# Copyright 2015 DataStax, Inc.
#
# 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.

from copy import deepcopy, copy
from datetime import date, datetime
import logging
import six
import warnings

from cassandra import util
from cassandra.cqltypes import DateType, SimpleDateType
from cassandra.cqlengine import ValidationError
from cassandra.cqlengine.functions import get_total_seconds

log = logging.getLogger(__name__)


class BaseValueManager(object):

    def __init__(self, instance, column, value):
        self.instance = instance
        self.column = column
        self.previous_value = deepcopy(value)
        self.value = value
        self.explicit = False

    @property
    def deleted(self):
        return self.value is None and self.previous_value is not None

    @property
    def changed(self):
        """
        Indicates whether or not this value has changed.

        :rtype: boolean

        """
        return self.value != self.previous_value

    def reset_previous_value(self):
        self.previous_value = copy(self.value)

    def getval(self):
        return self.value

    def setval(self, val):
        self.value = val

    def delval(self):
        self.value = None

    def get_property(self):
        _get = lambda slf: self.getval()
        _set = lambda slf, val: self.setval(val)
        _del = lambda slf: self.delval()

        if self.column.can_delete:
            return property(_get, _set, _del)
        else:
            return property(_get, _set)


class Column(object):

    # the cassandra type this column maps to
    db_type = None
    value_manager = BaseValueManager

    instance_counter = 0

    primary_key = False
    """
    bool flag, indicates this column is a primary key. The first primary key defined
    on a model is the partition key (unless partition keys are set), all others are cluster keys
    """

    partition_key = False

    """
    indicates that this column should be the partition key, defining
    more than one partition key column creates a compound partition key
    """

    index = False
    """
    bool flag, indicates an index should be created for this column
    """

    db_field = None
    """
    the fieldname this field will map to in the database
    """

    default = None
    """
    the default value, can be a value or a callable (no args)
    """

    required = False
    """
    boolean, is the field required? Model validation will raise and
    exception if required is set to True and there is a None value assigned
    """

    clustering_order = None
    """
    only applicable on clustering keys (primary keys that are not partition keys)
    determines the order that the clustering keys are sorted on disk
    """

    polymorphic_key = False
    """
    *Deprecated*

    see :attr:`~.discriminator_column`
    """

    discriminator_column = False
    """
    boolean, if set to True, this column will be used for discriminating records
    of inherited models.

    Should only be set on a column of an abstract model being used for inheritance.

    There may only be one discriminator column per model. See :attr:`~.__discriminator_value__`
    for how to specify the value of this column on specialized models.
    """

    static = False
    """
    boolean, if set to True, this is a static column, with a single value per partition
    """

    def __init__(self,
                 primary_key=False,
                 partition_key=False,
                 index=False,
                 db_field=None,
                 default=None,
                 required=False,
                 clustering_order=None,
                 polymorphic_key=False,
                 discriminator_column=False,
                 static=False):
        self.partition_key = partition_key
        self.primary_key = partition_key or primary_key
        self.index = index
        self.db_field = db_field
        self.default = default
        self.required = required
        self.clustering_order = clustering_order

        if polymorphic_key:
            msg = "polymorphic_key is deprecated. Use discriminator_column instead."
            warnings.warn(msg, DeprecationWarning)
            log.warning(msg)

        self.discriminator_column = discriminator_column or polymorphic_key
        self.polymorphic_key = self.discriminator_column

        # the column name in the model definition
        self.column_name = None
        self.static = static

        self.value = None

        # keep track of instantiation order
        self.position = Column.instance_counter
        Column.instance_counter += 1

    def validate(self, value):
        """
        Returns a cleaned and validated value. Raises a ValidationError
        if there's a problem
        """
        if value is None:
            if self.required:
                raise ValidationError('{0} - None values are not allowed'.format(self.column_name or self.db_field))
        return value

    def to_python(self, value):
        """
        Converts data from the database into python values
        raises a ValidationError if the value can't be converted
        """
        return value

    def to_database(self, value):
        """
        Converts python value into database value
        """
        if value is None and self.has_default:
            return self.get_default()
        return value

    @property
    def has_default(self):
        return self.default is not None

    @property
    def is_primary_key(self):
        return self.primary_key

    @property
    def can_delete(self):
        return not self.primary_key

    def get_default(self):
        if self.has_default:
            if callable(self.default):
                return self.default()
            else:
                return self.default

    def get_column_def(self):
        """
        Returns a column definition for CQL table definition
        """
        static = "static" if self.static else ""
        return '{0} {1} {2}'.format(self.cql, self.db_type, static)

    # TODO: make columns use cqltypes under the hood
    # until then, this bridges the gap in using types along with cassandra.metadata for CQL generation
    def cql_parameterized_type(self):
        return self.db_type

    def set_column_name(self, name):
        """
        Sets the column name during document class construction
        This value will be ignored if db_field is set in __init__
        """
        self.column_name = name

    @property
    def db_field_name(self):
        """ Returns the name of the cql name of this column """
        return self.db_field or self.column_name

    @property
    def db_index_name(self):
        """ Returns the name of the cql index """
        return 'index_{0}'.format(self.db_field_name)

    @property
    def cql(self):
        return self.get_cql()

    def get_cql(self):
        return '"{0}"'.format(self.db_field_name)

    def _val_is_null(self, val):
        """ determines if the given value equates to a null value for the given column type """
        return val is None

    @property
    def sub_columns(self):
        return []


class Blob(Column):
    """
    Stores a raw binary value
    """
    db_type = 'blob'

    def to_database(self, value):

        if not isinstance(value, (six.binary_type, bytearray)):
            raise Exception("expecting a binary, got a %s" % type(value))

        val = super(Bytes, self).to_database(value)
        return bytearray(val)

    def to_python(self, value):
        return value

Bytes = Blob


class Ascii(Column):
    """
    Stores a US-ASCII character string
    """
    db_type = 'ascii'


class Inet(Column):
    """
    Stores an IP address in IPv4 or IPv6 format
    """
    db_type = 'inet'


class Text(Column):
    """
    Stores a UTF-8 encoded string
    """
    db_type = 'text'

    def __init__(self, min_length=None, max_length=None, **kwargs):
        """
        :param int min_length: Sets the minimum length of this string, for validation purposes.
            Defaults to 1 if this is a ``required`` column. Otherwise, None.
        :param int max_lemgth: Sets the maximum length of this string, for validation purposes.
        """
        self.min_length = min_length or (1 if kwargs.get('required', False) else None)
        self.max_length = max_length
        super(Text, self).__init__(**kwargs)

    def validate(self, value):
        value = super(Text, self).validate(value)
        if value is None:
            return
        if not isinstance(value, (six.string_types, bytearray)) and value is not None:
            raise ValidationError('{0} {1} is not a string'.format(self.column_name, type(value)))
        if self.max_length:
            if len(value) > self.max_length:
                raise ValidationError('{0} is longer than {1} characters'.format(self.column_name, self.max_length))
        if self.min_length:
            if len(value) < self.min_length:
                raise ValidationError('{0} is shorter than {1} characters'.format(self.column_name, self.min_length))
        return value


class Integer(Column):
    """
    Stores a 32-bit signed integer value
    """

    db_type = 'int'

    def validate(self, value):
        val = super(Integer, self).validate(value)
        if val is None:
            return
        try:
            return int(val)
        except (TypeError, ValueError):
            raise ValidationError("{0} {1} can't be converted to integral value".format(self.column_name, value))

    def to_python(self, value):
        return self.validate(value)

    def to_database(self, value):
        return self.validate(value)


class TinyInt(Integer):
    """
    Stores an 8-bit signed integer value

    .. versionadded:: 2.6.0

    requires C* 2.2+ and protocol v4+
    """
    db_type = 'tinyint'


class SmallInt(Integer):
    """
    Stores a 16-bit signed integer value

    .. versionadded:: 2.6.0

    requires C* 2.2+ and protocol v4+
    """
    db_type = 'smallint'


class BigInt(Integer):
    """
    Stores a 64-bit signed integer value
    """
    db_type = 'bigint'


class VarInt(Column):
    """
    Stores an arbitrary-precision integer
    """
    db_type = 'varint'

    def validate(self, value):
        val = super(VarInt, self).validate(value)
        if val is None:
            return
        try:
            return int(val)
        except (TypeError, ValueError):
            raise ValidationError(
                "{0} {1} can't be converted to integral value".format(self.column_name, value))

    def to_python(self, value):
        return self.validate(value)

    def to_database(self, value):
        return self.validate(value)


class CounterValueManager(BaseValueManager):
    def __init__(self, instance, column, value):
        super(CounterValueManager, self).__init__(instance, column, value)
        self.value = self.value or 0
        self.previous_value = self.previous_value or 0


class Counter(Integer):
    """
    Stores a counter that can be inremented and decremented
    """
    db_type = 'counter'

    value_manager = CounterValueManager

    def __init__(self,
                 index=False,
                 db_field=None,
                 required=False):
        super(Counter, self).__init__(
            primary_key=False,
            partition_key=False,
            index=index,
            db_field=db_field,
            default=0,
            required=required,
        )


class DateTime(Column):
    """
    Stores a datetime value
    """
    db_type = 'timestamp'

    def to_python(self, value):
        if value is None:
            return
        if isinstance(value, datetime):
            return value
        elif isinstance(value, date):
            return datetime(*(value.timetuple()[:6]))
        try:
            return datetime.utcfromtimestamp(value)
        except TypeError:
            return datetime.utcfromtimestamp(DateType.deserialize(value))

    def to_database(self, value):
        value = super(DateTime, self).to_database(value)
        if value is None:
            return
        if not isinstance(value, datetime):
            if isinstance(value, date):
                value = datetime(value.year, value.month, value.day)
            else:
                raise ValidationError("{0} '{1}' is not a datetime object".format(self.column_name, value))
        epoch = datetime(1970, 1, 1, tzinfo=value.tzinfo)
        offset = get_total_seconds(epoch.tzinfo.utcoffset(epoch)) if epoch.tzinfo else 0

        return int((get_total_seconds(value - epoch) - offset) * 1000)


class Date(Column):
    """
    Stores a simple date, with no time-of-day

    .. versionchanged:: 2.6.0

        removed overload of Date and DateTime. DateTime is a drop-in replacement for legacy models

    requires C* 2.2+ and protocol v4+
    """
    db_type = 'date'

    def to_database(self, value):
        value = super(Date, self).to_database(value)
        if value is None:
            return

        # need to translate to int version because some dates are not representable in
        # string form (datetime limitation)
        d = value if isinstance(value, util.Date) else util.Date(value)
        return d.days_from_epoch + SimpleDateType.EPOCH_OFFSET_DAYS


class Time(Column):
    """
    Stores a timezone-naive time-of-day, with nanosecond precision

    .. versionadded:: 2.6.0

    requires C* 2.2+ and protocol v4+
    """
    db_type = 'time'

    def to_database(self, value):
        value = super(Time, self).to_database(value)
        if value is None:
            return
        # str(util.Time) yields desired CQL encoding
        return value if isinstance(value, util.Time) else util.Time(value)


class UUID(Column):
    """
    Stores a type 1 or 4 UUID
    """
    db_type = 'uuid'

    def validate(self, value):
        val = super(UUID, self).validate(value)
        if val is None:
            return
        from uuid import UUID as _UUID
        if isinstance(val, _UUID):
            return val
        if isinstance(val, six.string_types):
            try:
                return _UUID(val)
            except ValueError:
                # fall-through to error
                pass
        raise ValidationError("{0} {1} is not a valid uuid".format(
            self.column_name, value))

    def to_python(self, value):
        return self.validate(value)

    def to_database(self, value):
        return self.validate(value)

from uuid import UUID as pyUUID, getnode


class TimeUUID(UUID):
    """
    UUID containing timestamp
    """

    db_type = 'timeuuid'

    @classmethod
    def from_datetime(self, dt):
        """
        generates a UUID for a given datetime

        :param dt: datetime
        :type dt: datetime
        :return: uuid1

        .. deprecated:: 2.6.0

            Use :func:`cassandra.util.uuid_from_time`

        """
        msg = "cqlengine.columns.TimeUUID.from_datetime is deprecated. Use cassandra.util.uuid_from_time instead."
        warnings.warn(msg, DeprecationWarning)
        log.warning(msg)
        return util.uuid_from_time(dt)


class Boolean(Column):
    """
    Stores a boolean True or False value
    """
    db_type = 'boolean'

    def validate(self, value):
        """ Always returns a Python boolean. """
        value = super(Boolean, self).validate(value)

        if value is not None:
            value = bool(value)

        return value

    def to_python(self, value):
        return self.validate(value)


class BaseFloat(Column):
    def validate(self, value):
        value = super(BaseFloat, self).validate(value)
        if value is None:
            return
        try:
            return float(value)
        except (TypeError, ValueError):
            raise ValidationError("{0} {1} is not a valid float".format(self.column_name, value))

    def to_python(self, value):
        return self.validate(value)

    def to_database(self, value):
        return self.validate(value)


class Float(BaseFloat):
    """
    Stores a single-precision floating-point value
    """
    db_type = 'float'

    def __init__(self, double_precision=None, **kwargs):
        if double_precision is None or bool(double_precision):
            msg = "Float(double_precision=True) is deprecated. Use Double() type instead."
            double_precision = True
            warnings.warn(msg, DeprecationWarning)
            log.warning(msg)

        self.db_type = 'double' if double_precision else 'float'

        super(Float, self).__init__(**kwargs)


class Double(BaseFloat):
    """
    Stores a double-precision floating-point value
    """
    db_type = 'double'


class Decimal(Column):
    """
    Stores a variable precision decimal value
    """
    db_type = 'decimal'

    def validate(self, value):
        from decimal import Decimal as _Decimal
        from decimal import InvalidOperation
        val = super(Decimal, self).validate(value)
        if val is None:
            return
        try:
            return _Decimal(repr(val)) if isinstance(val, float) else _Decimal(val)
        except InvalidOperation:
            raise ValidationError("{0} '{1}' can't be coerced to decimal".format(self.column_name, val))

    def to_python(self, value):
        return self.validate(value)

    def to_database(self, value):
        return self.validate(value)


class BaseContainerColumn(Column):
    """
    Base Container type for collection-like columns.

    https://cassandra.apache.org/doc/cql3/CQL.html#collections
    """

    def __init__(self, value_type, **kwargs):
        """
        :param value_type: a column class indicating the types of the value
        """
        inheritance_comparator = issubclass if isinstance(value_type, type) else isinstance
        if not inheritance_comparator(value_type, Column):
            raise ValidationError('value_type must be a column class')
        if inheritance_comparator(value_type, BaseContainerColumn):
            raise ValidationError('container types cannot be nested')
        if value_type.db_type is None:
            raise ValidationError('value_type cannot be an abstract column type')

        if isinstance(value_type, type):
            self.value_type = value_type
            self.value_col = self.value_type()
        else:
            self.value_col = value_type
            self.value_type = self.value_col.__class__

        super(BaseContainerColumn, self).__init__(**kwargs)

    def validate(self, value):
        value = super(BaseContainerColumn, self).validate(value)
        # It is dangerous to let collections have more than 65535.
        # See: https://issues.apache.org/jira/browse/CASSANDRA-5428
        if value is not None and len(value) > 65535:
            raise ValidationError("{0} Collection can't have more than 65535 elements.".format(self.column_name))
        return value

    def _val_is_null(self, val):
        return not val

    @property
    def sub_columns(self):
        return [self.value_col]


class Set(BaseContainerColumn):
    """
    Stores a set of unordered, unique values

    http://www.datastax.com/documentation/cql/3.1/cql/cql_using/use_set_t.html
    """
    def __init__(self, value_type, strict=True, default=set, **kwargs):
        """
        :param value_type: a column class indicating the types of the value
        :param strict: sets whether non set values will be coerced to set
            type on validation, or raise a validation error, defaults to True
        """
        self.strict = strict
        self.db_type = 'set<{0}>'.format(value_type.db_type)
        super(Set, self).__init__(value_type, default=default, **kwargs)

    def validate(self, value):
        val = super(Set, self).validate(value)
        if val is None:
            return
        types = (set,) if self.strict else (set, list, tuple)
        if not isinstance(val, types):
            if self.strict:
                raise ValidationError('{0} {1} is not a set object'.format(self.column_name, val))
            else:
                raise ValidationError('{0} {1} cannot be coerced to a set object'.format(self.column_name, val))

        if None in val:
            raise ValidationError("{0} None not allowed in a set".format(self.column_name))

        return set(self.value_col.validate(v) for v in val)

    def to_python(self, value):
        if value is None:
            return set()
        return set(self.value_col.to_python(v) for v in value)

    def to_database(self, value):
        if value is None:
            return None
        return set(self.value_col.to_database(v) for v in value)


class List(BaseContainerColumn):
    """
    Stores a list of ordered values

    http://www.datastax.com/documentation/cql/3.1/cql/cql_using/use_list_t.html
    """
    def __init__(self, value_type, default=list, **kwargs):
        """
        :param value_type: a column class indicating the types of the value
        """
        self.db_type = 'list<{0}>'.format(value_type.db_type)
        return super(List, self).__init__(value_type=value_type, default=default, **kwargs)

    def validate(self, value):
        val = super(List, self).validate(value)
        if val is None:
            return
        if not isinstance(val, (set, list, tuple)):
            raise ValidationError('{0} {1} is not a list object'.format(self.column_name, val))
        if None in val:
            raise ValidationError("{0} None is not allowed in a list".format(self.column_name))
        return [self.value_col.validate(v) for v in val]

    def to_python(self, value):
        if value is None:
            return []
        return [self.value_col.to_python(v) for v in value]

    def to_database(self, value):
        if value is None:
            return None
        return [self.value_col.to_database(v) for v in value]


class Map(BaseContainerColumn):
    """
    Stores a key -> value map (dictionary)

    http://www.datastax.com/documentation/cql/3.1/cql/cql_using/use_map_t.html
    """
    def __init__(self, key_type, value_type, default=dict, **kwargs):
        """
        :param key_type: a column class indicating the types of the key
        :param value_type: a column class indicating the types of the value
        """

        self.db_type = 'map<{0}, {1}>'.format(key_type.db_type, value_type.db_type)

        inheritance_comparator = issubclass if isinstance(key_type, type) else isinstance
        if not inheritance_comparator(key_type, Column):
            raise ValidationError('key_type must be a column class')
        if inheritance_comparator(key_type, BaseContainerColumn):
            raise ValidationError('container types cannot be nested')
        if key_type.db_type is None:
            raise ValidationError('key_type cannot be an abstract column type')

        if isinstance(key_type, type):
            self.key_type = key_type
            self.key_col = self.key_type()
        else:
            self.key_col = key_type
            self.key_type = self.key_col.__class__
        super(Map, self).__init__(value_type, default=default, **kwargs)

    def validate(self, value):
        val = super(Map, self).validate(value)
        if val is None:
            return
        if not isinstance(val, dict):
            raise ValidationError('{0} {1} is not a dict object'.format(self.column_name, val))
        if None in val:
            raise ValidationError("{0} None is not allowed in a map".format(self.column_name))
        return dict((self.key_col.validate(k), self.value_col.validate(v)) for k, v in val.items())

    def to_python(self, value):
        if value is None:
            return {}
        if value is not None:
            return dict((self.key_col.to_python(k), self.value_col.to_python(v)) for k, v in value.items())

    def to_database(self, value):
        if value is None:
            return None
        return dict((self.key_col.to_database(k), self.value_col.to_database(v)) for k, v in value.items())

    @property
    def sub_columns(self):
        return [self.key_col, self.value_col]


class UDTValueManager(BaseValueManager):
    @property
    def changed(self):
        return self.value != self.previous_value or self.value.has_changed_fields()

    def reset_previous_value(self):
        self.value.reset_changed_fields()
        self.previous_value = copy(self.value)


class UserDefinedType(Column):
    """
    User Defined Type column

    http://www.datastax.com/documentation/cql/3.1/cql/cql_using/cqlUseUDT.html

    These columns are represented by a specialization of :class:`cassandra.cqlengine.usertype.UserType`.

    Please see :ref:`user_types` for examples and discussion.
    """

    value_manager = UDTValueManager

    def __init__(self, user_type, **kwargs):
        """
        :param type user_type: specifies the :class:`~.cqlengine.usertype.UserType` model of the column
        """
        self.user_type = user_type
        self.db_type = "frozen<%s>" % user_type.type_name()
        super(UserDefinedType, self).__init__(**kwargs)

    @property
    def sub_columns(self):
        return list(self.user_type._fields.values())


def resolve_udts(col_def, out_list):
    for col in col_def.sub_columns:
        resolve_udts(col, out_list)
    if isinstance(col_def, UserDefinedType):
        out_list.append(col_def.user_type)


class _PartitionKeysToken(Column):
    """
    virtual column representing token of partition columns.
    Used by filter(pk__token=Token(...)) filters
    """

    def __init__(self, model):
        self.partition_columns = model._partition_keys.values()
        super(_PartitionKeysToken, self).__init__(partition_key=True)

    @property
    def db_field_name(self):
        return 'token({0})'.format(', '.join(['"{0}"'.format(c.db_field_name) for c in self.partition_columns]))

    def to_database(self, value):
        from cqlengine.functions import Token
        assert isinstance(value, Token)
        value.set_columns(self.partition_columns)
        return value

    def get_cql(self):
        return "token({0})".format(", ".join(c.cql for c in self.partition_columns))
