# 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
from data_process import convert_example, create_dataloader, load_dict, read_custom_data
from metric import SequenceAccuracy

from paddlenlp.data import Pad, Stack, Tuple
from paddlenlp.datasets import load_dataset
from paddlenlp.transformers import (
    ErnieCtmTokenizer,
    ErnieCtmWordtagModel,
    LinearDecayWithWarmup,
)
from paddlenlp.utils.log import logger


def parse_args():
    parser = argparse.ArgumentParser()

    # yapf: disable
    parser.add_argument("--data_dir", default="./data", type=str, help="The input data dir, should contain train.json.")
    parser.add_argument("--init_from_ckpt", default=None, type=str, help="The path of checkpoint to be loaded.")
    parser.add_argument("--output_dir", default="./output", type=str, help="The output directory where the model predictions and 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("--learning_rate", default=5e-5, type=float, help="The initial learning rate for Adam.")
    parser.add_argument("--num_train_epochs", default=3, type=int, help="Total number of training epochs to perform.", )
    parser.add_argument("--logging_steps", type=int, default=5, help="Log every X updates steps.")
    parser.add_argument("--save_steps", type=int, default=100, help="Save checkpoint every X updates steps.")
    parser.add_argument("--batch_size", default=32, type=int, help="Batch size per GPU/CPU for training.", )
    parser.add_argument("--weight_decay", default=0.0, type=float, help="Weight decay if we apply some.")
    parser.add_argument("--warmup_steps", default=0, type=int, help="Linear warmup over warmup_steps. If > 0: Override warmup_proportion")
    parser.add_argument("--warmup_proportion", default=0.0, type=float, help="Linear warmup proportion over total steps.")
    parser.add_argument("--adam_epsilon", default=1e-6, type=float, help="Epsilon for Adam optimizer.")
    parser.add_argument("--seed", default=1000, type=int, help="random seed for initialization")
    parser.add_argument("--device", default="gpu", type=str, help="The device to select to train the model, is must be cpu/gpu/xpu.")
    # yapf: enable

    args = parser.parse_args()
    return 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, tags, tags_to_idx):
    model.eval()
    metric.reset()
    losses = []
    for batch in data_loader():
        input_ids, token_type_ids, seq_len, tags = batch
        loss, seq_logits = model(input_ids, token_type_ids, lengths=seq_len, tag_labels=tags)[:2]
        loss = loss.mean()
        losses.append(loss.numpy())

        correct = metric.compute(
            pred=seq_logits.reshape([-1, len(tags_to_idx)]), label=tags.reshape([-1]), ignore_index=tags_to_idx["O"]
        )
        metric.update(correct)
    acc = metric.accumulate()
    logger.info("eval loss: %.5f, acc: %.5f" % (np.mean(losses), acc))
    model.train()
    metric.reset()


def do_train(args):
    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)

    train_ds = load_dataset(
        read_custom_data, filename=os.path.join(args.data_dir, "train.txt"), is_test=False, lazy=False
    )
    dev_ds = load_dataset(read_custom_data, filename=os.path.join(args.data_dir, "dev.txt"), is_test=False, lazy=False)
    tags_to_idx = load_dict(os.path.join(args.data_dir, "tags.txt"))

    tokenizer = ErnieCtmTokenizer.from_pretrained("wordtag")
    model = ErnieCtmWordtagModel.from_pretrained("wordtag", num_labels=len(tags_to_idx))

    trans_func = partial(convert_example, tokenizer=tokenizer, max_seq_len=args.max_seq_len, tags_to_idx=tags_to_idx)

    def batchify_fn(samples):
        fn = Tuple(  # noqa: E731
            Pad(axis=0, pad_val=tokenizer.pad_token_id, dtype="int64"),  # input_ids
            Pad(axis=0, pad_val=tokenizer.pad_token_type_id, dtype="int64"),  # token_type_ids
            Stack(dtype="int64"),  # seq_len
            Pad(axis=0, pad_val=tags_to_idx["O"], dtype="int64"),  # tags
        )
        return fn(samples)

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

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

    if paddle.distributed.get_world_size() > 1:
        model = paddle.DataParallel(model)

    num_training_steps = len(train_data_loader) * args.num_train_epochs
    warmup = args.warmup_steps if args.warmup_steps > 0 else args.warmup_proportion
    lr_scheduler = LinearDecayWithWarmup(args.learning_rate, num_training_steps, warmup)

    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=lr_scheduler,
        epsilon=args.adam_epsilon,
        parameters=model.parameters(),
        weight_decay=args.weight_decay,
        apply_decay_param_fun=lambda x: x in decay_params,
    )

    logger.info("Total steps: %s" % num_training_steps)
    logger.info("WarmUp steps: %s" % warmup)

    metric = SequenceAccuracy()

    total_loss = 0
    global_step = 0

    for epoch in range(1, args.num_train_epochs + 1):
        logger.info(f"Epoch {epoch} beginning")
        start_time = time.time()

        for total_step, batch in enumerate(train_data_loader):
            global_step += 1
            input_ids, token_type_ids, seq_len, tags = batch

            loss = model(input_ids, token_type_ids, lengths=seq_len, tag_labels=tags)[0]

            loss = loss.mean()
            total_loss += loss
            loss.backward()

            optimizer.step()
            optimizer.clear_grad()
            lr_scheduler.step()

            if global_step % args.logging_steps == 0 and rank == 0:
                end_time = time.time()
                speed = float(args.logging_steps) / (end_time - start_time)
                logger.info(
                    "global step %d, epoch: %d, loss: %.5f, speed: %.2f step/s"
                    % (global_step, epoch, total_loss / args.logging_steps, speed)
                )
                start_time = time.time()
                total_loss = 0

            if (global_step % args.save_steps == 0 or global_step == num_training_steps) and rank == 0:
                output_dir = os.path.join(args.output_dir, "model_%d" % (global_step))
                if not os.path.exists(output_dir):
                    os.makedirs(output_dir)
                model_to_save = model._layers if isinstance(model, paddle.DataParallel) else model
                model_to_save.save_pretrained(output_dir)
                tokenizer.save_pretrained(output_dir)

        evaluate(model, metric, dev_data_loader, tags, tags_to_idx)


def print_arguments(args):
    """print arguments"""
    print("-----------  Configuration Arguments -----------")
    for arg, value in sorted(vars(args).items()):
        print("%s: %s" % (arg, value))
    print("------------------------------------------------")


if __name__ == "__main__":
    args = parse_args()
    print_arguments(args)
    do_train(args)
