# 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, is_auto
from jax._src.lib import xla_client as xc
from jax._src.lib import xla_extension_version

Shape = tuple[int, ...]

class AutoLayout:

  def __repr__(self):
    return "AUTO"


if xla_extension_version >= 274:
  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(),
                               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) -> str:
      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,  # type: ignore
                               sub_byte_size)
      return str(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}')

else:
  class DeviceLocalLayout:  # type: ignore
    layout: xc.PjRtLayout

    AUTO = AutoLayout()

    def __init__(self, layout: xc.PjRtLayout):
      self._layout = layout
      self._layout_str = str(self._layout)

    @staticmethod
    def from_pjrt_layout(pjrt_layout: xc.PjRtLayout):
      return DeviceLocalLayout(pjrt_layout)  # type: ignore

    def __repr__(self):
      return f'DeviceLocalLayout({self._layout_str})'

    def __hash__(self):
      return hash(self._layout)

    def __eq__(self, other):
      if not isinstance(other, DeviceLocalLayout):
        return False
      return self._layout == other._layout

    def _to_xla_layout(self, dtype) -> str:
      return self._layout_str

    def check_compatible_aval(self, aval_shape: Shape):
      pass


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 is_auto(sharding))):
      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)