# -*- coding: UTF-8 -*-

# 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 os
import shutil
import tempfile

import numpy as np

import paddle
from paddle.distributed.fleet.meta_parallel.sharding.group_sharded_optimizer_stage2 import (
    GroupShardedOptimizerStage2,
)
from paddle.distributed.fleet.meta_parallel.sharding.group_sharded_stage2 import (
    GroupShardedStage2,
)
from paddle.distributed.fleet.meta_parallel.sharding.group_sharded_stage3 import (
    GroupShardedStage3,
)
from paddle.distributed.fleet.meta_parallel.sharding.group_sharded_utils import (
    GroupShardedScaler,
)
from paddle.fluid import core
from paddle.nn import Linear

epoch = 10
paddle.seed(2022)
np.random.seed(2022)
base_lr = 0.1
momentum_rate = 0.9
l2_decay = 1e-4


class MLP(paddle.nn.Layer):
    def __init__(self, linear_size=1024, param_attr=None, bias_attr=None):
        super().__init__()

        self._linear1 = Linear(linear_size, linear_size)
        self._linear2 = Linear(linear_size, linear_size)
        self._linear3 = Linear(linear_size, 10)

    def forward(self, inputs):
        y = self._linear1(inputs)
        y = self._linear2(y)
        y = self._linear3(y)
        return y


class Encoder(paddle.nn.Layer):
    def __init__(self, encoder):
        super().__init__()
        self.first_stage = paddle.nn.Linear(1024, 1024)
        self.encoder = encoder

    def forward(self, x):
        x = self.encoder(x)
        x = self.first_stage(x)
        return x


class Decoder(paddle.nn.Layer):
    def __init__(self, decoder):
        super().__init__()
        self.decoder = decoder
        self.final_stage = paddle.nn.Linear(1024, 1024)
        self.group_norm = paddle.nn.GroupNorm(64, 1024)

    def forward(self, x):
        x = self.final_stage(x)
        x = self.decoder(x)
        x = self.group_norm(x)
        return x


class SpecialModel(paddle.nn.Layer):
    def __init__(self):
        super().__init__()
        self.shared = paddle.nn.Linear(1024, 1024, bias_attr=False)
        self.encoder = Encoder(self.shared)
        self.decoder = Decoder(self.shared)
        self.final_stage = paddle.nn.Linear(1024, 2, bias_attr=False)

        self.extra_parameters = [self.shared.weight]

    def forward(self, x):
        x = self.shared(x)
        x = self.encoder(x)
        x = self.decoder(x)
        x = self.final_stage(x)
        return x


class RandomDataset(paddle.io.Dataset):
    def __init__(self, num_samples=2000, linear_size=1024):
        self.num_samples = num_samples
        self.linear_size = linear_size

    def __getitem__(self, idx):
        img = np.random.rand(self.linear_size).astype('float32')
        label = np.ones(1).astype('int64')
        return img, label

    def __len__(self):
        return self.num_samples


def optimizer_setting(model, use_pure_fp16, opt_group=False):
    clip = paddle.nn.ClipGradByGlobalNorm(clip_norm=1.0)
    optimizer = paddle.optimizer.AdamW(
        parameters=[{"params": list(model.parameters())}]
        if opt_group
        else list(model.parameters()),
        learning_rate=0.001,
        weight_decay=0.00001,
        grad_clip=clip,
        multi_precision=use_pure_fp16,
    )

    return optimizer


def train_mlp(
    model,
    sharding_stage,
    use_pure_fp16=False,
    use_bfp16=False,
    accumulate_grad=False,
    batch_size=100,
    opt_group=False,
    linear_size=1000,
    sync_comm=False,
    test_minimize=False,
    save_model=False,
    exclude_test=[],
):
    group = paddle.distributed.new_group([0, 1])
    if opt_group:
        optimizer = optimizer_setting(
            model=model, use_pure_fp16=use_pure_fp16, opt_group=opt_group
        )
    else:
        optimizer = optimizer_setting(model=model, use_pure_fp16=use_pure_fp16)

    if use_pure_fp16:
        model = paddle.amp.decorate(
            models=model,
            level='O2',
            save_dtype='float32',
            dtype='bfloat16' if use_bfp16 else 'float16',
        )
        scaler = paddle.amp.GradScaler(init_loss_scaling=32768)
        scaler = GroupShardedScaler(scaler)
    if sharding_stage == 2:
        optimizer = GroupShardedOptimizerStage2(
            params=optimizer._parameter_list, optim=optimizer, group=group
        )
        model = GroupShardedStage2(
            model, optimizer, group=group, buffer_max_size=2**21
        )
    elif sharding_stage == 3:
        model = GroupShardedStage3(
            model,
            optimizer=optimizer,
            group=group,
            sync_comm=sync_comm,
            segment_size=2**15,
            exclude_layer=exclude_test,
        )

    # check optimizer.minimize() error
    if test_minimize:
        try:
            optimizer.minimize()
        except:
            print(
                "====== Find sharding_stage3_optimizer.minimize() error ======"
            )
        return

    paddle.seed(2023)
    np.random.seed(2023)
    train_loader = paddle.io.DataLoader(
        RandomDataset(),
        batch_size=batch_size,
        shuffle=False,
        drop_last=True,
        num_workers=0,
    )

    for eop in range(epoch):
        model.train()
        for batch_id, data in enumerate(train_loader()):
            img, label = data
            label.stop_gradient = True
            img.stop_gradient = True
            with paddle.amp.auto_cast(
                use_pure_fp16,
                level='O2',
                dtype='bfloat16' if use_bfp16 else 'float16',
            ):
                out = model(img)
                loss = paddle.nn.functional.cross_entropy(
                    input=out, label=label
                )
            avg_loss = paddle.mean(x=loss.cast(dtype=paddle.float32))

            if batch_size == 20:
                avg_loss = avg_loss / 5

            if not use_pure_fp16:
                avg_loss.backward()
            else:
                scaler.scale(avg_loss).backward()

            if not accumulate_grad:
                if not use_pure_fp16:
                    optimizer.step()
                else:
                    scaler.step(optimizer)
                    scaler.update()
                optimizer.clear_grad()
        if accumulate_grad:
            if not use_pure_fp16:
                optimizer.step()
            else:
                scaler.step(optimizer)
                scaler.update()
            optimizer.clear_grad()
    if sharding_stage == 3:
        model.get_all_parameters()

    if save_model:
        return model, optimizer
    return model.parameters()


def test_stage2_stage3():
    paddle.distributed.init_parallel_env()
    (
        mlp,
        mlp1,
        mlp2,
        mlp3,
        mlp4,
        mlp5,
        mlp6,
        mlp7,
        mlp8,
        mlp9,
        mlp10,
        mlp11,
        mlp12,
    ) = (
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
        MLP(),
    )
    state_dict = mlp.state_dict()
    mlp1.set_state_dict(state_dict)
    mlp2.set_state_dict(state_dict)
    mlp3.set_state_dict(state_dict)
    mlp4.set_state_dict(state_dict)
    mlp5.set_state_dict(state_dict)
    mlp6.set_state_dict(state_dict)
    mlp7.set_state_dict(state_dict)
    mlp8.set_state_dict(state_dict)
    mlp9.set_state_dict(state_dict)
    mlp10.set_state_dict(state_dict)
    mlp11.set_state_dict(state_dict)
    mlp12.set_state_dict(state_dict)

    # fp32
    stage2_params = train_mlp(
        mlp1, sharding_stage=2, use_pure_fp16=False, opt_group=False
    )
    stage3_params = train_mlp(
        mlp2, sharding_stage=3, use_pure_fp16=False, opt_group=False
    )

    for i in range(len(stage2_params)):
        np.testing.assert_allclose(
            stage2_params[i].numpy(),
            stage3_params[i].numpy(),
            rtol=1e-6,
            atol=1e-6,
        )

    # fp32 accumulate grad
    stage3_params = train_mlp(
        mlp3,
        sharding_stage=3,
        use_pure_fp16=False,
        accumulate_grad=True,
        opt_group=True,
    )
    stage3_params_add = train_mlp(
        mlp4,
        sharding_stage=3,
        use_pure_fp16=False,
        accumulate_grad=True,
        batch_size=20,
        opt_group=True,
    )
    for i in range(len(stage3_params)):
        np.testing.assert_allclose(
            stage3_params[i].numpy(),
            stage3_params_add[i].numpy(),
            rtol=1e-6,
            atol=1e-4,
        )

    # fp16
    stage2_params = train_mlp(
        mlp5, sharding_stage=2, use_pure_fp16=True, opt_group=False
    )
    stage3_params = train_mlp(
        mlp6, sharding_stage=3, use_pure_fp16=True, opt_group=False
    )
    for i in range(len(stage2_params)):
        np.testing.assert_allclose(
            stage2_params[i].numpy(),
            stage3_params[i].numpy(),
            rtol=1e-4,
            atol=1e-3,
        )

    # fp16 sync_comm
    stage3_params = train_mlp(
        mlp7, sharding_stage=3, use_pure_fp16=True, opt_group=False
    )
    stage3_params_re = train_mlp(
        mlp8,
        sharding_stage=3,
        use_pure_fp16=True,
        opt_group=False,
        sync_comm=True,
    )
    for i in range(len(stage3_params)):
        np.testing.assert_allclose(
            stage3_params[i].numpy(), stage3_params_re[i].numpy(), rtol=1e-6
        )

    # bfp16
    nccl_version = core.nccl_version()

    if (
        nccl_version >= 21000
        and paddle.device.cuda.get_device_properties().major >= 8
    ):
        stage2_params = train_mlp(
            mlp11,
            sharding_stage=2,
            use_pure_fp16=True,
            opt_group=False,
            use_bfp16=True,
        )
        stage3_params = train_mlp(
            mlp12,
            sharding_stage=3,
            use_pure_fp16=True,
            opt_group=False,
            use_bfp16=True,
        )
        for i in range(len(stage2_params)):
            np.testing.assert_allclose(
                stage2_params[i].astype("float32").numpy(),
                stage3_params[i].astype("float32").numpy(),
                rtol=1e-4,
                atol=1e-3,
            )

    # test for share layer parameters and exclude_layer function.
    sm1, sm2, sm3, sm4 = (
        SpecialModel(),
        SpecialModel(),
        SpecialModel(),
        SpecialModel(),
    )
    st_dict = sm1.state_dict()
    sm2.set_state_dict(st_dict)
    sm3.set_state_dict(st_dict)
    sm4.set_state_dict(st_dict)

    # fp16 for special model
    stage2_params = train_mlp(
        sm1,
        sharding_stage=2,
        use_pure_fp16=True,
        opt_group=False,
        linear_size=1024,
    )
    stage3_params = train_mlp(
        sm2,
        sharding_stage=3,
        use_pure_fp16=True,
        opt_group=False,
        linear_size=1024,
        exclude_test=["GroupNorm"],
    )
    for i in range(len(stage2_params)):
        np.testing.assert_allclose(
            stage2_params[i].numpy(),
            stage3_params[i].numpy(),
            rtol=1e-4,
            atol=1e-3,
        )

    # fp32 for special model
    stage2_params = train_mlp(
        sm3,
        sharding_stage=2,
        use_pure_fp16=False,
        opt_group=False,
        linear_size=1024,
    )
    stage3_params = train_mlp(
        sm4,
        sharding_stage=3,
        use_pure_fp16=False,
        opt_group=False,
        linear_size=1024,
        exclude_test=[id(sm4.decoder.group_norm)],
    )
    for i in range(len(stage2_params)):
        np.testing.assert_allclose(
            stage2_params[i].numpy(),
            stage3_params[i].numpy(),
            rtol=1e-6,
            atol=1e-4,
        )

    # save/load model
    output_dir = tempfile.mkdtemp()
    model_file = os.path.join(output_dir, "model.pdmodel")
    optimizer_file = os.path.join(output_dir, "model.pdopt")
    model_stage3, optimizer_stage3 = train_mlp(
        mlp9,
        sharding_stage=3,
        use_pure_fp16=False,
        opt_group=False,
        save_model=True,
    )
    paddle.save(model_stage3.state_dict(), model_file)
    paddle.save(optimizer_stage3.state_dict(), optimizer_file)
    m_state_dict = paddle.load(model_file)
    opt_state_dict = paddle.load(optimizer_file)
    model_stage3.set_state_dict(m_state_dict)
    optimizer_stage3.set_state_dict(opt_state_dict)
    shutil.rmtree(output_dir)

    # check optimizer.minimize() error
    train_mlp(
        mlp10,
        sharding_stage=3,
        use_pure_fp16=False,
        opt_group=False,
        test_minimize=True,
    )


if __name__ == '__main__':
    test_stage2_stage3()
