# 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.

import argparse
import os
import random
import time
from functools import partial

import numpy as np
import paddle
import paddle.nn.functional as F

from paddlenlp.data import DataCollatorWithPadding
from paddlenlp.datasets import load_dataset
from paddlenlp.transformers import SkepForSequenceClassification, SkepTokenizer

parser = argparse.ArgumentParser()
parser.add_argument(
    "--model_name",
    choices=["skep_ernie_1.0_large_ch", "skep_ernie_2.0_large_en"],
    default="skep_ernie_1.0_large_ch",
    help="Select which model to train, defaults to skep_ernie_1.0_large_ch.",
)
parser.add_argument(
    "--save_dir",
    default="./checkpoints",
    type=str,
    help="The output directory where the model checkpoints will be written.",
)
parser.add_argument(
    "--max_seq_len",
    default=128,
    type=int,
    help="The maximum total input sequence length after tokenization. Sequences longer than this will be truncated, sequences shorter will be padded.",
)
parser.add_argument("--batch_size", default=16, type=int, help="Batch size per GPU/CPU for training.")
parser.add_argument("--learning_rate", default=5e-5, type=float, help="The initial learning rate for Adam.")
parser.add_argument("--weight_decay", default=0.0, type=float, help="Weight decay if we apply some.")
parser.add_argument("--epochs", default=3, type=int, help="Total number of training epochs to perform.")
parser.add_argument("--init_from_ckpt", type=str, default=None, help="The path of checkpoint to be loaded.")
parser.add_argument("--seed", type=int, default=1000, help="random seed for initialization")
parser.add_argument(
    "--device",
    choices=["cpu", "gpu", "xpu"],
    default="gpu",
    help="Select which device to train model, defaults to gpu.",
)
args = parser.parse_args()


def set_seed(seed):
    """Sets random seed."""
    random.seed(seed)
    np.random.seed(seed)
    paddle.seed(seed)


@paddle.no_grad()
def evaluate(model, metric, data_loader):
    """
    Given a dataset, it evals model and computes the metric.

    Args:
        model(obj:`paddle.nn.Layer`): A model to classify texts.
        metric(obj:`paddle.metric.Metric`): The evaluation metric.
        data_loader(obj:`paddle.io.DataLoader`): The dataset loader which generates batches.
    """
    model.eval()
    metric.reset()
    losses = []
    for batch in data_loader:
        input_ids, token_type_ids, labels = batch["input_ids"], batch["token_type_ids"], batch["labels"]
        loss, logits = model(input_ids, token_type_ids, labels=labels)
        losses.append(loss.numpy())
        correct = metric.compute(logits, labels)
        metric.update(correct)
    acc = metric.accumulate()
    print("eval loss: %.5f, accuracy: %.5f" % (np.mean(losses), acc))
    model.train()
    metric.reset()


def convert_example_to_feature(example, tokenizer, max_seq_len=512, is_test=False, dataset_name="chnsenticorp"):
    """
    Builds model inputs from a sequence or a pair of sequence for sequence classification tasks
    by concatenating and adding special tokens.

    Args:
        example(obj:`dict`): Dict of input data, containing text and label if it have label.
        tokenizer(obj:`PretrainedTokenizer`): This tokenizer inherits from :class:`~paddlenlp.transformers.PretrainedTokenizer`
            which contains most of the methods. Users should refer to the superclass for more information regarding methods.
        max_seq_len(obj:`int`): The maximum total input sequence length after tokenization.
            Sequences longer than this will be truncated, sequences shorter will be padded.
        is_test(obj:`False`, defaults to `False`): Whether the example contains label or not.
        dataset_name((obj:`str`, defaults to "chnsenticorp"): The dataset name, "chnsenticorp" or "sst-2".

    Returns:
        input_ids(obj:`list[int]`): The list of token ids.
        token_type_ids(obj: `list[int]`): The list of token_type_ids.
        label(obj:`int`, optional): The input label if not is_test.
    """

    if dataset_name == "sst-2":
        encoded_inputs = tokenizer(text=example["sentence"], max_seq_len=max_seq_len)
    elif dataset_name == "chnsenticorp":
        encoded_inputs = tokenizer(text=example["text"], max_seq_len=max_seq_len)

    input_ids = encoded_inputs["input_ids"]
    token_type_ids = encoded_inputs["token_type_ids"]

    if not is_test:
        if dataset_name == "sst-2":
            label = example["labels"]
        elif dataset_name == "chnsenticorp":
            label = example["label"]
        else:
            raise RuntimeError(f"Got unkown datatset name {dataset_name}, it must be processed on your own.")

        return {"input_ids": input_ids, "token_type_ids": token_type_ids, "label": label}
    else:
        return {"input_ids": input_ids, "token_type_ids": token_type_ids}


def create_dataloader(dataset, mode="train", batch_size=1, batchify_fn=None, trans_fn=None):
    if trans_fn:
        dataset = dataset.map(trans_fn)

    shuffle = True if mode == "train" else False
    if mode == "train":
        batch_sampler = paddle.io.DistributedBatchSampler(dataset, batch_size=batch_size, shuffle=shuffle)
    else:
        batch_sampler = paddle.io.BatchSampler(dataset, batch_size=batch_size, shuffle=shuffle)

    return paddle.io.DataLoader(dataset=dataset, batch_sampler=batch_sampler, collate_fn=batchify_fn, return_list=True)


if __name__ == "__main__":
    paddle.set_device(args.device)
    rank = paddle.distributed.get_rank()
    if paddle.distributed.get_world_size() > 1:
        paddle.distributed.init_parallel_env()

    set_seed(args.seed)
    if args.model_name == "skep_ernie_1.0_large_ch":
        dataset_name = "chnsenticorp"
        train_ds, dev_ds = load_dataset(dataset_name, splits=["train", "dev"])

    else:
        dataset_name = "sst-2"
        train_ds, dev_ds = load_dataset("glue", dataset_name, splits=["train", "dev"])
    label_map = {0: "negative", 1: "positive"}

    tokenizer = SkepTokenizer.from_pretrained(args.model_name)
    model = SkepForSequenceClassification.from_pretrained(args.model_name, num_labels=len(label_map))

    trans_func = partial(
        convert_example_to_feature, tokenizer=tokenizer, max_seq_len=args.max_seq_len, dataset_name=dataset_name
    )

    data_collator = DataCollatorWithPadding(tokenizer, padding=True)

    train_data_loader = create_dataloader(
        train_ds, mode="train", batch_size=args.batch_size, batchify_fn=data_collator, trans_fn=trans_func
    )

    dev_data_loader = create_dataloader(
        dev_ds, mode="dev", batch_size=args.batch_size, batchify_fn=data_collator, trans_fn=trans_func
    )

    if args.init_from_ckpt and os.path.isfile(args.init_from_ckpt):
        state_dict = paddle.load(args.init_from_ckpt)
        model.set_dict(state_dict)
    model = paddle.DataParallel(model)

    num_training_steps = len(train_data_loader) * args.epochs
    # Generate parameter names needed to perform weight decay.
    # All bias and LayerNorm parameters are excluded.
    decay_params = [p.name for n, p in model.named_parameters() if not any(nd in n for nd in ["bias", "norm"])]
    optimizer = paddle.optimizer.AdamW(
        learning_rate=args.learning_rate,
        parameters=model.parameters(),
        weight_decay=args.weight_decay,
        apply_decay_param_fun=lambda x: x in decay_params,
    )
    metric = paddle.metric.Accuracy()

    # start to train model
    model.train()
    global_step = 0
    tic_train = time.time()
    for epoch in range(1, args.epochs + 1):
        for step, batch in enumerate(train_data_loader, start=1):
            input_ids, token_type_ids, labels = batch["input_ids"], batch["token_type_ids"], batch["labels"]
            loss, logits = model(input_ids, token_type_ids, labels=labels)
            probs = F.softmax(logits, axis=1)
            correct = metric.compute(probs, labels)
            metric.update(correct)
            acc = metric.accumulate()

            global_step += 1
            if global_step % 10 == 0 and rank == 0:
                print(
                    "global step %d, epoch: %d, batch: %d, loss: %.5f, accuracy: %.5f, speed: %.2f step/s"
                    % (global_step, epoch, step, loss, acc, 10 / (time.time() - tic_train))
                )
                tic_train = time.time()
            loss.backward()
            optimizer.step()
            optimizer.clear_grad()
            if global_step % 100 == 0 and rank == 0:
                save_dir = os.path.join(args.save_dir, "model_%d" % global_step)
                if not os.path.exists(save_dir):
                    os.makedirs(save_dir)
                evaluate(model, metric, dev_data_loader)
                # Need better way to get inner model of DataParallel
                model._layers.save_pretrained(save_dir)
                tokenizer.save_pretrained(save_dir)
