import pickle
from collections import defaultdict
from pathlib import Path

import librosa as librosa
from torch.utils.data import Dataset
import torch

import variables as V
from ml_lib.modules.util import F_x


class BinaryMasksDataset(Dataset):
    _to_label = defaultdict(lambda: -1)
    _to_label.update(dict(clear=V.CLEAR, mask=V.MASK))

    @property
    def sample_shape(self):
        return self[0][0].shape

    def __init__(self, data_root, setting, mel_transforms, transforms=None, stretch_dataset=False,
                 use_preprocessed=True):
        self.use_preprocessed = use_preprocessed
        self.stretch = stretch_dataset
        assert isinstance(setting, str), f'Setting has to be a string, but was: {type(setting)}.'
        assert setting in V.DATA_OPTIONS, f'Setting must match one of: {V.DATA_OPTIONS}.'
        super(BinaryMasksDataset, self).__init__()

        self.data_root = Path(data_root)
        self.setting = setting
        self._wav_folder = self.data_root / 'wav'
        self._mel_folder = self.data_root / 'mel'
        self.container_ext = '.pik'
        self._mel_transform = mel_transforms

        self._labels = self._build_labels()
        self._wav_files = list(sorted(self._labels.keys()))
        self._transforms = transforms or F_x(in_shape=None)

    def _build_labels(self):
        labeldict = dict()
        with open(Path(self.data_root) / 'lab' / 'labels.csv', mode='r') as f:
            # Exclude the header
            _ = next(f)
            for row in f:
                if self.setting not in row:
                    continue
                filename, label = row.strip().split(',')
                labeldict[filename] = self._to_label[label.lower()] if not self.setting == 'test' else filename
        if self.stretch and self.setting == V.DATA_OPTIONS.train:
            additional_dict = ({f'X{key}': val for key, val in labeldict.items()})
            additional_dict.update({f'XX{key}': val for key, val in labeldict.items()})
            additional_dict.update({f'XXX{key}': val for key, val in labeldict.items()})
            labeldict.update(additional_dict)

        # Delete File if one exists.
        if not self.use_preprocessed:
            for key in labeldict.keys():
                try:
                    (self._mel_folder / (key.replace('.wav', '') + self.container_ext)).unlink()
                except FileNotFoundError:
                    pass

        return labeldict

    def __len__(self):
        return len(self._labels)

    def _compute_or_retrieve(self, filename):

        if not (self._mel_folder / (filename + self.container_ext)).exists():
            raw_sample, sr = librosa.core.load(self._wav_folder / (filename.replace('X', '') + '.wav'))
            mel_sample = self._mel_transform(raw_sample)
            self._mel_folder.mkdir(exist_ok=True, parents=True)
            with (self._mel_folder / (filename + self.container_ext)).open(mode='wb') as f:
                pickle.dump(mel_sample, f, protocol=pickle.HIGHEST_PROTOCOL)

        with (self._mel_folder / (filename + self.container_ext)).open(mode='rb') as f:
            mel_sample = pickle.load(f, fix_imports=True)
        return mel_sample

    def __getitem__(self, item):

        key: str = list(self._labels.keys())[item]
        filename = key.replace('.wav', '')
        mel_sample = self._compute_or_retrieve(filename)
        label = self._labels[key]

        transformed_samples = self._transforms(mel_sample)

        if self.setting != V.DATA_OPTIONS.test:
            # In test, filenames instead of labels are returned. This is a little hacky though.
            label = torch.as_tensor(label, dtype=torch.float)

        return transformed_samples, label