# Copyright (c) 2020 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 math
import os
import random
import time
from functools import partial

import numpy as np
import paddle
import paddle.nn.functional as F
from paddle.io import DataLoader
from paddle.metric import Accuracy
from paddleslim.nas.ofa import OFA, DistillConfig, RunConfig, utils
from paddleslim.nas.ofa.convert_super import Convert, supernet

from paddlenlp.data import Pad, Stack, Tuple
from paddlenlp.datasets import load_dataset
from paddlenlp.metrics import AccuracyAndF1, Mcc, PearsonAndSpearman
from paddlenlp.transformers import (
    BertForSequenceClassification,
    BertModel,
    BertTokenizer,
    LinearDecayWithWarmup,
)
from paddlenlp.utils.log import logger

METRIC_CLASSES = {
    "cola": Mcc,
    "sst-2": Accuracy,
    "mrpc": AccuracyAndF1,
    "sts-b": PearsonAndSpearman,
    "qqp": AccuracyAndF1,
    "mnli": Accuracy,
    "qnli": Accuracy,
    "rte": Accuracy,
}

MODEL_CLASSES = {
    "bert": (BertForSequenceClassification, BertTokenizer),
}


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

    # Required parameters
    parser.add_argument(
        "--task_name",
        default=None,
        type=str,
        required=True,
        help="The name of the task to train selected in the list: " + ", ".join(METRIC_CLASSES.keys()),
    )
    parser.add_argument(
        "--model_type",
        default=None,
        type=str,
        required=True,
        help="Model type selected in the list: " + ", ".join(MODEL_CLASSES.keys()),
    )
    parser.add_argument(
        "--model_name_or_path",
        default=None,
        type=str,
        required=True,
        help="Path to pre-trained model or shortcut name selected in the list: "
        + ", ".join(
            sum([list(classes[-1].pretrained_init_configuration.keys()) for classes in MODEL_CLASSES.values()], [])
        ),
    )
    parser.add_argument(
        "--output_dir",
        default=None,
        type=str,
        required=True,
        help="The output directory where the model predictions and checkpoints will be written.",
    )
    parser.add_argument(
        "--max_seq_length",
        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=8,
        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("--adam_epsilon", default=1e-8, type=float, help="Epsilon for Adam optimizer.")
    parser.add_argument("--max_grad_norm", default=1.0, type=float, help="Max gradient norm.")
    parser.add_argument("--lambda_logit", default=1.0, type=float, help="lambda for logit loss.")
    parser.add_argument("--lambda_rep", default=0.1, type=float, help="lambda for hidden state distillation loss.")
    parser.add_argument(
        "--num_train_epochs",
        default=3,
        type=int,
        help="Total number of training epochs to perform.",
    )
    parser.add_argument(
        "--max_steps",
        default=-1,
        type=int,
        help="If > 0: set total number of training steps to perform. Override num_train_epochs.",
    )
    parser.add_argument("--warmup_steps", default=0, type=int, help="Linear warmup over warmup_steps.")
    parser.add_argument("--logging_steps", type=int, default=500, help="Log every X updates steps.")
    parser.add_argument("--save_steps", type=int, default=500, help="Save checkpoint every X updates steps.")
    parser.add_argument("--seed", type=int, default=42, help="random seed for initialization")
    parser.add_argument(
        "--device",
        default="gpu",
        type=str,
        choices=["gpu", "cpu", "xpu"],
        help="The device to select to train the model, is must be cpu/gpu/xpu.",
    )
    parser.add_argument(
        "--width_mult_list", nargs="+", type=float, default=[1.0, 5 / 6, 2 / 3, 0.5], help="width mult in compress"
    )
    parser.add_argument(
        "--depth_mult_list", nargs="+", type=float, default=[1.0, 0.75, 0.5], help="width mult in compress"
    )
    args = parser.parse_args()
    return args


def set_seed(args):
    random.seed(args.seed + paddle.distributed.get_rank())
    np.random.seed(args.seed + paddle.distributed.get_rank())
    paddle.seed(args.seed + paddle.distributed.get_rank())


def evaluate(model, criterion, metric, data_loader, width_mult=1.0, depth_mult=1.0):
    with paddle.no_grad():
        model.eval()
        metric.reset()
        for batch in data_loader:
            input_ids, segment_ids, labels = batch
            logits = model(input_ids, segment_ids, attention_mask=[None, None])
            if isinstance(logits, tuple):
                logits = logits[0]
            loss = criterion(logits, labels)
            correct = metric.compute(logits, labels)
            metric.update(correct)
        results = metric.accumulate()
        # Teacher model's evaluation
        if width_mult == 100:
            print("teacher_model, eval loss: %f, %s: %s\n" % (loss.numpy(), metric.name(), results), end="")
        else:
            print(
                "depth_mult: %f, width_mult: %f, eval loss: %f, %s: %s\n"
                % (depth_mult, width_mult, loss.numpy(), metric.name(), results),
                end="",
            )
        model.train()


# monkey patch for bert forward to accept [attention_mask, head_mask] as  attention_mask
def bert_forward(self, input_ids, token_type_ids=None, position_ids=None, attention_mask=[None, None], depth_mult=1.0):
    wtype = self.pooler.dense.fn.weight.dtype if hasattr(self.pooler.dense, "fn") else self.pooler.dense.weight.dtype
    if attention_mask[0] is None:
        attention_mask[0] = paddle.unsqueeze((input_ids == self.pad_token_id).astype(wtype) * -1e9, axis=[1, 2])
    embedding_output = self.embeddings(input_ids=input_ids, position_ids=position_ids, token_type_ids=token_type_ids)
    encoder_outputs = self.encoder(embedding_output, attention_mask, depth_mult=depth_mult)
    sequence_output = encoder_outputs
    pooled_output = self.pooler(sequence_output)
    return sequence_output, pooled_output


BertModel.forward = bert_forward


def transformer_encoder_forward(self, src, src_mask=None, depth_mult=1.0):
    output = src

    depth = round(self.num_layers * depth_mult)
    kept_layers_index = []
    for i in range(1, depth + 1):
        kept_layers_index.append(math.floor(i / depth_mult) - 1)

    for i in kept_layers_index:
        output = self.layers[i](output, src_mask=src_mask)

    if self.norm is not None:
        output = self.norm(output)

    return output


paddle.nn.TransformerEncoder.forward = transformer_encoder_forward


def sequence_forward(self, input_ids, token_type_ids=None, position_ids=None, attention_mask=[None, None], depth=1.0):
    _, pooled_output = self.bert(
        input_ids,
        token_type_ids=token_type_ids,
        position_ids=position_ids,
        attention_mask=attention_mask,
        depth_mult=depth,
    )

    pooled_output = self.dropout(pooled_output)
    logits = self.classifier(pooled_output)
    return logits


BertForSequenceClassification.forward = sequence_forward


def soft_cross_entropy(inp, target):
    inp_likelihood = F.log_softmax(inp, axis=-1)
    target_prob = F.softmax(target, axis=-1)
    return -1.0 * paddle.mean(paddle.sum(inp_likelihood * target_prob, axis=-1))


def convert_example(example, tokenizer, label_list, max_seq_length=512, is_test=False):
    """convert a glue example into necessary features"""
    if not is_test:
        # `label_list == None` is for regression task
        label_dtype = "int64" if label_list else "float32"
        # Get the label
        label = example["labels"]
        label = np.array([label], dtype=label_dtype)
    # Convert raw text to feature
    if (int(is_test) + len(example)) == 2:
        example = tokenizer(example["sentence"], max_seq_len=max_seq_length)
    else:
        example = tokenizer(example["sentence1"], text_pair=example["sentence2"], max_seq_len=max_seq_length)

    if not is_test:
        return example["input_ids"], example["token_type_ids"], label
    else:
        return example["input_ids"], example["token_type_ids"]


def do_train(args):
    paddle.set_device(args.device)
    if paddle.distributed.get_world_size() > 1:
        paddle.distributed.init_parallel_env()

    set_seed(args)

    args.task_name = args.task_name.lower()
    metric_class = METRIC_CLASSES[args.task_name]
    args.model_type = args.model_type.lower()
    model_class, tokenizer_class = MODEL_CLASSES[args.model_type]

    train_ds = load_dataset("glue", args.task_name, splits="train")

    tokenizer = tokenizer_class.from_pretrained(args.model_name_or_path)
    trans_func = partial(
        convert_example, tokenizer=tokenizer, label_list=train_ds.label_list, max_seq_length=args.max_seq_length
    )
    train_ds = train_ds.map(trans_func, lazy=True)
    train_batch_sampler = paddle.io.DistributedBatchSampler(train_ds, batch_size=args.batch_size, shuffle=True)
    batchify_fn = lambda samples, fn=Tuple(
        Pad(axis=0, pad_val=tokenizer.pad_token_id),  # input
        Pad(axis=0, pad_val=tokenizer.pad_token_type_id),  # segment
        Stack(dtype="int64" if train_ds.label_list else "float32"),  # label
    ): fn(samples)
    train_data_loader = DataLoader(
        dataset=train_ds, batch_sampler=train_batch_sampler, collate_fn=batchify_fn, num_workers=0, return_list=True
    )
    if args.task_name == "mnli":
        dev_ds_matched, dev_ds_mismatched = load_dataset(
            "glue", args.task_name, splits=["dev_matched", "dev_mismatched"]
        )
        dev_ds_matched = dev_ds_matched.map(trans_func, lazy=True)
        dev_ds_mismatched = dev_ds_mismatched.map(trans_func, lazy=True)
        dev_batch_sampler_matched = paddle.io.BatchSampler(dev_ds_matched, batch_size=args.batch_size, shuffle=False)
        dev_data_loader_matched = DataLoader(
            dataset=dev_ds_matched,
            batch_sampler=dev_batch_sampler_matched,
            collate_fn=batchify_fn,
            num_workers=0,
            return_list=True,
        )
        dev_batch_sampler_mismatched = paddle.io.BatchSampler(
            dev_ds_mismatched, batch_size=args.batch_size, shuffle=False
        )
        dev_data_loader_mismatched = DataLoader(
            dataset=dev_ds_mismatched,
            batch_sampler=dev_batch_sampler_mismatched,
            collate_fn=batchify_fn,
            num_workers=0,
            return_list=True,
        )
    else:
        dev_ds = load_dataset("glue", args.task_name, splits="dev")
        dev_ds = dev_ds.map(trans_func, lazy=True)
        dev_batch_sampler = paddle.io.BatchSampler(dev_ds, batch_size=args.batch_size, shuffle=False)
        dev_data_loader = DataLoader(
            dataset=dev_ds, batch_sampler=dev_batch_sampler, collate_fn=batchify_fn, num_workers=0, return_list=True
        )

    num_labels = 1 if train_ds.label_list is None else len(train_ds.label_list)

    # Step1: Initialize the origin BERT model.
    model = model_class.from_pretrained(args.model_name_or_path, num_classes=num_labels)
    origin_weights = model.state_dict()

    # Step2: Convert origin model to supernet.
    sp_config = supernet(expand_ratio=args.width_mult_list)
    model = Convert(sp_config).convert(model)
    # Use weights saved in the dictionary to initialize supernet.
    utils.set_state_dict(model, origin_weights)

    # Step3: Define teacher model.
    teacher_model = model_class.from_pretrained(args.model_name_or_path, num_classes=num_labels)
    new_dict = utils.utils.remove_model_fn(teacher_model, origin_weights)
    teacher_model.set_state_dict(new_dict)
    del origin_weights, new_dict

    default_run_config = {"elastic_depth": args.depth_mult_list}
    run_config = RunConfig(**default_run_config)

    # Step4: Config about distillation.
    mapping_layers = ["bert.embeddings"]
    for idx in range(model.bert.config["num_hidden_layers"]):
        mapping_layers.append("bert.encoder.layers.{}".format(idx))

    default_distill_config = {
        "lambda_distill": args.lambda_rep,
        "teacher_model": teacher_model,
        "mapping_layers": mapping_layers,
    }
    distill_config = DistillConfig(**default_distill_config)

    # Step5: Config in supernet training.
    ofa_model = OFA(model, run_config=run_config, distill_config=distill_config, elastic_order=["depth"])
    # elastic_order=['width'])

    criterion = paddle.nn.CrossEntropyLoss() if train_ds.label_list else paddle.nn.MSELoss()

    metric = metric_class()

    if args.task_name == "mnli":
        dev_data_loader = (dev_data_loader_matched, dev_data_loader_mismatched)

    if paddle.distributed.get_world_size() > 1:
        ofa_model.model = paddle.DataParallel(ofa_model.model, find_unused_parameters=True)

    if args.max_steps > 0:
        num_training_steps = args.max_steps
        num_train_epochs = math.ceil(num_training_steps / len(train_data_loader))
    else:
        num_training_steps = len(train_data_loader) * args.num_train_epochs
        num_train_epochs = args.num_train_epochs

    lr_scheduler = LinearDecayWithWarmup(args.learning_rate, num_training_steps, args.warmup_steps)

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

    global_step = 0
    tic_train = time.time()
    for epoch in range(num_train_epochs):
        # Step6: Set current epoch and task.
        ofa_model.set_epoch(epoch)
        ofa_model.set_task("depth")

        for step, batch in enumerate(train_data_loader):
            global_step += 1
            input_ids, segment_ids, labels = batch

            for depth_mult in args.depth_mult_list:
                for width_mult in args.width_mult_list:
                    # Step7: Broadcast supernet config from width_mult,
                    # and use this config in supernet training.
                    net_config = utils.dynabert_config(ofa_model, width_mult, depth_mult)
                    ofa_model.set_net_config(net_config)
                    logits, teacher_logits = ofa_model(input_ids, segment_ids, attention_mask=[None, None])
                    rep_loss = ofa_model.calc_distill_loss()
                    if args.task_name == "sts-b":
                        logit_loss = 0.0
                    else:
                        logit_loss = soft_cross_entropy(logits, teacher_logits.detach())
                    loss = rep_loss + args.lambda_logit * logit_loss
                    loss.backward()
            optimizer.step()
            lr_scheduler.step()
            ofa_model.model.clear_gradients()

            if global_step % args.logging_steps == 0:
                if paddle.distributed.get_rank() == 0:
                    logger.info(
                        "global step %d, epoch: %d, batch: %d, loss: %f, speed: %.2f step/s"
                        % (global_step, epoch, step, loss, args.logging_steps / (time.time() - tic_train))
                    )
                tic_train = time.time()

            if global_step % args.save_steps == 0:
                if args.task_name == "mnli":
                    evaluate(teacher_model, criterion, metric, dev_data_loader_matched, width_mult=100)
                    evaluate(teacher_model, criterion, metric, dev_data_loader_mismatched, width_mult=100)
                else:
                    evaluate(teacher_model, criterion, metric, dev_data_loader, width_mult=100)
                for depth_mult in args.depth_mult_list:
                    for width_mult in args.width_mult_list:
                        net_config = utils.dynabert_config(ofa_model, width_mult, depth_mult)
                        ofa_model.set_net_config(net_config)
                        tic_eval = time.time()
                        if args.task_name == "mnli":
                            evaluate(ofa_model, criterion, metric, dev_data_loader_matched, width_mult, depth_mult)
                            evaluate(ofa_model, criterion, metric, dev_data_loader_mismatched, width_mult, depth_mult)
                            print("eval done total : %s s" % (time.time() - tic_eval))
                        else:
                            evaluate(ofa_model, criterion, metric, dev_data_loader, width_mult, depth_mult)
                            print("eval done total : %s s" % (time.time() - tic_eval))

                        if paddle.distributed.get_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)
                            # need better way to get inner model of DataParallel
                            model_to_save = model._layers if isinstance(model, paddle.DataParallel) else model
                            model_to_save.save_pretrained(output_dir)
                            tokenizer.save_pretrained(output_dir)
            if global_step >= num_training_steps:
                return


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)
