# Copyright 2021 Huawei Technologies Co., Ltd
#
# 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.
# ============================================================================
"""
Create train or eval dataset.
"""
import math
import numpy as np
import mindspore.dataset.engine as de
import librosa
import soundfile as sf

TRAIN_INPUT_PAD_LENGTH = 1501
TRAIN_LABEL_PAD_LENGTH = 350
TEST_INPUT_PAD_LENGTH = 3500

class LoadAudioAndTranscript():
    """
    parse audio and transcript
    """
    def __init__(self,
                 audio_conf=None,
                 normalize=False,
                 labels=None):
        super(LoadAudioAndTranscript, self).__init__()
        self.window_stride = audio_conf.window_stride
        self.window_size = audio_conf.window_size
        self.sample_rate = audio_conf.sample_rate
        self.window = audio_conf.window
        self.is_normalization = normalize
        self.labels = labels

    def load_audio(self, path):
        """
        load audio
        """
        sound, _ = sf.read(path, dtype='int16')
        sound = sound.astype('float32') / 32767
        if len(sound.shape) > 1:
            if sound.shape[1] == 1:
                sound = sound.squeeze()
            else:
                sound = sound.mean(axis=1)
        return sound

    def parse_audio(self, audio_path):
        """
        parse audio
        """
        audio = self.load_audio(audio_path)
        n_fft = int(self.sample_rate * self.window_size)
        win_length = n_fft
        hop_length = int(self.sample_rate * self.window_stride)
        D = librosa.stft(y=audio, n_fft=n_fft, hop_length=hop_length, win_length=win_length, window=self.window)
        mag, _ = librosa.magphase(D)
        mag = np.log1p(mag)
        if self.is_normalization:
            mean = mag.mean()
            std = mag.std()
            mag = (mag - mean) / std
        return mag

    def parse_transcript(self, transcript_path):
        with open(transcript_path, 'r', encoding='utf8') as transcript_file:
            transcript = transcript_file.read().replace('\n', '')
        transcript = list(filter(None, [self.labels.get(x) for x in list(transcript)]))
        return transcript


class ASRDataset(LoadAudioAndTranscript):
    """
        create ASRDataset

        Args:
            audio_conf: Config containing the sample rate, window and the window length/stride in seconds
            manifest_filepath (str): manifest_file path.
            labels (list): List containing all the possible characters to map to
            normalize: Apply standard mean and deviation normalization to audio tensor
            batch_size (int): Dataset batch size (default=32)
        """
    def __init__(self, audio_conf=None,
                 manifest_filepath='',
                 labels=None,
                 normalize=False,
                 batch_size=32,
                 is_training=True):
        with open(manifest_filepath) as f:
            ids = f.readlines()

        ids = [x.strip().split(',') for x in ids]
        self.is_training = is_training
        self.ids = ids
        self.blank_id = int(labels.index('_'))
        self.bins = [ids[i:i + batch_size] for i in range(0, len(ids), batch_size)]
        if len(self.ids) % batch_size != 0:
            self.bins = self.bins[:-1]
            self.bins.append(ids[-batch_size:])
        self.size = len(self.bins)
        self.batch_size = batch_size
        self.labels_map = {labels[i]: i for i in range(len(labels))}
        super(ASRDataset, self).__init__(audio_conf, normalize, self.labels_map)

    def __getitem__(self, index):
        batch_idx = self.bins[index]
        batch_size = len(batch_idx)
        batch_spect, batch_script, target_indices = [], [], []
        input_length = np.zeros(batch_size, np.float32)
        for data in batch_idx:
            audio_path, transcript_path = data[0], data[1]
            spect = self.parse_audio(audio_path)
            transcript = self.parse_transcript(transcript_path)
            batch_spect.append(spect)
            batch_script.append(transcript)
        freq_size = np.shape(batch_spect[-1])[0]

        if self.is_training:
            # 1501 is the max length in train dataset(LibriSpeech).
            # The length is fixed to this value because Mindspore does not support dynamic shape currently
            inputs = np.zeros((batch_size, 1, freq_size, TRAIN_INPUT_PAD_LENGTH), dtype=np.float32)
            # The target length is fixed to this value because Mindspore does not support dynamic shape currently
            # 350 may be greater than the max length of labels in train dataset(LibriSpeech).
            targets = np.ones((self.batch_size, TRAIN_LABEL_PAD_LENGTH), dtype=np.int32) * self.blank_id
            for k, spect_, scripts_ in zip(range(batch_size), batch_spect, batch_script):
                seq_length = np.shape(spect_)[1]
                input_length[k] = seq_length
                script_length = len(scripts_)
                targets[k, :script_length] = scripts_
                for m in range(350):
                    target_indices.append([k, m])
                inputs[k, 0, :, 0:seq_length] = spect_
            targets = np.reshape(targets, (-1,))
        else:
            inputs = np.zeros((batch_size, 1, freq_size, TEST_INPUT_PAD_LENGTH), dtype=np.float32)
            targets = []
            for k, spect_, scripts_ in zip(range(batch_size), batch_spect, batch_script):
                seq_length = np.shape(spect_)[1]
                input_length[k] = seq_length
                targets.extend(scripts_)
                for m in range(len(scripts_)):
                    target_indices.append([k, m])
                inputs[k, 0, :, 0:seq_length] = spect_

        return inputs, input_length, np.array(target_indices, dtype=np.int64), np.array(targets, dtype=np.int32)

    def __len__(self):
        return self.size

class DistributedSampler():
    """
    function to distribute and shuffle sample
    """
    def __init__(self, dataset, rank, group_size, shuffle=True, seed=0):
        self.dataset = dataset
        self.rank = rank
        self.group_size = group_size
        self.dataset_len = len(self.dataset)
        self.num_samplers = int(math.ceil(self.dataset_len * 1.0 / self.group_size))
        self.total_size = self.num_samplers * self.group_size
        self.shuffle = shuffle
        self.seed = seed

    def __iter__(self):
        if self.shuffle:
            self.seed = (self.seed + 1) & 0xffffffff
            np.random.seed(self.seed)
            indices = np.random.permutation(self.dataset_len).tolist()
        else:
            indices = list(range(self.dataset_len))

        indices += indices[:(self.total_size - len(indices))]
        indices = indices[self.rank::self.group_size]
        return iter(indices)

    def __len__(self):
        return self.num_samplers


def create_dataset(audio_conf, manifest_filepath, labels, normalize, batch_size, train_mode=True,
                   rank=None, group_size=None):
    """
    create train dataset

    Args:
        audio_conf: Config containing the sample rate, window and the window length/stride in seconds
        manifest_filepath (str): manifest_file path.
        labels (list): list containing all the possible characters to map to
        normalize: Apply standard mean and deviation normalization to audio tensor
        train_mode (bool): Whether dataset is use for train or eval (default=True).
        batch_size (int): Dataset batch size
        rank (int): The shard ID within num_shards (default=None).
        group_size (int): Number of shards that the dataset should be divided into (default=None).

    Returns:
        Dataset.
    """

    dataset = ASRDataset(audio_conf=audio_conf, manifest_filepath=manifest_filepath, labels=labels, normalize=normalize,
                         batch_size=batch_size, is_training=train_mode)

    sampler = DistributedSampler(dataset, rank, group_size, shuffle=True)

    ds = de.GeneratorDataset(dataset, ["inputs", "input_length", "target_indices", "label_values"], sampler=sampler)
    ds = ds.repeat(1)
    return ds