import torch
import functools
import torch.nn as nn
import torch.nn.functional as F
from typing import Any, Dict, Optional, Tuple

from src.models.audio_jepa_module import AudioJEPAModule
from src.models.components.random_projection_quantizer import RandomProjectionQuantizer


class RQAJEPAModule(AudioJEPAModule):
    """
    RQA-JEPA Lightning Module.
    Extends AudioJEPAModule with Random Projection Quantization loss.

    Args:
        optimizer (torch.optim.Optimizer): Optimizer configuration.
        net (Dict[str, Any]): Configuration for sub-modules.
        warmup_pct (float): Percentage of total steps for warmup.
        final_lr_ratio (float): Ratio of final learning rate to initial learning rate.
        ema_decay (float): Initial EMA decay rate.
        ema_end_decay (float): Final EMA decay rate.
        ema_anneal_end_step (int): Step at which EMA decay reaches ema_end_decay.
        spectrogram_adjustment_mode (str): 'pad' or 'truncate' for spectrogram time dimension.
        jepa_criterion (torch.nn.Module): Loss function for JEPA (defaults to MSELoss).
        rq_criterion (torch.nn.Module): Loss function for RQ (defaults to CrossEntropyLoss).
        rq_lambda (float): Weight for JEPA loss (1 - rq_lambda is used for RQ loss).
        codebook_dim (int): Codebook dimension for RandomProjectionQuantizer.
        vocab_size (int): Vocabulary size for RandomProjectionQuantizer.
        rq_input_type (str): 'teacher' or 'spectrogram'. Source for quantization targets.
    """

    def __init__(
        self,
        optimizer: torch.optim.Optimizer,
        net: Dict[str, Any],
        warmup_pct: float = 0.1,
        final_lr_ratio: float = 0.001,
        ema_decay: float = 0.996,
        ema_end_decay: float = 1.0,
        ema_anneal_end_step: Optional[int] = None,
        spectrogram_adjustment_mode: str = "pad",
        jepa_criterion: Optional[torch.nn.Module] = None,
        rq_criterion: Optional[torch.nn.Module] = None,
        rq_lambda: float = 0.5,
        codebook_dim: int = 16,
        vocab_size: int = 8192,
        rq_input_type: str = "teacher",
    ):
        super().__init__(
            optimizer=optimizer,
            net=net,
            warmup_pct=warmup_pct,
            final_lr_ratio=final_lr_ratio,
            ema_decay=ema_decay,
            ema_end_decay=ema_end_decay,
            ema_anneal_end_step=ema_anneal_end_step,
            spectrogram_adjustment_mode=spectrogram_adjustment_mode,
            criterion=jepa_criterion,  # Pass jepa_criterion as criterion to base class
        )
        self.save_hyperparameters(
            logger=False, ignore=["jepa_criterion", "rq_criterion", "net", "optimizer"]
        )

        self.rq_lambda = rq_lambda
        # Store rq_criterion separately
        if rq_criterion is not None:
            self.rq_criterion = (
                rq_criterion()
                if isinstance(rq_criterion, (type, functools.partial))
                or callable(rq_criterion)
                and not isinstance(rq_criterion, nn.Module)
                else rq_criterion
            )
        else:
            self.rq_criterion = nn.CrossEntropyLoss()

        self.rq_input_type = rq_input_type
        if self.rq_input_type not in ["teacher", "spectrogram"]:
            raise ValueError(
                f"rq_input_type must be 'teacher' or 'spectrogram', got {self.rq_input_type}"
            )

        # Random Projection Quantizer
        # Determine input dimension for quantizer
        if self.rq_input_type == "teacher":
            # Input to quantizer is teacher output which has encoder_dim
            quantizer_input_dim = net.get("encoder", {}).get("embed_dim", 768)
        else:  # spectrogram
            # Input is raw patches
            # patch_embed is locally available on self
            patch_size = self.patch_embed.patch_size
            in_chans = self.patch_embed.in_chans
            quantizer_input_dim = patch_size[0] * patch_size[1] * in_chans

        self.quantizer = RandomProjectionQuantizer(
            input_dim=quantizer_input_dim, cb_dim=codebook_dim, cb_vocab=vocab_size
        )
        # Freeze quantizer (it is random and fixed)
        for p in self.quantizer.parameters():
            p.requires_grad = False

        # Projection head for RQ prediction
        # Takes predictor output (pred_dim) and predicts code indices (vocab_size)
        predictor_config = net.get("predictor", {})
        predictor_embed_dim = predictor_config.get("embed_dim", 768)
        self.rq_proj = nn.Linear(predictor_embed_dim, vocab_size)

    def _calculate_combined_loss(
        self,
        predictions_raw: torch.Tensor,
        teacher_targets: torch.Tensor,
        rq_logits: torch.Tensor,
        rq_targets: torch.Tensor,
    ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
        """
        Calculates both JEPA and RQ losses and combines them.
        """
        # --- JEPA Loss ---
        # Project back to encoder dimension for JEPA loss
        predictions_jepa = self.predictor_output_proj(
            predictions_raw
        )  # [B, N_mask, encoder_dim]

        jepa_loss = self.criterion(
            predictions_jepa, teacher_targets
        )  # Uses self.criterion (mapped from jepa_criterion)

        # --- RQ Loss ---
        # Calculate Scale RQ Loss
        # Flatten for loss calculation
        rq_loss = self.rq_criterion(
            rq_logits.reshape(-1, self.hparams.vocab_size), rq_targets.reshape(-1)
        )

        # --- Combine ---
        total_loss = self.rq_lambda * jepa_loss + (1 - self.rq_lambda) * rq_loss

        return total_loss, jepa_loss, rq_loss

    def _get_raw_patches(self, spec: torch.Tensor) -> torch.Tensor:
        """
        Extract raw key-value patches from spectrogram.

        Args:
             spec (torch.Tensor): Adjusted spectrogram [B, C, F, T].

        Returns:
             torch.Tensor: Flattened patches [B, N, patch_dim]
        """
        patch_size = self.patch_embed.patch_size  # (H, W)

        # Using kernel_size=patch_size, stride=patch_size ensures non-overlapping patches
        # F.unfold returns [B, C*pH*pW, L]
        patches = F.unfold(spec, kernel_size=patch_size, stride=patch_size)  # [B, D, N]
        patches = patches.transpose(1, 2)  # [B, N, D]

        return patches

    def _get_rq_targets_input(
        self, spec: torch.Tensor, teacher_full: torch.Tensor, mask_indices: torch.Tensor
    ) -> torch.Tensor:
        """
        Helper to get the input for the RQ quantizer (either teacher embeddings or raw patches).
        Only returns the targets for the MASKED locations.
        """
        if self.rq_input_type == "teacher":
            # Teacher targets at masked locations
            return teacher_full[:, mask_indices, :]  # [B, N_mask, encoder_dim]
        else:
            # Raw patches at masked locations
            # Check if spec is None, which implies logic error in caller
            if spec is None:
                raise ValueError(
                    "Spectrogram cannot be None when rq_input_type is 'spectrogram'"
                )
            raw_patches = self._get_raw_patches(spec)  # [B, N, patch_dim]
            return raw_patches[:, mask_indices, :]  # [B, N_mask, patch_dim]

    def training_step(self, batch: Dict[str, Any], batch_idx: int) -> torch.Tensor:
        waveform = batch["waveform"]

        patches, current_grid_size = self._process_audio(waveform)
        B, N, D = patches.shape

        mask = self.mask_generator(1, device=self.device, grid_size=current_grid_size)
        mask = mask.expand(B, -1)

        student_out = self.compute_student(patches, mask, current_grid_size)
        predictions_raw = self.compute_predictor(student_out, mask, current_grid_size)

        self._update_teacher()

        with torch.no_grad():
            teacher_full = self.teacher(patches, grid_size=current_grid_size)

        # Prepare targets and logits for RQA-JEPA
        m = mask[0]
        mask_indices = torch.nonzero(m).flatten()

        # Teacher targets always needed for JEPA loss
        teacher_targets = teacher_full[:, mask_indices, :]  # [B, N_mask, encoder_dim]

        # RQ Targets (Quantized)
        with torch.no_grad():
            # Need spec for 'spectrogram' mode
            spec = None
            if self.rq_input_type == "spectrogram":
                # Re-compute spectrogram as we don't have it exposed from _process_audio
                spec = self.spectrogram(waveform)
                spec = self._adjust_spectrogram(spec)

            rq_targets_input = self._get_rq_targets_input(
                spec, teacher_full, mask_indices
            )
            rq_targets = self.quantizer(rq_targets_input)  # [B, N_mask]

        # RQ Logits
        rq_logits = self.rq_proj(predictions_raw)  # [B, N_mask, vocab_size]

        loss, jepa_loss, rq_loss = self._calculate_combined_loss(
            predictions_raw, teacher_targets, rq_logits, rq_targets
        )

        self.log(
            "train/loss", loss, on_step=True, on_epoch=True, prog_bar=True, batch_size=B
        )
        self.log(
            "train/jepa_loss", jepa_loss, on_step=True, on_epoch=True, batch_size=B
        )
        self.log("train/rq_loss", rq_loss, on_step=True, on_epoch=True, batch_size=B)
        return loss

    def validation_step(self, batch: Dict[str, Any], batch_idx: int) -> torch.Tensor:
        waveform = batch["waveform"]

        patches, current_grid_size = self._process_audio(waveform)
        B, N, D = patches.shape

        mask = self.mask_generator(1, device=self.device, grid_size=current_grid_size)
        mask = mask.expand(B, -1)

        student_out = self.compute_student(patches, mask, current_grid_size)
        predictions_raw = self.compute_predictor(student_out, mask, current_grid_size)

        with torch.no_grad():
            teacher_full = self.teacher(patches, grid_size=current_grid_size)

            # Prepare targets and logits for RQA-JEPA
            m = mask[0]
            mask_indices = torch.nonzero(m).flatten()

            # Teacher targets at masked locations
            teacher_targets = teacher_full[
                :, mask_indices, :
            ]  # [B, N_mask, encoder_dim]

            # RQ Targets (Quantized)
            spec = None
            if self.rq_input_type == "spectrogram":
                spec = self.spectrogram(waveform)
                spec = self._adjust_spectrogram(spec)

            rq_targets_input = self._get_rq_targets_input(
                spec, teacher_full, mask_indices
            )
            rq_targets = self.quantizer(rq_targets_input)  # [B, N_mask]

            # RQ Logits
            rq_logits = self.rq_proj(predictions_raw)  # [B, N_mask, vocab_size]

            loss, jepa_loss, rq_loss = self._calculate_combined_loss(
                predictions_raw, teacher_targets, rq_logits, rq_targets
            )

        self.log(
            "val/loss", loss, on_step=False, on_epoch=True, prog_bar=True, batch_size=B
        )
        self.log("val/jepa_loss", jepa_loss, on_step=False, on_epoch=True, batch_size=B)
        self.log("val/rq_loss", rq_loss, on_step=False, on_epoch=True, batch_size=B)
        return loss