# 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 unittest

import numpy as np

import paddle
import paddle.distributed as dist
from paddle.nn import Linear

paddle.seed(1024)
np.random.seed(2021)

batch = 5
in_dim = 10
out_dim = 20


class SimpleNet(paddle.nn.Layer):
    def __init__(self, train_id):
        super().__init__()
        self.w1 = self.create_parameter(
            shape=[in_dim, out_dim], dtype="float32"
        )
        self.w2 = self.create_parameter(
            shape=[in_dim, out_dim], dtype="float32"
        )
        self.share_net = Linear(out_dim, 10)

        self.unused_param = self.create_parameter(
            shape=[out_dim, in_dim], dtype="float64"
        )

        # just for test sync_params_buffers
        # self.register_buffer("queue", paddle.randn([10, 5]))
        # self.queue = paddle.nn.functional.normalize(self.queue, axis=0)
        # self.register_buffer("queue_ptr", paddle.zeros([1], 'int64'))

        self.trainer_id = train_id

    def forward(self, x):
        is_use = (
            paddle.equal_all(x, paddle.ones(shape=(batch, in_dim))).item()
            and self.trainer_id == 1
        )

        if is_use:
            tmp = paddle.matmul(x, self.w1)
        else:
            tmp = paddle.matmul(x, self.w2)

        return self.share_net(tmp)


class TestDistTraining(unittest.TestCase):
    def test_multiple_gpus(self):
        self.trainer_id = dist.get_rank()
        self.pg = dist.init_parallel_env()

        model_a = SimpleNet(self.trainer_id)
        model_b = SimpleNet(self.trainer_id)

        state_dict = model_a.state_dict()
        model_b.set_state_dict(state_dict)

        model_a = paddle.DataParallel(
            model_a, find_unused_parameters=True, group=self.pg
        )
        model_b = paddle.DataParallel(
            model_b, find_unused_parameters=True, group=self.pg
        )

        ones_input = paddle.ones(shape=(batch, in_dim))
        ones_input.stop_gradient = True

        w1_grad_sum = np.zeros((in_dim, out_dim), dtype='float32')
        w2_grad_sum = np.zeros((in_dim, out_dim), dtype='float32')

        for step_id in range(5):
            random_input = paddle.rand(shape=(batch, in_dim))
            random_input.stop_gradient = True

            if step_id % 2 == 0:
                out_a = model_a(random_input)
                out_b = model_b(random_input)
            else:
                out_a = model_a(ones_input)
                out_b = model_b(ones_input)

            out_a.sum().backward()
            out_b.sum().backward()

            self.check_gradient(model_a.parameters())
            self.check_gradient(model_b.parameters())

            # test acc gradient
            w1_grad_sum = self.check_acc(
                model_a._layers.w1.grad,
                w1_grad_sum,
                model_b._layers.w1.grad,
            )
            w2_grad_sum = self.check_acc(
                model_a._layers.w2.grad,
                w2_grad_sum,
                model_b._layers.w2.grad,
            )

            model_a.clear_gradients()

    def check_acc(self, grad, grad_sum, acc_grad):
        if grad is not None:
            grad_sum = grad_sum + grad.numpy(False)
            acc_grad = acc_grad.numpy(False) if acc_grad is not None else None
            np.testing.assert_allclose(grad_sum, acc_grad, rtol=1e-6)
        return grad_sum

    def print_trainer_0(self, *args):
        if self.trainer_id == 0:
            print(*args)

    def broadcast_param(self, param, root):
        self.pg.process_group.broadcast(param, root)
        return param

    def check_gradient(self, params):
        other_param = []
        for param in params:
            if param.trainable and (param.grad is not None):
                grad = param.grad
                other_grad = self.broadcast_param(grad, root=1)
                if self.trainer_id == 0:
                    np.testing.assert_allclose(
                        other_grad.numpy(False), grad.numpy(False)
                    )


if __name__ == '__main__':
    unittest.main()
