# 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 random
import unittest

import numpy as np

import paddle
import paddle.fluid.core as core
import paddle.nn as nn
from paddle.distributed.fleet import auto
from paddle.fluid.dygraph.parallel import ParallelEnv
from paddle.static import InputSpec
from paddle.static.amp.bf16.amp_utils import _valid_types
from paddle.static.amp.fp16_utils import find_true_prev_op
from paddle.vision.datasets import MNIST

paddle.enable_static()


def apply_pass(use_bf16=False):
    strategy = auto.Strategy()
    strategy.auto_mode = "semi"
    strategy.reinit = True
    if use_bf16:
        amp = strategy.amp
        amp.enable = True
        amp.enable_bf16 = True
    return strategy


class MnistDataset(MNIST):
    def __init__(self, mode, return_label=True):
        super().__init__(mode=mode)
        self.return_label = return_label

    def __getitem__(self, idx):
        img = np.reshape(self.images[idx], [1, 28, 28])
        if self.return_label:
            return img, np.array(self.labels[idx]).astype('int64')
        return (img,)

    def __len__(self):
        return len(self.images)


def reset_prog():
    paddle.fluid.framework.switch_main_program(paddle.static.Program())
    paddle.fluid.framework.switch_startup_program(paddle.static.Program())


class Model(nn.Layer):
    def __init__(self):
        super().__init__()
        self.flatten = nn.Flatten()
        self.fc1 = nn.Linear(784, 120)
        self.relu1 = nn.ReLU()
        self.fc2 = nn.Linear(120, 10)

    def forward(self, input):
        input.stop_gradient = True
        x = self.flatten(input)
        x = self.relu1(self.fc1(x))
        x = self.fc2(x)
        return x


class TestBF16Pass(unittest.TestCase):
    def setUp(self):
        self.rtol = 1e-5
        self.atol = 1e-8
        self.batch_size = 256
        self.batch_num = 10
        self.dataset = MnistDataset("train")
        self.eval_dataset = MnistDataset("test")

    def init(self, engine):
        paddle.seed(2021)
        np.random.seed(2021)
        random.seed(2021)
        place = paddle.fluid.CUDAPlace(ParallelEnv().dev_id)
        engine._executor = paddle.static.Executor(place)

    def get_engine(self, use_bf16=False):
        reset_prog()

        strategy = apply_pass(use_bf16)
        model = Model()
        opt = paddle.optimizer.SGD(0.001, parameters=model.parameters())
        loss = nn.CrossEntropyLoss()
        engine = auto.Engine(model, loss, opt, strategy=strategy)
        self.init(engine)
        return engine

    def check_program(self, program):
        bf16_op_list = {
            "matmul_v2",
            "elementwise_add",
            "relu",
            "elementwise_add_grad",
            "matmul_v2_grad",
            "relu_grad",
        }

        fp32_op_list = {
            "flatten_contiguous_range",
            "reduce_mean",
            "softmax_with_cross_entropy",
            "fill_constant",
            "reduce_mean_grad",
            "softmax_with_cross_entropy_grad",
        }

        for block in program.blocks:
            for op in block.ops:
                if op not in bf16_op_list and op not in fp32_op_list:
                    continue

                for in_name in op.input_names:
                    for in_var_name in op.input(in_name):
                        var = None
                        try:
                            var = block.var(in_var_name)
                        except ValueError as e:
                            var = block._var_recursive(in_var_name)
                        if var is None or var.type not in _valid_types:
                            break

                        if op.type in bf16_op_list:
                            assert var.dtype == core.VarDesc.VarType.BF16
                            if "cast_bf16" in in_var_name:
                                if "@GRAD" in in_var_name:
                                    tmp_in_var_name = in_var_name[
                                        : in_var_name.find("@GRAD")
                                    ]
                                else:
                                    tmp_in_var_name = in_var_name
                                prev_op = find_true_prev_op(
                                    block.ops, op, tmp_in_var_name
                                )
                                assert prev_op is not None
                                assert prev_op.type == "cast"
                                for in_name in prev_op.input_names:
                                    for in_var_name in prev_op.input(in_name):
                                        var = block.var(in_var_name)
                                        assert (
                                            var.dtype
                                            == core.VarDesc.VarType.FP32
                                        )

                        elif op.type in fp32_op_list:
                            if (
                                op.type == "softmax_with_cross_entropy"
                                or op.type == "softmax_with_cross_entropy_grad"
                            ) and in_var_name == "label0":
                                continue
                            assert var.dtype == core.VarDesc.VarType.FP32
                            if "cast_fp32" in in_var_name:
                                prev_op = find_true_prev_op(
                                    block.ops, op, tmp_in_var_name
                                )
                                assert prev_op is not None
                                assert prev_op.type == "cast"
                                for in_name in prev_op.input_names:
                                    for in_var_name in prev_op.input(in_name):
                                        var = block.var(in_var_name)
                                        assert (
                                            var.dtype
                                            == core.VarDesc.VarType.BF16
                                        )

                for out_name in op.output_names:
                    for out_var_name in op.output(out_name):
                        var = None
                        try:
                            var = block.var(out_var_name)
                        except ValueError as e:
                            var = block._var_recursive(out_var_name)

                        if var is None or var.type not in _valid_types:
                            break
                        if op.type in bf16_op_list:
                            assert var.dtype == core.VarDesc.VarType.BF16
                        elif op.type in fp32_op_list:
                            assert var.dtype == core.VarDesc.VarType.FP32

    def test_bf16_pass(self):
        bf16_o1_engine = self.get_engine(True)
        inputs_spec = [InputSpec([None, 1, 28, 28], 'float32', 'input0')]
        labels_spec = [InputSpec([None, 1], 'int64', 'label0')]
        bf16_o1_engine.prepare(
            inputs_spec=inputs_spec, labels_spec=labels_spec, mode="train"
        )
        self.check_program(bf16_o1_engine._dist_main_progs["train"][0])
        print("BF16!check program successfully!")


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