#     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.
#
""" This module maintains the parameter specification classes.

These are used for function, lambdas, generators. They are also a factory
for the respective variable objects. One of the difficulty of Python and
its parameter parsing is that they are allowed to be nested like this:

(a,b), c

Much like in assignments, which are very similar to parameters, except
that parameters may also be assigned from a dictionary, they are no less
flexible.

"""

from nuitka import Variables
from nuitka.PythonVersions import python_version


class TooManyArguments(Exception):
    def __init__(self, real_exception):
        Exception.__init__(self)

        self.real_exception = real_exception

    def getRealException(self):
        return self.real_exception


class ParameterSpec:
    # These got many attributes, in part duplicating name and instance of
    # variables, pylint: disable=R0902

    def __init__(self, ps_name, ps_normal_args, ps_kw_only_args, ps_list_star_arg,
                 ps_dict_star_arg, ps_default_count):
        if type(ps_normal_args) is str:
            if ps_normal_args == "":
                ps_normal_args = ()
            else:
                ps_normal_args = ps_normal_args.split(',')

        if type(ps_kw_only_args) is str:
            if ps_kw_only_args == "":
                ps_kw_only_args = ()
            else:
                ps_kw_only_args = ps_kw_only_args.split(',')

        assert None not in ps_normal_args

        self.owner = None

        self.name = ps_name
        self.normal_args = tuple(ps_normal_args)
        self.normal_variables = None

        assert ps_list_star_arg is None or type(ps_list_star_arg) is str, \
          ps_list_star_arg
        assert ps_dict_star_arg is None or type(ps_dict_star_arg) is str, \
          ps_dict_star_arg

        self.list_star_arg = ps_list_star_arg if ps_list_star_arg else None
        self.dict_star_arg = ps_dict_star_arg if ps_dict_star_arg else None

        self.list_star_variable = None
        self.dict_star_variable = None

        self.default_count = ps_default_count

        self.kw_only_args = tuple(ps_kw_only_args)
        self.kw_only_variables = None

    def makeClone(self):
        return ParameterSpec(
            ps_name          = self.name,
            ps_normal_args   = self.normal_args,
            ps_kw_only_args  = self.kw_only_args,
            ps_list_star_arg = self.list_star_arg,
            ps_dict_star_arg = self.dict_star_arg,
            ps_default_count = self.default_count
        )

    def getDetails(self):
        return {
            "ps_name"          : self.name,
            "ps_normal_args"   : ','.join(self.normal_args),
            "ps_kw_only_args"  : ','.join(self.kw_only_args),
            "ps_list_star_arg" : self.list_star_arg if self.list_star_arg is not None else "",
            "ps_dict_star_arg" : self.dict_star_arg if self.dict_star_arg is not None else "",
            "ps_default_count" : self.default_count
        }

    def checkValid(self):
        arg_names = self.getParameterNames()

        # Check for duplicate arguments, could happen.
        for arg_name in arg_names:
            if arg_names.count(arg_name) != 1:
                return "duplicate argument '%s' in function definition" % arg_name

        return None

    def __repr__(self):
        parts = [
            str(normal_arg)
            for normal_arg
            in self.normal_args
        ]

        if self.list_star_arg is not None:
            parts.append("*%s" % self.list_star_arg)

        if self.dict_star_variable is not None:
            parts.append("**%s" % self.dict_star_variable)

        if parts:
            return "<ParameterSpec '%s'>" % ','.join(parts)
        else:
            return "<NoParameters>"

    def getArgumentCount(self):
        return len(self.normal_args)

    def setOwner(self, owner):
        if self.owner is not None:
            return

        self.owner = owner
        self.normal_variables = []

        for normal_arg in self.normal_args:
            if type(normal_arg) is str:
                normal_variable = Variables.ParameterVariable(
                    owner          = self.owner,
                    parameter_name = normal_arg
                )
            else:
                assert False, normal_arg

            self.normal_variables.append(normal_variable)

        if self.list_star_arg:
            self.list_star_variable = Variables.ParameterVariable(
                owner          = owner,
                parameter_name = self.list_star_arg
            )
        else:
            self.list_star_variable = None

        if self.dict_star_arg:
            self.dict_star_variable = Variables.ParameterVariable(
                owner          = owner,
                parameter_name = self.dict_star_arg
            )
        else:
            self.dict_star_variable = None

        self.kw_only_variables = [
            Variables.ParameterVariable(
                owner          = self.owner,
                parameter_name = kw_only_arg
            )
            for kw_only_arg in
            self.kw_only_args
        ]

    def getDefaultCount(self):
        return self.default_count

    def hasDefaultParameters(self):
        return self.getDefaultCount() > 0

    def getTopLevelVariables(self):
        return self.normal_variables + self.kw_only_variables

    def getAllVariables(self):
        result = list(self.normal_variables)

        result += self.kw_only_variables

        if self.list_star_variable is not None:
            result.append(self.list_star_variable)

        if self.dict_star_variable is not None:
            result.append(self.dict_star_variable)

        return result

    def getParameterNames(self):
        result = list(self.normal_args)

        result += self.kw_only_args

        if self.list_star_arg is not None:
            result.append(self.list_star_arg)

        if self.dict_star_arg is not None:
            result.append(self.dict_star_arg)

        return result

    def getStarListArgumentName(self):
        return self.list_star_arg

    def getListStarArgVariable(self):
        return self.list_star_variable

    def getStarDictArgumentName(self):
        return self.dict_star_arg

    def getDictStarArgVariable(self):
        return self.dict_star_variable

    def getKwOnlyVariables(self):
        return self.kw_only_variables

    def allowsKeywords(self):
        # Abstract method, pylint: disable=R0201
        return True

    def getKeywordRefusalText(self):
        return "%s() takes no keyword arguments" % self.name

    def getArgumentNames(self):
        return self.normal_args

    def getKwOnlyParameterNames(self):
        return self.kw_only_args

    def getKwOnlyParameterCount(self):
        return len(self.kw_only_args)


# Note: Based loosely on "inspect.getcallargs" with corrections.
def matchCall(func_name, args, star_list_arg, star_dict_arg, num_defaults,
              positional, pairs, improved = False):
    # This is of incredible code complexity, but there really is no other way to
    # express this with less statements, branches, or variables.
    # pylint: disable=R0912,R0914,R0915

    assert type(positional) is tuple, positional
    assert type(pairs) in (tuple, list), pairs

    # Make a copy, we are going to modify it.
    pairs = list(pairs)

    result = {}

    assigned_tuple_params = []

    def assign(arg, value):
        if type(arg) is str:
            # Normal case:
            result[ arg ] = value
        else:
            # Tuple argument case:

            assigned_tuple_params.append(arg)
            value = iter(value.getIterationValues())

            for i, subarg in enumerate(arg):
                try:
                    subvalue = next(value)
                except StopIteration:
                    raise TooManyArguments(
                        ValueError(
                            "need more than %d %s to unpack" % (
                                i,
                                "values" if i > 1 else "value"
                            )
                        )
                    )

                # Recurse into tuple argument values, could be more tuples.
                assign(subarg, subvalue)

            # Check that not too many values we provided.
            try:
                next(value)
            except StopIteration:
                pass
            else:
                raise TooManyArguments(
                    ValueError("too many values to unpack")
                )

    def isAssigned(arg):
        if type(arg) is str:
            return arg in result

        return arg in assigned_tuple_params

    num_pos = len(positional)
    num_total = num_pos + len(pairs)
    num_args = len(args)

    for arg, value in zip(args, positional):
        assign(arg, value)

    # Python3 does this check earlier.
    if python_version >= 300 and not star_dict_arg:
        for pair in pairs:
            if pair[0] not in args:
                message = "'%s' is an invalid keyword argument for this function" % pair[0]

                raise TooManyArguments(
                    TypeError(message)
                )

    if star_list_arg:
        if num_pos > num_args:
            assign(star_list_arg, positional[ -(num_pos-num_args) : ])
        else:
            assign(star_list_arg, ())
    elif 0 < num_args < num_total:
        if num_defaults == 0:
            if num_args == 1:
                raise TooManyArguments(
                    TypeError(
                        "%s() takes exactly one argument (%d given)" % (
                            func_name,
                            num_total
                        )
                    )
                )
            else:
                raise TooManyArguments(
                    TypeError(
                        "%s expected %d arguments, got %d" % (
                            func_name,
                            num_args,
                            num_total
                        )
                    )
                )

        else:
            raise TooManyArguments(
                TypeError(
                    "%s() takes at most %d %s (%d given)" % (
                        func_name,
                        num_args,
                        "argument" if num_args == 1 else "arguments",
                        num_total
                    )
                )
            )
    elif num_args == 0 and num_total:
        if star_dict_arg:
            if num_pos:
                # Could use num_pos, but Python also uses num_total.
                raise TooManyArguments(
                    TypeError(
                        "%s() takes exactly 0 arguments (%d given)" % (
                            func_name,
                            num_total
                        )
                    )
                )
        else:
            raise TooManyArguments(
                TypeError(
                    "%s() takes no arguments (%d given)" % (
                        func_name,
                        num_total
                    )
                )
            )

    named_argument_names = [
        pair[0]
        for pair in
        pairs
    ]

    for arg in args:
        if type(arg) is str and arg in named_argument_names:
            if isAssigned(arg):
                raise TooManyArguments(
                    TypeError(
                        "%s() got multiple values for keyword argument '%s'" % (
                            func_name,
                            arg
                        )
                    )
                )
            else:
                new_pairs = []

                for pair in pairs:
                    if arg == pair[0]:
                        assign(arg, pair[1])
                    else:
                        new_pairs.append(pair)

                assert len(new_pairs) == len(pairs) - 1

                pairs = new_pairs

    # Fill in any missing values with the None to indicate "default".
    if num_defaults > 0:
        for arg in args[ -num_defaults : ]:
            if not isAssigned(arg):
                assign(arg, None)

    if star_dict_arg:
        assign(star_dict_arg, pairs)
    elif pairs:
        unexpected = next(iter(dict(pairs)))

        if improved:
            message = "%s() got an unexpected keyword argument '%s'" % (
                func_name,
                unexpected
            )
        else:
            message = "'%s' is an invalid keyword argument for this function" % unexpected

        raise TooManyArguments(
            TypeError(message)
        )

    unassigned = num_args - len(
        [
            arg
            for arg in args
            if isAssigned(arg)
        ]
    )

    if unassigned:
        num_required = num_args - num_defaults

        if num_required > 0 or improved:
            if num_defaults == 0 and num_args != 1:
                raise TooManyArguments(
                    TypeError(
                        "%s expected %d arguments, got %d" % (
                            func_name,
                            num_args,
                            num_total
                        )
                    )
                )

            if num_required == 1:
                arg_desc = "1 argument" if python_version < 350 else "one argument"
            else:
                arg_desc = "%d arguments" % num_required

            raise TooManyArguments(
                TypeError(
                    "%s() takes %s %s (%d given)" % (
                        func_name,
                        "at least" if num_defaults > 0 else "exactly",
                        arg_desc,
                        num_total
                    )
                )
            )
        else:
            raise TooManyArguments(
                TypeError(
                    "%s expected %s%s, got %d" % (
                        func_name,
                        ( "at least " if python_version < 300 else "" )
                            if num_defaults > 0
                        else "exactly ",
                        "%d arguments" % num_required,
                        num_total
                    )
                )
            )

    return result
