# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.


import logging
import os
import sys

import numpy as np
import torch
import torch.nn.functional as F

from .. import FairseqDataset, BaseWrapperDataset
from ..data_utils import compute_mask_indices, get_buckets, get_bucketed_sizes


logger = logging.getLogger(__name__)


class RawAudioDataset(FairseqDataset):
    def __init__(
        self,
        sample_rate,
        max_sample_size=None,
        min_sample_size=0,
        shuffle=True,
        pad=False,
        normalize=False,
        compute_mask_indices=False,
        **mask_compute_kwargs,
    ):
        super().__init__()

        self.sample_rate = sample_rate
        self.sizes = []
        self.max_sample_size = (
            max_sample_size if max_sample_size is not None else sys.maxsize
        )
        self.min_sample_size = min_sample_size
        self.pad = pad
        self.shuffle = shuffle
        self.normalize = normalize
        self.compute_mask_indices = compute_mask_indices
        if self.compute_mask_indices:
            self.mask_compute_kwargs = mask_compute_kwargs
            self._features_size_map = {}
            self._C = mask_compute_kwargs['encoder_embed_dim']
            self._conv_feature_layers = eval(
                mask_compute_kwargs['conv_feature_layers']
            )

    def __getitem__(self, index):
        raise NotImplementedError()

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

    def postprocess(self, feats, curr_sample_rate):
        if feats.dim() == 2:
            feats = feats.mean(-1)

        if curr_sample_rate != self.sample_rate:
            raise Exception(f"sample rate: {curr_sample_rate}, need {self.sample_rate}")

        assert feats.dim() == 1, feats.dim()

        if self.normalize:
            with torch.no_grad():
                feats = F.layer_norm(feats, feats.shape)
        return feats

    def crop_to_max_size(self, wav, target_size):
        size = len(wav)
        diff = size - target_size
        if diff <= 0:
            return wav

        start = np.random.randint(0, diff + 1)
        end = size - diff + start
        return wav[start:end]

    def _compute_mask_indices(self, dims, padding_mask):
        B, T, C = dims
        mask_indices, mask_channel_indices = None, None
        if self.mask_compute_kwargs['mask_prob'] > 0:
            mask_indices = compute_mask_indices(
                (B, T),
                padding_mask,
                self.mask_compute_kwargs['mask_prob'],
                self.mask_compute_kwargs['mask_length'],
                self.mask_compute_kwargs['mask_selection'],
                self.mask_compute_kwargs['mask_other'],
                min_masks=2,
                no_overlap=self.mask_compute_kwargs['no_mask_overlap'],
                min_space=self.mask_compute_kwargs['mask_min_space'],
            )
            mask_indices = torch.from_numpy(mask_indices)
        if self.mask_compute_kwargs['mask_channel_prob'] > 0:
            mask_channel_indices = compute_mask_indices(
                (B, C),
                None,
                self.mask_compute_kwargs['mask_channel_prob'],
                self.mask_compute_kwargs['mask_channel_length'],
                self.mask_compute_kwargs['mask_channel_selection'],
                self.mask_compute_kwargs['mask_channel_other'],
                no_overlap=self.mask_compute_kwargs['no_mask_channel_overlap'],
                min_space=self.mask_compute_kwargs['mask_channel_min_space'],
            )
            mask_channel_indices = (
                torch.from_numpy(mask_channel_indices)
                .unsqueeze(1)
                .expand(-1, T, -1)
            )

        return mask_indices, mask_channel_indices

    @staticmethod
    def _bucket_tensor(tensor, num_pad, value):
        return F.pad(tensor, (0, num_pad), value=value)

    def collater(self, samples):
        samples = [s for s in samples if s["source"] is not None]
        if len(samples) == 0:
            return {}

        sources = [s["source"] for s in samples]
        sizes = [len(s) for s in sources]

        if self.pad:
            target_size = min(max(sizes), self.max_sample_size)
        else:
            target_size = min(min(sizes), self.max_sample_size)

        collated_sources = sources[0].new_zeros(len(sources), target_size)
        padding_mask = (
            torch.BoolTensor(collated_sources.shape).fill_(False) if self.pad else None
        )
        for i, (source, size) in enumerate(zip(sources, sizes)):
            diff = size - target_size
            if diff == 0:
                collated_sources[i] = source
            elif diff < 0:
                assert self.pad
                collated_sources[i] = torch.cat(
                    [source, source.new_full((-diff,), 0.0)]
                )
                padding_mask[i, diff:] = True
            else:
                collated_sources[i] = self.crop_to_max_size(source, target_size)

        input = {"source": collated_sources}
        out = {"id": torch.LongTensor([s["id"] for s in samples])}
        if self.pad:
            input["padding_mask"] = padding_mask

        if hasattr(self, 'num_buckets') and self.num_buckets > 0:
            assert self.pad, "Cannot bucket without padding first."
            bucket = max(self._bucketed_sizes[s['id']] for s in samples)
            num_pad = bucket - collated_sources.size(-1)
            if num_pad:
                input['source'] = self._bucket_tensor(
                    collated_sources, num_pad, 0
                )
                input['padding_mask'] = self._bucket_tensor(
                    padding_mask, num_pad, True
                )

        if self.compute_mask_indices:
            B = input['source'].size(0)
            T = self._get_mask_indices_dims(input['source'].size(-1))
            padding_mask_reshaped = input['padding_mask'].clone()
            extra = padding_mask_reshaped.size(1) % T
            if extra > 0:
                padding_mask_reshaped = padding_mask_reshaped[:, :-extra]
            padding_mask_reshaped = padding_mask_reshaped.view(
                padding_mask_reshaped.size(0), T, -1
            )
            padding_mask_reshaped = padding_mask_reshaped.all(-1)
            input['padding_count'] = (
                padding_mask_reshaped.sum(-1).max().item()
            )
            mask_indices, mask_channel_indices = self._compute_mask_indices(
                (B, T, self._C), padding_mask_reshaped,
            )
            input["mask_indices"] = mask_indices
            input["mask_channel_indices"] = mask_channel_indices
            out['sample_size'] = mask_indices.sum().item()

        out["net_input"] = input
        return out

    def _get_mask_indices_dims(self, size, padding=0, dilation=1):
        if size not in self._features_size_map:
            L_in = size
            for (_, kernel_size, stride) in self._conv_feature_layers:
                L_out = L_in + 2*padding - dilation*(kernel_size-1) - 1
                L_out = 1 + L_out // stride
                L_in = L_out
            self._features_size_map[size] = L_out
        return self._features_size_map[size]

    def num_tokens(self, index):
        return self.size(index)

    def size(self, index):
        """Return an example's size as a float or tuple. This value is used when
        filtering a dataset with ``--max-positions``."""
        if self.pad:
            return self.sizes[index]
        return min(self.sizes[index], self.max_sample_size)

    def ordered_indices(self):
        """Return an ordered list of indices. Batches will be constructed based
        on this order."""

        if self.shuffle:
            order = [np.random.permutation(len(self))]
        else:
            order = [np.arange(len(self))]

        order.append(self.sizes)
        return np.lexsort(order)[::-1]


class FileAudioDataset(RawAudioDataset):
    def __init__(
        self,
        manifest_path,
        sample_rate,
        max_sample_size=None,
        min_sample_size=0,
        shuffle=True,
        pad=False,
        normalize=False,
        num_buckets=0,
        compute_mask_indices=False,
        **mask_compute_kwargs,
    ):
        super().__init__(
            sample_rate=sample_rate,
            max_sample_size=max_sample_size,
            min_sample_size=min_sample_size,
            shuffle=shuffle,
            pad=pad,
            normalize=normalize,
            compute_mask_indices=compute_mask_indices,
            **mask_compute_kwargs,
        )

        self.fnames = []
        self.line_inds = set()

        skipped = 0
        with open(manifest_path, "r") as f:
            self.root_dir = f.readline().strip()
            for i, line in enumerate(f):
                items = line.strip().split("\t")
                assert len(items) == 2, line
                sz = int(items[1])
                if min_sample_size is not None and sz < min_sample_size:
                    skipped += 1
                    continue
                self.fnames.append(items[0])
                self.line_inds.add(i)
                self.sizes.append(sz)
        self.set_bucket_info(num_buckets)
        logger.info(f"loaded {len(self.fnames)}, skipped {skipped} samples")

    def set_bucket_info(self, num_buckets):
        self.num_buckets = num_buckets
        if self.num_buckets > 0:
            self._collated_sizes = np.minimum(
                np.array(self.sizes), self.max_sample_size,
            )
            self.buckets = get_buckets(
                self._collated_sizes, self.num_buckets,
            )
            self._bucketed_sizes = get_bucketed_sizes(
                self._collated_sizes, self.buckets
            )
            logger.info(
                f"{len(self.buckets)} bucket(s) for the audio dataset: "
                f"{self.buckets}"
            )

    def __getitem__(self, index):
        import soundfile as sf

        fname = os.path.join(self.root_dir, self.fnames[index])
        wav, curr_sample_rate = sf.read(fname)
        feats = torch.from_numpy(wav).float()
        feats = self.postprocess(feats, curr_sample_rate)
        return {"id": index, "source": feats}
