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# Copyright 2025 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.

from typing import Callable, Optional, Union

import numpy as np
import torch
import torch.nn as nn

from transformers.utils.generic import OutputRecorder, check_model_inputs

from ...activations import ACT2FN
from ...cache_utils import Cache, DynamicCache, EncoderDecoderCache
from ...generation import GenerationMixin
from ...masking_utils import create_causal_mask
from ...modeling_attn_mask_utils import _prepare_4d_attention_mask, _prepare_4d_attention_mask_for_sdpa
from ...modeling_flash_attention_utils import FlashAttentionKwargs
from ...modeling_layers import GradientCheckpointingLayer
from ...modeling_outputs import (
    BaseModelOutput,
    BaseModelOutputWithPast,
    BaseModelOutputWithPastAndCrossAttentions,
    Seq2SeqLMOutput,
    Seq2SeqModelOutput,
)
from ...modeling_rope_utils import ROPE_INIT_FUNCTIONS, dynamic_rope_update
from ...modeling_utils import ALL_ATTENTION_FUNCTIONS, PreTrainedModel
from ...processing_utils import Unpack
from ...utils import TransformersKwargs, auto_docstring, can_return_tuple
from .configuration_moonshine import MoonshineConfig


class MoonshineEncoderMLP(nn.Module):
    def __init__(self, config, hidden_act):
        super().__init__()
        self.config = config
        self.activation_fn = ACT2FN[hidden_act]
        self.fc1 = nn.Linear(config.hidden_size, config.intermediate_size)
        self.fc2 = nn.Linear(config.intermediate_size, config.hidden_size)

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        hidden_states = self.fc1(hidden_states)
        hidden_states = self.activation_fn(hidden_states)
        hidden_states = self.fc2(hidden_states)
        return hidden_states


class MoonshineDecoderMLP(nn.Module):
    def __init__(self, config, hidden_act):
        super().__init__()
        self.config = config
        self.activation_fn = ACT2FN[hidden_act]
        self.fc1 = nn.Linear(config.hidden_size, config.intermediate_size * 2)
        self.fc2 = nn.Linear(config.intermediate_size, config.hidden_size)

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        hidden_states = self.fc1(hidden_states)
        hidden_states, gate = hidden_states.chunk(2, dim=-1)
        hidden_states = self.activation_fn(gate) * hidden_states
        hidden_states = self.fc2(hidden_states)
        return hidden_states


def repeat_kv(hidden_states: torch.Tensor, n_rep: int) -> torch.Tensor:
    """
    This is the equivalent of torch.repeat_interleave(x, dim=1, repeats=n_rep). The hidden states go from (batch,
    num_key_value_heads, seqlen, head_dim) to (batch, num_attention_heads, seqlen, head_dim)
    """
    batch, num_key_value_heads, slen, head_dim = hidden_states.shape
    if n_rep == 1:
        return hidden_states
    hidden_states = hidden_states[:, :, None, :, :].expand(batch, num_key_value_heads, n_rep, slen, head_dim)
    return hidden_states.reshape(batch, num_key_value_heads * n_rep, slen, head_dim)


def eager_attention_forward(
    module: nn.Module,
    query: torch.Tensor,
    key: torch.Tensor,
    value: torch.Tensor,
    attention_mask: Optional[torch.Tensor],
    scaling: float,
    dropout: float = 0.0,
    **kwargs: Unpack[TransformersKwargs],
):
    key_states = repeat_kv(key, module.num_key_value_groups)
    value_states = repeat_kv(value, module.num_key_value_groups)

    attn_weights = torch.matmul(query, key_states.transpose(2, 3)) * scaling
    if attention_mask is not None:
        causal_mask = attention_mask[:, :, :, : key_states.shape[-2]]
        attn_weights = attn_weights + causal_mask

    attn_weights = nn.functional.softmax(attn_weights, dim=-1, dtype=torch.float32).to(query.dtype)
    attn_weights = nn.functional.dropout(attn_weights, p=dropout, training=module.training)
    attn_output = torch.matmul(attn_weights, value_states)
    attn_output = attn_output.transpose(1, 2).contiguous()

    return attn_output, attn_weights


def rotate_half(x):
    """Rotates half the hidden dims of the input."""
    x1 = x[..., 0::2]
    x2 = x[..., 1::2]
    return torch.stack((-x2, x1), dim=-1).flatten(-2)


def apply_rotary_pos_emb(q, k, cos, sin, position_ids=None, unsqueeze_dim=1):
    """Applies Rotary Position Embedding to the query and key tensors.

    Args:
        q (`torch.Tensor`): The query tensor.
        k (`torch.Tensor`): The key tensor.
        cos (`torch.Tensor`): The cosine part of the rotary embedding.
        sin (`torch.Tensor`): The sine part of the rotary embedding.
        position_ids (`torch.Tensor`, *optional*):
            Deprecated and unused.
        unsqueeze_dim (`int`, *optional*, defaults to 1):
            The 'unsqueeze_dim' argument specifies the dimension along which to unsqueeze cos[position_ids] and
            sin[position_ids] so that they can be properly broadcasted to the dimensions of q and k. For example, note
            that cos[position_ids] and sin[position_ids] have the shape [batch_size, seq_len, head_dim]. Then, if q and
            k have the shape [batch_size, heads, seq_len, head_dim], then setting unsqueeze_dim=1 makes
            cos[position_ids] and sin[position_ids] broadcastable to the shapes of q and k. Similarly, if q and k have
            the shape [batch_size, seq_len, heads, head_dim], then set unsqueeze_dim=2.
    Returns:
        `tuple(torch.Tensor)` comprising of the query and key tensors rotated using the Rotary Position Embedding.
    """
    cos = cos.unsqueeze(unsqueeze_dim)
    sin = sin.unsqueeze(unsqueeze_dim)

    # Interleave them instead of usual shape
    cos = cos[..., : cos.shape[-1] // 2].repeat_interleave(2, dim=-1)
    sin = sin[..., : sin.shape[-1] // 2].repeat_interleave(2, dim=-1)

    # Keep half or full tensor for later concatenation
    rotary_dim = cos.shape[-1]
    q_rot, q_pass = q[..., :rotary_dim], q[..., rotary_dim:]
    k_rot, k_pass = k[..., :rotary_dim], k[..., rotary_dim:]

    # Apply rotary embeddings on the first half or full tensor
    q_embed = (q_rot * cos) + (rotate_half(q_rot) * sin)
    k_embed = (k_rot * cos) + (rotate_half(k_rot) * sin)

    # Concatenate back to full shape
    q_embed = torch.cat([q_embed, q_pass], dim=-1)
    k_embed = torch.cat([k_embed, k_pass], dim=-1)
    return q_embed, k_embed


class MoonshineAttention(nn.Module):
    """Multi-headed attention from 'Attention Is All You Need' paper"""

    def __init__(
        self,
        config: MoonshineConfig,
        layer_idx: int,
        is_causal: bool,
        num_attention_heads: int,
        num_key_value_heads: int,
    ):
        super().__init__()
        config.update({"num_attention_heads": num_attention_heads, "num_key_value_heads": num_key_value_heads})
        self.config = config
        self.layer_idx = layer_idx
        self.head_dim = getattr(config, "head_dim", config.hidden_size // config.num_attention_heads)
        self.num_key_value_groups = config.num_attention_heads // config.num_key_value_heads
        self.scaling = self.head_dim**-0.5
        self.attention_dropout = config.attention_dropout
        self.is_causal = is_causal

        self.q_proj = nn.Linear(
            config.hidden_size, config.num_attention_heads * self.head_dim, bias=config.attention_bias
        )
        self.k_proj = nn.Linear(
            config.hidden_size, config.num_key_value_heads * self.head_dim, bias=config.attention_bias
        )
        self.v_proj = nn.Linear(
            config.hidden_size, config.num_key_value_heads * self.head_dim, bias=config.attention_bias
        )
        self.o_proj = nn.Linear(config.num_attention_heads * self.head_dim, config.hidden_size, bias=False)

        # Pad head dimension to the next specified multiple.
        if self.config.pad_head_dim_to_multiple_of is not None:
            target_multiple = self.config.pad_head_dim_to_multiple_of
            target_head_dim = target_multiple * ((self.head_dim + target_multiple - 1) // target_multiple)
            self.head_dim_padding = target_head_dim - self.head_dim
        else:
            self.head_dim_padding = 0

    def forward(
        self,
        hidden_states: torch.Tensor,
        position_embeddings: Optional[tuple[torch.Tensor, torch.Tensor]] = None,
        attention_mask: Optional[torch.Tensor] = None,
        past_key_value: Optional[Cache] = None,
        cache_position: Optional[torch.LongTensor] = None,
        key_value_states: Optional[torch.Tensor] = None,
        **kwargs: Unpack[FlashAttentionKwargs],
    ) -> tuple[torch.Tensor, Optional[torch.Tensor], Optional[tuple[torch.Tensor]]]:
        bsz, q_len = hidden_states.shape[:-1]

        query_states = (
            self.q_proj(hidden_states).view(bsz, q_len, self.config.num_key_value_heads, self.head_dim).transpose(1, 2)
        )

        is_cross_attention = key_value_states is not None
        if past_key_value is not None:
            is_updated = past_key_value.is_updated.get(self.layer_idx)
            if is_cross_attention:
                # after the first generated id, we can subsequently re-use all key/value_states from cache
                past_key_value.is_updated[self.layer_idx] = True
                past_key_value = past_key_value.cross_attention_cache
            else:
                past_key_value = past_key_value.self_attention_cache

        # use key_value_states if cross attention
        current_states = key_value_states if key_value_states is not None else hidden_states
        if is_cross_attention and past_key_value and is_updated:
            key_states = past_key_value.layers[self.layer_idx].keys
            value_states = past_key_value.layers[self.layer_idx].values
        else:
            key_states = (
                self.k_proj(current_states)
                .view(bsz, -1, self.config.num_key_value_heads, self.head_dim)
                .transpose(1, 2)
            )
            value_states = (
                self.v_proj(current_states)
                .view(bsz, -1, self.config.num_key_value_heads, self.head_dim)
                .transpose(1, 2)
            )
            if is_cross_attention and past_key_value is not None:
                key_states, value_states = past_key_value.update(
                    key_states, value_states, self.layer_idx, {"cache_position": cache_position}
                )

        if not is_cross_attention:
            cos, sin = position_embeddings
            query_states, key_states = apply_rotary_pos_emb(query_states, key_states, cos, sin)

            if past_key_value is not None:
                cache_kwargs = {"sin": sin, "cos": cos, "cache_position": cache_position}
                key_states, value_states = past_key_value.update(
                    key_states, value_states, self.layer_idx, cache_kwargs
                )

        attention_interface: Callable = eager_attention_forward
        if self.config._attn_implementation != "eager":
            attention_interface = ALL_ATTENTION_FUNCTIONS[self.config._attn_implementation]

        is_causal = self.is_causal and attention_mask is None and q_len > 1

        if self.head_dim_padding > 0:
            query_states = torch.nn.functional.pad(query_states, (0, self.head_dim_padding))
            key_states = torch.nn.functional.pad(key_states, (0, self.head_dim_padding))
            value_states = torch.nn.functional.pad(value_states, (0, self.head_dim_padding))

        attn_output, attn_weights = attention_interface(
            self,
            query_states,
            key_states,
            value_states,
            attention_mask,
            dropout=0.0 if not self.training else self.attention_dropout,
            scaling=self.scaling,
            is_causal=is_causal,
            **kwargs,
        )

        if self.head_dim_padding > 0:
            attn_output = attn_output[..., : -self.head_dim_padding]

        attn_output = attn_output.reshape(bsz, q_len, -1).contiguous()
        attn_output = self.o_proj(attn_output)
        return attn_output, attn_weights


class MoonshineRotaryEmbedding(nn.Module):
    def __init__(self, config: MoonshineConfig, device=None):
        super().__init__()
        # BC: "rope_type" was originally "type"
        if hasattr(config, "rope_scaling") and isinstance(config.rope_scaling, dict):
            self.rope_type = config.rope_scaling.get("rope_type", config.rope_scaling.get("type"))
        else:
            self.rope_type = "default"
        self.max_seq_len_cached = config.max_position_embeddings
        self.original_max_seq_len = config.max_position_embeddings

        self.config = config
        self.rope_init_fn = ROPE_INIT_FUNCTIONS[self.rope_type]

        inv_freq, self.attention_scaling = self.rope_init_fn(self.config, device)
        self.register_buffer("inv_freq", inv_freq, persistent=False)
        self.original_inv_freq = self.inv_freq

    @torch.no_grad()
    @dynamic_rope_update  # power user: used with advanced RoPE types (e.g. dynamic rope)
    def forward(self, x, position_ids):
        inv_freq_expanded = self.inv_freq[None, :, None].float().expand(position_ids.shape[0], -1, 1).to(x.device)
        position_ids_expanded = position_ids[:, None, :].float()

        device_type = x.device.type if isinstance(x.device.type, str) and x.device.type != "mps" else "cpu"
        with torch.autocast(device_type=device_type, enabled=False):  # Force float32
            freqs = (inv_freq_expanded.float() @ position_ids_expanded.float()).transpose(1, 2)
            emb = torch.cat((freqs, freqs), dim=-1)
            cos = emb.cos() * self.attention_scaling
            sin = emb.sin() * self.attention_scaling

        return cos.to(dtype=x.dtype), sin.to(dtype=x.dtype)


class MoonshineEncoderLayer(GradientCheckpointingLayer):
    def __init__(self, config: MoonshineConfig, layer_idx: int):
        super().__init__()
        self.hidden_size = config.hidden_size

        self.self_attn = MoonshineAttention(
            config=config,
            layer_idx=layer_idx,
            is_causal=False,
            num_attention_heads=config.encoder_num_attention_heads,
            num_key_value_heads=config.encoder_num_key_value_heads,
        )

        self.mlp = MoonshineEncoderMLP(config, config.encoder_hidden_act)
        self.input_layernorm = nn.LayerNorm(config.hidden_size, bias=False)
        self.post_attention_layernorm = nn.LayerNorm(config.hidden_size, bias=False)

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.LongTensor] = None,
        past_key_value: Optional[Cache] = None,
        use_cache: Optional[bool] = False,
        cache_position: Optional[torch.LongTensor] = None,
        position_embeddings: Optional[tuple[torch.Tensor, torch.Tensor]] = None,  # necessary, but kept here for BC
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple[torch.Tensor]:
        residual = hidden_states
        hidden_states = self.input_layernorm(hidden_states)
        # Self Attention
        hidden_states, _ = self.self_attn(
            hidden_states=hidden_states,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_value=past_key_value,
            use_cache=use_cache,
            cache_position=cache_position,
            position_embeddings=position_embeddings,
            **kwargs,
        )
        hidden_states = residual + hidden_states

        # Fully Connected
        residual = hidden_states
        hidden_states = self.post_attention_layernorm(hidden_states)
        hidden_states = self.mlp(hidden_states)
        hidden_states = residual + hidden_states
        return hidden_states


class MoonshineDecoderLayer(GradientCheckpointingLayer):
    def __init__(self, config: MoonshineConfig, layer_idx: Optional[int] = None):
        super().__init__()
        self.hidden_size = config.hidden_size

        self.self_attn = MoonshineAttention(
            config=config,
            layer_idx=layer_idx,
            is_causal=True,
            num_attention_heads=config.decoder_num_attention_heads,
            num_key_value_heads=config.decoder_num_key_value_heads,
        )
        self.encoder_attn = MoonshineAttention(
            config=config,
            layer_idx=layer_idx,
            is_causal=False,
            num_attention_heads=config.decoder_num_attention_heads,
            num_key_value_heads=config.decoder_num_key_value_heads,
        )

        self.mlp = MoonshineDecoderMLP(config, config.decoder_hidden_act)
        self.input_layernorm = nn.LayerNorm(config.hidden_size, bias=False)
        self.post_attention_layernorm = nn.LayerNorm(config.hidden_size, bias=False)
        self.final_layernorm = nn.LayerNorm(config.hidden_size, bias=False)

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: Optional[torch.Tensor] = None,
        encoder_hidden_states: Optional[torch.Tensor] = None,
        encoder_attention_mask: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.LongTensor] = None,
        encoder_position_ids: Optional[torch.LongTensor] = None,
        past_key_value: Optional[Cache] = None,
        use_cache: Optional[bool] = False,
        cache_position: Optional[torch.LongTensor] = None,
        position_embeddings: Optional[tuple[torch.Tensor, torch.Tensor]] = None,
        encoder_position_embeddings: Optional[tuple[torch.Tensor, torch.Tensor]] = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple[torch.FloatTensor, Optional[tuple[torch.FloatTensor, torch.FloatTensor]]]:
        residual = hidden_states
        hidden_states = self.input_layernorm(hidden_states)

        hidden_states, _ = self.self_attn(
            hidden_states=hidden_states,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_value=past_key_value,
            use_cache=use_cache,
            cache_position=cache_position,
            position_embeddings=position_embeddings,
            **kwargs,
        )
        hidden_states = residual + hidden_states

        if encoder_hidden_states is not None:
            residual = hidden_states
            hidden_states = self.post_attention_layernorm(hidden_states)
            hidden_states, _ = self.encoder_attn(
                hidden_states=hidden_states,
                key_value_states=encoder_hidden_states,
                attention_mask=encoder_attention_mask,
                past_key_value=past_key_value,
                use_cache=use_cache,
            )
            hidden_states = residual + hidden_states

        residual = hidden_states
        hidden_states = self.final_layernorm(hidden_states)
        hidden_states = self.mlp(hidden_states)
        hidden_states = residual + hidden_states
        return hidden_states


@auto_docstring
class MoonshinePreTrainedModel(PreTrainedModel):
    config: MoonshineConfig
    base_model_prefix = "model"
    main_input_name = "input_values"
    supports_gradient_checkpointing = True
    _no_split_modules = ["MoonshineEncoderLayer", "MoonshineDecoderLayer"]
    _supports_flash_attn = True
    _supports_sdpa = True

    _can_compile_fullgraph = True
    # TODO arthur, how do we separate when it cross / self coming from different layer?

    def _get_feat_extract_output_lengths(self, input_lengths: torch.LongTensor):
        """
        Computes the output length of the convolutional layers
        """
        output_conv1_length = int((input_lengths - 127) / 64 + 1)
        output_conv2_length = int((output_conv1_length - 7) / 3 + 1)
        output_conv3_length = int((output_conv2_length - 3) / 2 + 1)

        return output_conv3_length


class MoonshineEncoder(MoonshinePreTrainedModel):
    """
    Transformer encoder consisting of *config.num_hidden_layers* layers. Each layer is a [`MoonshineEncoderLayer`]

    Args:
        config: MoonshineConfig
    """

    main_input_name = "input_values"
    _can_record_outputs = {
        "attentions": MoonshineAttention,
        "hidden_states": MoonshineEncoderLayer,
    }

    def __init__(self, config: MoonshineConfig):
        super().__init__(config)
        self.config = config
        embed_dim = config.hidden_size

        self.conv1 = nn.Conv1d(1, embed_dim, kernel_size=127, stride=64, bias=False)
        self.conv2 = nn.Conv1d(embed_dim, 2 * embed_dim, kernel_size=7, stride=3)
        self.conv3 = nn.Conv1d(2 * embed_dim, embed_dim, kernel_size=3, stride=2)
        self.groupnorm = nn.GroupNorm(num_groups=1, num_channels=embed_dim, eps=1e-5)
        self.rotary_emb = MoonshineRotaryEmbedding(config=config)

        self.layers = nn.ModuleList(
            [MoonshineEncoderLayer(config, idx) for idx in range(config.encoder_num_hidden_layers)]
        )
        self.layer_norm = nn.LayerNorm(embed_dim, bias=False)
        self.gradient_checkpointing = False
        self.post_init()

    def get_input_embeddings(self) -> nn.Module:
        return self.conv1

    def set_input_embeddings(self, value: nn.Module):
        self.conv1 = value

    @check_model_inputs
    def forward(
        self,
        input_values: torch.FloatTensor,
        attention_mask: Optional[torch.Tensor] = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> BaseModelOutputWithPast:
        r"""
        Args:
            input_values (`torch.FloatTensor` of shape `(batch_size, audio_length)`):
                Float values of the raw speech waveform. Raw speech waveform can be
                obtained by loading a `.flac` or `.wav` audio file into an array of type `list[float]`, a
                `numpy.ndarray` or a `torch.Tensor`, *e.g.* via the torchcodec libary (`pip install torchcodec`) or
                the soundfile library (`pip install soundfile`). To prepare the array into
                `input_values`, the [`AutoFeatureExtractor`] should be used for padding
                and conversion into a tensor of type `torch.FloatTensor`.
            attention_mask (`torch.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
                Mask to avoid performing attention on padding indices in `input_values`. Mask values selected in `[0, 1]`:
                - 1 for tokens that are **not masked**,
                - 0 for tokens that are **masked**.
                [What are attention masks?](../glossary#attention-mask)
        """
        input_values = input_values.unsqueeze(1)
        hidden_states = nn.functional.tanh(self.conv1(input_values))
        hidden_states = self.groupnorm(hidden_states)
        hidden_states = nn.functional.gelu(self.conv2(hidden_states))
        hidden_states = nn.functional.gelu(self.conv3(hidden_states))
        hidden_states = hidden_states.permute(0, 2, 1)

        # attention mask downsampling
        if attention_mask is not None:
            mask_len = self._get_feat_extract_output_lengths(attention_mask.shape[-1])
            downsample_stride = 64 * 3 * 2  # conv strides
            attention_mask = attention_mask[..., ::downsample_stride][..., :mask_len]
            if self.config._attn_implementation == "flash_attention_2":
                attention_mask = attention_mask if (attention_mask == 0.0).any() else None
            elif self.config._attn_implementation == "sdpa":
                attention_mask = _prepare_4d_attention_mask_for_sdpa(attention_mask, hidden_states.dtype)
            else:
                attention_mask = _prepare_4d_attention_mask(attention_mask, hidden_states.dtype)

        position_ids = torch.arange(0, hidden_states.shape[1], device=hidden_states.device).unsqueeze(0)
        position_embeddings = self.rotary_emb(hidden_states, position_ids)

        for encoder_layer in self.layers:
            hidden_states = encoder_layer(
                hidden_states,
                attention_mask=attention_mask,
                position_ids=position_ids,
                position_embeddings=position_embeddings,
                **kwargs,
            )

        hidden_states = self.layer_norm(hidden_states)

        return BaseModelOutputWithPast(
            last_hidden_state=hidden_states,
        )


@auto_docstring
class MoonshineDecoder(MoonshinePreTrainedModel):
    main_input_name = "input_ids"
    _can_record_outputs = {
        "attentions": OutputRecorder(MoonshineAttention, index=1, layer_name="self_attn"),
        "hidden_states": MoonshineDecoderLayer,
        "cross_attentions": OutputRecorder(MoonshineAttention, index=1, layer_name="encoder_attn"),
    }

    def __init__(self, config: MoonshineConfig):
        super().__init__(config)
        self.padding_idx = config.pad_token_id
        self.vocab_size = config.vocab_size

        self.embed_tokens = nn.Embedding(config.vocab_size, config.hidden_size, self.padding_idx)
        self.layers = nn.ModuleList(
            [MoonshineDecoderLayer(config, idx) for idx in range(config.decoder_num_hidden_layers)]
        )
        self.norm = nn.LayerNorm(config.hidden_size, bias=False)
        self.rotary_emb = MoonshineRotaryEmbedding(config=config)
        self.gradient_checkpointing = False

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

    @check_model_inputs
    def forward(
        self,
        input_ids: Optional[torch.LongTensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.LongTensor] = None,
        past_key_values: Optional[Cache] = None,
        inputs_embeds: Optional[torch.FloatTensor] = None,
        use_cache: Optional[bool] = None,
        cache_position: Optional[torch.LongTensor] = None,
        encoder_hidden_states: Optional[torch.FloatTensor] = None,
        encoder_attention_mask: Optional[torch.Tensor] = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> Union[tuple, BaseModelOutputWithPast]:
        r"""
        encoder_hidden_states (`torch.FloatTensor` of shape `(batch_size, encoder_sequence_length, hidden_size)`, *optional*):
            Sequence of hidden-states at the output of the last layer of the encoder. Used in the cross-attention
            of the decoder.
        encoder_attention_mask (`torch.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
            Mask to avoid performing attention on padding indices in `encoder_hidden_states`. Mask values selected in `[0, 1]`:
            - 1 for tokens that are **not masked**,
            - 0 for tokens that are **masked**.
            [What are attention masks?](../glossary#attention-mask)
        """
        if (input_ids is None) ^ (inputs_embeds is not None):
            raise ValueError("You must specify exactly one of input_ids or inputs_embeds")

        if inputs_embeds is None:
            inputs_embeds = self.embed_tokens(input_ids)

        if use_cache and past_key_values is None:
            self_attention_cache = DynamicCache()
            cross_attention_cache = DynamicCache()
            past_key_values = EncoderDecoderCache(self_attention_cache, cross_attention_cache)

        if cache_position is None:
            past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
            cache_position = torch.arange(
                past_seen_tokens, past_seen_tokens + inputs_embeds.shape[1], device=inputs_embeds.device
            )

        if position_ids is None:
            position_ids = cache_position.unsqueeze(0)

        causal_mask = create_causal_mask(
            config=self.config,
            input_embeds=inputs_embeds,
            attention_mask=attention_mask,
            cache_position=cache_position,
            past_key_values=past_key_values,
            position_ids=position_ids,
        )

        hidden_states = inputs_embeds
        position_embeddings = self.rotary_emb(hidden_states, position_ids)

        if encoder_attention_mask is not None:
            mask_len = encoder_hidden_states.shape[-2]
            downsample_stride = 64 * 3 * 2  # conv strides
            encoder_attention_mask = encoder_attention_mask[..., ::downsample_stride][..., :mask_len]
            if self.config._attn_implementation == "flash_attention_2":
                encoder_attention_mask = encoder_attention_mask if (encoder_attention_mask == 0.0).any() else None
            elif self.config._attn_implementation == "sdpa":
                encoder_attention_mask = _prepare_4d_attention_mask_for_sdpa(
                    encoder_attention_mask, hidden_states.dtype, hidden_states.shape[-2]
                )
            else:
                encoder_attention_mask = _prepare_4d_attention_mask(
                    encoder_attention_mask, hidden_states.dtype, hidden_states.shape[-2]
                )

        for decoder_layer in self.layers:
            hidden_states = decoder_layer(
                hidden_states,
                causal_mask,
                encoder_hidden_states,  # as a positional argument for gradient checkpointing
                encoder_attention_mask=encoder_attention_mask,
                position_ids=position_ids,
                past_key_value=past_key_values,
                use_cache=use_cache,
                cache_position=cache_position,
                position_embeddings=position_embeddings,
                **kwargs,
            )

        hidden_states = self.norm(hidden_states)

        return BaseModelOutputWithPastAndCrossAttentions(
            last_hidden_state=hidden_states,
            past_key_values=past_key_values if use_cache else None,
        )


def _compute_mask_indices(
    shape: tuple[int, int],
    mask_prob: float,
    mask_length: int,
    attention_mask: Optional[torch.LongTensor] = None,
    min_masks: int = 0,
) -> np.ndarray:
    """
    Computes random mask spans for a given shape. Used to implement [SpecAugment: A Simple Data Augmentation Method for
    ASR](https://huggingface.co/papers/1904.08779). Note that this method is not optimized to run on TPU and should be run on
    CPU as part of the preprocessing during training.

    Args:
        shape: The shape for which to compute masks. This should be of a tuple of size 2 where
               the first element is the batch size and the second element is the length of the axis to span.
        mask_prob:  The percentage of the whole axis (between 0 and 1) which will be masked. The number of
                    independently generated mask spans of length `mask_length` is computed by
                    `mask_prob*shape[1]/mask_length`. Note that due to overlaps, `mask_prob` is an upper bound and the
                    actual percentage will be smaller.
        mask_length: size of the mask
        min_masks: minimum number of masked spans
        attention_mask: A (right-padded) attention mask which independently shortens the feature axis of
                        each batch dimension.
    """
    batch_size, sequence_length = shape

    if mask_length < 1:
        raise ValueError("`mask_length` has to be bigger than 0.")

    if mask_length > sequence_length:
        raise ValueError(
            f"`mask_length` has to be smaller than `sequence_length`, but got `mask_length`: {mask_length}"
            f" and `sequence_length`: {sequence_length}`"
        )

    # epsilon is used for probabilistic rounding
    epsilon = np.random.rand(1).item()

    def compute_num_masked_span(input_length):
        """Given input length, compute how many spans should be masked"""
        num_masked_span = int(mask_prob * input_length / mask_length + epsilon)
        num_masked_span = max(num_masked_span, min_masks)

        # make sure num masked span <= sequence_length
        if num_masked_span * mask_length > sequence_length:
            num_masked_span = sequence_length // mask_length

        # make sure num_masked span is also <= input_length - (mask_length - 1)
        if input_length - (mask_length - 1) < num_masked_span:
            num_masked_span = max(input_length - (mask_length - 1), 0)

        return num_masked_span

    # compute number of masked spans in batch
    input_lengths = (
        attention_mask.detach().sum(-1).tolist()
        if attention_mask is not None
        else [sequence_length for _ in range(batch_size)]
    )

    # SpecAugment mask to fill
    spec_aug_mask = np.zeros((batch_size, sequence_length), dtype=bool)
    spec_aug_mask_idxs = []

    max_num_masked_span = compute_num_masked_span(sequence_length)

    if max_num_masked_span == 0:
        return spec_aug_mask

    for input_length in input_lengths:
        # compute num of masked spans for this input
        num_masked_span = compute_num_masked_span(input_length)

        # get random indices to mask
        spec_aug_mask_idx = np.random.choice(
            np.arange(input_length - (mask_length - 1)), num_masked_span, replace=False
        )

        # pick first sampled index that will serve as a dummy index to pad vector
        # to ensure same dimension for all batches due to probabilistic rounding
        # Picking first sample just pads those vectors twice.
        if len(spec_aug_mask_idx) == 0:
            # this case can only happen if `input_length` is strictly smaller then
            # `sequence_length` in which case the last token has to be a padding
            # token which we can use as a dummy mask id
            dummy_mask_idx = sequence_length - 1
        else:
            dummy_mask_idx = spec_aug_mask_idx[0]

        spec_aug_mask_idx = np.concatenate(
            [spec_aug_mask_idx, np.ones(max_num_masked_span - num_masked_span, dtype=np.int32) * dummy_mask_idx]
        )
        spec_aug_mask_idxs.append(spec_aug_mask_idx)

    spec_aug_mask_idxs = np.array(spec_aug_mask_idxs)

    # expand masked indices to masked spans
    spec_aug_mask_idxs = np.broadcast_to(
        spec_aug_mask_idxs[:, :, None], (batch_size, max_num_masked_span, mask_length)
    )
    spec_aug_mask_idxs = spec_aug_mask_idxs.reshape(batch_size, max_num_masked_span * mask_length)

    # add offset to the starting indexes so that indexes now create a span
    offsets = np.arange(mask_length)[None, None, :]
    offsets = np.broadcast_to(offsets, (batch_size, max_num_masked_span, mask_length)).reshape(
        batch_size, max_num_masked_span * mask_length
    )
    spec_aug_mask_idxs = spec_aug_mask_idxs + offsets

    # ensure that we cannot have indices larger than sequence_length
    if spec_aug_mask_idxs.max() > sequence_length - 1:
        spec_aug_mask_idxs[spec_aug_mask_idxs > sequence_length - 1] = sequence_length - 1

    # scatter indices to mask
    np.put_along_axis(spec_aug_mask, spec_aug_mask_idxs, 1, -1)

    return spec_aug_mask


@auto_docstring
class MoonshineModel(MoonshinePreTrainedModel):
    def __init__(self, config: MoonshineConfig):
        super().__init__(config)

        self.encoder = MoonshineEncoder(config)
        self.decoder = MoonshineDecoder(config)
        # Initialize weights and apply final processing
        self.post_init()

    def get_input_embeddings(self):
        return self.decoder.embed_tokens

    def set_input_embeddings(self, value):
        self.decoder.embed_tokens = value

    def get_encoder(self):
        return self.encoder

    def get_decoder(self):
        return self.decoder

    def freeze_encoder(self):
        """
        Calling this function will disable the gradient computation for the Moonshine encoder so that its parameters will
        not be updated during training.
        """
        self.encoder._freeze_parameters()

    def _mask_input_features(
        self,
        input_features: torch.FloatTensor,
        attention_mask: Optional[torch.LongTensor] = 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 input_features

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

        if self.config.mask_time_prob > 0 and self.training:
            # generate indices & apply SpecAugment along time axis
            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=input_features.device, dtype=torch.bool)
            mask_time_indices = mask_time_indices[:, None].expand(-1, hidden_size, -1)
            input_features[mask_time_indices] = 0

        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=input_features.device, dtype=torch.bool)
            input_features[mask_feature_indices] = 0

        return input_features

    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        input_values: Optional[torch.FloatTensor] = None,
        attention_mask: Optional[torch.LongTensor] = None,
        decoder_input_ids: Optional[torch.LongTensor] = None,
        decoder_attention_mask: Optional[torch.LongTensor] = None,
        encoder_outputs: Optional[tuple[tuple[torch.FloatTensor]]] = None,
        past_key_values: Optional[Union[EncoderDecoderCache, tuple[torch.FloatTensor]]] = None,
        decoder_inputs_embeds: Optional[tuple[torch.FloatTensor]] = None,
        decoder_position_ids: Optional[tuple[torch.LongTensor]] = None,
        use_cache: Optional[bool] = None,
        cache_position: Optional[torch.LongTensor] = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> Seq2SeqModelOutput:
        r"""
        input_values (`torch.FloatTensor` of shape `(batch_size, audio_length)`):
            Float values of the raw speech waveform. Raw speech waveform can be
            obtained by loading a `.flac` or `.wav` audio file into an array of type `list[float]`, a
            `numpy.ndarray` or a `torch.Tensor`, *e.g.* via the torchcodec libary (`pip install torchcodec`) or
            the soundfile library (`pip install soundfile`). To prepare the array into
            `input_values`, the [`AutoFeatureExtractor`] should be used for padding
            and conversion into a tensor of type `torch.FloatTensor`.
        decoder_position_ids (`torch.LongTensor` of shape `(batch_size, target_sequence_length)`):
            Indices of positions of each input sequence tokens in the position embeddings.
            Used to calculate the position embeddings up to `config.decoder_config.max_position_embeddings`

        Example:

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

        >>> model = MoonshineModel.from_pretrained("UsefulSensors/moonshine-tiny")
        >>> feature_extractor = AutoFeatureExtractor.from_pretrained("UsefulSensors/moonshine-tiny")
        >>> ds = load_dataset("hf-internal-testing/librispeech_asr_dummy", "clean", split="validation")
        >>> inputs = feature_extractor(ds[0]["audio"]["array"], return_tensors="pt")
        >>> input_values = inputs.input_values
        >>> decoder_input_ids = torch.tensor([[1, 1]]) * model.config.decoder_start_token_id
        >>> last_hidden_state = model(input_values, decoder_input_ids=decoder_input_ids).last_hidden_state
        >>> list(last_hidden_state.shape)
        [1, 2, 288]
        ```
        """
        if encoder_outputs is None:
            encoder_outputs: BaseModelOutput = self.encoder(input_values, attention_mask=attention_mask, **kwargs)

        decoder_outputs: BaseModelOutputWithPastAndCrossAttentions = self.decoder(
            input_ids=decoder_input_ids,
            attention_mask=decoder_attention_mask,
            encoder_attention_mask=attention_mask,
            encoder_hidden_states=encoder_outputs.last_hidden_state,
            past_key_values=past_key_values,
            inputs_embeds=decoder_inputs_embeds,
            position_ids=decoder_position_ids,
            use_cache=use_cache,
            cache_position=cache_position,
            **kwargs,
        )

        return Seq2SeqModelOutput(
            last_hidden_state=decoder_outputs.last_hidden_state,
            past_key_values=decoder_outputs.past_key_values,
            decoder_hidden_states=decoder_outputs.hidden_states,
            decoder_attentions=decoder_outputs.attentions,
            cross_attentions=decoder_outputs.cross_attentions,
            encoder_last_hidden_state=encoder_outputs.last_hidden_state,
            encoder_hidden_states=encoder_outputs.hidden_states,
            encoder_attentions=encoder_outputs.attentions,
        )


def shift_tokens_right(input_ids: torch.Tensor, pad_token_id: int, decoder_start_token_id: int):
    """
    Shift input ids one token to the right.
    """
    shifted_input_ids = input_ids.new_zeros(input_ids.shape)
    shifted_input_ids[:, 1:] = input_ids[:, :-1].clone()
    shifted_input_ids[:, 0] = decoder_start_token_id

    if pad_token_id is None:
        raise ValueError("self.model.config.pad_token_id has to be defined.")
    # replace possible -100 values in labels by `pad_token_id`
    shifted_input_ids.masked_fill_(shifted_input_ids == -100, pad_token_id)

    return shifted_input_ids


@auto_docstring(
    custom_intro="""
    The Moonshine Model with a language modeling head. Can be used for automatic speech recognition.
    """
)
class MoonshineForConditionalGeneration(MoonshinePreTrainedModel, GenerationMixin):
    _tied_weights_keys = ["proj_out.weight"]

    def __init__(self, config: MoonshineConfig):
        super().__init__(config)
        self.model = MoonshineModel(config)
        self.proj_out = nn.Linear(config.hidden_size, config.vocab_size, bias=False)

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

    def get_encoder(self):
        return self.model.get_encoder()

    def get_decoder(self):
        return self.model.get_decoder()

    def get_output_embeddings(self):
        return self.proj_out

    def set_output_embeddings(self, new_embeddings):
        self.proj_out = new_embeddings

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

    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        input_values: Optional[torch.FloatTensor] = None,
        attention_mask: Optional[torch.LongTensor] = None,
        decoder_input_ids: Optional[torch.LongTensor] = None,
        decoder_attention_mask: Optional[torch.LongTensor] = None,
        encoder_outputs: Optional[tuple[tuple[torch.FloatTensor]]] = None,
        past_key_values: Optional[Union[EncoderDecoderCache, tuple[torch.FloatTensor]]] = None,
        decoder_inputs_embeds: Optional[tuple[torch.FloatTensor]] = None,
        decoder_position_ids: Optional[tuple[torch.LongTensor]] = None,
        use_cache: Optional[bool] = None,
        cache_position: Optional[torch.LongTensor] = None,
        labels: Optional[torch.LongTensor] = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> Seq2SeqLMOutput:
        r"""
        input_values (`torch.FloatTensor` of shape `(batch_size, audio_length)`):
            Float values of the raw speech waveform. Raw speech waveform can be
            obtained by loading a `.flac` or `.wav` audio file into an array of type `list[float]`, a
            `numpy.ndarray` or a `torch.Tensor`, *e.g.* via the torchcodec libary (`pip install torchcodec`) or
            the soundfile library (`pip install soundfile`). To prepare the array into
            `input_values`, the [`AutoFeatureExtractor`] should be used for padding
            and conversion into a tensor of type `torch.FloatTensor`.
        decoder_position_ids (`torch.LongTensor` of shape `(batch_size, target_sequence_length)`):
            Indices of positions of each input sequence tokens in the position embeddings.
            Used to calculate the position embeddings up to `config.decoder_config.max_position_embeddings`

        Example:

        ```python
        >>> import torch
        >>> from transformers import AutoProcessor, MoonshineForConditionalGeneration
        >>> from datasets import load_dataset

        >>> processor = AutoProcessor.from_pretrained("UsefulSensors/moonshine-tiny")
        >>> model = MoonshineForConditionalGeneration.from_pretrained("UsefulSensors/moonshine-tiny")

        >>> ds = load_dataset("hf-internal-testing/librispeech_asr_dummy", "clean", split="validation")

        >>> inputs = processor(ds[0]["audio"]["array"], return_tensors="pt")
        >>> input_values = inputs.input_values

        >>> generated_ids = model.generate(input_values, max_new_tokens=100)

        >>> transcription = processor.batch_decode(generated_ids, skip_special_tokens=True)[0]
        >>> transcription
        'Mr. Quilter is the apostle of the middle classes, and we are glad to welcome his gospel.'
        ```"""

        if labels is not None:
            if decoder_input_ids is None and decoder_inputs_embeds is None:
                decoder_input_ids = shift_tokens_right(
                    labels, self.config.pad_token_id, self.config.decoder_start_token_id
                )

        outputs: Seq2SeqModelOutput = self.model(
            input_values,
            attention_mask=attention_mask,
            decoder_input_ids=decoder_input_ids,
            encoder_outputs=encoder_outputs,
            decoder_attention_mask=decoder_attention_mask,
            past_key_values=past_key_values,
            decoder_inputs_embeds=decoder_inputs_embeds,
            decoder_position_ids=decoder_position_ids,
            use_cache=use_cache,
            cache_position=cache_position,
            **kwargs,
        )
        logits = self.proj_out(outputs.last_hidden_state)

        loss = None
        if labels is not None:
            loss = self.loss_function(logits=logits, labels=labels, vocab_size=self.config.vocab_size)

        return Seq2SeqLMOutput(
            loss=loss,
            logits=logits,
            past_key_values=outputs.past_key_values,
            decoder_hidden_states=outputs.decoder_hidden_states,
            decoder_attentions=outputs.decoder_attentions,
            cross_attentions=outputs.cross_attentions,
            encoder_last_hidden_state=outputs.encoder_last_hidden_state,
            encoder_hidden_states=outputs.encoder_hidden_states,
            encoder_attentions=outputs.encoder_attentions,
        )


__all__ = ["MoonshineModel", "MoonshinePreTrainedModel", "MoonshineForConditionalGeneration"]