#     Copyright 2016, 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 function statements.

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

"""

from nuitka.nodes.AssignNodes import (
    ExpressionTargetTempVariableRef,
    ExpressionTargetVariableRef,
    StatementAssignmentVariable,
    StatementReleaseVariable
)
from nuitka.nodes.BuiltinIteratorNodes import (
    ExpressionBuiltinIter1,
    StatementSpecialUnpackCheck
)
from nuitka.nodes.BuiltinNextNodes import ExpressionSpecialUnpack
from nuitka.nodes.BuiltinRefNodes import ExpressionBuiltinRef
from nuitka.nodes.CallNodes import ExpressionCallNoKeywords
from nuitka.nodes.CodeObjectSpecs import CodeObjectSpec
from nuitka.nodes.ConstantRefNodes import (
    ExpressionConstantNoneRef,
    makeConstantRefNode
)
from nuitka.nodes.ContainerMakingNodes import ExpressionMakeTuple
from nuitka.nodes.CoroutineNodes import (
    ExpressionCoroutineObjectBody,
    ExpressionMakeCoroutineObject
)
from nuitka.nodes.FunctionNodes import (
    ExpressionFunctionBody,
    ExpressionFunctionCall,
    ExpressionFunctionCreation,
    ExpressionFunctionRef
)
from nuitka.nodes.GeneratorNodes import (
    ExpressionGeneratorObjectBody,
    ExpressionMakeGeneratorObject,
    StatementGeneratorReturn
)
from nuitka.nodes.ParameterSpecs import ParameterSpec
from nuitka.nodes.ReturnNodes import StatementReturn
from nuitka.nodes.VariableRefNodes import (
    ExpressionTempVariableRef,
    ExpressionVariableRef
)
from nuitka.PythonVersions import python_version
from nuitka.tree import SyntaxErrors

from .Helpers import (
    buildFrameNode,
    buildNode,
    buildNodeList,
    detectFunctionBodyKind,
    extractDocFromBody,
    getKind,
    makeDictCreationOrConstant,
    makeStatementsSequenceFromStatement,
    mangleName
)
from .ReformulationTryFinallyStatements import makeTryFinallyStatement


def _insertFinalReturnStatement(function_statements_body, return_class,
                                source_ref):
    return_statement = return_class(
        expression = ExpressionConstantNoneRef(
            source_ref = source_ref
        ),
        source_ref = source_ref
    )

    if function_statements_body is None:
        function_statements_body = makeStatementsSequenceFromStatement(
            statement = return_statement,
        )
    elif not function_statements_body.isStatementAborting():
        function_statements_body.setStatements(
            function_statements_body.getStatements() +
            (
                return_statement,
            )
        )

    return function_statements_body


def buildFunctionNode(provider, node, source_ref):
    # Functions have way too many details, pylint: disable=R0912,R0914

    assert getKind(node) == "FunctionDef"

    function_statement_nodes, function_doc = extractDocFromBody(node)

    function_kind, flags, _written_variables, _non_local_declarations, _global_declarations = \
      detectFunctionBodyKind(
        nodes = function_statement_nodes
    )

    outer_body, function_body, code_object = buildFunctionWithParsing(
        provider      = provider,
        function_kind = function_kind,
        name          = node.name,
        function_doc  = function_doc,
        flags         = flags,
        node          = node,
        source_ref    = source_ref
    )

    if function_kind == "Function":
        code_body = function_body
    elif function_kind == "Generator":
        code_body = ExpressionGeneratorObjectBody(
            provider   = function_body,
            name       = node.name,
            flags      = flags,
            source_ref = source_ref
        )

        for variable in function_body.getVariables():
            code_body.getVariableForReference(variable.getName())
    else:
        assert False, function_kind

    if function_kind == "Generator":
        function_body.setBody(
            makeStatementsSequenceFromStatement(
                statement = StatementReturn(
                    expression = ExpressionMakeGeneratorObject(
                        generator_ref = ExpressionFunctionRef(
                            function_body = code_body,
                            source_ref    = source_ref
                        ),
                        code_object   = code_object,
                        source_ref    = source_ref
                    ),
                    source_ref = source_ref
                )
            )
        )

    decorators = buildNodeList(
        provider   = provider,
        nodes      = reversed(node.decorator_list),
        source_ref = source_ref
    )

    defaults = buildNodeList(
        provider   = provider,
        nodes      = node.args.defaults,
        source_ref = source_ref
    )

    kw_defaults = buildParameterKwDefaults(
        provider      = provider,
        node          = node,
        function_body = function_body,
        source_ref    = source_ref
    )

    function_statements_body = buildFrameNode(
        provider    = code_body,
        nodes       = function_statement_nodes,
        code_object = code_object,
        source_ref  = source_ref
    )

    if function_kind == "Function":
        # TODO: Generators might have to raise GeneratorExit instead.
        function_statements_body = _insertFinalReturnStatement(
            function_statements_body = function_statements_body,
            return_class             = StatementReturn,
            source_ref               = source_ref
        )

    if function_statements_body.isStatementsFrame():
        function_statements_body = makeStatementsSequenceFromStatement(
            statement = function_statements_body
        )

    code_body.setBody(
        function_statements_body
    )

    annotations = buildParameterAnnotations(provider, node, source_ref)

    function_creation = ExpressionFunctionCreation(
        function_ref = ExpressionFunctionRef(
            function_body = outer_body,
            source_ref    = source_ref
        ),
        code_object  = code_object,
        defaults     = defaults,
        kw_defaults  = kw_defaults,
        annotations  = annotations,
        source_ref   = source_ref
    )

    # Add the "staticmethod" decorator to __new__ methods if not provided.

    # CPython made these optional, but secretly applies them when it does
    # "class __new__".  We add them earlier, so our optimization will see it.
    if node.name == "__new__" and \
       provider.isExpressionClassBody():

        for decorator in decorators:
            if decorator.isExpressionVariableRef() and \
               decorator.getVariableName() == "staticmethod":
                break
        else:
            decorators.append(
                ExpressionBuiltinRef(
                    builtin_name = "staticmethod",
                    source_ref   = source_ref
                )
            )

    if python_version >= 360 and \
       node.name == "__init_subclass__" and \
       provider.isExpressionClassBody():

        for decorator in decorators:
            if decorator.isExpressionVariableRef() and \
               decorator.getVariableName() == "classmethod":
                break
        else:
            decorators.append(
                ExpressionBuiltinRef(
                    builtin_name = "classmethod",
                    source_ref   = source_ref
                )
            )

    decorated_function = function_creation
    for decorator in decorators:
        decorated_function = ExpressionCallNoKeywords(
            called     = decorator,
            args       = ExpressionMakeTuple(
                elements   = (decorated_function,),
                source_ref = source_ref
            ),
            source_ref = decorator.getSourceReference()
        )

    result = StatementAssignmentVariable(
        variable_ref = ExpressionTargetVariableRef(
            variable_name = mangleName(node.name, provider),
            source_ref    = source_ref
        ),
        source       = decorated_function,
        source_ref   = source_ref
    )

    if python_version >= 340:
        function_body.qualname_setup = result.getTargetVariableRef()

    return result


def buildAsyncFunctionNode(provider, node, source_ref):
    # We are creating a function here that creates coroutine objects, with
    # many details each, pylint: disable=R0914
    assert getKind(node) == "AsyncFunctionDef"

    function_statement_nodes, function_doc = extractDocFromBody(node)

    creator_function_body, _, code_object = buildFunctionWithParsing(
        provider      = provider,
        function_kind = "Coroutine",
        name          = node.name,
        flags         = set(),
        function_doc  = function_doc,
        node          = node,
        source_ref    = source_ref
    )

    function_body = ExpressionCoroutineObjectBody(
        provider   = creator_function_body,
        name       = node.name,
        flags      = set(),
        source_ref = source_ref
    )

    decorators = buildNodeList(
        provider   = provider,
        nodes      = reversed(node.decorator_list),
        source_ref = source_ref
    )

    defaults = buildNodeList(
        provider   = provider,
        nodes      = node.args.defaults,
        source_ref = source_ref
    )

    function_statements_body = buildFrameNode(
        provider    = function_body,
        nodes       = function_statement_nodes,
        code_object = code_object,
        source_ref  = source_ref
    )

    function_statements_body = _insertFinalReturnStatement(
        function_statements_body = function_statements_body,
        return_class             = StatementGeneratorReturn,
        source_ref               = source_ref
    )

    if function_statements_body.isStatementsFrame():
        function_statements_body = makeStatementsSequenceFromStatement(
            statement = function_statements_body
        )

    function_body.setBody(
        function_statements_body
    )

    annotations = buildParameterAnnotations(provider, node, source_ref)

    kw_defaults = buildParameterKwDefaults(
        provider      = provider,
        node          = node,
        function_body = creator_function_body,
        source_ref    = source_ref
    )

    creator_function_body.setBody(
        makeStatementsSequenceFromStatement(
            statement = StatementReturn(
                expression = ExpressionMakeCoroutineObject(
                    coroutine_ref = ExpressionFunctionRef(
                        function_body = function_body,
                        source_ref    = source_ref
                    ),
                    code_object   = code_object,
                    source_ref    = source_ref
                ),
                source_ref = source_ref
            )
        )
    )

    function_creation = ExpressionFunctionCreation(
        function_ref = ExpressionFunctionRef(
            function_body = creator_function_body,
            source_ref    = source_ref
        ),
        code_object  = code_object,
        defaults     = defaults,
        kw_defaults  = kw_defaults,
        annotations  = annotations,
        source_ref   = source_ref
    )

    decorated_function = function_creation
    for decorator in decorators:
        decorated_function = ExpressionCallNoKeywords(
            called     = decorator,
            args       = ExpressionMakeTuple(
                elements   = (decorated_function,),
                source_ref = source_ref
            ),
            source_ref = decorator.getSourceReference()
        )


    result = StatementAssignmentVariable(
        variable_ref = ExpressionTargetVariableRef(
            variable_name = mangleName(node.name, provider),
            source_ref    = source_ref
        ),
        source       = decorated_function,
        source_ref   = source_ref
    )

    function_body.qualname_setup = result.getTargetVariableRef()

    return result


def buildParameterKwDefaults(provider, node, function_body, source_ref):
    # Build keyword only arguments default values. We are hiding here, that it
    # is a Python3 only feature.

    if python_version >= 300:
        kw_only_names = function_body.getParameters().getKwOnlyParameterNames()

        if kw_only_names:
            keys = []
            values = []

            for kw_only_name, kw_default in \
              zip(kw_only_names, node.args.kw_defaults):
                if kw_default is not None:
                    keys.append(
                        makeConstantRefNode(
                            constant   = kw_only_name,
                            source_ref = source_ref
                        )
                    )
                    values.append(
                        buildNode(provider, kw_default, source_ref)
                    )

            kw_defaults = makeDictCreationOrConstant(
                keys       = keys,
                values     = values,
                source_ref = source_ref
            )
        else:
            kw_defaults = None
    else:
        kw_defaults = None

    return kw_defaults


def buildParameterAnnotations(provider, node, source_ref):
    # Too many branches, because there is too many cases, pylint: disable=R0912

    # Build annotations. We are hiding here, that it is a Python3 only feature.
    if python_version < 300:
        return None


    # Starting with Python 3.4, the names of parameters are mangled in
    # annotations as well.
    if python_version < 340:
        mangle = lambda variable_name: variable_name
    else:
        mangle = lambda variable_name: mangleName(variable_name, provider)

    keys = []
    values = []

    def addAnnotation(key, value):
        keys.append(
            makeConstantRefNode(
                constant      = mangle(key),
                source_ref    = source_ref,
                user_provided = True
            )
        )
        values.append(value)

    def extractArg(arg):
        if getKind(arg) == "Name":
            assert arg.annotation is None
        elif getKind(arg) == "arg":
            if arg.annotation is not None:
                addAnnotation(
                    key   = arg.arg,
                    value = buildNode(provider, arg.annotation, source_ref)
                )
        elif getKind(arg) == "Tuple":
            for arg in arg.elts:
                extractArg(arg)
        else:
            assert False, getKind(arg)

    for arg in node.args.args:
        extractArg(arg)

    for arg in node.args.kwonlyargs:
        extractArg(arg)

    if python_version < 340:
        if node.args.varargannotation is not None:
            addAnnotation(
                key   = node.args.vararg,
                value = buildNode(
                    provider, node.args.varargannotation, source_ref
                )
            )

        if node.args.kwargannotation is not None:
            addAnnotation(
                key   = node.args.kwarg,
                value = buildNode(
                    provider, node.args.kwargannotation, source_ref
                )
            )
    else:
        if node.args.vararg is not None:
            extractArg(node.args.vararg)
        if node.args.kwarg is not None:
            extractArg(node.args.kwarg)

    # Return value annotation (not there for lambdas)
    if hasattr(node, "returns") and node.returns is not None:
        addAnnotation(
            key   = "return",
            value = buildNode(
                provider, node.returns, source_ref
            )
        )

    if keys:
        return makeDictCreationOrConstant(
            keys       = keys,
            values     = values,
            source_ref = source_ref
        )
    else:
        return None


def buildFunctionWithParsing(provider, function_kind, name, function_doc, flags,
                             node, source_ref):
    # This contains a complex re-formulation for nested parameter functions.
    # pylint: disable=R0914

    kind = getKind(node)

    assert kind in ("FunctionDef", "Lambda", "AsyncFunctionDef"), "unsupported for kind " + kind

    def extractArg(arg):
        if arg is None:
            return None
        elif type(arg) is str:
            return mangleName(arg, provider)
        elif getKind(arg) == "Name":
            return mangleName(arg.id, provider)
        elif getKind(arg) == "arg":
            return mangleName(arg.arg, provider)
        elif getKind(arg) == "Tuple":
            # These are to be re-formulated on the outside.
            assert False
        else:
            assert False, getKind(arg)

    special_args = {}

    def extractNormalArgs(args):
        normal_args = []

        for arg in args:
            if type(arg) is not str and getKind(arg) == "Tuple":
                special_arg_name = ".%d" % (len(special_args) + 1)

                special_args[special_arg_name] = arg.elts
                normal_args.append(special_arg_name)
            else:
                normal_args.append(extractArg(arg))

        return normal_args

    normal_args = extractNormalArgs(node.args.args)

    parameters = ParameterSpec(
        ps_name          = name,
        ps_normal_args   = normal_args,
        ps_kw_only_args  = [
            extractArg(arg)
            for arg in
            node.args.kwonlyargs
            ]
              if python_version >= 300 else
            [],
        ps_list_star_arg = extractArg(node.args.vararg),
        ps_dict_star_arg = extractArg(node.args.kwarg),
        ps_default_count = len(node.args.defaults)
    )

    message = parameters.checkValid()

    if message is not None:
        SyntaxErrors.raiseSyntaxError(
            message,
            source_ref
        )

    code_object = CodeObjectSpec(
        co_name           = name,
        co_kind           = function_kind,
        co_varnames       = parameters.getParameterNames(),
        co_argcount       = parameters.getArgumentCount(),
        co_kwonlyargcount = parameters.getKwOnlyParameterCount(),
        co_has_starlist   = parameters.getStarListArgumentName() is not None,
        co_has_stardict   = parameters.getStarDictArgumentName() is not None
    )

    outer_body = ExpressionFunctionBody(
        provider   = provider,
        name       = name,
        flags      = flags,
        doc        = function_doc,
        parameters = parameters,
        source_ref = source_ref
    )

    if special_args:
        inner_name = name.strip("<>") + "$inner"
        inner_arg_names = []
        iter_vars = []

        values = []

        statements = []

        def unpackFrom(source, arg_names):
            accesses = []

            sub_special_index = 0

            iter_var = outer_body.allocateTempVariable(None, "arg_iter_%d" % len(iter_vars))
            iter_vars.append(iter_var)

            statements.append(
                StatementAssignmentVariable(
                    variable_ref = ExpressionTargetTempVariableRef(
                        variable   = iter_var,
                        source_ref = source_ref
                    ),
                    source       = ExpressionBuiltinIter1(
                        value      = source,
                        source_ref = source_ref
                    ),
                    source_ref   = source_ref
                )
            )

            for element_index, arg_name in enumerate(arg_names):
                if getKind(arg_name) == "Name":
                    inner_arg_names.append(arg_name.id)

                    arg_var = outer_body.allocateTempVariable(None, "tmp_" + arg_name.id)

                    statements.append(
                        StatementAssignmentVariable(
                            variable_ref = ExpressionTargetTempVariableRef(
                                variable   = arg_var,
                                source_ref = source_ref
                            ),
                            source       = ExpressionSpecialUnpack(
                                value      = ExpressionTempVariableRef(
                                    variable   = iter_var,
                                    source_ref = source_ref
                                ),
                                count      = element_index + 1,
                                expected   = len(arg_names),
                                source_ref = source_ref
                            ),
                            source_ref   = source_ref
                        )
                    )

                    accesses.append(
                        ExpressionTempVariableRef(
                            variable   = arg_var,
                            source_ref = source_ref
                        )
                    )
                elif getKind(arg_name) == "Tuple":
                    accesses.extend(
                        unpackFrom(
                            source    = ExpressionSpecialUnpack(
                                value      = ExpressionTempVariableRef(
                                    variable   = iter_var,
                                    source_ref = source_ref
                                ),
                                count      = element_index + 1,
                                expected   = len(arg_names),
                                source_ref = source_ref
                            ),
                            arg_names = arg_name.elts
                        )
                    )

                    sub_special_index += 1
                else:
                    assert False, arg_name

            statements.append(
                StatementSpecialUnpackCheck(
                    iterator   = ExpressionTempVariableRef(
                        variable   = iter_var,
                        source_ref = source_ref
                    ),
                    count      = len(arg_names),
                    source_ref = source_ref
                )
            )

            return accesses

        for arg_name in parameters.getParameterNames():
            if arg_name.startswith('.'):
                source = ExpressionVariableRef(
                    variable_name = arg_name,
                    source_ref    = source_ref
                )

                values.extend(
                    unpackFrom(source, special_args[arg_name])
                )
            else:
                values.append(
                    ExpressionVariableRef(
                        variable_name = arg_name,
                        source_ref    = source_ref
                    )
                )

                inner_arg_names.append(arg_name)

        inner_parameters = ParameterSpec(
            ps_name          = inner_name,
            ps_normal_args   = inner_arg_names,
            ps_kw_only_args  = (),
            ps_list_star_arg = None,
            ps_dict_star_arg = None,
            ps_default_count = None
        )

        function_body = ExpressionFunctionBody(
            provider   = outer_body,
            name       = inner_name,
            flags      = flags,
            doc        = function_doc,
            parameters = inner_parameters,
            source_ref = source_ref
        )

        statements.append(
            StatementReturn(
                ExpressionFunctionCall(
                    function   = ExpressionFunctionCreation(
                        function_ref = ExpressionFunctionRef(
                            function_body = function_body,
                            source_ref    = source_ref
                        ),
                        code_object  = code_object,
                        defaults     = (),
                        kw_defaults  = None,
                        annotations  = None,
                        source_ref   = source_ref
                    ),
                    values     = values,
                    source_ref = source_ref
                ),
                source_ref = source_ref
            )
        )

        outer_body.setBody(
            makeStatementsSequenceFromStatement(
                statement = makeTryFinallyStatement(
                    provider,
                    tried      = statements,
                    final      = [
                        StatementReleaseVariable(
                            variable   = variable,
                            source_ref = source_ref
                        )
                        for variable in
                        outer_body.getTempVariables()
                    ]   ,
                    source_ref = source_ref,
                    public_exc = False
                )
            )
        )
    else:
        function_body = outer_body

    return outer_body, function_body, code_object


def addFunctionVariableReleases(function):
    assert function.isExpressionFunctionBody() or \
           function.isExpressionClassBody() or \
           function.isExpressionGeneratorObjectBody() or \
           function.isExpressionCoroutineObjectBody()


    releases = []

    # We attach everything to the function definition source location.
    source_ref = function.getSourceReference()

    for variable in function.getLocalVariables():
        # Shared variables are freed by function object attachment.
        if variable.getOwner() is not function:
            continue

        releases.append(
            StatementReleaseVariable(
                variable   = variable,
                source_ref = source_ref
            )
        )

    if releases:
        body = function.getBody()

        if body.isStatementsFrame():
            body = makeStatementsSequenceFromStatement(
                statement = body
            )

        body = makeTryFinallyStatement(
            provider   = function,
            tried      = body,
            final      = releases,
            source_ref = source_ref
        )

        function.setBody(
            makeStatementsSequenceFromStatement(
                statement = body
            )
        )

        # assert body.isStatementAborting(), body.asXmlText()
