# ext/declarative/base.py
# Copyright (C) 2005-2018 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Internal implementation for declarative."""

from ...schema import Table, Column
from ...orm import mapper, class_mapper, synonym
from ...orm.interfaces import MapperProperty
from ...orm.properties import ColumnProperty, CompositeProperty
from ...orm.attributes import QueryableAttribute
from ...orm.base import _is_mapped_class
from ... import util, exc
from ...util import topological
from ...sql import expression
from ... import event
from . import clsregistry
import collections
import weakref
from sqlalchemy.orm import instrumentation

declared_attr = declarative_props = None


def _declared_mapping_info(cls):
    # deferred mapping
    if _DeferredMapperConfig.has_cls(cls):
        return _DeferredMapperConfig.config_for_cls(cls)
    # regular mapping
    elif _is_mapped_class(cls):
        return class_mapper(cls, configure=False)
    else:
        return None


def _resolve_for_abstract(cls):
    if cls is object:
        return None

    if _get_immediate_cls_attr(cls, '__abstract__', strict=True):
        for sup in cls.__bases__:
            sup = _resolve_for_abstract(sup)
            if sup is not None:
                return sup
        else:
            return None
    else:
        return cls


def _get_immediate_cls_attr(cls, attrname, strict=False):
    """return an attribute of the class that is either present directly
    on the class, e.g. not on a superclass, or is from a superclass but
    this superclass is a mixin, that is, not a descendant of
    the declarative base.

    This is used to detect attributes that indicate something about
    a mapped class independently from any mapped classes that it may
    inherit from.

    """
    if not issubclass(cls, object):
        return None

    for base in cls.__mro__:
        _is_declarative_inherits = hasattr(base, '_decl_class_registry')
        if attrname in base.__dict__ and (
            base is cls or
            ((base in cls.__bases__ if strict else True)
                and not _is_declarative_inherits)
        ):
            return getattr(base, attrname)
    else:
        return None


def _as_declarative(cls, classname, dict_):
    global declared_attr, declarative_props
    if declared_attr is None:
        from .api import declared_attr
        declarative_props = (declared_attr, util.classproperty)

    if _get_immediate_cls_attr(cls, '__abstract__', strict=True):
        return

    _MapperConfig.setup_mapping(cls, classname, dict_)


def _check_declared_props_nocascade(obj, name, cls):

    if isinstance(obj, declarative_props):
        if getattr(obj, '_cascading', False):
            util.warn(
                "@declared_attr.cascading is not supported on the %s "
                "attribute on class %s.  This attribute invokes for "
                "subclasses in any case." % (name, cls))
        return True
    else:
        return False


class _MapperConfig(object):

    @classmethod
    def setup_mapping(cls, cls_, classname, dict_):
        defer_map = _get_immediate_cls_attr(
            cls_, '_sa_decl_prepare_nocascade', strict=True) or \
            hasattr(cls_, '_sa_decl_prepare')

        if defer_map:
            cfg_cls = _DeferredMapperConfig
        else:
            cfg_cls = _MapperConfig
        cfg_cls(cls_, classname, dict_)

    def __init__(self, cls_, classname, dict_):

        self.cls = cls_

        # dict_ will be a dictproxy, which we can't write to, and we need to!
        self.dict_ = dict(dict_)
        self.classname = classname
        self.mapped_table = None
        self.properties = util.OrderedDict()
        self.declared_columns = set()
        self.column_copies = {}
        self._setup_declared_events()

        # temporary registry.  While early 1.0 versions
        # set up the ClassManager here, by API contract
        # we can't do that until there's a mapper.
        self.cls._sa_declared_attr_reg = {}

        self._scan_attributes()

        clsregistry.add_class(self.classname, self.cls)

        self._extract_mappable_attributes()

        self._extract_declared_columns()

        self._setup_table()

        self._setup_inheritance()

        self._early_mapping()

    def _early_mapping(self):
        self.map()

    def _setup_declared_events(self):
        if _get_immediate_cls_attr(self.cls, '__declare_last__'):
            @event.listens_for(mapper, "after_configured")
            def after_configured():
                self.cls.__declare_last__()

        if _get_immediate_cls_attr(self.cls, '__declare_first__'):
            @event.listens_for(mapper, "before_configured")
            def before_configured():
                self.cls.__declare_first__()

    def _scan_attributes(self):
        cls = self.cls
        dict_ = self.dict_
        column_copies = self.column_copies
        mapper_args_fn = None
        table_args = inherited_table_args = None
        tablename = None

        for base in cls.__mro__:
            class_mapped = base is not cls and \
                _declared_mapping_info(base) is not None and \
                not _get_immediate_cls_attr(
                    base, '_sa_decl_prepare_nocascade', strict=True)

            if not class_mapped and base is not cls:
                self._produce_column_copies(base)

            for name, obj in vars(base).items():
                if name == '__mapper_args__':
                    check_decl = \
                        _check_declared_props_nocascade(obj, name, cls)
                    if not mapper_args_fn and (
                        not class_mapped or
                        check_decl
                    ):
                        # don't even invoke __mapper_args__ until
                        # after we've determined everything about the
                        # mapped table.
                        # make a copy of it so a class-level dictionary
                        # is not overwritten when we update column-based
                        # arguments.
                        mapper_args_fn = lambda: dict(cls.__mapper_args__)  # noqa
                elif name == '__tablename__':
                    check_decl = \
                        _check_declared_props_nocascade(obj, name, cls)
                    if not tablename and (
                        not class_mapped or
                        check_decl
                    ):
                        tablename = cls.__tablename__
                elif name == '__table_args__':
                    check_decl = \
                        _check_declared_props_nocascade(obj, name, cls)
                    if not table_args and (
                        not class_mapped or
                        check_decl
                    ):
                        table_args = cls.__table_args__
                        if not isinstance(
                                table_args, (tuple, dict, type(None))):
                            raise exc.ArgumentError(
                                "__table_args__ value must be a tuple, "
                                "dict, or None")
                        if base is not cls:
                            inherited_table_args = True
                elif class_mapped:
                    if isinstance(obj, declarative_props):
                        util.warn("Regular (i.e. not __special__) "
                                  "attribute '%s.%s' uses @declared_attr, "
                                  "but owning class %s is mapped - "
                                  "not applying to subclass %s."
                                  % (base.__name__, name, base, cls))
                    continue
                elif base is not cls:
                    # we're a mixin, abstract base, or something that is
                    # acting like that for now.
                    if isinstance(obj, Column):
                        # already copied columns to the mapped class.
                        continue
                    elif isinstance(obj, MapperProperty):
                        raise exc.InvalidRequestError(
                            "Mapper properties (i.e. deferred,"
                            "column_property(), relationship(), etc.) must "
                            "be declared as @declared_attr callables "
                            "on declarative mixin classes.")
                    elif isinstance(obj, declarative_props):
                        oldclassprop = isinstance(obj, util.classproperty)
                        if not oldclassprop and obj._cascading:
                            if name in dict_:
                                # unfortunately, while we can use the user-
                                # defined attribute here to allow a clean
                                # override, if there's another
                                # subclass below then it still tries to use
                                # this.  not sure if there is enough information
                                # here to add this as a feature later on.
                                util.warn(
                                    "Attribute '%s' on class %s cannot be "
                                    "processed due to "
                                    "@declared_attr.cascading; "
                                    "skipping" % (name, cls))
                            dict_[name] = column_copies[obj] = \
                                ret = obj.__get__(obj, cls)
                            setattr(cls, name, ret)
                        else:
                            if oldclassprop:
                                util.warn_deprecated(
                                    "Use of sqlalchemy.util.classproperty on "
                                    "declarative classes is deprecated.")
                            dict_[name] = column_copies[obj] = \
                                ret = getattr(cls, name)
                        if isinstance(ret, (Column, MapperProperty)) and \
                                ret.doc is None:
                            ret.doc = obj.__doc__

        if inherited_table_args and not tablename:
            table_args = None

        self.table_args = table_args
        self.tablename = tablename
        self.mapper_args_fn = mapper_args_fn

    def _produce_column_copies(self, base):
        cls = self.cls
        dict_ = self.dict_
        column_copies = self.column_copies
        # copy mixin columns to the mapped class
        for name, obj in vars(base).items():
            if isinstance(obj, Column):
                if getattr(cls, name) is not obj:
                    # if column has been overridden
                    # (like by the InstrumentedAttribute of the
                    # superclass), skip
                    continue
                elif obj.foreign_keys:
                    raise exc.InvalidRequestError(
                        "Columns with foreign keys to other columns "
                        "must be declared as @declared_attr callables "
                        "on declarative mixin classes. ")
                elif name not in dict_ and not (
                        '__table__' in dict_ and
                        (obj.name or name) in dict_['__table__'].c
                ):
                    column_copies[obj] = copy_ = obj.copy()
                    copy_._creation_order = obj._creation_order
                    setattr(cls, name, copy_)
                    dict_[name] = copy_

    def _extract_mappable_attributes(self):
        cls = self.cls
        dict_ = self.dict_

        our_stuff = self.properties

        late_mapped = _get_immediate_cls_attr(
                    cls, '_sa_decl_prepare_nocascade', strict=True)

        for k in list(dict_):

            if k in ('__table__', '__tablename__', '__mapper_args__'):
                continue

            value = dict_[k]
            if isinstance(value, declarative_props):
                if isinstance(value, declared_attr) and value._cascading:
                    util.warn(
                        "Use of @declared_attr.cascading only applies to "
                        "Declarative 'mixin' and 'abstract' classes.  "
                        "Currently, this flag is ignored on mapped class "
                        "%s" % self.cls)

                value = getattr(cls, k)

            elif isinstance(value, QueryableAttribute) and \
                    value.class_ is not cls and \
                    value.key != k:
                # detect a QueryableAttribute that's already mapped being
                # assigned elsewhere in userland, turn into a synonym()
                value = synonym(value.key)
                setattr(cls, k, value)

            if (isinstance(value, tuple) and len(value) == 1 and
                    isinstance(value[0], (Column, MapperProperty))):
                util.warn("Ignoring declarative-like tuple value of attribute "
                          "%s: possibly a copy-and-paste error with a comma "
                          "left at the end of the line?" % k)
                continue
            elif not isinstance(value, (Column, MapperProperty)):
                # using @declared_attr for some object that
                # isn't Column/MapperProperty; remove from the dict_
                # and place the evaluated value onto the class.
                if not k.startswith('__'):
                    dict_.pop(k)