# Copyright (c) 2020, NVIDIA CORPORATION.  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.

import os
import shutil
import tempfile

import pytest
import torch
from lhotse import CutSet, MonoCut
from lhotse.testing.dummies import DummyManifest
from omegaconf import DictConfig

from nemo.collections.asr.data.audio_to_text_lhotse import LhotseSpeechToTextBpeDataset
from nemo.collections.asr.models import ASRModel
from nemo.collections.asr.models.rnnt_bpe_models import EncDecRNNTBPEModel
from nemo.collections.asr.parts.submodules import rnnt_beam_decoding as beam_decode
from nemo.collections.asr.parts.submodules import rnnt_greedy_decoding as greedy_decode
from nemo.collections.asr.parts.utils.rnnt_utils import Hypothesis
from nemo.collections.common import tokenizers
from nemo.core.utils import numba_utils
from nemo.core.utils.numba_utils import __NUMBA_MINIMUM_VERSION__

NUMBA_RNNT_LOSS_AVAILABLE = numba_utils.numba_cpu_is_supported(
    __NUMBA_MINIMUM_VERSION__
) or numba_utils.numba_cuda_is_supported(__NUMBA_MINIMUM_VERSION__)


@pytest.fixture()
def asr_model(test_data_dir):
    preprocessor = {'cls': 'nemo.collections.asr.modules.AudioToMelSpectrogramPreprocessor', 'params': dict({})}

    model_defaults = {'enc_hidden': 1024, 'pred_hidden': 64}

    encoder = {
        'cls': 'nemo.collections.asr.modules.ConvASREncoder',
        'params': {
            'feat_in': 64,
            'activation': 'relu',
            'conv_mask': True,
            'jasper': [
                {
                    'filters': model_defaults['enc_hidden'],
                    'repeat': 1,
                    'kernel': [1],
                    'stride': [1],
                    'dilation': [1],
                    'dropout': 0.0,
                    'residual': False,
                    'separable': True,
                    'se': True,
                    'se_context_size': -1,
                }
            ],
        },
    }

    decoder = {
        '_target_': 'nemo.collections.asr.modules.RNNTDecoder',
        'prednet': {
            'pred_hidden': model_defaults['pred_hidden'],
            'pred_rnn_layers': 1,
        },
    }

    joint = {
        '_target_': 'nemo.collections.asr.modules.RNNTJoint',
        'jointnet': {
            'joint_hidden': 32,
            'activation': 'relu',
        },
    }

    decoding = {'strategy': 'greedy_batch', 'greedy': {'max_symbols': 30}}

    tokenizer = {'dir': os.path.join(test_data_dir, "asr", "tokenizers", "an4_wpe_128"), 'type': 'wpe'}

    loss = {'loss_name': 'default', 'warprnnt_numba_kwargs': {'fastemit_lambda': 0.001}}

    modelConfig = DictConfig(
        {
            'preprocessor': DictConfig(preprocessor),
            'model_defaults': DictConfig(model_defaults),
            'encoder': DictConfig(encoder),
            'decoder': DictConfig(decoder),
            'joint': DictConfig(joint),
            'tokenizer': DictConfig(tokenizer),
            'decoding': DictConfig(decoding),
            'loss': DictConfig(loss),
        }
    )

    model_instance = EncDecRNNTBPEModel(cfg=modelConfig)
    return model_instance


class NestedRNNTModel(ASRModel):
    def __init__(self, cfg: DictConfig, trainer: 'Trainer' = None):
        super().__init__(cfg=cfg, trainer=trainer)

        if 'inner_model' in self.cfg:
            self.register_nemo_submodule(
                "inner_model", config_field="inner_model", model=EncDecRNNTBPEModel(self.cfg.inner_model)
            )
        else:
            # Restore a model from pretrained checkpoint
            self.register_nemo_submodule(
                "inner_model",
                config_field="inner_model",
                model=ASRModel.from_pretrained('stt_en_conformer_transducer_small', map_location='cpu'),
            )

        self.linear = torch.nn.Linear(
            self.inner_model.tokenizer.vocab_size + 1, self.inner_model.tokenizer.vocab_size + 1
        )
        self.inner_model.freeze()

    setup_training_data = lambda *args, **kwargs: None
    setup_validation_data = lambda *args, **kwargs: None
    transcribe = lambda *args, **kwargs: []


class TestEncDecRNNTBPEModel:
    @pytest.mark.skipif(
        not NUMBA_RNNT_LOSS_AVAILABLE,
        reason='RNNTLoss has not been compiled with appropriate numba version.',
    )
    @pytest.mark.with_downloads()
    @pytest.mark.unit
    def test_constructor(self, asr_model):
        asr_model.train()
        # TODO: make proper config and assert correct number of weights
        # Check to/from config_dict:
        confdict = asr_model.to_config_dict()
        instance2 = EncDecRNNTBPEModel.from_config_dict(confdict)
        assert isinstance(instance2, EncDecRNNTBPEModel)

    @pytest.mark.with_downloads()
    @pytest.mark.skipif(
        not NUMBA_RNNT_LOSS_AVAILABLE,
        reason='RNNTLoss has not been compiled with appropriate numba version.',
    )
    @pytest.mark.unit
    def test_forward(self, asr_model):
        asr_model = asr_model.eval()

        asr_model.preprocessor.featurizer.dither = 0.0
        asr_model.preprocessor.featurizer.pad_to = 0

        asr_model.compute_eval_loss = False

        input_signal = torch.randn(size=(4, 512))
        length = torch.randint(low=161, high=500, size=[4])

        with torch.no_grad():
            # batch size 1
            logprobs_instance = []
            for i in range(input_signal.size(0)):
                logprobs_ins, _ = asr_model.forward(
                    input_signal=input_signal[i : i + 1], input_signal_length=length[i : i + 1]
                )
                logprobs_instance.append(logprobs_ins)
            logits_instance = torch.cat(logprobs_instance, 0)

            # batch size 4
            logprobs_batch, _ = asr_model.forward(input_signal=input_signal, input_signal_length=length)

        assert logits_instance.shape == logprobs_batch.shape
        diff = torch.mean(torch.abs(logits_instance - logprobs_batch))
        assert diff <= 1e-6
        diff = torch.max(torch.abs(logits_instance - logprobs_batch))
        assert diff <= 1e-6

    @pytest.mark.unit
    def test_predict_step(self, asr_model):
        asr_model = asr_model.eval()
        cuts = DummyManifest(CutSet, begin_id=0, end_id=1, with_data=True)
        dataset = LhotseSpeechToTextBpeDataset(tokenizer=asr_model.tokenizer, return_cuts=True)
        batch = dataset[cuts]
        outputs = asr_model.predict_step(batch, 0)
        assert len(outputs) == 1
        assert len(outputs[0]) == 2
        assert isinstance(outputs[0][0], MonoCut)
        assert isinstance(outputs[0][1], Hypothesis)

    @pytest.mark.with_downloads()
    @pytest.mark.skipif(
        not NUMBA_RNNT_LOSS_AVAILABLE,
        reason='RNNTLoss has not been compiled with appropriate numba version.',
    )
    @pytest.mark.unit
    def test_save_restore_artifact(self, asr_model):
        asr_model.train()

        with tempfile.TemporaryDirectory() as tmp_dir:
            path = os.path.join(tmp_dir, 'rnnt_bpe.nemo')
            asr_model.save_to(path)

            new_model = EncDecRNNTBPEModel.restore_from(path)
            assert isinstance(new_model, type(asr_model))
            assert new_model.vocab_path.endswith('_vocab.txt')

            assert len(new_model.tokenizer.tokenizer.get_vocab()) == 128

    @pytest.mark.with_downloads()
    @pytest.mark.skipif(
        not NUMBA_RNNT_LOSS_AVAILABLE,
        reason='RNNTLoss has not been compiled with appropriate numba version.',
    )
    @pytest.mark.unit
    def test_save_restore_artifact_spe(self, asr_model, test_data_dir):
        asr_model.train()

        with tempfile.TemporaryDirectory() as tmpdir:
            tokenizer_dir = os.path.join(test_data_dir, "asr", "tokenizers", "an4_spe_128")
            asr_model.change_vocabulary(new_tokenizer_dir=tokenizer_dir, new_tokenizer_type='bpe')

            save_path = os.path.join(tmpdir, 'ctc_bpe.nemo')
            asr_model.train()
            asr_model.save_to(save_path)

            new_model = EncDecRNNTBPEModel.restore_from(save_path)
            assert isinstance(new_model, type(asr_model))
            assert isinstance(new_model.tokenizer, tokenizers.SentencePieceTokenizer)
            assert new_model.model_path.endswith('_tokenizer.model')
            assert new_model.vocab_path.endswith('_vocab.txt')
            assert new_model.spe_vocab_path.endswith('_tokenizer.vocab')

    @pytest.mark.with_downloads()
    @pytest.mark.unit
    def test_save_restore_artifact_agg(self, asr_model, test_data_dir):
        tokenizer_dir = os.path.join(test_data_dir, "asr", "tokenizers", "an4_spe_128")
        tok_en = {"dir": tokenizer_dir, "type": "wpe"}
        # the below is really an english tokenizer but we pretend it is spanish
        tok_es = {"dir": tokenizer_dir, "type": "wpe"}
        tcfg = DictConfig({"type": "agg", "langs": {"en": tok_en, "es": tok_es}})
        with tempfile.TemporaryDirectory() as tmpdir:
            asr_model.change_vocabulary(new_tokenizer_dir=tcfg, new_tokenizer_type="agg")

            save_path = os.path.join(tmpdir, "ctc_agg.nemo")
            asr_model.train()
            asr_model.save_to(save_path)

            new_model = EncDecRNNTBPEModel.restore_from(save_path)
            assert isinstance(new_model, type(asr_model))
            assert isinstance(new_model.tokenizer, tokenizers.AggregateTokenizer)

            # should be double
            assert new_model.tokenizer.tokenizer.vocab_size == 254
            assert len(new_model.tokenizer.tokenizer.get_vocab()) == 254

    @pytest.mark.with_downloads()
    @pytest.mark.skipif(
        not NUMBA_RNNT_LOSS_AVAILABLE,
        reason='RNNTLoss has not been compiled with appropriate numba version.',
    )
    @pytest.mark.unit
    def test_vocab_change(self, test_data_dir, asr_model):
        with tempfile.TemporaryDirectory() as tmpdir:
            old_tokenizer_dir = os.path.join(test_data_dir, "asr", "tokenizers", "an4_wpe_128", 'vocab.txt')
            new_tokenizer_dir = os.path.join(tmpdir, 'tokenizer')

            os.makedirs(new_tokenizer_dir, exist_ok=True)
            shutil.copy2(old_tokenizer_dir, new_tokenizer_dir)

            nw1 = asr_model.num_weights
            asr_model.change_vocabulary(new_tokenizer_dir=new_tokenizer_dir, new_tokenizer_type='wpe')
            # No change
            assert nw1 == asr_model.num_weights

            with open(os.path.join(new_tokenizer_dir, 'vocab.txt'), 'a+') as f:
                f.write("!\n")
                f.write('$\n')
                f.write('@\n')

            asr_model.change_vocabulary(new_tokenizer_dir=new_tokenizer_dir, new_tokenizer_type='wpe')

            # rnn embedding + joint + bias
            pred_embedding = 3 * (asr_model.decoder.pred_hidden)
            joint_joint = 3 * (asr_model.joint.joint_hidden + 1)
            assert asr_model.num_weights == (nw1 + (pred_embedding + joint_joint))

    @pytest.mark.with_downloads()
    @pytest.mark.skipif(
        not NUMBA_RNNT_LOSS_AVAILABLE,
        reason='RNNTLoss has not been compiled with appropriate numba version.',
    )
    @pytest.mark.unit
    def test_decoding_change(self, asr_model):
        assert isinstance(asr_model.decoding.decoding, greedy_decode.GreedyBatchedRNNTInfer)

        new_strategy = DictConfig({})
        new_strategy.strategy = 'greedy'
        new_strategy.greedy = DictConfig({'max_symbols': 10})
        asr_model.change_decoding_strategy(decoding_cfg=new_strategy)
        assert isinstance(asr_model.decoding.decoding, greedy_decode.GreedyRNNTInfer)

        new_strategy = DictConfig({})
        new_strategy.strategy = 'beam'
        new_strategy.beam = DictConfig({'beam_size': 1})
        asr_model.change_decoding_strategy(decoding_cfg=new_strategy)
        assert isinstance(asr_model.decoding.decoding, beam_decode.BeamRNNTInfer)
        assert asr_model.decoding.decoding.search_type == "default"

        new_strategy = DictConfig({})
        new_strategy.strategy = 'beam'
        new_strategy.beam = DictConfig({'beam_size': 2})
        asr_model.change_decoding_strategy(decoding_cfg=new_strategy)
        assert isinstance(asr_model.decoding.decoding, beam_decode.BeamRNNTInfer)
        assert asr_model.decoding.decoding.search_type == "default"

        new_strategy = DictConfig({})
        new_strategy.strategy = 'tsd'
        new_strategy.beam = DictConfig({'beam_size': 2})
        asr_model.change_decoding_strategy(decoding_cfg=new_strategy)
        assert isinstance(asr_model.decoding.decoding, beam_decode.BeamRNNTInfer)
        assert asr_model.decoding.decoding.search_type == "tsd"

        new_strategy = DictConfig({})
        new_strategy.strategy = 'alsd'
        new_strategy.beam = DictConfig({'beam_size': 2})
        asr_model.change_decoding_strategy(decoding_cfg=new_strategy)
        assert isinstance(asr_model.decoding.decoding, beam_decode.BeamRNNTInfer)
        assert asr_model.decoding.decoding.search_type == "alsd"

    @pytest.mark.with_downloads()
    @pytest.mark.unit
    @pytest.mark.skipif(
        not NUMBA_RNNT_LOSS_AVAILABLE,
        reason='RNNTLoss has not been compiled with appropriate numba version.',
    )
    def test_save_restore_nested_model(self):
        with tempfile.TemporaryDirectory() as tmp_dir:
            model = NestedRNNTModel(cfg=DictConfig({}), trainer=None)
            path = os.path.join(tmp_dir, 'rnnt_bpe.nemo')
            model.save_to(path)

            new_model = NestedRNNTModel.restore_from(path, map_location='cpu')
            assert model.__class__.__name__ == NestedRNNTModel.__name__
            assert new_model.__class__.__name__ == NestedRNNTModel.__name__
            assert isinstance(new_model, type(model))

            assert new_model.inner_model.vocab_path.endswith('_vocab.txt')
            assert len(new_model.inner_model.tokenizer.tokenizer.get_vocab()) == 1024

            # Unpack the nemo file
            NestedRNNTModel._save_restore_connector._unpack_nemo_file(path, tmp_dir)

            # Check size of the checkpoint, which contains weights from pretrained model + linear layer
            fp_weights = os.path.join(tmp_dir, 'model_weights.ckpt')
            assert os.path.getsize(fp_weights) > 50 * (2**20)  # Assert the weights are more than 50 MB

            # Check if param after restoration is exact match
            original_state_dict = model.inner_model.state_dict()
            new_state_dict = new_model.inner_model.state_dict()

            for (old_name, old_param), (new_name, new_param) in zip(
                original_state_dict.items(), new_state_dict.items()
            ):
                assert old_name == new_name
                assert (old_param - new_param).float().abs().mean() < 1e-6