# Copyright (c) OpenMMLab. All rights reserved.
import argparse
import os.path as osp
import time
from functools import partial
from typing import Optional

import matplotlib.pyplot as plt
import numpy as np
import torch
from mmengine.config import Config, DictAction
from mmengine.dataset import pseudo_collate, worker_init_fn
from mmengine.dist import get_rank, init_dist
from mmengine.logging import MMLogger
from mmengine.model.wrappers import MMDistributedDataParallel, is_model_wrapper
from mmengine.runner import load_checkpoint
from mmengine.utils import mkdir_or_exist
from sklearn.manifold import TSNE
from torch.utils.data import DataLoader

from mmselfsup.models.utils import Extractor
from mmselfsup.registry import DATA_SAMPLERS, DATASETS, MODELS
from mmselfsup.utils import register_all_modules


def parse_args():
    parser = argparse.ArgumentParser(description='t-SNE visualization')
    parser.add_argument('config', help='train config file path')
    parser.add_argument('--checkpoint', default=None, help='checkpoint file')
    parser.add_argument('--work-dir', help='the dir to save logs and models')
    parser.add_argument(
        '--launcher',
        choices=['none', 'pytorch', 'slurm', 'mpi'],
        default='none',
        help='job launcher')
    parser.add_argument(
        '--dataset-config',
        default='configs/benchmarks/classification/tsne_imagenet.py',
        help='extract dataset config file path')
    parser.add_argument(
        '--max-num-class',
        type=int,
        default=20,
        help='the maximum number of classes to apply t-SNE algorithms, now the'
        'function supports maximum 20 classes')
    parser.add_argument('--seed', type=int, default=0, help='random seed')
    parser.add_argument(
        '--deterministic',
        action='store_true',
        help='whether to set deterministic options for CUDNN backend.')
    parser.add_argument(
        '--cfg-options',
        nargs='+',
        action=DictAction,
        help='override some settings in the used config, the key-value pair '
        'in xxx=yyy format will be merged into config file. If the value to '
        'be overwritten is a list, it should be like key="[a,b]" or key=a,b '
        'It also allows nested list/tuple values, e.g. key="[(a,b),(c,d)]" '
        'Note that the quotation marks are necessary and that no white space '
        'is allowed.')

    # t-SNE settings
    parser.add_argument(
        '--n-components', type=int, default=2, help='the dimension of results')
    parser.add_argument(
        '--perplexity',
        type=float,
        default=30.0,
        help='The perplexity is related to the number of nearest neighbors'
        'that is used in other manifold learning algorithms.')
    parser.add_argument(
        '--early-exaggeration',
        type=float,
        default=12.0,
        help='Controls how tight natural clusters in the original space are in'
        'the embedded space and how much space will be between them.')
    parser.add_argument(
        '--learning-rate',
        type=float,
        default=200.0,
        help='The learning rate for t-SNE is usually in the range'
        '[10.0, 1000.0]. If the learning rate is too high, the data may look'
        'like a ball with any point approximately equidistant from its nearest'
        'neighbours. If the learning rate is too low, most points may look'
        'compressed in a dense cloud with few outliers.')
    parser.add_argument(
        '--n-iter',
        type=int,
        default=1000,
        help='Maximum number of iterations for the optimization. Should be at'
        'least 250.')
    parser.add_argument(
        '--n-iter-without-progress',
        type=int,
        default=300,
        help='Maximum number of iterations without progress before we abort'
        'the optimization.')
    parser.add_argument(
        '--init', type=str, default='random', help='The init method')
    args = parser.parse_args()
    return args


def main():
    args = parse_args()

    # register all modules in mmselfsup into the registries
    register_all_modules()

    cfg = Config.fromfile(args.config)
    if args.cfg_options is not None:
        cfg.merge_from_dict(args.cfg_options)
    # set cudnn_benchmark
    if cfg.get('cudnn_benchmark', False):
        torch.backends.cudnn.benchmark = True
    # work_dir is determined in this priority: CLI > segment in file > filename
    if args.work_dir is not None:
        # update configs according to CLI args if args.work_dir is not None
        cfg.work_dir = args.work_dir
    elif cfg.get('work_dir', None) is None:
        # use config filename as default work_dir if cfg.work_dir is None
        work_type = args.config.split('/')[1]
        cfg.work_dir = osp.join('./work_dirs', work_type,
                                osp.splitext(osp.basename(args.config))[0])

    # init distributed env first, since logger depends on the dist info.
    if args.launcher == 'none':
        distributed = False
    else:
        distributed = True
        init_dist(args.launcher)

    # create work_dir
    timestamp = time.strftime('%Y%m%d_%H%M%S', time.localtime())
    tsne_work_dir = osp.join(cfg.work_dir, f'tsne_{timestamp}/')
    mkdir_or_exist(osp.abspath(tsne_work_dir))

    # init the logger before other steps
    log_file = osp.join(tsne_work_dir, 'extract.log')
    logger = MMLogger.get_instance(
        'mmselfsup',
        logger_name='mmselfsup',
        log_file=log_file,
        log_level=cfg.log_level)

    # build the dataset
    dataset_cfg = Config.fromfile(args.dataset_config)
    extract_dataloader_cfg = dataset_cfg.get('extract_dataloader')
    extract_dataset_cfg = extract_dataloader_cfg.pop('dataset')
    if isinstance(extract_dataset_cfg, dict):
        dataset = DATASETS.build(extract_dataset_cfg)
        if hasattr(dataset, 'full_init'):
            dataset.full_init()

    # compress dataset, select that the label is less then max_num_class
    subset_idx_list = []
    for i in range(len(dataset)):
        if dataset.get_data_info(i)['gt_label'] < args.max_num_class:
            subset_idx_list.append(i)
    dataset.get_subset_(subset_idx_list)
    logger.info(f'Apply t-SNE to visualize {len(subset_idx_list)} samples.')

    # build sampler
    sampler_cfg = extract_dataloader_cfg.pop('sampler')
    if isinstance(sampler_cfg, dict):
        sampler = DATA_SAMPLERS.build(
            sampler_cfg, default_args=dict(dataset=dataset, seed=args.seed))

    # build dataloader
    init_fn: Optional[partial]
    if args.seed is not None:
        init_fn = partial(
            worker_init_fn,
            num_workers=extract_dataloader_cfg.get('num_workers'),
            rank=get_rank(),
            seed=args.seed)
    else:
        init_fn = None

    tsne_dataloader = DataLoader(
        dataset=dataset,
        sampler=sampler,
        collate_fn=pseudo_collate,
        worker_init_fn=init_fn,
        **extract_dataloader_cfg)

    # build the model
    # get backbone out_indices from pool_cfg in tsne_dataset_config
    cfg.model.backbone.out_indices = dataset_cfg.pool_cfg.get(
        'in_indices', [4])
    logger.info(
        f'The output indices of backbone is {cfg.model.backbone.out_indices}.')
    model = MODELS.build(cfg.model)
    model.init_weights()

    # model is determined in this priority: init_cfg > checkpoint > random
    if hasattr(cfg.model.backbone, 'init_cfg'):
        if getattr(cfg.model.backbone.init_cfg, 'type', None) == 'Pretrained':
            logger.info(
                f'Use pretrained model: '
                f'{cfg.model.backbone.init_cfg.checkpoint} to extract features'
            )
    elif args.checkpoint is not None:
        logger.info(f'Use checkpoint: {args.checkpoint} to extract features')
        load_checkpoint(model, args.checkpoint, map_location='cpu')
    else:
        logger.info('No pretrained or checkpoint is given, use random init.')

    if torch.cuda.is_available():
        model = model.cuda()

    if distributed:
        model = MMDistributedDataParallel(
            module=model.cuda(),
            device_ids=[torch.cuda.current_device()],
            broadcast_buffers=False)

    if is_model_wrapper(model):
        model = model.module

    # build extractor and extract features
    extractor = Extractor(
        extract_dataloader=tsne_dataloader,
        seed=args.seed,
        pool_cfg=dataset_cfg.pool_cfg,
        dist_mode=distributed)
    features = extractor(model)
    labels = tsne_dataloader.dataset.get_gt_labels()

    # save features
    mkdir_or_exist(f'{tsne_work_dir}features/')
    logger.info(f'Save features to {tsne_work_dir}features/')
    if distributed:
        rank = get_rank()
        if rank == 0:
            for key, val in features.items():
                output_file = \
                    f'{tsne_work_dir}features/{dataset_cfg.name}_{key}.npy'
                np.save(output_file, val)
    else:
        for key, val in features.items():
            output_file = \
                f'{tsne_work_dir}features/{dataset_cfg.name}_{key}.npy'
            np.save(output_file, val)

    # build t-SNE model
    tsne_model = TSNE(
        n_components=args.n_components,
        perplexity=args.perplexity,
        early_exaggeration=args.early_exaggeration,
        learning_rate=args.learning_rate,
        n_iter=args.n_iter,
        n_iter_without_progress=args.n_iter_without_progress,
        init=args.init)

    # run and get results
    mkdir_or_exist(f'{tsne_work_dir}saved_pictures/')
    logger.info('Running t-SNE......')
    for key, val in features.items():
        result = tsne_model.fit_transform(val)
        res_min, res_max = result.min(0), result.max(0)
        res_norm = (result - res_min) / (res_max - res_min)
        plt.figure(figsize=(10, 10))
        plt.scatter(
            res_norm[:, 0],
            res_norm[:, 1],
            alpha=1.0,
            s=15,
            c=labels,
            cmap='tab20')
        plt.savefig(f'{tsne_work_dir}saved_pictures/{key}.png')
    logger.info(f'Saved results to {tsne_work_dir}saved_pictures/')


if __name__ == '__main__':
    main()