# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You 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.

import ctypes
import decimal
import warnings

from functools import wraps
from typing import Any, Optional, Type, Tuple, Union

from pyignite.datatypes.base import IgniteDataType
from .constants import *

FALLBACK = False

try:
    from pyignite import _cutils
except ImportError:
    FALLBACK = True


LONG_MASK = 0xffffffff
DIGITS_PER_INT = 9


def is_pow2(value: int) -> bool:
    """ Check if value is power of two. """
    return value > 0 and ((value & (value - 1)) == 0)


def is_iterable(value: Any) -> bool:
    """ Check if value is iterable. """
    try:
        iter(value)
        return True
    except TypeError:
        return False


def is_binary(value):
    """
    Check if a value is a pythonic representation of a Complex object.
    """
    return all([
        hasattr(value, 'type_name'),
        hasattr(value, 'type_id'),
        hasattr(value, 'schema'),
        hasattr(value, 'schema_id'),
    ])


def is_hinted(value):
    """
    Check if a value is a tuple of data item and its type hint.
    """
    return (
        isinstance(value, tuple)
        and len(value) == 2
        and issubclass(value[1], IgniteDataType)
    )


def is_wrapped(value: Any) -> bool:
    """
    Check if a value is of WrappedDataObject type.
    """
    return (
        type(value) is tuple
        and len(value) == 2
        and type(value[0]) is bytes
        and type(value[1]) is int
    )


def int_overflow(value: int) -> int:
    """
    Simulates 32bit integer overflow.
    """
    return ((value ^ 0x80000000) & 0xffffffff) - 0x80000000


def hashcode(data: Union[str, bytes, bytearray, memoryview]) -> int:
    """
    Calculate hash code used for identifying objects in Ignite binary API.

    :param data: UTF-8-encoded string identifier of binary buffer or byte array
    :return: hash code.
    """
    if FALLBACK:
        return __hashcode_fallback(data)

    return _cutils.hashcode(data)


def __hashcode_fallback(data: Union[str, bytes, bytearray, memoryview]) -> int:
    if data is None:
        return 0
    
    if isinstance(data, str):
        """
        For strings we iterate over code point which are of the int type
        and can take up to 4 bytes and can only be positive.
        """
        result = 0
        for char in data:
            try:
                char_val = ord(char)
                result = int_overflow(31 * result + char_val)
            except TypeError:
                pass
    else:
        """
        For byte array we iterate over bytes which only take 1 byte. But
        according to protocol, bytes during hashing should be treated as signed
        integer numbers 8 bits long. On other hand elements in Python's `bytes`
        are unsigned. For this reason we use ctypes.c_byte() to make them
        signed.
        """
        result = 1
        for byte in data:
            byte = ctypes.c_byte(byte).value
            result = int_overflow(31 * result + byte)
    return result


def cache_id(cache: Union[str, int]) -> int:
    """
    Create a cache ID from cache name.

    :param cache: cache name or ID,
    :return: cache ID.
    """
    return cache if type(cache) is int else hashcode(cache)


def entity_id(cache: Union[str, int]) -> Optional[int]:
    """
    Create a type ID from type name or field ID from field name.

    :param cache: entity name or ID,
    :return: entity ID.
    """
    if cache is None:
        return None
    return cache if type(cache) is int else hashcode(cache.lower())


def schema_id(schema: Union[int, dict]) -> int:
    """
    Calculate Complex Object schema ID.

    :param schema: a dict of field names: field types,
    :return: schema ID.
    """
    if FALLBACK:
        return __schema_id_fallback(schema)
    return _cutils.schema_id(schema)


def __schema_id_fallback(schema: Union[int, dict]) -> int:
    if isinstance(schema, int):
        return schema

    if schema is None:
        return 0

    s_id = FNV1_OFFSET_BASIS if schema else 0
    for field_name in schema.keys():
        field_id = __hashcode_fallback(field_name.lower())
        s_id ^= (field_id & 0xff)
        s_id = int_overflow(s_id * FNV1_PRIME)
        s_id ^= ((field_id >> 8) & 0xff)
        s_id = int_overflow(s_id * FNV1_PRIME)
        s_id ^= ((field_id >> 16) & 0xff)
        s_id = int_overflow(s_id * FNV1_PRIME)
        s_id ^= ((field_id >> 24) & 0xff)
        s_id = int_overflow(s_id * FNV1_PRIME)
    return s_id


def decimal_hashcode(value: decimal.Decimal) -> int:
    """
    This is a translation of `java.math.BigDecimal` class `hashCode()` method
    to Python.

    :param value: pythonic decimal value,
    :return: hashcode.
    """
    sign, digits, scale = value.normalize().as_tuple()
    sign = -1 if sign else 1
    value = int(''.join([str(d) for d in digits]))

    if value < MAX_LONG:
        # this is the case when Java BigDecimal digits are stored
        # compactly, in the internal 64-bit integer field
        int_hash = (
            (unsigned(value, ctypes.c_ulonglong) >> 32) * 31
            + (value & LONG_MASK)
        ) & LONG_MASK
    else:
        # digits are not fit in the 64-bit long, so they get split internally
        # to an array of values within 32-bit integer range each (it is really
        # a part of `java.math.BigInteger` class internals)
        magnitude = []
        order = 0
        while True:
            elem = value >> order
            if elem > 1:
                magnitude.insert(0, ctypes.c_int(elem).value)
                order += 32
            else:
                break

        int_hash = 0
        for v in magnitude:
            int_hash = (31 * int_hash + (v & LONG_MASK)) & LONG_MASK

    return ctypes.c_int(31 * int_hash * sign - scale).value


def datetime_hashcode(value: int) -> int:
    """
    Calculates hashcode from UNIX epoch.

    :param value: UNIX time,
    :return: Java hashcode.
    """
    return (value & LONG_MASK) ^ (unsigned(value, ctypes.c_ulonglong) >> 32)


def status_to_exception(exc: Type[Exception]):
    """
    Converts erroneous status code with error message to an exception
    of the given class.

    :param exc: the class of exception to raise,
    :return: decorator.
    """
    def ste_decorator(fn):
        @wraps(fn)
        def ste_wrapper(*args, **kwargs):
            result = fn(*args, **kwargs)
            if result.status != 0:
                raise exc(result.message)
            return result.value
        return ste_wrapper
    return ste_decorator


def get_field_by_id(
    obj: 'GenericObjectMeta', field_id: int
) -> Tuple[Any, IgniteDataType]:
    """
    Returns a complex object's field value, given the field's entity ID.

    :param obj: complex object,
    :param field_id: field ID,
    :return: complex object field's value and type.
    """
    for fname, ftype in obj._schema.items():
        if entity_id(fname) == field_id:
            return getattr(obj, fname, getattr(ftype, 'default')), ftype


def unsigned(value: int, c_type: ctypes._SimpleCData = ctypes.c_uint) -> int:
    """ Convert signed integer value to unsigned. """
    return c_type(value).value


def capitalize(string: str) -> str:
    """
    Capitalizing the string, assuming the first character is a letter.
    Does not touch any other character, unlike the `string.capitalize()`.
    """
    return string[:1].upper() + string[1:]


def process_delimiter(name: str, delimiter: str) -> str:
    """
    Splits the name by delimiter, capitalize each part, merge.
    """
    return ''.join([capitalize(x) for x in name.split(delimiter)])


def deprecated(version, reason):
    def decorator_deprecated(fn):
        @wraps(fn)
        def wrapper_deprecated(*args, **kwds):
            warnings.warn(f'Deprecated since {version}. The reason: {reason}', category=DeprecationWarning)
            return fn(*args, **kwds)
        return wrapper_deprecated
    return decorator_deprecated