# Copyright 2021 ASAPP Inc. and the HuggingFace Inc. team. 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.
"""PyTorch SEW model."""

import math

import torch
from torch import nn

from ... import initialization as init
from ...activations import ACT2FN
from ...integrations.deepspeed import is_deepspeed_zero3_enabled
from ...integrations.fsdp import is_fsdp_managed_module
from ...modeling_outputs import BaseModelOutput
from ...modeling_utils import PreTrainedModel
from ...utils import auto_docstring
from ..wav2vec2.modeling_wav2vec2 import (
    Wav2Vec2Attention,
    Wav2Vec2EncoderLayer,
    Wav2Vec2FeatureEncoder,
    Wav2Vec2FeedForward,
    Wav2Vec2ForCTC,
    Wav2Vec2ForSequenceClassification,
    Wav2Vec2GroupNormConvLayer,
    Wav2Vec2LayerNormConvLayer,
    Wav2Vec2NoLayerNormConvLayer,
    Wav2Vec2SamePadLayer,
    _compute_mask_indices,
)
from .configuration_sew import SEWConfig


_HIDDEN_STATES_START_POSITION = 1


class SEWNoLayerNormConvLayer(Wav2Vec2NoLayerNormConvLayer):
    pass


class SEWLayerNormConvLayer(Wav2Vec2LayerNormConvLayer):
    pass


class SEWGroupNormConvLayer(Wav2Vec2GroupNormConvLayer):
    pass


class SEWPositionalConvEmbedding(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.conv = nn.Conv1d(
            config.hidden_size,
            config.hidden_size,
            kernel_size=config.num_conv_pos_embeddings,
            padding=config.num_conv_pos_embeddings // 2,
            groups=config.num_conv_pos_embedding_groups,
            stride=config.squeeze_factor,
        )

        weight_norm = nn.utils.weight_norm
        if hasattr(nn.utils.parametrizations, "weight_norm"):
            weight_norm = nn.utils.parametrizations.weight_norm

        if is_deepspeed_zero3_enabled():
            import deepspeed

            with deepspeed.zero.GatheredParameters(self.conv.weight, modifier_rank=0):
                self.conv = weight_norm(self.conv, name="weight", dim=2)
            if hasattr(self.conv, "parametrizations"):
                weight_g = self.conv.parametrizations.weight.original0
                weight_v = self.conv.parametrizations.weight.original1
            else:
                weight_g = self.conv.weight_g
                weight_v = self.conv.weight_v
            deepspeed.zero.register_external_parameter(self, weight_v)
            deepspeed.zero.register_external_parameter(self, weight_g)
        else:
            self.conv = weight_norm(self.conv, name="weight", dim=2)

        self.padding = SEWSamePadLayer(config.num_conv_pos_embeddings)
        self.activation = ACT2FN[config.feat_extract_activation]

    def forward(self, hidden_states):
        hidden_states = self.conv(hidden_states)
        hidden_states = self.padding(hidden_states)
        hidden_states = self.activation(hidden_states)

        return hidden_states


class SEWSamePadLayer(Wav2Vec2SamePadLayer):
    pass


class SEWUpsampling(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.projection = nn.Linear(config.hidden_size, config.hidden_size * config.squeeze_factor)
        self.activation = ACT2FN[config.feat_extract_activation]
        self.squeeze_factor = config.squeeze_factor

    def forward(self, hidden_states):
        hidden_states = self.projection(hidden_states)
        hidden_states = self.activation(hidden_states)

        if self.squeeze_factor > 1:
            # transform embedding channels to sequence length
            bsz, src_len, src_embed_dim = hidden_states.size()
            tgt_len = src_len * self.squeeze_factor
            tgt_embed_dim = src_embed_dim // self.squeeze_factor
            hidden_states = hidden_states.reshape(bsz, src_len, self.squeeze_factor, tgt_embed_dim)
            hidden_states = hidden_states.reshape(bsz, tgt_len, tgt_embed_dim)

        return hidden_states


class SEWFeatureEncoder(Wav2Vec2FeatureEncoder):
    pass


class SEWAttention(Wav2Vec2Attention):
    pass


class SEWFeedForward(Wav2Vec2FeedForward):
    pass


class SEWEncoderLayer(Wav2Vec2EncoderLayer):
    pass


class SEWEncoder(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.config = config
        self.pos_conv_embed = SEWPositionalConvEmbedding(config)
        self.pool = nn.AvgPool1d(config.squeeze_factor, config.squeeze_factor)
        self.layer_norm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)
        self.dropout = nn.Dropout(config.hidden_dropout)
        self.layers = nn.ModuleList([SEWEncoderLayer(config) for _ in range(config.num_hidden_layers)])
        self.upsample = SEWUpsampling(config)
        self.gradient_checkpointing = False

    def forward(
        self,
        hidden_states,
        attention_mask=None,
        output_attentions=False,
        output_hidden_states=False,
        return_dict=True,
    ):
        all_hidden_states = () if output_hidden_states else None
        all_self_attentions = () if output_attentions else None

        if attention_mask is not None:
            expand_attention_mask = attention_mask.unsqueeze(-1).repeat(1, 1, hidden_states.shape[2])
            if self.config._attn_implementation == "flash_attention_2":
                # make sure padded tokens output 0
                hidden_states[~expand_attention_mask] = 0.0
                # 2d mask is passed through the layers
                attention_mask = attention_mask if (attention_mask is not None and 0 in attention_mask) else None
            else:
                # make sure padded tokens output 0
                hidden_states[~expand_attention_mask] = 0.0
                input_lengths = (attention_mask.long()).sum(-1)
                # apply pooling formula to get real output_lengths
                output_lengths = input_lengths // self.config.squeeze_factor
                max_encoder_length = hidden_states.shape[1] // self.config.squeeze_factor
                attention_ids = (
                    torch.arange(0, max_encoder_length, device=output_lengths.device)
                    .view(1, -1)
                    .expand(output_lengths.shape[0], -1)
                )
                attention_mask = (attention_ids < output_lengths.view(-1, 1)).long()

                # extend attention_mask
                attention_mask = 1.0 - attention_mask[:, None, None, :].to(dtype=hidden_states.dtype)
                attention_mask = attention_mask * torch.finfo(hidden_states.dtype).min
                attention_mask = attention_mask.expand(
                    attention_mask.shape[0], 1, attention_mask.shape[-1], attention_mask.shape[-1]
                )

        n_input_timesteps = hidden_states.shape[1]

        hidden_states = hidden_states.transpose(1, 2)
        position_embeddings = self.pos_conv_embed(hidden_states)
        pooled_hidden_states = self.pool(hidden_states)
        min_length = min(position_embeddings.size(-1), pooled_hidden_states.size(-1))
        hidden_states = pooled_hidden_states[..., :min_length] + position_embeddings[..., :min_length]
        hidden_states = hidden_states.transpose(1, 2)

        hidden_states = self.layer_norm(hidden_states)
        hidden_states = self.dropout(hidden_states)

        synced_gpus = is_deepspeed_zero3_enabled() or is_fsdp_managed_module(self)

        for layer in self.layers:
            if output_hidden_states:
                all_hidden_states = all_hidden_states + (hidden_states,)

            # add LayerDrop (see https://huggingface.co/papers/1909.11556 for description)
            dropout_probability = torch.rand([])

            skip_the_layer = self.training and dropout_probability < self.config.layerdrop
            if not skip_the_layer or synced_gpus:
                # under fsdp or deepspeed zero3 all gpus must run in sync
                layer_outputs = layer(
                    hidden_states, attention_mask=attention_mask, output_attentions=output_attentions
                )
                hidden_states = layer_outputs[0]

            if skip_the_layer:
                layer_outputs = (None, None)

            if output_attentions:
                all_self_attentions = all_self_attentions + (layer_outputs[1],)

        if output_hidden_states:
            all_hidden_states = all_hidden_states + (hidden_states,)

        hidden_states = self.upsample(hidden_states)
        if hidden_states.shape[1] < n_input_timesteps:
            hidden_states = nn.functional.pad(hidden_states, (0, 0, 0, n_input_timesteps - hidden_states.shape[1]))

        if not return_dict:
            return tuple(v for v in [hidden_states, all_hidden_states, all_self_attentions] if v is not None)
        return BaseModelOutput(
            last_hidden_state=hidden_states,
            hidden_states=all_hidden_states,
            attentions=all_self_attentions,
        )


@auto_docstring
class SEWPreTrainedModel(PreTrainedModel):
    config: SEWConfig
    base_model_prefix = "sew"
    main_input_name = "input_values"
    input_modalities = "audio"
    supports_gradient_checkpointing = True
    _supports_flash_attn = True
    _supports_sdpa = True
    _supports_flex_attn = False  # needs a proper look into the mask creation

    @torch.no_grad()
    def _init_weights(self, module):
        """Initialize the weights"""
        if isinstance(module, SEWPositionalConvEmbedding):
            init.normal_(
                module.conv.weight,
                mean=0,
                std=2 * math.sqrt(1 / (module.conv.kernel_size[0] * module.conv.in_channels)),
            )
            init.constant_(module.conv.bias, 0)
        elif isinstance(module, nn.Linear):
            init.normal_(module.weight, mean=0.0, std=self.config.initializer_range)
        elif isinstance(module, (nn.LayerNorm, nn.GroupNorm)):
            init.zeros_(module.bias)
            init.ones_(module.weight)
        elif isinstance(module, nn.Conv1d):
            if is_deepspeed_zero3_enabled():
                import deepspeed

                if hasattr(module, "weight_v") and hasattr(module, "weight_g"):
                    with deepspeed.zero.GatheredParameters([module.weight_v, module.weight_g], modifier_rank=0):
                        init.kaiming_normal_(module.weight)
                else:
                    with deepspeed.zero.GatheredParameters(module.weight, modifier_rank=0):
                        init.kaiming_normal_(module.weight)
            else:
                init.kaiming_normal_(module.weight)

        if isinstance(module, (nn.Linear, nn.Conv1d)) and module.bias is not None:
            init.zeros_(module.bias)

    def _get_feat_extract_output_lengths(self, input_lengths: torch.LongTensor | int):
        """
        Computes the output length of the convolutional layers
        """

        def _conv_out_length(input_length, kernel_size, stride):
            # 1D convolutional layer output length formula taken
            # from https://pytorch.org/docs/stable/generated/torch.nn.Conv1d.html
            return torch.div(input_length - kernel_size, stride, rounding_mode="floor") + 1

        for kernel_size, stride in zip(self.config.conv_kernel, self.config.conv_stride):
            input_lengths = _conv_out_length(input_lengths, kernel_size, stride)

        return input_lengths

    def _get_feature_vector_attention_mask(self, feature_vector_length: int, attention_mask: torch.LongTensor):
        output_lengths = self._get_feat_extract_output_lengths(attention_mask.sum(-1)).to(torch.long)
        batch_size = attention_mask.shape[0]

        attention_mask = torch.zeros(
            (batch_size, feature_vector_length), dtype=attention_mask.dtype, device=attention_mask.device
        )
        # these two operations makes sure that all values before the output lengths idxs are attended to
        attention_mask[(torch.arange(attention_mask.shape[0], device=attention_mask.device), output_lengths - 1)] = 1
        attention_mask = attention_mask.flip([-1]).cumsum(-1).flip([-1]).bool()
        return attention_mask


@auto_docstring
class SEWModel(SEWPreTrainedModel):
    def __init__(self, config: SEWConfig):
        super().__init__(config)
        self.config = config
        self.feature_extractor = SEWFeatureEncoder(config)
        self.layer_norm = nn.LayerNorm(config.conv_dim[-1], eps=config.layer_norm_eps)

        self.project_features = config.conv_dim[-1] != config.hidden_size
        if self.project_features:
            self.feature_projection = nn.Linear(config.conv_dim[-1], config.hidden_size)
        self.feature_dropout = nn.Dropout(config.feat_proj_dropout)

        if config.mask_time_prob > 0.0 or config.mask_feature_prob > 0.0:
            self.masked_spec_embed = nn.Parameter(torch.Tensor(config.hidden_size).uniform_())

        self.encoder = SEWEncoder(config)

        # Initialize weights and apply final processing
        self.post_init()

    # Copied from transformers.models.wav2vec2.modeling_wav2vec2.Wav2Vec2Model._mask_hidden_states
    def _mask_hidden_states(
        self,
        hidden_states: torch.FloatTensor,
        mask_time_indices: torch.FloatTensor | None = None,
        attention_mask: torch.LongTensor | None = None,
    ):
        """
        Masks extracted features along time axis and/or along feature axis according to
        [SpecAugment](https://huggingface.co/papers/1904.08779).
        """

        # `config.apply_spec_augment` can set masking to False
        if not getattr(self.config, "apply_spec_augment", True):
            return hidden_states

        # generate indices & apply SpecAugment along time axis
        batch_size, sequence_length, hidden_size = hidden_states.size()

        if mask_time_indices is not None:
            # apply SpecAugment along time axis with given mask_time_indices
            hidden_states[mask_time_indices] = self.masked_spec_embed.to(hidden_states.dtype)
        elif self.config.mask_time_prob > 0 and self.training:
            mask_time_indices = _compute_mask_indices(
                (batch_size, sequence_length),
                mask_prob=self.config.mask_time_prob,
                mask_length=self.config.mask_time_length,
                attention_mask=attention_mask,
                min_masks=self.config.mask_time_min_masks,
            )
            mask_time_indices = torch.tensor(mask_time_indices, device=hidden_states.device, dtype=torch.bool)
            hidden_states[mask_time_indices] = self.masked_spec_embed.to(hidden_states.dtype)

        if self.config.mask_feature_prob > 0 and self.training:
            # generate indices & apply SpecAugment along feature axis
            mask_feature_indices = _compute_mask_indices(
                (batch_size, hidden_size),
                mask_prob=self.config.mask_feature_prob,
                mask_length=self.config.mask_feature_length,
                min_masks=self.config.mask_feature_min_masks,
            )
            mask_feature_indices = torch.tensor(mask_feature_indices, device=hidden_states.device, dtype=torch.bool)
            mask_feature_indices = mask_feature_indices[:, None].expand(-1, sequence_length, -1)
            hidden_states[mask_feature_indices] = 0

        return hidden_states

    @auto_docstring
    def forward(
        self,
        input_values: torch.Tensor | None,
        attention_mask: torch.Tensor | None = None,
        mask_time_indices: torch.FloatTensor | None = None,
        output_attentions: bool | None = None,
        output_hidden_states: bool | None = None,
        return_dict: bool | None = None,
        **kwargs,
    ) -> tuple | BaseModelOutput:
        r"""
        mask_time_indices (`torch.BoolTensor` of shape `(batch_size, sequence_length)`, *optional*):
            Indices to mask extracted features for contrastive loss. When in training mode, model learns to predict
            masked extracted features in *config.proj_codevector_dim* space.
        """
        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        extract_features = self.feature_extractor(input_values)
        extract_features = extract_features.transpose(1, 2)
        extract_features = self.layer_norm(extract_features)

        if self.project_features:
            extract_features = self.feature_projection(extract_features)
        hidden_states = self.feature_dropout(extract_features)

        if attention_mask is not None:
            # compute reduced attention_mask corresponding to feature vectors
            attention_mask = self._get_feature_vector_attention_mask(hidden_states.shape[1], attention_mask)

        hidden_states = self._mask_hidden_states(hidden_states, mask_time_indices=mask_time_indices)

        encoder_outputs = self.encoder(
            hidden_states,
            attention_mask=attention_mask,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
        )

        hidden_states = encoder_outputs[0]

        if not return_dict:
            return (hidden_states,) + encoder_outputs[1:]

        return BaseModelOutput(
            last_hidden_state=hidden_states,
            hidden_states=encoder_outputs.hidden_states,
            attentions=encoder_outputs.attentions,
        )


class SEWForCTC(Wav2Vec2ForCTC):
    pass


class SEWForSequenceClassification(Wav2Vec2ForSequenceClassification):
    pass


__all__ = ["SEWForCTC", "SEWForSequenceClassification", "SEWModel", "SEWPreTrainedModel"]
