# Copyright (c) 2021 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.

from __future__ import division
from __future__ import print_function

import unittest
import os

import paddle
import numpy as np
import paddle.distributed as dist
import paddle.fluid as fluid
from paddle.fluid.dygraph.nn import Linear

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

batch = 5
in_dim = 10
out_dim = 20


class SimpleNet(fluid.Layer):
    def __init__(self, train_id):
        super(SimpleNet, self).__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))).numpy()[0] 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 TestDistTraning(unittest.TestCase):
    def test_multiple_gpus(self):
        dist.init_parallel_env()
        self.trainer_id = dist.get_rank()

        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)
        model_b = paddle.DataParallel(model_b, find_unused_parameters=True)

        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()
            acc_grad = acc_grad.numpy() 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):
        paddle.distributed.broadcast(param, root)
        return param

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


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