# Copyright 2023 The JAX Authors.
#
# 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
#
#     https://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 ific language governing permissions and
# limitations under the License.

from __future__ import annotations

from typing import Union

import numpy as np
from jax._src.dtypes import iinfo, issubdtype
from jax._src.sharding import Sharding
from jax._src.sharding_impls import AUTO as AutoSharding
from jax._src.lib import xla_client as xc

Shape = tuple[int, ...]

class AutoLayout:

  def __repr__(self):
    return "AUTO"


class DeviceLocalLayout:
  major_to_minor: tuple[int, ...]
  _tiling: tuple[tuple[int, ...], ...] | None
  _sub_byte_element_size_in_bits: int

  AUTO = AutoLayout()

  def __init__(self, major_to_minor: tuple[int, ...],
                _tiling: tuple[tuple[int, ...], ...] | None = None,
                _sub_byte_element_size_in_bits: int = 0):
    self.major_to_minor = tuple(major_to_minor)
    self._tiling = None if _tiling is None else tuple(map(tuple, _tiling))
    self._sub_byte_element_size_in_bits = _sub_byte_element_size_in_bits

  @staticmethod
  def from_pjrt_layout(pjrt_layout: xc.PjRtLayout):
    xla_layout = pjrt_layout._xla_layout()
    return DeviceLocalLayout(xla_layout.minor_to_major()[::-1],  # pytype: disable=wrong-arg-types
                             xla_layout.tiling(),  # type: ignore[arg-type]
                             xla_layout.element_size_in_bits())

  def __repr__(self):
    return (
        f'DeviceLocalLayout(major_to_minor={self.major_to_minor},'
        f' _tiling={self._tiling},'
        f' _sub_byte_element_size_in_bits={self._sub_byte_element_size_in_bits})'
    )

  def __hash__(self):
    return hash((self.major_to_minor, self._tiling,
                  self._sub_byte_element_size_in_bits))

  def __eq__(self, other):
    if not isinstance(other, DeviceLocalLayout):
      return False
    return (self.major_to_minor == other.major_to_minor and
            self._tiling == other._tiling and
            self._sub_byte_element_size_in_bits == other._sub_byte_element_size_in_bits)

  def _to_xla_layout(self, dtype) -> xc.Layout:
    if self._tiling is None:
      xla_layout = xc.Layout(self.major_to_minor[::-1])
    else:
      if self._sub_byte_element_size_in_bits != 0:
        sub_byte_size = self._sub_byte_element_size_in_bits
      elif issubdtype(dtype, np.integer):
        sub_byte_size = iinfo(dtype).bits if iinfo(dtype).bits < 8 else 0
      else:
        sub_byte_size = 0
      xla_layout = xc.Layout(self.major_to_minor[::-1], self._tiling,
                              sub_byte_size)
    return xla_layout

  def check_compatible_aval(self, aval_shape: Shape):
    if len(self.major_to_minor) != len(aval_shape):
      raise ValueError(
          f'Length of major_to_minor and the rank of the value should match.'
          f' Got major_to_minor={self.major_to_minor} and shape={aval_shape}')


LayoutOptions = Union[DeviceLocalLayout, None, AutoLayout]  # pytype: disable=invalid-annotation
ShardingOptions = Union[Sharding, None, AutoSharding]


class Layout:
  __slots__ = ['device_local_layout', 'sharding']

  def __init__(self, device_local_layout: LayoutOptions = None,
               sharding: ShardingOptions = None):
    # If layout is concrete and sharding is not, error.
    if (isinstance(device_local_layout, DeviceLocalLayout) and
        (sharding is None or isinstance(sharding, AutoSharding))):
      raise ValueError(
          'Sharding has to be concrete when layout is of type'
          f' {type(device_local_layout)}. Please pass a'
          ' `jax.sharding.NamedSharding`, `jax.sharding.PositionalSharding` or'
          ' `jax.sharding.SingleDeviceSharding` to the sharding argument. Got'
          f' sharding {sharding}'
      )
    if not isinstance(
        device_local_layout, (DeviceLocalLayout, type(None), AutoLayout)):
      raise TypeError(
          'Invalid value received for the device_local_layout argument.'
          ' Expected values are `None`, `DeviceLocalLayout.AUTO` or an'
          f' instance of `DeviceLocalLayout`. Got {device_local_layout} of'
          f' type {type(device_local_layout)}'
      )
    if not isinstance(
        sharding, (Sharding, type(None), AutoSharding)):
      raise TypeError(
          'Invalid value received for the sharding argument. Expected values'
          ' are `None`, `pjit.AUTO` or an instance of `jax.Sharding`. Got'
          f' {sharding} of type {type(sharding)}')

    self.device_local_layout = device_local_layout
    self.sharding = sharding

  def __repr__(self):
    return (f'Layout(device_local_layout={self.device_local_layout},'
            f' sharding={self.sharding})')

  def __hash__(self):
    return hash((self.device_local_layout, self.sharding))

  def __eq__(self, other):
    if not isinstance(other, Layout):
      return False
    return (self.device_local_layout == other.device_local_layout and
            self.sharding == other.sharding)