# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
#
# 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.

import paddle.fluid.framework as framework
import paddle.fluid.data_feeder as data_feeder
import paddle.fluid.layer_helper as layer_helper
from paddle.distributed.communication.group import (
    _get_global_group,
    _warn_cur_rank_not_in_group,
    _get_or_throw_group_rank,
)


def _broadcast_in_dygraph(
    tensor, src_rank_in_group, group, sync_op, use_calc_stream
):
    if use_calc_stream:
        return group.process_group.broadcast_on_calc_stream(
            tensor, src_rank_in_group
        )

    task = group.process_group.broadcast(tensor, src_rank_in_group, sync_op)
    if sync_op:
        task.wait()

    return task


def _broadcast_in_static_mode(
    tensor, src_rank_in_group, group, sync_op, use_calc_stream
):
    data_feeder.check_variable_and_dtype(
        tensor,
        'tensor',
        [
            'float16',
            'float32',
            'float64',
            'int32',
            'int64',
            'int8',
            'uint8',
            'bool',
        ],
        'broadcast',
    )

    op_type = 'c_broadcast'
    helper = layer_helper.LayerHelper(op_type, **locals())
    ring_id = 0 if group is None else group.id

    helper.append_op(
        type=op_type,
        inputs={'X': [tensor]},
        outputs={'Out': [tensor]},
        attrs={
            'root': src_rank_in_group,
            'use_calc_stream': sync_op,
            'ring_id': ring_id,
        },
    )
    return None


def broadcast(tensor, src, group=None, sync_op=True, use_calc_stream=False):
    """

    Broadcast a tensor to all devices.

    Args:
        tensor (Tensor): The tensor to broadcast. Support float16, float32, float64, int32, int64, int8, uint8 or bool as its data type.
        src (int, optional): Rank of the source device.
        group (Group, optional): Communicate in which group. If none is given, use the global group as default.
        sync_op (bool, optional): Indicate whether the communication is sync or not. If none is given, use true as default.
        use_calc_stream (bool, optional): Indicate whether the communication is done on calculation stream. If none is given, use false as default. This
            option is designed for high performance demand, be careful to turn it on except you are clearly know its meaning.

    Returns:
        Return a task object.

    Warning:
        This API only supports the dygraph mode now.

    Examples:
        .. code-block:: python

            # required: distributed
            import paddle
            import paddle.distributed as dist

            dist.init_parallel_env()
            local_rank = dist.get_rank()
            if local_rank == 0:
                data = paddle.to_tensor([[4, 5, 6], [4, 5, 6]])
            else:
                data = paddle.to_tensor([[1, 2, 3], [1, 2, 3]])
            task = dist.stream.broadcast(data, src=1, sync_op=False)
            task.wait()
            out = data.numpy()
            # [[1, 2, 3], [1, 2, 3]] (2 GPUs)
    """
    if _warn_cur_rank_not_in_group(group):
        return

    if not sync_op and use_calc_stream:
        raise RuntimeError(
            "use_calc_stream can only be True in sync op behavior."
        )

    if framework.in_dygraph_mode():
        group = _get_global_group() if group is None else group
        src_rank_in_group = _get_or_throw_group_rank(src, group)

        return _broadcast_in_dygraph(
            tensor, src_rank_in_group, group, sync_op, use_calc_stream
        )
    else:
        assert group is None, "Group can not be used in static mode for now."
        return _broadcast_in_static_mode(
            tensor, src, group, sync_op, use_calc_stream
        )