if node is None and allow_none:
        return None

    if type(node) is str:
        return "Name", mangleName(node, provider)

    kind = getKind(node)

    if hasattr(node, "ctx"):
        assert getKind(node.ctx) in ("Store", "Del")

    if kind == "Name":
        return kind, mangleName(node.id, provider)
    elif kind == "Attribute":
        return kind, (buildNode(provider, node.value, source_ref), node.attr)
    elif kind == "Subscript":
        slice_kind = getKind(node.slice)

        if slice_kind == "Index":
            return (
                "Subscript",
                (
                    buildNode(provider, node.value, source_ref),
                    buildNode(provider, node.slice.value, source_ref),
                ),
            )
        elif slice_kind == "Slice":
            lower = buildNode(provider, node.slice.lower, source_ref, True)
            upper = buildNode(provider, node.slice.upper, source_ref, True)

            if node.slice.step is not None:
                step = buildNode(provider, node.slice.step, source_ref)

                return (
                    "Subscript",
                    (
                        buildNode(provider, node.value, source_ref),
                        makeExpressionBuiltinSlice(
                            start=lower, stop=upper, step=step, source_ref=source_ref
                        ),
                    ),
                )
            else:
                return (
                    "Slice",
                    (buildNode(provider, node.value, source_ref), lower, upper),
                )
        elif slice_kind == "ExtSlice":
            return (
                "Subscript",
                (
                    buildNode(provider, node.value, source_ref),
                    buildExtSliceNode(provider, node, source_ref),
                ),
            )
        elif slice_kind == "Ellipsis":
            return (
                "Subscript",
                (
                    buildNode(provider, node.value, source_ref),
                    ExpressionConstantEllipsisRef(source_ref=source_ref),
                ),
            )
        elif python_version >= 0x390:
            return (
                "Subscript",
                (
                    buildNode(provider, node.value, source_ref),
                    buildNode(provider, node.slice, source_ref),
                ),
            )
        else:
            assert False, slice_kind
    elif kind in ("Tuple", "List"):
        return (
            "Tuple",
            tuple(
                decodeAssignTarget(
                    provider=provider,
                    node=sub_node,
                    source_ref=source_ref,
                    allow_none=False,
                )
                for sub_node in node.elts
            ),
        )
    elif kind == "Starred":
        return (
            "Starred",
            decodeAssignTarget(
                provider=provider,
                node=node.value,
                source_ref=source_ref,
                allow_none=False,
            ),
        )
    else:
        assert False, (source_ref, kind)


def buildAssignNode(provider, node, source_ref):
    assert len(node.targets) >= 1, source_ref

    # Evaluate the right hand side first, so it can get names provided
    # before the left hand side exists.
    source = buildNode(provider, node.value, source_ref)

    if len(node.targets) == 1:
        # Simple assignment case, one source, one target.

        return buildAssignmentStatements(
            provider=provider,
            node=node.targets[0],
            source=source,
            source_ref=source_ref,
        )
    else:
        # Complex assignment case, one source, but multiple targets. We keep the
        # source in a temporary variable, and then assign from it multiple
        # times.

        temp_scope = provider.allocateTempScope("assign_unpack")

        tmp_source = provider.allocateTempVariable(
            temp_scope=temp_scope, name="assign_source"
        )

        statements = [
            StatementAssignmentVariable(
                variable=tmp_source, source=source, source_ref=source_ref
            )
        ]

        for target in node.targets:
            statements.append(
                buildAssignmentStatements(
                    provider=provider,
                    node=target,
                    source=ExpressionTempVariableRef(
                        variable=tmp_source, source_ref=source_ref
                    ),
                    source_ref=source_ref,
                )
            )

        return makeTryFinallyStatement(
            provider=provider,
            tried=statements,
            final=StatementReleaseVariable(variable=tmp_source, source_ref=source_ref),
            source_ref=source_ref,
        )


def buildAnnAssignNode(provider, node, source_ref):
    """Python3.6 annotation assignment."""
    # There are many cases to deal with here.

    if provider.isCompiledPythonModule() or provider.isExpressionClassBody():
        provider.markAsNeedsAnnotationsDictionary()

    # Evaluate the right hand side first, so it can get names provided
    # before the left hand side exists.
    statements = []

    if node.value is not None:
        source = buildNode(provider, node.value, source_ref)

        statements.append(
            buildAssignmentStatements(
                provider=provider,
                node=node.target,
                source=source,
                source_ref=source_ref,
            )
        )

        # Only name referencing annotations are effective right now.
        if statements[-1].isStatementAssignmentVariableName():
            variable_name = statements[-1].getVariableName()
        else:
            variable_name = None
    else:
        # Only name referencing annotations are effective right now.
        kind, detail = decodeAssignTarget(
            provider=provider, node=node.target, source_ref=source_ref
        )

        if kind == "Name":
            variable_name = detail
        else:
            variable_name = None

    # Only annotations for modules and classes are really made, for functions
    # they are ignored like comments.
    if variable_name is not None:
        if provider.isExpressionClassBody() or provider.isCompiledPythonModule():
            annotation = buildAnnotationNode(provider, node.annotation, source_ref)

            # TODO: As CPython core considers this implementation detail, and it seems
            # mostly useless to support having this as a closure taken name after a
            # __del__ on annotations, we might do this except in full compat mode. It
            # will produce only noise for all annotations in classes otherwise.
            if python_version < 0x370:
                ref_class = ExpressionVariableLocalNameRef
            else:
                ref_class = ExpressionVariableNameRef

            statements.append(
                StatementAssignmentSubscript(
                    subscribed=ref_class(
                        provider=provider,
                        variable_name="__annotations__",
                        source_ref=source_ref,
                    ),
                    subscript=makeConstantRefNode(
                        constant=variable_name, source_ref=source_ref
                    ),
                    source=annotation,
                    source_ref=source_ref,
                )
            )
        else:
            # Functions.
            if node.simple:
                provider.getVariableForAssignment(variable_name)

    return makeStatementsSequence(
        statements=statements, allow_none=True, source_ref=source_ref
    )


def buildDeleteStatementFromDecoded(provider, kind, detail, source_ref):
    # This function is a case driven by returns, pylint: disable=too-many-return-statements

    if kind in ("Name", "Name_Exception"):
        # Note: Name_Exception is a "del" for exception handlers that doesn't
        # insist on the variable being defined, user code may do it too, and
        # that will be fine, so make that tolerant.
        return StatementDelVariableName(
            provider=provider,
            variable_name=detail,
            tolerant=kind == "Name_Exception",
            source_ref=source_ref,
        )
    elif kind == "Attribute":
        lookup_source, attribute_name = detail

        return StatementDelAttribute(
            expression=lookup_source,
            attribute_name=mangleName(attribute_name, provider),
            source_ref=source_ref,
        )
    elif kind == "Subscript":
        subscribed, subscript = detail

        return StatementDelSubscript(
            subscribed=subscribed, subscript=subscript, source_ref=source_ref
        )
    elif kind == "Slice":
        lookup_source, lower, upper = detail

        use_sliceobj = python_version >= 0x300

        if use_sliceobj:
            return StatementDelSubscript(
                subscribed=lookup_source,
                subscript=makeExpressionBuiltinSlice(
                    start=lower, stop=upper, step=None, source_ref=source_ref
                ),
                source_ref=source_ref,
            )
        else:
            return StatementDelSlice(
                expression=lookup_source,
                lower=lower,
                upper=upper,
                source_ref=source_ref,
            )
    elif kind == "Tuple":
        result = []

        for sub_node in detail:
            result.append(
                buildDeleteStatementFromDecoded(
                    provider=provider,
                    kind=sub_node[0],
                    detail=sub_node[1],
                    source_ref=source_ref,
                )
            )

        if result:
            return makeStatementsSequenceOrStatement(
                statements=result, source_ref=source_ref
            )
        else:
            return None
    else:
        assert False, (kind, detail, source_ref)


def buildDeleteNode(provider, node, source_ref):
    # Build "del" statements.

    # Note: Each delete is sequential. It can succeed, and the failure of a
    # later one does not prevent the former to succeed. We can therefore have a
    # simple sequence of "del" statements that each only delete one thing
    # therefore. In output tree "del" therefore only ever has single arguments.

    statements = []

    for target in node.targets:
        kind, detail = decodeAssignTarget(
            provider=provider, node=target, source_ref=source_ref
        )

        statements.append(
            buildDeleteStatementFromDecoded(
                provider=provider, kind=kind, detail=detail, source_ref=source_ref
            )
        )

    return makeStatementsSequenceOrStatement(
        statements=statements, source_ref=source_ref
    )


def _buildInplaceAssignVariableNode(
    provider, variable_name, operator, expression, source_ref
):
    inplace_node = makeExpressionOperationBinaryInplace(
        operator=operator,
        left=ExpressionVariableNameRef(
            provider=provider, variable_name=variable_name, source_ref=source_ref
        ),
        right=expression,
        source_ref=source_ref,
    )

    inplace_node.markAsInplaceSuspect()

    return (
        StatementAssignmentVariableName(
            provider=provider,
            variable_name=variable_name,
            source=inplace_node,
            source_ref=source_ref,
        ),
    )


def _buildInplaceAssignAttributeNode(
    provider, lookup_source, attribute_name, operator, expression, source_ref
):
    temp_scope = provider.allocateTempScope("inplace_assign")

    tmp_variable = provider.allocateTempVariable(temp_scope=temp_scope, name="value")

    # First assign the target value to a temporary variable.
    preserve_to_tmp = StatementAssignmentVariable(
        variable=tmp_variable,
        source=ExpressionAttributeLookup(
            expression=lookup_source.makeClone(),
            attribute_name=attribute_name,
            source_ref=source_ref,
        ),
        source_ref=source_ref,
    )

    # Second assign the in-place result to a temporary variable
    inplace_to_tmp = StatementAssignmentVariable(
        variable=tmp_variable,
        source=makeExpressionOperationBinaryInplace(
            operator=operator,
            left=ExpressionTempVariableRef(
                variable=tmp_variable, source_ref=source_ref
            ),
            right=expression,
            source_ref=source_ref,
        ),
        source_ref=source_ref,
    )

    # Third, copy it back.
    copy_back_from_tmp = StatementAssignmentAttribute(
        expression=lookup_source.makeClone(),
        attribute_name=attribute_name,
        source=ExpressionTempVariableRef(variable=tmp_variable, source_ref=source_ref),
        source_ref=source_ref,
    )

    return (
        preserve_to_tmp,
        # making sure the above temporary variable is deleted in any case.
        makeTryFinallyStatement(
            provider=provider,
            tried=(inplace_to_tmp, copy_back_from_tmp),
            final=StatementReleaseVariable(
                variable=tmp_variable, source_ref=source_ref
            ),
            source_ref=source_ref,
        ),
    )


def _buildInplaceAssignSubscriptNode(
    provider,
    subscribed,
    subscript,
    tmp_variable1,
    tmp_variable2,
    tmp_variable3,
    operator,
    expression,
    source_ref,
):
    # First assign the subscribed value to a temporary variable.
    preserve_to_tmp1 = StatementAssignmentVariable(
        variable=tmp_variable1, source=subscribed, source_ref=source_ref
    )
    # Second assign the subscript value to a temporary variable
    statements = (
        StatementAssignmentVariable(
            variable=tmp_variable2, source=subscript, source_ref=source_ref
        ),
        StatementAssignmentVariable(
            variable=tmp_variable3,
            source=ExpressionSubscriptLookup(
                expression=ExpressionTempVariableRef(
                    variable=tmp_variable1, source_ref=source_ref
                ),
                subscript=ExpressionTempVariableRef(
                    variable=tmp_variable2, source_ref=source_ref
                ),
                source_ref=source_ref,
            ),
            source_ref=source_ref,
        ),
        StatementAssignmentVariable(
            variable=tmp_variable3,
            source=makeExpressionOperationBinaryInplace(
                operator=operator,
                left=ExpressionTempVariableRef(
                    variable=tmp_variable3, source_ref=source_ref
                ),
                right=expression,
                source_ref=source_ref,
            ),
            source_ref=source_ref,
        ),
        StatementAssignmentSubscript(
            subscribed=ExpressionTempVariableRef(
                variable=tmp_variable1, source_ref=source_ref
            ),
            subscript=ExpressionTempVariableRef(
                variable=tmp_variable2, source_ref=source_ref
            ),
            source=ExpressionTempVariableRef(
                variable=tmp_variable3, source_ref=source_ref
            ),
            source_ref=source_ref,
        ),
    )

    return (
        preserve_to_tmp1,
        makeTryFinallyStatement(
            provider=provider,
            tried=statements,
            final=(
                StatementReleaseVariable(variable=tmp_variable1, source_ref=source_ref),
                StatementReleaseVariable(variable=tmp_variable2, source_ref=source_ref),
                StatementReleaseVariable(variable=tmp_variable3, source_ref=source_ref),
            ),
            source_ref=source_ref,
        ),
    )


def _buildInplaceAssignSliceNode(
    provider,
    lookup_source,
    lower,
    upper,
    tmp_variable1,
    tmp_variable2,
    tmp_variable3,
    tmp_variable4,
    operator,
    expression,
    source_ref,
):

    # Due to the 3 inputs, which we need to also put into temporary variables,
    # there are too many variables here, but they are needed.
    # pylint: disable=too-many-locals

    # First assign the target value, lower and upper to temporary variables.
    copy_to_tmp = StatementAssignmentVariable(
        variable=tmp_variable1, source=lookup_source, source_ref=source_ref
    )

    final_statements = [
        StatementReleaseVariable(variable=tmp_variable1, source_ref=source_ref)
    ]
    statements = []

    if lower is not None:
        statements.append(
            StatementAssignmentVariable(
                variable=tmp_variable2, source=lower, source_ref=source_ref
            )
        )
        final_statements.append(
            StatementReleaseVariable(variable=tmp_variable2, source_ref=source_ref)
        )

        lower_ref1 = ExpressionTempVariableRef(
            variable=tmp_variable2, source_ref=source_ref
        )
        lower_ref2 = ExpressionTempVariableRef(
            variable=tmp_variable2, source_ref=source_ref
        )
    else:
        assert tmp_variable2 is None

        lower_ref1 = lower_ref2 = None

    if upper is not None:
        statements.append(
            StatementAssignmentVariable(
                variable=tmp_variable3, source=upper, source_ref=source_ref
            )
        )
        final_statements.append(
            StatementReleaseVariable(variable=tmp_variable3, source_ref=source_ref)
        )

        upper_ref1 = ExpressionTempVariableRef(
            variable=tmp_variable3, source_ref=source_ref
        )
        upper_ref2 = ExpressionTempVariableRef(
            variable=tmp_variable3, source_ref=source_ref
        )
    else:
        assert tmp_variable3 is None

        upper_ref1 = upper_ref2 = None

    use_sliceobj = python_version >= 0x300

    # Second assign the in-place result over the original value.
    if use_sliceobj:
        statements += (
            StatementAssignmentVariable(
                variable=tmp_variable4,
                source=ExpressionSubscriptLookup(
                    expression=ExpressionTempVariableRef(
                        variable=tmp_variable1, source_ref=source_ref
                    ),
                    subscript=makeExpressionBuiltinSlice(
                        start=lower_ref2,
                        stop=upper_ref2,
                        step=None,
                        source_ref=source_ref,
                    ),
                    source_ref=source_ref,
                ),
                source_ref=source_ref,
            ),
            StatementAssignmentVariable(
                variable=tmp_variable4,
                source=makeExpressionOperationBinaryInplace(
                    operator=operator,
                    left=ExpressionTempVariableRef(
                        variable=tmp_variable4, source_ref=source_ref
                    ),
                    right=expression,
                    source_ref=source_ref,
                ),
                source_ref=source_ref,
            ),
            StatementAssignmentSubscript(
                subscribed=ExpressionTempVariableRef(
                    variable=tmp_variable1, source_ref=source_ref
                ),
                subscript=makeExpressionBuiltinSlice(
                    start=lower_ref1, stop=upper_ref1, step=None, source_ref=source_ref
                ),
                source=ExpressionTempVariableRef(
                    variable=tmp_variable4, source_ref=source_ref
                ),
                source_ref=source_ref,
            ),
        )
    else:
        statements += (
            StatementAssignmentVariable(
                variable=tmp_variable4,
                source=ExpressionSliceLookup(
                    expression=ExpressionTempVariableRef(
                        variable=tmp_variable1, source_ref=source_ref
                    ),
                    lower=lower_ref2,
                    upper=upper_ref2,
                    source_ref=source_ref,
                ),
                source_ref=source_ref,
            ),
            StatementAssignmentVariable(
                variable=tmp_variable4,
                source=makeExpressionOperationBinaryInplace(
                    operator=operator,
                    left=ExpressionTempVariableRef(
                        variable=tmp_variable4, source_ref=source_ref
                    ),
                    right=expression,
                    source_ref=source_ref,
                ),
                source_ref=source_ref,
            ),
            StatementAssignmentSlice(
                expression=ExpressionTempVariableRef(
                    variable=tmp_variable1, source_ref=source_ref
                ),
                lower=lower_ref1,
                upper=upper_ref1,
                source=ExpressionTempVariableRef(
                    variable=tmp_variable4, source_ref=source_ref
                ),
                source_ref=source_ref,
            ),
        )

    final_statements.append(
        StatementReleaseVariable(variable=tmp_variable4, source_ref=source_ref)
    )

    return (
        copy_to_tmp,
        makeTryFinallyStatement(
            provider=provider,
            tried=statements,
            final=final_statements,
            source_ref=source_ref,
        ),
    )


def buildInplaceAssignNode(provider, node, source_ref):
    # There are many inplace assignment variables, and the detail is unpacked
    # into names, so we end up with a lot of variables, which is on purpose,
    # pylint: disable=too-many-locals

    operator = getKind(node.op)

    operator = "I" + operator
    if operator == "IDiv":
        operator = "ITrueDiv" if getFutureSpec().isFutureDivision() else "IOldDiv"

    expression = buildNode(provider, node.value, source_ref)

    kind, detail = decodeAssignTarget(
        provider=provider, node=node.target, source_ref=source_ref
    )

    if kind == "Name":
        statements = _buildInplaceAssignVariableNode(
            provider=provider,
            variable_name=detail,
            operator=operator,
            expression=expression,
            source_ref=source_ref,
        )
    elif kind == "Attribute":
        lookup_source, attribute_name = detail

        statements = _buildInplaceAssignAttributeNode(
            provider=provider,
            lookup_source=lookup_source,
            attribute_name=mangleName(attribute_name, provider),
            operator=operator,
            expression=expression,
            source_ref=source_ref,
        )
    elif kind == "Subscript":
        subscribed, subscript = detail

        temp_scope = provider.allocateTempScope("inplace_assign_subscr")

        tmp_variable1 = provider.allocateTempVariable(
            temp_scope=temp_scope, name="target"
        )
        tmp_variable2 = provider.allocateTempVariable(
            temp_scope=temp_scope, name="subscript"
        )
        tmp_variable3 = provider.allocateTempVariable(
            temp_scope=temp_scope, name="value"
        )

        statements = _buildInplaceAssignSubscriptNode(
            provider=provider,
            subscribed=subscribed,
            subscript=subscript,
            tmp_variable1=tmp_variable1,
            tmp_variable2=tmp_variable2,
            tmp_variable3=tmp_variable3,
            operator=operator,
            expression=expression,
            source_ref=source_ref,
        )
    elif kind == "Slice":
        lookup_source, lower, upper = detail

        temp_scope = provider.allocateTempScope("inplace_assign_slice")

        tmp_variable1 = provider.allocateTempVariable(
            temp_scope=temp_scope, name="target"
        )
        if lower is not None:
            tmp_variable2 = provider.allocateTempVariable(
                temp_scope=temp_scope, name="lower"
            )
        else:
            tmp_variable2 = None

        if upper is not None:
            tmp_variable3 = provider.allocateTempVariable(
                temp_scope=temp_scope, name="upper"
            )
        else:
            tmp_variable3 = None

        tmp_variable4 = provider.allocateTempVariable(
            temp_scope=temp_scope, name="value"
        )

        statements = _buildInplaceAssignSliceNode(
            provider=provider,
            lookup_source=lookup_source,
            lower=lower,
            upper=upper,
            tmp_variable1=tmp_variable1,
            tmp_variable2=tmp_variable2,
            tmp_variable3=tmp_variable3,
            tmp_variable4=tmp_variable4,
            operator=operator,
            expression=expression,
            source_ref=source_ref,
        )
    else:
        assert False, kind

    return makeStatementsSequenceFromStatements(*statements)


def buildNamedExprNode(provider, node, source_ref):
    """Assignment expressions, Python3.8 or higher only."""

    outline_body = ExpressionOutlineBody(
        provider=provider, name="assignment_expr", source_ref=source_ref
    )

    tmp_value = outline_body.allocateTempVariable(temp_scope=None, name="value")

    value = buildNode(provider=provider, node=node.value, source_ref=source_ref)

    locals_owner = provider
    while locals_owner.isExpressionOutlineFunction():
        locals_owner = locals_owner.getParentVariableProvider()

    variable_name = node.target.id

    if (
        locals_owner.isExpressionGeneratorObjectBody()
        and locals_owner.name == "<genexpr>"
    ):
        locals_owner.addNonlocalsDeclaration(
            (variable_name,), user_provided=False, source_ref=source_ref
        )

    statements = (
        StatementAssignmentVariable(
            variable=tmp_value, source=value, source_ref=source_ref
        ),
        StatementAssignmentVariableName(
            provider=locals_owner,
            variable_name=variable_name,
            source=ExpressionTempVariableRef(variable=tmp_value, source_ref=source_ref),
            source_ref=source_ref,
        ),
        StatementReturn(
            expression=ExpressionTempVariableRef(
                variable=tmp_value, source_ref=source_ref
            ),
            source_ref=source_ref,
        ),
    )

    outline_body.setChild(
        "body",
        makeStatementsSequenceFromStatement(
            statement=makeTryFinallyStatement(
                provider=provider,
                tried=statements,
                final=StatementReleaseVariable(
                    variable=tmp_value, source_ref=source_ref
                ),
                source_ref=source_ref,
            )
        ),
    )

    return outline_body
