# coding=utf-8
# Copyright 2020 Microsoft and the Hugging Face Inc. team.
#
# 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 DeBERTa model."""

from typing import Optional, Union

import torch
from torch import nn
from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss

from ...activations import ACT2FN
from ...modeling_layers import GradientCheckpointingLayer
from ...modeling_outputs import (
    BaseModelOutput,
    MaskedLMOutput,
    QuestionAnsweringModelOutput,
    SequenceClassifierOutput,
    TokenClassifierOutput,
)
from ...modeling_utils import PreTrainedModel
from ...utils import auto_docstring, logging
from .configuration_deberta import DebertaConfig


logger = logging.get_logger(__name__)


class DebertaLayerNorm(nn.Module):
    """LayerNorm module in the TF style (epsilon inside the square root)."""

    def __init__(self, size, eps=1e-12):
        super().__init__()
        self.weight = nn.Parameter(torch.ones(size))
        self.bias = nn.Parameter(torch.zeros(size))
        self.variance_epsilon = eps

    def forward(self, hidden_states):
        input_type = hidden_states.dtype
        hidden_states = hidden_states.float()
        mean = hidden_states.mean(-1, keepdim=True)
        variance = (hidden_states - mean).pow(2).mean(-1, keepdim=True)
        hidden_states = (hidden_states - mean) / torch.sqrt(variance + self.variance_epsilon)
        hidden_states = hidden_states.to(input_type)
        y = self.weight * hidden_states + self.bias
        return y


class DebertaSelfOutput(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.hidden_size, config.hidden_size)
        self.LayerNorm = DebertaLayerNorm(config.hidden_size, config.layer_norm_eps)
        self.dropout = nn.Dropout(config.hidden_dropout_prob)

    def forward(self, hidden_states, input_tensor):
        hidden_states = self.dense(hidden_states)
        hidden_states = self.dropout(hidden_states)
        hidden_states = self.LayerNorm(hidden_states + input_tensor)
        return hidden_states


@torch.jit.script
def build_relative_position(query_layer, key_layer):
    """
    Build relative position according to the query and key

    We assume the absolute position of query \\(P_q\\) is range from (0, query_size) and the absolute position of key
    \\(P_k\\) is range from (0, key_size), The relative positions from query to key is \\(R_{q \\rightarrow k} = P_q -
    P_k\\)

    Args:
        query_size (int): the length of query
        key_size (int): the length of key

    Return:
        `torch.LongTensor`: A tensor with shape [1, query_size, key_size]

    """

    query_size = query_layer.size(-2)
    key_size = key_layer.size(-2)

    q_ids = torch.arange(query_size, dtype=torch.long, device=query_layer.device)
    k_ids = torch.arange(key_size, dtype=torch.long, device=key_layer.device)
    rel_pos_ids = q_ids[:, None] - k_ids.view(1, -1).repeat(query_size, 1)
    rel_pos_ids = rel_pos_ids[:query_size, :]
    rel_pos_ids = rel_pos_ids.unsqueeze(0)
    return rel_pos_ids


@torch.jit.script
def c2p_dynamic_expand(c2p_pos, query_layer, relative_pos):
    return c2p_pos.expand([query_layer.size(0), query_layer.size(1), query_layer.size(2), relative_pos.size(-1)])


@torch.jit.script
def p2c_dynamic_expand(c2p_pos, query_layer, key_layer):
    return c2p_pos.expand([query_layer.size(0), query_layer.size(1), key_layer.size(-2), key_layer.size(-2)])


@torch.jit.script
def pos_dynamic_expand(pos_index, p2c_att, key_layer):
    return pos_index.expand(p2c_att.size()[:2] + (pos_index.size(-2), key_layer.size(-2)))


###### To support a general trace, we have to define these operation as they use python objects (sizes) ##################
# which are not supported by torch.jit.trace.
# Full credits to @Szustarol
@torch.jit.script
def scaled_size_sqrt(query_layer: torch.Tensor, scale_factor: int):
    return torch.sqrt(torch.tensor(query_layer.size(-1), dtype=torch.float) * scale_factor)


@torch.jit.script
def build_rpos(query_layer: torch.Tensor, key_layer: torch.Tensor, relative_pos):
    if query_layer.size(-2) != key_layer.size(-2):
        return build_relative_position(query_layer, key_layer)
    else:
        return relative_pos


@torch.jit.script
def compute_attention_span(query_layer: torch.Tensor, key_layer: torch.Tensor, max_relative_positions: int):
    return torch.tensor(min(max(query_layer.size(-2), key_layer.size(-2)), max_relative_positions))


@torch.jit.script
def uneven_size_corrected(p2c_att, query_layer: torch.Tensor, key_layer: torch.Tensor, relative_pos):
    if query_layer.size(-2) != key_layer.size(-2):
        pos_index = relative_pos[:, :, :, 0].unsqueeze(-1)
        return torch.gather(p2c_att, dim=2, index=pos_dynamic_expand(pos_index, p2c_att, key_layer))
    else:
        return p2c_att


########################################################################################################################


class DisentangledSelfAttention(nn.Module):
    """
    Disentangled self-attention module

    Parameters:
        config (`str`):
            A model config class instance with the configuration to build a new model. The schema is similar to
            *BertConfig*, for more details, please refer [`DebertaConfig`]

    """

    def __init__(self, config):
        super().__init__()
        if config.hidden_size % config.num_attention_heads != 0:
            raise ValueError(
                f"The hidden size ({config.hidden_size}) is not a multiple of the number of attention "
                f"heads ({config.num_attention_heads})"
            )
        self.num_attention_heads = config.num_attention_heads
        self.attention_head_size = int(config.hidden_size / config.num_attention_heads)
        self.all_head_size = self.num_attention_heads * self.attention_head_size
        self.in_proj = nn.Linear(config.hidden_size, self.all_head_size * 3, bias=False)
        self.q_bias = nn.Parameter(torch.zeros((self.all_head_size), dtype=torch.float))
        self.v_bias = nn.Parameter(torch.zeros((self.all_head_size), dtype=torch.float))
        self.pos_att_type = config.pos_att_type if config.pos_att_type is not None else []

        self.relative_attention = getattr(config, "relative_attention", False)
        self.talking_head = getattr(config, "talking_head", False)

        if self.talking_head:
            self.head_logits_proj = nn.Linear(config.num_attention_heads, config.num_attention_heads, bias=False)
            self.head_weights_proj = nn.Linear(config.num_attention_heads, config.num_attention_heads, bias=False)
        else:
            self.head_logits_proj = None
            self.head_weights_proj = None

        if self.relative_attention:
            self.max_relative_positions = getattr(config, "max_relative_positions", -1)
            if self.max_relative_positions < 1:
                self.max_relative_positions = config.max_position_embeddings
            self.pos_dropout = nn.Dropout(config.hidden_dropout_prob)

            if "c2p" in self.pos_att_type:
                self.pos_proj = nn.Linear(config.hidden_size, self.all_head_size, bias=False)
            if "p2c" in self.pos_att_type:
                self.pos_q_proj = nn.Linear(config.hidden_size, self.all_head_size)

        self.dropout = nn.Dropout(config.attention_probs_dropout_prob)

    def transpose_for_scores(self, x):
        new_x_shape = x.size()[:-1] + (self.num_attention_heads, -1)
        x = x.view(new_x_shape)
        return x.permute(0, 2, 1, 3)

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor,
        output_attentions: bool = False,
        query_states: Optional[torch.Tensor] = None,
        relative_pos: Optional[torch.Tensor] = None,
        rel_embeddings: Optional[torch.Tensor] = None,
    ) -> tuple[torch.Tensor, Optional[torch.Tensor]]:
        """
        Call the module

        Args:
            hidden_states (`torch.FloatTensor`):
                Input states to the module usually the output from previous layer, it will be the Q,K and V in
                *Attention(Q,K,V)*

            attention_mask (`torch.BoolTensor`):
                An attention mask matrix of shape [*B*, *N*, *N*] where *B* is the batch size, *N* is the maximum
                sequence length in which element [i,j] = *1* means the *i* th token in the input can attend to the *j*
                th token.

            output_attentions (`bool`, *optional*):
                Whether return the attention matrix.

            query_states (`torch.FloatTensor`, *optional*):
                The *Q* state in *Attention(Q,K,V)*.

            relative_pos (`torch.LongTensor`):
                The relative position encoding between the tokens in the sequence. It's of shape [*B*, *N*, *N*] with
                values ranging in [*-max_relative_positions*, *max_relative_positions*].

            rel_embeddings (`torch.FloatTensor`):
                The embedding of relative distances. It's a tensor of shape [\\(2 \\times
                \\text{max_relative_positions}\\), *hidden_size*].


        """
        if query_states is None:
            qp = self.in_proj(hidden_states)  # .split(self.all_head_size, dim=-1)
            query_layer, key_layer, value_layer = self.transpose_for_scores(qp).chunk(3, dim=-1)
        else:
            ws = self.in_proj.weight.chunk(self.num_attention_heads * 3, dim=0)
            qkvw = [torch.cat([ws[i * 3 + k] for i in range(self.num_attention_heads)], dim=0) for k in range(3)]
            q = torch.matmul(qkvw[0], query_states.t().to(dtype=qkvw[0].dtype))
            k = torch.matmul(qkvw[1], hidden_states.t().to(dtype=qkvw[1].dtype))
            v = torch.matmul(qkvw[2], hidden_states.t().to(dtype=qkvw[2].dtype))
            query_layer, key_layer, value_layer = [self.transpose_for_scores(x) for x in [q, k, v]]

        query_layer = query_layer + self.transpose_for_scores(self.q_bias[None, None, :])
        value_layer = value_layer + self.transpose_for_scores(self.v_bias[None, None, :])

        rel_att: int = 0
        # Take the dot product between "query" and "key" to get the raw attention scores.
        scale_factor = 1 + len(self.pos_att_type)
        scale = scaled_size_sqrt(query_layer, scale_factor)
        query_layer = query_layer / scale.to(dtype=query_layer.dtype)
        attention_scores = torch.matmul(query_layer, key_layer.transpose(-1, -2))

        if self.relative_attention and rel_embeddings is not None and relative_pos is not None:
            rel_embeddings = self.pos_dropout(rel_embeddings)
            rel_att = self.disentangled_att_bias(query_layer, key_layer, relative_pos, rel_embeddings, scale_factor)

        if rel_att is not None:
            attention_scores = attention_scores + rel_att

        # bxhxlxd
        if self.head_logits_proj is not None:
            attention_scores = self.head_logits_proj(attention_scores.permute(0, 2, 3, 1)).permute(0, 3, 1, 2)

        attention_mask = attention_mask.bool()
        attention_scores = attention_scores.masked_fill(~(attention_mask), torch.finfo(query_layer.dtype).min)
        # bsz x height x length x dimension
        attention_probs = nn.functional.softmax(attention_scores, dim=-1)

        attention_probs = self.dropout(attention_probs)
        if self.head_weights_proj is not None:
            attention_probs = self.head_weights_proj(attention_probs.permute(0, 2, 3, 1)).permute(0, 3, 1, 2)

        context_layer = torch.matmul(attention_probs, value_layer)
        context_layer = context_layer.permute(0, 2, 1, 3).contiguous()
        new_context_layer_shape = context_layer.size()[:-2] + (-1,)
        context_layer = context_layer.view(new_context_layer_shape)
        if not output_attentions:
            return (context_layer, None)
        return (context_layer, attention_probs)

    def disentangled_att_bias(
        self,
        query_layer: torch.Tensor,
        key_layer: torch.Tensor,
        relative_pos: torch.Tensor,
        rel_embeddings: torch.Tensor,
        scale_factor: int,
    ):
        if relative_pos is None:
            relative_pos = build_relative_position(query_layer, key_layer, query_layer.device)
        if relative_pos.dim() == 2:
            relative_pos = relative_pos.unsqueeze(0).unsqueeze(0)
        elif relative_pos.dim() == 3:
            relative_pos = relative_pos.unsqueeze(1)
        # bxhxqxk
        elif relative_pos.dim() != 4:
            raise ValueError(f"Relative position ids must be of dim 2 or 3 or 4. {relative_pos.dim()}")

        att_span = compute_attention_span(query_layer, key_layer, self.max_relative_positions)
        relative_pos = relative_pos.long()
        rel_embeddings = rel_embeddings[
            self.max_relative_positions - att_span : self.max_relative_positions + att_span, :
        ].unsqueeze(0)

        score = 0

        # content->position
        if "c2p" in self.pos_att_type:
            pos_key_layer = self.pos_proj(rel_embeddings)
            pos_key_layer = self.transpose_for_scores(pos_key_layer)
            c2p_att = torch.matmul(query_layer, pos_key_layer.transpose(-1, -2))
            c2p_pos = torch.clamp(relative_pos + att_span, 0, att_span * 2 - 1)
            c2p_att = torch.gather(c2p_att, dim=-1, index=c2p_dynamic_expand(c2p_pos, query_layer, relative_pos))
            score += c2p_att

        # position->content
        if "p2c" in self.pos_att_type:
            pos_query_layer = self.pos_q_proj(rel_embeddings)
            pos_query_layer = self.transpose_for_scores(pos_query_layer)
            pos_query_layer /= scaled_size_sqrt(pos_query_layer, scale_factor)
            r_pos = build_rpos(
                query_layer,
                key_layer,
                relative_pos,
            )
            p2c_pos = torch.clamp(-r_pos + att_span, 0, att_span * 2 - 1)
            p2c_att = torch.matmul(key_layer, pos_query_layer.transpose(-1, -2).to(dtype=key_layer.dtype))
            p2c_att = torch.gather(
                p2c_att, dim=-1, index=p2c_dynamic_expand(p2c_pos, query_layer, key_layer)
            ).transpose(-1, -2)

            p2c_att = uneven_size_corrected(p2c_att, query_layer, key_layer, relative_pos)
            score += p2c_att

        return score


class DebertaEmbeddings(nn.Module):
    """Construct the embeddings from word, position and token_type embeddings."""

    def __init__(self, config):
        super().__init__()
        pad_token_id = getattr(config, "pad_token_id", 0)
        self.embedding_size = getattr(config, "embedding_size", config.hidden_size)
        self.word_embeddings = nn.Embedding(config.vocab_size, self.embedding_size, padding_idx=pad_token_id)

        self.position_biased_input = getattr(config, "position_biased_input", True)
        if not self.position_biased_input:
            self.position_embeddings = None
        else:
            self.position_embeddings = nn.Embedding(config.max_position_embeddings, self.embedding_size)

        if config.type_vocab_size > 0:
            self.token_type_embeddings = nn.Embedding(config.type_vocab_size, self.embedding_size)
        else:
            self.token_type_embeddings = None

        if self.embedding_size != config.hidden_size:
            self.embed_proj = nn.Linear(self.embedding_size, config.hidden_size, bias=False)
        else:
            self.embed_proj = None

        self.LayerNorm = DebertaLayerNorm(config.hidden_size, config.layer_norm_eps)
        self.dropout = nn.Dropout(config.hidden_dropout_prob)
        self.config = config

        # position_ids (1, len position emb) is contiguous in memory and exported when serialized
        self.register_buffer(
            "position_ids", torch.arange(config.max_position_embeddings).expand((1, -1)), persistent=False
        )

    def forward(self, input_ids=None, token_type_ids=None, position_ids=None, mask=None, inputs_embeds=None):
        if input_ids is not None:
            input_shape = input_ids.size()
        else:
            input_shape = inputs_embeds.size()[:-1]

        seq_length = input_shape[1]

        if position_ids is None:
            position_ids = self.position_ids[:, :seq_length]

        if token_type_ids is None:
            token_type_ids = torch.zeros(input_shape, dtype=torch.long, device=self.position_ids.device)

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

        if self.position_embeddings is not None:
            position_embeddings = self.position_embeddings(position_ids.long())
        else:
            position_embeddings = torch.zeros_like(inputs_embeds)

        embeddings = inputs_embeds
        if self.position_biased_input:
            embeddings = embeddings + position_embeddings
        if self.token_type_embeddings is not None:
            token_type_embeddings = self.token_type_embeddings(token_type_ids)
            embeddings = embeddings + token_type_embeddings

        if self.embed_proj is not None:
            embeddings = self.embed_proj(embeddings)

        embeddings = self.LayerNorm(embeddings)

        if mask is not None:
            if mask.dim() != embeddings.dim():
                if mask.dim() == 4:
                    mask = mask.squeeze(1).squeeze(1)
                mask = mask.unsqueeze(2)
            mask = mask.to(embeddings.dtype)

            embeddings = embeddings * mask

        embeddings = self.dropout(embeddings)
        return embeddings


class DebertaAttention(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.self = DisentangledSelfAttention(config)
        self.output = DebertaSelfOutput(config)
        self.config = config

    def forward(
        self,
        hidden_states,
        attention_mask,
        output_attentions: bool = False,
        query_states=None,
        relative_pos=None,
        rel_embeddings=None,
    ) -> tuple[torch.Tensor, Optional[torch.Tensor]]:
        self_output, att_matrix = self.self(
            hidden_states,
            attention_mask,
            output_attentions,
            query_states=query_states,
            relative_pos=relative_pos,
            rel_embeddings=rel_embeddings,
        )
        if query_states is None:
            query_states = hidden_states
        attention_output = self.output(self_output, query_states)

        if output_attentions:
            return (attention_output, att_matrix)
        else:
            return (attention_output, None)


# Copied from transformers.models.bert.modeling_bert.BertIntermediate with Bert->Deberta
class DebertaIntermediate(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.hidden_size, config.intermediate_size)
        if isinstance(config.hidden_act, str):
            self.intermediate_act_fn = ACT2FN[config.hidden_act]
        else:
            self.intermediate_act_fn = config.hidden_act

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        hidden_states = self.dense(hidden_states)
        hidden_states = self.intermediate_act_fn(hidden_states)
        return hidden_states


class DebertaOutput(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.intermediate_size, config.hidden_size)
        self.LayerNorm = DebertaLayerNorm(config.hidden_size, config.layer_norm_eps)
        self.dropout = nn.Dropout(config.hidden_dropout_prob)
        self.config = config

    def forward(self, hidden_states, input_tensor):
        hidden_states = self.dense(hidden_states)
        hidden_states = self.dropout(hidden_states)
        hidden_states = self.LayerNorm(hidden_states + input_tensor)
        return hidden_states


class DebertaLayer(GradientCheckpointingLayer):
    def __init__(self, config):
        super().__init__()
        self.attention = DebertaAttention(config)
        self.intermediate = DebertaIntermediate(config)
        self.output = DebertaOutput(config)

    def forward(
        self,
        hidden_states,
        attention_mask,
        query_states=None,
        relative_pos=None,
        rel_embeddings=None,
        output_attentions: bool = False,
    ) -> tuple[torch.Tensor, Optional[torch.Tensor]]:
        attention_output, att_matrix = self.attention(
            hidden_states,
            attention_mask,
            output_attentions=output_attentions,
            query_states=query_states,
            relative_pos=relative_pos,
            rel_embeddings=rel_embeddings,
        )
        intermediate_output = self.intermediate(attention_output)
        layer_output = self.output(intermediate_output, attention_output)

        if output_attentions:
            return (layer_output, att_matrix)
        else:
            return (layer_output, None)


class DebertaEncoder(nn.Module):
    """Modified BertEncoder with relative position bias support"""

    def __init__(self, config):
        super().__init__()
        self.layer = nn.ModuleList([DebertaLayer(config) for _ in range(config.num_hidden_layers)])
        self.relative_attention = getattr(config, "relative_attention", False)
        if self.relative_attention:
            self.max_relative_positions = getattr(config, "max_relative_positions", -1)
            if self.max_relative_positions < 1:
                self.max_relative_positions = config.max_position_embeddings
            self.rel_embeddings = nn.Embedding(self.max_relative_positions * 2, config.hidden_size)
        self.gradient_checkpointing = False

    def get_rel_embedding(self):
        rel_embeddings = self.rel_embeddings.weight if self.relative_attention else None
        return rel_embeddings

    def get_attention_mask(self, attention_mask):
        if attention_mask.dim() <= 2:
            extended_attention_mask = attention_mask.unsqueeze(1).unsqueeze(2)
            attention_mask = extended_attention_mask * extended_attention_mask.squeeze(-2).unsqueeze(-1)
        elif attention_mask.dim() == 3:
            attention_mask = attention_mask.unsqueeze(1)

        return attention_mask

    def get_rel_pos(self, hidden_states, query_states=None, relative_pos=None):
        if self.relative_attention and relative_pos is None:
            if query_states is not None:
                relative_pos = build_relative_position(query_states, hidden_states)
            else:
                relative_pos = build_relative_position(hidden_states, hidden_states)
        return relative_pos

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor,
        output_hidden_states: bool = True,
        output_attentions: bool = False,
        query_states=None,
        relative_pos=None,
        return_dict: bool = True,
    ):
        attention_mask = self.get_attention_mask(attention_mask)
        relative_pos = self.get_rel_pos(hidden_states, query_states, relative_pos)

        all_hidden_states: Optional[tuple[torch.Tensor]] = (hidden_states,) if output_hidden_states else None
        all_attentions = () if output_attentions else None

        next_kv = hidden_states

        rel_embeddings = self.get_rel_embedding()
        for i, layer_module in enumerate(self.layer):
            hidden_states, att_m = layer_module(
                next_kv,
                attention_mask,
                query_states=query_states,
                relative_pos=relative_pos,
                rel_embeddings=rel_embeddings,
                output_attentions=output_attentions,
            )

            if output_hidden_states:
                all_hidden_states = all_hidden_states + (hidden_states,)

            if query_states is not None:
                query_states = hidden_states
            else:
                next_kv = hidden_states

            if output_attentions:
                all_attentions = all_attentions + (att_m,)

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


@auto_docstring
class DebertaPreTrainedModel(PreTrainedModel):
    config: DebertaConfig
    base_model_prefix = "deberta"
    _keys_to_ignore_on_load_unexpected = ["position_embeddings"]
    supports_gradient_checkpointing = True

    def _init_weights(self, module):
        """Initialize the weights."""
        if isinstance(module, nn.Linear):
            # Slightly different from the TF version which uses truncated_normal for initialization
            # cf https://github.com/pytorch/pytorch/pull/5617
            module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
            if module.bias is not None:
                module.bias.data.zero_()
        elif isinstance(module, nn.Embedding):
            module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
            if module.padding_idx is not None:
                module.weight.data[module.padding_idx].zero_()
        elif isinstance(module, (nn.LayerNorm, DebertaLayerNorm)):
            module.weight.data.fill_(1.0)
            module.bias.data.zero_()
        elif isinstance(module, DisentangledSelfAttention):
            module.q_bias.data.zero_()
            module.v_bias.data.zero_()
        elif isinstance(module, (LegacyDebertaLMPredictionHead, DebertaLMPredictionHead)):
            module.bias.data.zero_()


@auto_docstring
class DebertaModel(DebertaPreTrainedModel):
    def __init__(self, config):
        super().__init__(config)

        self.embeddings = DebertaEmbeddings(config)
        self.encoder = DebertaEncoder(config)
        self.z_steps = 0
        self.config = config
        # Initialize weights and apply final processing
        self.post_init()

    def get_input_embeddings(self):
        return self.embeddings.word_embeddings

    def set_input_embeddings(self, new_embeddings):
        self.embeddings.word_embeddings = new_embeddings

    def _prune_heads(self, heads_to_prune):
        """
        Prunes heads of the model. heads_to_prune: dict of {layer_num: list of heads to prune in this layer} See base
        class PreTrainedModel
        """
        raise NotImplementedError("The prune function is not implemented in DeBERTa model.")

    @auto_docstring
    def forward(
        self,
        input_ids: Optional[torch.Tensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        token_type_ids: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.Tensor] = None,
        inputs_embeds: Optional[torch.Tensor] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[tuple, BaseModelOutput]:
        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

        if input_ids is not None and inputs_embeds is not None:
            raise ValueError("You cannot specify both input_ids and inputs_embeds at the same time")
        elif input_ids is not None:
            self.warn_if_padding_and_no_attention_mask(input_ids, attention_mask)
            input_shape = input_ids.size()
        elif inputs_embeds is not None:
            input_shape = inputs_embeds.size()[:-1]
        else:
            raise ValueError("You have to specify either input_ids or inputs_embeds")

        device = input_ids.device if input_ids is not None else inputs_embeds.device

        if attention_mask is None:
            attention_mask = torch.ones(input_shape, device=device)
        if token_type_ids is None:
            token_type_ids = torch.zeros(input_shape, dtype=torch.long, device=device)

        embedding_output = self.embeddings(
            input_ids=input_ids,
            token_type_ids=token_type_ids,
            position_ids=position_ids,
            mask=attention_mask,
            inputs_embeds=inputs_embeds,
        )

        encoder_outputs = self.encoder(
            embedding_output,
            attention_mask,
            output_hidden_states=True,
            output_attentions=output_attentions,
            return_dict=return_dict,
        )
        encoded_layers = encoder_outputs[1]

        if self.z_steps > 1:
            hidden_states = encoded_layers[-2]
            layers = [self.encoder.layer[-1] for _ in range(self.z_steps)]
            query_states = encoded_layers[-1]
            rel_embeddings = self.encoder.get_rel_embedding()
            attention_mask = self.encoder.get_attention_mask(attention_mask)
            rel_pos = self.encoder.get_rel_pos(embedding_output)
            for layer in layers[1:]:
                query_states = layer(
                    hidden_states,
                    attention_mask,
                    output_attentions=False,
                    query_states=query_states,
                    relative_pos=rel_pos,
                    rel_embeddings=rel_embeddings,
                )
                encoded_layers.append(query_states)

        sequence_output = encoded_layers[-1]

        if not return_dict:
            return (sequence_output,) + encoder_outputs[(1 if output_hidden_states else 2) :]

        return BaseModelOutput(
            last_hidden_state=sequence_output,
            hidden_states=encoder_outputs.hidden_states if output_hidden_states else None,
            attentions=encoder_outputs.attentions,
        )


class LegacyDebertaPredictionHeadTransform(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.embedding_size = getattr(config, "embedding_size", config.hidden_size)

        self.dense = nn.Linear(config.hidden_size, self.embedding_size)
        if isinstance(config.hidden_act, str):
            self.transform_act_fn = ACT2FN[config.hidden_act]
        else:
            self.transform_act_fn = config.hidden_act
        self.LayerNorm = nn.LayerNorm(self.embedding_size, eps=config.layer_norm_eps)

    def forward(self, hidden_states):
        hidden_states = self.dense(hidden_states)
        hidden_states = self.transform_act_fn(hidden_states)
        hidden_states = self.LayerNorm(hidden_states)
        return hidden_states


class LegacyDebertaLMPredictionHead(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.transform = LegacyDebertaPredictionHeadTransform(config)

        self.embedding_size = getattr(config, "embedding_size", config.hidden_size)
        # The output weights are the same as the input embeddings, but there is
        # an output-only bias for each token.
        self.decoder = nn.Linear(self.embedding_size, config.vocab_size, bias=False)

        self.bias = nn.Parameter(torch.zeros(config.vocab_size))

        # Need a link between the two variables so that the bias is correctly resized with `resize_token_embeddings`
        self.decoder.bias = self.bias

    def _tie_weights(self):
        self.decoder.bias = self.bias

    def forward(self, hidden_states):
        hidden_states = self.transform(hidden_states)
        hidden_states = self.decoder(hidden_states)
        return hidden_states


# Copied from transformers.models.bert.modeling_bert.BertOnlyMLMHead with Bert->LegacyDeberta
class LegacyDebertaOnlyMLMHead(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.predictions = LegacyDebertaLMPredictionHead(config)

    def forward(self, sequence_output: torch.Tensor) -> torch.Tensor:
        prediction_scores = self.predictions(sequence_output)
        return prediction_scores


class DebertaLMPredictionHead(nn.Module):
    """https://github.com/microsoft/DeBERTa/blob/master/DeBERTa/deberta/bert.py#L270"""

    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.hidden_size, config.hidden_size)

        if isinstance(config.hidden_act, str):
            self.transform_act_fn = ACT2FN[config.hidden_act]
        else:
            self.transform_act_fn = config.hidden_act

        self.LayerNorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps, elementwise_affine=True)

        self.bias = nn.Parameter(torch.zeros(config.vocab_size))

    # note that the input embeddings must be passed as an argument
    def forward(self, hidden_states, word_embeddings):
        hidden_states = self.dense(hidden_states)
        hidden_states = self.transform_act_fn(hidden_states)
        hidden_states = self.LayerNorm(
            hidden_states
        )  # original used MaskedLayerNorm, but passed no mask. This is equivalent.
        hidden_states = torch.matmul(hidden_states, word_embeddings.weight.t()) + self.bias
        return hidden_states


class DebertaOnlyMLMHead(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.lm_head = DebertaLMPredictionHead(config)

    # note that the input embeddings must be passed as an argument
    def forward(self, sequence_output, word_embeddings):
        prediction_scores = self.lm_head(sequence_output, word_embeddings)
        return prediction_scores


@auto_docstring
class DebertaForMaskedLM(DebertaPreTrainedModel):
    _tied_weights_keys = ["cls.predictions.decoder.weight", "cls.predictions.decoder.bias"]

    def __init__(self, config):
        super().__init__(config)
        self.legacy = config.legacy
        self.deberta = DebertaModel(config)
        if self.legacy:
            self.cls = LegacyDebertaOnlyMLMHead(config)
        else:
            self._tied_weights_keys = ["lm_predictions.lm_head.weight", "deberta.embeddings.word_embeddings.weight"]
            self.lm_predictions = DebertaOnlyMLMHead(config)

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

    def get_output_embeddings(self):
        if self.legacy:
            return self.cls.predictions.decoder
        else:
            return self.lm_predictions.lm_head.dense

    def set_output_embeddings(self, new_embeddings):
        if self.legacy:
            self.cls.predictions.decoder = new_embeddings
            self.cls.predictions.bias = new_embeddings.bias
        else:
            self.lm_predictions.lm_head.dense = new_embeddings
            self.lm_predictions.lm_head.bias = new_embeddings.bias

    @auto_docstring
    def forward(
        self,
        input_ids: Optional[torch.Tensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        token_type_ids: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.Tensor] = None,
        inputs_embeds: Optional[torch.Tensor] = None,
        labels: Optional[torch.Tensor] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[tuple, MaskedLMOutput]:
        r"""
        labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
            Labels for computing the masked language modeling loss. Indices should be in `[-100, 0, ...,
            config.vocab_size]` (see `input_ids` docstring) Tokens with indices set to `-100` are ignored (masked), the
            loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`
        """

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

        outputs = self.deberta(
            input_ids,
            attention_mask=attention_mask,
            token_type_ids=token_type_ids,
            position_ids=position_ids,
            inputs_embeds=inputs_embeds,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
        )

        sequence_output = outputs[0]
        if self.legacy:
            prediction_scores = self.cls(sequence_output)
        else:
            prediction_scores = self.lm_predictions(sequence_output, self.deberta.embeddings.word_embeddings)

        masked_lm_loss = None
        if labels is not None:
            loss_fct = CrossEntropyLoss()  # -100 index = padding token
            masked_lm_loss = loss_fct(prediction_scores.view(-1, self.config.vocab_size), labels.view(-1))

        if not return_dict:
            output = (prediction_scores,) + outputs[1:]
            return ((masked_lm_loss,) + output) if masked_lm_loss is not None else output

        return MaskedLMOutput(
            loss=masked_lm_loss,
            logits=prediction_scores,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
        )


class ContextPooler(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.pooler_hidden_size, config.pooler_hidden_size)
        self.dropout = nn.Dropout(config.pooler_dropout)
        self.config = config

    def forward(self, hidden_states):
        # We "pool" the model by simply taking the hidden state corresponding
        # to the first token.

        context_token = hidden_states[:, 0]
        context_token = self.dropout(context_token)
        pooled_output = self.dense(context_token)
        pooled_output = ACT2FN[self.config.pooler_hidden_act](pooled_output)
        return pooled_output

    @property
    def output_dim(self):
        return self.config.hidden_size


@auto_docstring(
    custom_intro="""
    DeBERTa Model transformer with a sequence classification/regression head on top (a linear layer on top of the
    pooled output) e.g. for GLUE tasks.
    """
)
class DebertaForSequenceClassification(DebertaPreTrainedModel):
    def __init__(self, config):
        super().__init__(config)

        num_labels = getattr(config, "num_labels", 2)
        self.num_labels = num_labels

        self.deberta = DebertaModel(config)
        self.pooler = ContextPooler(config)
        output_dim = self.pooler.output_dim

        self.classifier = nn.Linear(output_dim, num_labels)
        drop_out = getattr(config, "cls_dropout", None)
        drop_out = self.config.hidden_dropout_prob if drop_out is None else drop_out
        self.dropout = nn.Dropout(drop_out)

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

    def get_input_embeddings(self):
        return self.deberta.get_input_embeddings()

    def set_input_embeddings(self, new_embeddings):
        self.deberta.set_input_embeddings(new_embeddings)

    @auto_docstring
    def forward(
        self,
        input_ids: Optional[torch.Tensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        token_type_ids: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.Tensor] = None,
        inputs_embeds: Optional[torch.Tensor] = None,
        labels: Optional[torch.Tensor] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[tuple, 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).
        """
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        outputs = self.deberta(
            input_ids,
            token_type_ids=token_type_ids,
            attention_mask=attention_mask,
            position_ids=position_ids,
            inputs_embeds=inputs_embeds,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
        )

        encoder_layer = outputs[0]
        pooled_output = self.pooler(encoder_layer)
        pooled_output = self.dropout(pooled_output)
        logits = self.classifier(pooled_output)

        loss = None
        if labels is not None:
            if self.config.problem_type is None:
                if self.num_labels == 1:
                    # regression task
                    loss_fn = nn.MSELoss()
                    logits = logits.view(-1).to(labels.dtype)
                    loss = loss_fn(logits, labels.view(-1))
                elif labels.dim() == 1 or labels.size(-1) == 1:
                    label_index = (labels >= 0).nonzero()
                    labels = labels.long()
                    if label_index.size(0) > 0:
                        labeled_logits = torch.gather(
                            logits, 0, label_index.expand(label_index.size(0), logits.size(1))
                        )
                        labels = torch.gather(labels, 0, label_index.view(-1))
                        loss_fct = CrossEntropyLoss()
                        loss = loss_fct(labeled_logits.view(-1, self.num_labels).float(), labels.view(-1))
                    else:
                        loss = torch.tensor(0).to(logits)
                else:
                    log_softmax = nn.LogSoftmax(-1)
                    loss = -((log_softmax(logits) * labels).sum(-1)).mean()
            elif self.config.problem_type == "regression":
                loss_fct = MSELoss()
                if self.num_labels == 1:
                    loss = loss_fct(logits.squeeze(), labels.squeeze())
                else:
                    loss = loss_fct(logits, labels)
            elif self.config.problem_type == "single_label_classification":
                loss_fct = CrossEntropyLoss()
                loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
            elif self.config.problem_type == "multi_label_classification":
                loss_fct = BCEWithLogitsLoss()
                loss = loss_fct(logits, labels)
        if not return_dict:
            output = (logits,) + outputs[1:]
            return ((loss,) + output) if loss is not None else output

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


@auto_docstring
class DebertaForTokenClassification(DebertaPreTrainedModel):
    def __init__(self, config):
        super().__init__(config)
        self.num_labels = config.num_labels

        self.deberta = DebertaModel(config)
        self.dropout = nn.Dropout(config.hidden_dropout_prob)
        self.classifier = nn.Linear(config.hidden_size, config.num_labels)

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

    @auto_docstring
    def forward(
        self,
        input_ids: Optional[torch.Tensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        token_type_ids: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.Tensor] = None,
        inputs_embeds: Optional[torch.Tensor] = None,
        labels: Optional[torch.Tensor] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[tuple, TokenClassifierOutput]:
        r"""
        labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
            Labels for computing the token classification loss. Indices should be in `[0, ..., config.num_labels - 1]`.
        """
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        outputs = self.deberta(
            input_ids,
            attention_mask=attention_mask,
            token_type_ids=token_type_ids,
            position_ids=position_ids,
            inputs_embeds=inputs_embeds,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
        )

        sequence_output = outputs[0]

        sequence_output = self.dropout(sequence_output)
        logits = self.classifier(sequence_output)

        loss = None
        if labels is not None:
            loss_fct = CrossEntropyLoss()
            loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1))

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

        return TokenClassifierOutput(
            loss=loss, logits=logits, hidden_states=outputs.hidden_states, attentions=outputs.attentions
        )


@auto_docstring
class DebertaForQuestionAnswering(DebertaPreTrainedModel):
    def __init__(self, config):
        super().__init__(config)
        self.num_labels = config.num_labels

        self.deberta = DebertaModel(config)
        self.qa_outputs = nn.Linear(config.hidden_size, config.num_labels)

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

    @auto_docstring
    def forward(
        self,
        input_ids: Optional[torch.Tensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        token_type_ids: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.Tensor] = None,
        inputs_embeds: Optional[torch.Tensor] = None,
        start_positions: Optional[torch.Tensor] = None,
        end_positions: Optional[torch.Tensor] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
    ) -> Union[tuple, QuestionAnsweringModelOutput]:
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        outputs = self.deberta(
            input_ids,
            attention_mask=attention_mask,
            token_type_ids=token_type_ids,
            position_ids=position_ids,
            inputs_embeds=inputs_embeds,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
        )

        sequence_output = outputs[0]

        logits = self.qa_outputs(sequence_output)
        start_logits, end_logits = logits.split(1, dim=-1)
        start_logits = start_logits.squeeze(-1).contiguous()
        end_logits = end_logits.squeeze(-1).contiguous()

        total_loss = None
        if start_positions is not None and end_positions is not None:
            # If we are on multi-GPU, split add a dimension
            if len(start_positions.size()) > 1:
                start_positions = start_positions.squeeze(-1)
            if len(end_positions.size()) > 1:
                end_positions = end_positions.squeeze(-1)
            # sometimes the start/end positions are outside our model inputs, we ignore these terms
            ignored_index = start_logits.size(1)
            start_positions = start_positions.clamp(0, ignored_index)
            end_positions = end_positions.clamp(0, ignored_index)

            loss_fct = CrossEntropyLoss(ignore_index=ignored_index)
            start_loss = loss_fct(start_logits, start_positions)
            end_loss = loss_fct(end_logits, end_positions)
            total_loss = (start_loss + end_loss) / 2

        if not return_dict:
            output = (start_logits, end_logits) + outputs[1:]
            return ((total_loss,) + output) if total_loss is not None else output

        return QuestionAnsweringModelOutput(
            loss=total_loss,
            start_logits=start_logits,
            end_logits=end_logits,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
        )


__all__ = [
    "DebertaForMaskedLM",
    "DebertaForQuestionAnswering",
    "DebertaForSequenceClassification",
    "DebertaForTokenClassification",
    "DebertaModel",
    "DebertaPreTrainedModel",
]