# coding=utf-8
# Copyright 2022 The HuggingFace Inc. team. 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.
""" Finetuning any 🤗 Transformers model for image classification leveraging 🤗 Accelerate."""
import argparse
import json
import logging
import math
import os
from pathlib import Path

import datasets
import torch
from datasets import load_dataset, load_metric
from torch.utils.data import DataLoader
from torchvision.transforms import (
    CenterCrop,
    Compose,
    Normalize,
    RandomHorizontalFlip,
    RandomResizedCrop,
    Resize,
    ToTensor,
)
from tqdm.auto import tqdm

import transformers
from accelerate import Accelerator
from accelerate.utils import set_seed
from huggingface_hub import Repository
from transformers import (
    AutoConfig,
    AutoFeatureExtractor,
    AutoModelForImageClassification,
    SchedulerType,
    get_scheduler,
)
from transformers.utils import get_full_repo_name
from transformers.utils.versions import require_version


logger = logging.getLogger(__name__)

require_version("datasets>=2.0.0", "To fix: pip install -r examples/pytorch/image-classification/requirements.txt")


def parse_args():
    parser = argparse.ArgumentParser(description="Fine-tune a Transformers model on an image classification dataset")
    parser.add_argument(
        "--dataset_name",
        type=str,
        default="cifar10",
        help="The name of the Dataset (from the HuggingFace hub) to train on (could be your own, possibly private, dataset).",
    )
    parser.add_argument("--train_dir", type=str, default=None, help="A folder containing the training data.")
    parser.add_argument("--validation_dir", type=str, default=None, help="A folder containing the validation data.")
    parser.add_argument(
        "--max_train_samples",
        type=int,
        default=None,
        help="For debugging purposes or quicker training, truncate the number of training examples to this "
        "value if set.",
    )
    parser.add_argument(
        "--max_eval_samples",
        type=int,
        default=None,
        help="For debugging purposes or quicker training, truncate the number of evaluation examples to this "
        "value if set.",
    )
    parser.add_argument(
        "--train_val_split",
        type=float,
        default=0.15,
        help="Percent to split off of train for validation",
    )
    parser.add_argument(
        "--model_name_or_path",
        type=str,
        help="Path to pretrained model or model identifier from huggingface.co/models.",
        default="google/vit-base-patch16-224-in21k",
    )
    parser.add_argument(
        "--per_device_train_batch_size",
        type=int,
        default=8,
        help="Batch size (per device) for the training dataloader.",
    )
    parser.add_argument(
        "--per_device_eval_batch_size",
        type=int,
        default=8,
        help="Batch size (per device) for the evaluation dataloader.",
    )
    parser.add_argument(
        "--learning_rate",
        type=float,
        default=5e-5,
        help="Initial learning rate (after the potential warmup period) to use.",
    )
    parser.add_argument("--weight_decay", type=float, default=0.0, help="Weight decay to use.")
    parser.add_argument("--num_train_epochs", type=int, default=3, help="Total number of training epochs to perform.")
    parser.add_argument(
        "--max_train_steps",
        type=int,
        default=None,
        help="Total number of training steps to perform. If provided, overrides num_train_epochs.",
    )
    parser.add_argument(
        "--gradient_accumulation_steps",
        type=int,
        default=1,
        help="Number of updates steps to accumulate before performing a backward/update pass.",
    )
    parser.add_argument(
        "--lr_scheduler_type",
        type=SchedulerType,
        default="linear",
        help="The scheduler type to use.",
        choices=["linear", "cosine", "cosine_with_restarts", "polynomial", "constant", "constant_with_warmup"],
    )
    parser.add_argument(
        "--num_warmup_steps", type=int, default=0, help="Number of steps for the warmup in the lr scheduler."
    )
    parser.add_argument("--output_dir", type=str, default=None, help="Where to store the final model.")
    parser.add_argument("--seed", type=int, default=None, help="A seed for reproducible training.")
    parser.add_argument("--push_to_hub", action="store_true", help="Whether or not to push the model to the Hub.")
    parser.add_argument(
        "--hub_model_id", type=str, help="The name of the repository to keep in sync with the local `output_dir`."
    )
    parser.add_argument("--hub_token", type=str, help="The token to use to push to the Model Hub.")
    parser.add_argument(
        "--checkpointing_steps",
        type=str,
        default=None,
        help="Whether the various states should be saved at the end of every n steps, or 'epoch' for each epoch.",
    )
    parser.add_argument(
        "--resume_from_checkpoint",
        type=str,
        default=None,
        help="If the training should continue from a checkpoint folder.",
    )
    parser.add_argument(
        "--with_tracking",
        action="store_true",
        help="Whether to load in all available experiment trackers from the environment and use them for logging.",
    )
    args = parser.parse_args()

    # Sanity checks
    if args.dataset_name is None and args.train_dir is None and args.validation_dir is None:
        raise ValueError("Need either a dataset name or a training/validation folder.")

    if args.push_to_hub or args.with_tracking:
        if args.output_dir is None:
            raise ValueError(
                "Need an `output_dir` to create a repo when `--push_to_hub` or `with_tracking` is specified."
            )

    if args.output_dir is not None:
        os.makedirs(args.output_dir, exist_ok=True)

    return args


def main():
    args = parse_args()

    # Initialize the accelerator. We will let the accelerator handle device placement for us in this example.
    # If we're using tracking, we also need to initialize it here and it will pick up all supported trackers in the environment
    accelerator = Accelerator(log_with="all", logging_dir=args.output_dir) if args.with_tracking else Accelerator()
    logger.info(accelerator.state)
    # Make one log on every process with the configuration for debugging.
    logging.basicConfig(
        format="%(asctime)s - %(levelname)s - %(name)s - %(message)s",
        datefmt="%m/%d/%Y %H:%M:%S",
        level=logging.INFO,
    )
    logger.info(accelerator.state)

    # Setup logging, we only want one process per machine to log things on the screen.
    # accelerator.is_local_main_process is only True for one process per machine.
    logger.setLevel(logging.INFO if accelerator.is_local_main_process else logging.ERROR)
    if accelerator.is_local_main_process:
        datasets.utils.logging.set_verbosity_warning()
        transformers.utils.logging.set_verbosity_info()
    else:
        datasets.utils.logging.set_verbosity_error()
        transformers.utils.logging.set_verbosity_error()

    # If passed along, set the training seed now.
    if args.seed is not None:
        set_seed(args.seed)

    # Handle the repository creation
    if accelerator.is_main_process:
        if args.push_to_hub:
            if args.hub_model_id is None:
                repo_name = get_full_repo_name(Path(args.output_dir).name, token=args.hub_token)
            else:
                repo_name = args.hub_model_id
            repo = Repository(args.output_dir, clone_from=repo_name)

            with open(os.path.join(args.output_dir, ".gitignore"), "w+") as gitignore:
                if "step_*" not in gitignore:
                    gitignore.write("step_*\n")
                if "epoch_*" not in gitignore:
                    gitignore.write("epoch_*\n")
        elif args.output_dir is not None:
            os.makedirs(args.output_dir, exist_ok=True)
    accelerator.wait_for_everyone()

    # Get the datasets: you can either provide your own training and evaluation files (see below)
    # or specify a Dataset from the hub (the dataset will be downloaded automatically from the datasets Hub).

    # In distributed training, the load_dataset function guarantees that only one local process can concurrently
    # download the dataset.
    if args.dataset_name is not None:
        # Downloading and loading a dataset from the hub.
        dataset = load_dataset(args.dataset_name, task="image-classification")
    else:
        data_files = {}
        if args.train_dir is not None:
            data_files["train"] = os.path.join(args.train_dir, "**")
        if args.validation_dir is not None:
            data_files["validation"] = os.path.join(args.validation_dir, "**")
        dataset = load_dataset(
            "imagefolder",
            data_files=data_files,
            cache_dir=args.cache_dir,
            task="image-classification",
        )
        # See more about loading custom images at
        # https://huggingface.co/docs/datasets/v2.0.0/en/image_process#imagefolder.

    # If we don't have a validation split, split off a percentage of train as validation.
    args.train_val_split = None if "validation" in dataset.keys() else args.train_val_split
    if isinstance(args.train_val_split, float) and args.train_val_split > 0.0:
        split = dataset["train"].train_test_split(args.train_val_split)
        dataset["train"] = split["train"]
        dataset["validation"] = split["test"]

    # Prepare label mappings.
    # We'll include these in the model's config to get human readable labels in the Inference API.
    labels = dataset["train"].features["labels"].names
    label2id = {label: str(i) for i, label in enumerate(labels)}
    id2label = {str(i): label for i, label in enumerate(labels)}

    # Load pretrained model and feature extractor
    #
    # In distributed training, the .from_pretrained methods guarantee that only one local process can concurrently
    # download model & vocab.
    config = AutoConfig.from_pretrained(
        args.model_name_or_path,
        num_labels=len(labels),
        i2label=id2label,
        label2id=label2id,
        finetuning_task="image-classification",
    )
    feature_extractor = AutoFeatureExtractor.from_pretrained(args.model_name_or_path)
    model = AutoModelForImageClassification.from_pretrained(
        args.model_name_or_path,
        from_tf=bool(".ckpt" in args.model_name_or_path),
        config=config,
    )

    # Preprocessing the datasets

    # Define torchvision transforms to be applied to each image.
    normalize = Normalize(mean=feature_extractor.image_mean, std=feature_extractor.image_std)
    train_transforms = Compose(
        [
            RandomResizedCrop(feature_extractor.size),
            RandomHorizontalFlip(),
            ToTensor(),
            normalize,
        ]
    )
    val_transforms = Compose(
        [
            Resize(feature_extractor.size),
            CenterCrop(feature_extractor.size),
            ToTensor(),
            normalize,
        ]
    )

    def preprocess_train(example_batch):
        """Apply _train_transforms across a batch."""
        example_batch["pixel_values"] = [train_transforms(image.convert("RGB")) for image in example_batch["image"]]
        return example_batch

    def preprocess_val(example_batch):
        """Apply _val_transforms across a batch."""
        example_batch["pixel_values"] = [val_transforms(image.convert("RGB")) for image in example_batch["image"]]
        return example_batch

    with accelerator.main_process_first():
        if args.max_train_samples is not None:
            dataset["train"] = dataset["train"].shuffle(seed=args.seed).select(range(args.max_train_samples))
        # Set the training transforms
        train_dataset = dataset["train"].with_transform(preprocess_train)
        if args.max_eval_samples is not None:
            dataset["validation"] = dataset["validation"].shuffle(seed=args.seed).select(range(args.max_eval_samples))
        # Set the validation transforms
        eval_dataset = dataset["validation"].with_transform(preprocess_val)

    # DataLoaders creation:
    def collate_fn(examples):
        pixel_values = torch.stack([example["pixel_values"] for example in examples])
        labels = torch.tensor([example["labels"] for example in examples])
        return {"pixel_values": pixel_values, "labels": labels}

    train_dataloader = DataLoader(
        train_dataset, shuffle=True, collate_fn=collate_fn, batch_size=args.per_device_train_batch_size
    )
    eval_dataloader = DataLoader(eval_dataset, collate_fn=collate_fn, batch_size=args.per_device_eval_batch_size)

    # Optimizer
    # Split weights in two groups, one with weight decay and the other not.
    no_decay = ["bias", "LayerNorm.weight"]
    optimizer_grouped_parameters = [
        {
            "params": [p for n, p in model.named_parameters() if not any(nd in n for nd in no_decay)],
            "weight_decay": args.weight_decay,
        },
        {
            "params": [p for n, p in model.named_parameters() if any(nd in n for nd in no_decay)],
            "weight_decay": 0.0,
        },
    ]
    optimizer = torch.optim.AdamW(optimizer_grouped_parameters, lr=args.learning_rate)

    # Scheduler and math around the number of training steps.
    num_update_steps_per_epoch = math.ceil(len(train_dataloader) / args.gradient_accumulation_steps)
    if args.max_train_steps is None:
        args.max_train_steps = args.num_train_epochs * num_update_steps_per_epoch
    else:
        args.num_train_epochs = math.ceil(args.max_train_steps / num_update_steps_per_epoch)

    lr_scheduler = get_scheduler(
        name=args.lr_scheduler_type,
        optimizer=optimizer,
        num_warmup_steps=args.num_warmup_steps,
        num_training_steps=args.max_train_steps,
    )

    # Prepare everything with our `accelerator`.
    model, optimizer, train_dataloader, eval_dataloader, lr_scheduler = accelerator.prepare(
        model, optimizer, train_dataloader, eval_dataloader, lr_scheduler
    )

    # Figure out how many steps we should save the Accelerator states
    if hasattr(args.checkpointing_steps, "isdigit"):
        checkpointing_steps = args.checkpointing_steps
        if args.checkpointing_steps.isdigit():
            checkpointing_steps = int(args.checkpointing_steps)
    else:
        checkpointing_steps = None

    # We need to initialize the trackers we use, and also store our configuration
    if args.with_tracking:
        experiment_config = vars(args)
        # TensorBoard cannot log Enums, need the raw value
        experiment_config["lr_scheduler_type"] = experiment_config["lr_scheduler_type"].value
        accelerator.init_trackers("image_classification_no_trainer", experiment_config)

    # Get the metric function
    metric = load_metric("accuracy")

    # Train!
    total_batch_size = args.per_device_train_batch_size * accelerator.num_processes * args.gradient_accumulation_steps

    logger.info("***** Running training *****")
    logger.info(f"  Num examples = {len(train_dataset)}")
    logger.info(f"  Num Epochs = {args.num_train_epochs}")
    logger.info(f"  Instantaneous batch size per device = {args.per_device_train_batch_size}")
    logger.info(f"  Total train batch size (w. parallel, distributed & accumulation) = {total_batch_size}")
    logger.info(f"  Gradient Accumulation steps = {args.gradient_accumulation_steps}")
    logger.info(f"  Total optimization steps = {args.max_train_steps}")
    # Only show the progress bar once on each machine.
    progress_bar = tqdm(range(args.max_train_steps), disable=not accelerator.is_local_main_process)
    completed_steps = 0
    # Potentially load in the weights and states from a previous save
    if args.resume_from_checkpoint:
        if args.resume_from_checkpoint is not None or args.resume_from_checkpoint != "":
            accelerator.print(f"Resumed from checkpoint: {args.resume_from_checkpoint}")
            accelerator.load_state(args.resume_from_checkpoint)
            resume_step = None
            path = args.resume_from_checkpoint
        else:
            # Get the most recent checkpoint
            dirs = [f.name for f in os.scandir(os.getcwd()) if f.is_dir()]
            dirs.sort(key=os.path.getctime)
            path = dirs[-1]  # Sorts folders by date modified, most recent checkpoint is the last
        if "epoch" in path:
            args.num_train_epochs -= int(path.replace("epoch_", ""))
        else:
            resume_step = int(path.replace("step_", ""))
            args.num_train_epochs -= resume_step // len(train_dataloader)
            resume_step = (args.num_train_epochs * len(train_dataloader)) - resume_step

    for epoch in range(args.num_train_epochs):
        model.train()
        if args.with_tracking:
            total_loss = 0
        for step, batch in enumerate(train_dataloader):
            # We need to skip steps until we reach the resumed step
            if args.resume_from_checkpoint and epoch == 0 and step < resume_step:
                continue
            outputs = model(**batch)
            loss = outputs.loss
            # We keep track of the loss at each epoch
            if args.with_tracking:
                total_loss += loss.detach().float()
            loss = loss / args.gradient_accumulation_steps
            accelerator.backward(loss)
            if step % args.gradient_accumulation_steps == 0 or step == len(train_dataloader) - 1:
                optimizer.step()
                lr_scheduler.step()
                optimizer.zero_grad()
                progress_bar.update(1)
                completed_steps += 1

            if isinstance(checkpointing_steps, int):
                if completed_steps % checkpointing_steps == 0:
                    output_dir = f"step_{completed_steps}"
                    if args.output_dir is not None:
                        output_dir = os.path.join(args.output_dir, output_dir)
                    accelerator.save_state(output_dir)

                    if args.push_to_hub and epoch < args.num_train_epochs - 1:
                        accelerator.wait_for_everyone()
                        unwrapped_model = accelerator.unwrap_model(model)
                        unwrapped_model.save_pretrained(
                            args.output_dir,
                            is_main_process=accelerator.is_main_process,
                            save_function=accelerator.save,
                        )
                        if accelerator.is_main_process:
                            feature_extractor.save_pretrained(args.output_dir)
                            repo.push_to_hub(
                                commit_message=f"Training in progress {completed_steps} steps",
                                blocking=False,
                                auto_lfs_prune=True,
                            )

            if completed_steps >= args.max_train_steps:
                break

        model.eval()
        samples_seen = 0
        for step, batch in enumerate(eval_dataloader):
            outputs = model(**batch)
            predictions = outputs.logits.argmax(dim=-1)
            predictions, references = accelerator.gather((predictions, batch["labels"]))
            # If we are in a multiprocess environment, the last batch has duplicates
            if accelerator.num_processes > 1:
                if step == len(eval_dataloader):
                    predictions = predictions[: len(eval_dataloader.dataset) - samples_seen]
                    references = references[: len(eval_dataloader.dataset) - samples_seen]
                else:
                    samples_seen += references.shape[0]
            metric.add_batch(
                predictions=predictions,
                references=references,
            )

        eval_metric = metric.compute()
        logger.info(f"epoch {epoch}: {eval_metric}")

        if args.with_tracking:
            accelerator.log(
                {
                    "accuracy": eval_metric,
                    "train_loss": total_loss,
                    "epoch": epoch,
                    "step": completed_steps,
                },
            )

        if args.push_to_hub and epoch < args.num_train_epochs - 1:
            accelerator.wait_for_everyone()
            unwrapped_model = accelerator.unwrap_model(model)
            unwrapped_model.save_pretrained(
                args.output_dir, is_main_process=accelerator.is_main_process, save_function=accelerator.save
            )
            if accelerator.is_main_process:
                feature_extractor.save_pretrained(args.output_dir)
                repo.push_to_hub(
                    commit_message=f"Training in progress epoch {epoch}", blocking=False, auto_lfs_prune=True
                )

        if args.checkpointing_steps == "epoch":
            output_dir = f"epoch_{epoch}"
            if args.output_dir is not None:
                output_dir = os.path.join(args.output_dir, output_dir)
            accelerator.save_state(output_dir)

    if args.output_dir is not None:
        accelerator.wait_for_everyone()
        unwrapped_model = accelerator.unwrap_model(model)
        unwrapped_model.save_pretrained(
            args.output_dir, is_main_process=accelerator.is_main_process, save_function=accelerator.save
        )
        if accelerator.is_main_process:
            feature_extractor.save_pretrained(args.output_dir)
            if args.push_to_hub:
                repo.push_to_hub(commit_message="End of training", auto_lfs_prune=True)

    if args.output_dir is not None:
        with open(os.path.join(args.output_dir, "all_results.json"), "w") as f:
            json.dump({"eval_accuracy": eval_metric["accuracy"]}, f)


if __name__ == "__main__":
    main()
