import math
from typing import Optional, Tuple, Union

import numpy as np
import torch
import torch.nn.functional as F
import torch.utils.checkpoint
from torch import nn
from torch.nn import CrossEntropyLoss

from transformers.modeling_outputs import (
    SequenceClassifierOutput
)
from transformers.modeling_utils import PreTrainedModel
from transformers.utils import (
    add_start_docstrings,
    add_start_docstrings_to_model_forward,
    logging,
    replace_return_docstrings,
)
from transformers.models.whisper.configuration_whisper import WhisperConfig
from transformers.models.whisper.generation_whisper import WhisperGenerationMixin
from transformers.models.whisper.modeling_whisper import WhisperPreTrainedModel, WHISPER_ENCODER_INPUTS_DOCSTRING, _CONFIG_FOR_DOC, WhisperEncoder

class ViSpeechClassification(WhisperPreTrainedModel):
    def __init__(self, config):
        super().__init__(config)

        self.encoder = WhisperEncoder(config)
        num_layers = config.num_hidden_layers + 1  # transformer layers + input embeddings
        self.projector = nn.Sequential(
            nn.Linear(self.encoder.config.hidden_size, 1024),
            nn.ReLU(),
            nn.Dropout(config.dropout),
            
            nn.Linear(1024, 512),
            nn.ReLU(),
            nn.Dropout(config.dropout),
            
            nn.Linear(512, config.classifier_proj_size),
            nn.ReLU(),
            nn.Dropout(config.dropout)
        )
        
        self.classifier = nn.Linear(config.classifier_proj_size, config.num_labels)
        self.config.use_weighted_layer_sum = False

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

    def freeze_encoder(self):
        """
        Calling this function will disable the gradient computation for the Whisper encoder so that its parameters will
        not be updated during training. Only the projection layers and classification head will be updated.
        """
        self.encoder._freeze_parameters()

    def get_input_embeddings(self) -> nn.Module:
        return self.encoder.get_input_embeddings()

    def set_input_embeddings(self, value: nn.Module):
        self.encoder.set_input_embeddings(value)

    @add_start_docstrings_to_model_forward(WHISPER_ENCODER_INPUTS_DOCSTRING)
    @replace_return_docstrings(output_type=SequenceClassifierOutput, config_class=_CONFIG_FOR_DOC)
    def forward(
        self,
        input_features: Optional[torch.LongTensor] = None,
        head_mask: Optional[torch.Tensor] = None,
        encoder_outputs: Optional[Tuple[Tuple[torch.FloatTensor]]] = None,
        labels: Optional[torch.LongTensor] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[Tuple[torch.Tensor], SequenceClassifierOutput]:
        r"""
        labels (`torch.LongTensor` of shape `(batch_size,)`, *optional*):
            Labels for computing the sequence classification/regression loss. Indices should be in `[0, ...,
            config.num_labels - 1]`. If `config.num_labels == 1` a regression loss is computed (Mean-Square loss), If
            `config.num_labels > 1` a classification loss is computed (Cross-Entropy).

        Returns:

        Example:

        ```python
        >>> import torch
        >>> from transformers import AutoFeatureExtractor, WhisperForAudioClassification
        >>> from datasets import load_dataset

        >>> feature_extractor = AutoFeatureExtractor.from_pretrained("sanchit-gandhi/whisper-medium-fleurs-lang-id")
        >>> model = WhisperForAudioClassification.from_pretrained("sanchit-gandhi/whisper-medium-fleurs-lang-id")

        >>> ds = load_dataset("google/fleurs", "all", split="validation", streaming=True)
        >>> sample = next(iter(ds))

        >>> inputs = feature_extractor(
        ...     sample["audio"]["array"], sampling_rate=sample["audio"]["sampling_rate"], return_tensors="pt"
        ... )
        >>> input_features = inputs.input_features

        >>> with torch.no_grad():
        ...     logits = model(input_features).logits

        >>> predicted_class_ids = torch.argmax(logits).item()
        >>> predicted_label = model.config.id2label[predicted_class_ids]
        >>> predicted_label
        'Afrikaans'
        ```"""

        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
        )
        if self.config.use_weighted_layer_sum:
            output_hidden_states = True
        elif output_hidden_states is None:
            output_hidden_states = self.config.output_hidden_states

        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        if encoder_outputs is None:
            encoder_outputs = self.encoder(
                input_features,
                head_mask=head_mask,
                output_attentions=output_attentions,
                output_hidden_states=output_hidden_states,
                return_dict=return_dict,
            )

        if self.config.use_weighted_layer_sum:
            hidden_states = encoder_outputs[_HIDDEN_STATES_START_POSITION]
            hidden_states = torch.stack(hidden_states, dim=1)
            norm_weights = nn.functional.softmax(self.layer_weights, dim=-1)
            hidden_states = (hidden_states * norm_weights.view(-1, 1, 1)).sum(dim=1)
        else:
            hidden_states = encoder_outputs[0]
        
        hidden_states = self.projector(hidden_states)
        pooled_output = hidden_states.mean(dim=1)

        logits = self.classifier(pooled_output)

        loss = None

        if labels is not None:
            loss_fct = CrossEntropyLoss()
            # move labels to correct device to enable PP
            labels = labels.to(logits.device)
            loss = loss_fct(logits.view(-1, self.config.num_labels), labels.view(-1))

        if not return_dict:
            output = (logits,) + encoder_outputs[1:]
            return ((loss,) + output) if loss is not None else output

        return SequenceClassifierOutput(
            loss=loss,
            logits=logits,
            hidden_states=encoder_outputs.hidden_states,
            attentions=encoder_outputs.attentions,
        )