# Copyright (c) 2018 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 print_function

import multiprocessing
import os
import unittest
import paddle.fluid as fluid
import time
import numpy as np
import math
import sys

__all__ = ['TestParallelExecutorBase']


class TestParallelExecutorBase(unittest.TestCase):
    def check_network_convergence(self,
                                  method,
                                  use_cuda=True,
                                  memory_opt=True,
                                  iter=50,
                                  batch_size=None,
                                  allow_op_delay=False,
                                  feed_dict=None,
                                  seed=None,
                                  use_parallel_executor=True,
                                  use_reduce=False,
                                  optimizer=fluid.optimizer.Adam,
                                  use_fast_executor=False):
        def run_executor(exe, feed, fetch_list, program=None):
            if isinstance(exe, fluid.ParallelExecutor):
                res = exe.run(fetch_list=fetch_list, feed=feed)
            elif isinstance(exe, fluid.Executor):
                if program is None:
                    program = fluid.default_main_program()
                res = exe.run(program=program, feed=feed, fetch_list=fetch_list)
            else:
                raise ValueError('Unkown type exe')
            return res

        main = fluid.Program()
        startup = fluid.Program()
        startup.random_seed = 1  # Fix random seed
        main.random_seed = 1
        with fluid.program_guard(main, startup):
            if seed is not None:
                startup.random_seed = seed
                main.random_seed = seed

            loss = method(use_feed=feed_dict is not None)

            optimizer().minimize(loss)

            if memory_opt:
                fluid.memory_optimize(main)

            place = fluid.CUDAPlace(0) if use_cuda else fluid.CPUPlace()
            startup_exe = fluid.Executor(place)
            startup_exe.run(startup)
            exec_strategy = fluid.ExecutionStrategy()
            exec_strategy.allow_op_delay = allow_op_delay
            if use_fast_executor:
                exec_strategy.use_experimental_executor = True

            build_strategy = fluid.BuildStrategy()
            build_strategy.reduce_strategy = fluid.BuildStrategy.ReduceStrategy.Reduce \
                if use_reduce else fluid.BuildStrategy.ReduceStrategy.AllReduce

            if use_parallel_executor:
                exe = fluid.ParallelExecutor(
                    use_cuda,
                    loss_name=loss.name,
                    exec_strategy=exec_strategy,
                    build_strategy=build_strategy)
            else:
                exe = fluid.Executor(place=place)

            if batch_size is not None:
                batch_size *= fluid.core.get_cuda_device_count(
                ) if use_cuda else int(
                    os.environ.get('CPU_NUM', multiprocessing.cpu_count()))
            begin = time.time()
            first_loss, = run_executor(
                exe=exe, feed=feed_dict, fetch_list=[loss.name])

            for i in range(iter):
                run_executor(exe=exe, feed=feed_dict, fetch_list=[])

            last_loss, = run_executor(
                exe=exe, feed=feed_dict, fetch_list=[loss.name])
            end = time.time()

            if batch_size is not None:
                print("%.4f Instance per second" % (
                    (batch_size * iter + 2) / (end - begin)))

            avg_last_loss_val = np.array(last_loss).mean()
            avg_first_loss_val = np.array(first_loss).mean()
            if math.isnan(float(avg_last_loss_val)) or math.isnan(
                    float(avg_first_loss_val)):
                sys.exit("got NaN loss, training failed.")

            print(first_loss, last_loss)
            # self.assertGreater(first_loss[0], last_loss[0])
            return first_loss, last_loss
