"""Minimal implementation of BlipVisionModel intended to be only used 
within a vision language model."""
from typing import Optional, Union

import torch
import torch.nn as nn
from PIL import Image
from transformers import Blip2VisionConfig, BlipVisionConfig
from transformers.models.blip.modeling_blip import BlipAttention

from aphrodite.common.config import ModelConfig
from aphrodite.common.sequence import SequenceData
from aphrodite.inputs import LLMInputs
from aphrodite.modeling.layers.activation import get_act_fn
from aphrodite.modeling.layers.linear import (ColumnParallelLinear,
                                              RowParallelLinear)
from aphrodite.multimodal.image import (cached_get_tokenizer,
                                        repeat_and_pad_image_tokens)
from aphrodite.quantization import QuantizationConfig


def get_blip_patch_grid_length(*, image_size: int, patch_size: int) -> int:
    assert image_size % patch_size == 0
    return image_size // patch_size


def get_blip_num_patches(*, image_size: int, patch_size: int) -> int:
    grid_length = get_blip_patch_grid_length(image_size=image_size,
                                             patch_size=patch_size)
    return grid_length * grid_length


def get_blip_image_feature_size(
    hf_config: Union[BlipVisionConfig, Blip2VisionConfig], ) -> int:
    return get_blip_num_patches(image_size=hf_config.image_size,
                                patch_size=hf_config.patch_size)


def get_max_blip_image_tokens(
    hf_config: Union[BlipVisionConfig, Blip2VisionConfig], ) -> int:
    return get_blip_image_feature_size(hf_config)


def dummy_seq_data_for_blip(
    hf_config: Union[BlipVisionConfig, Blip2VisionConfig],
    seq_len: int,
    *,
    image_token_id: int,
    image_feature_size_override: Optional[int] = None,
):
    if image_feature_size_override is None:
        image_feature_size = get_blip_image_feature_size(hf_config)
    else:
        image_feature_size = image_feature_size_override

    token_ids = [image_token_id] * image_feature_size
    token_ids += [0] * (seq_len - image_feature_size)
    return SequenceData(token_ids)


def dummy_image_for_blip(
    hf_config: Union[BlipVisionConfig, Blip2VisionConfig],
    num_images: int,
    *,
    image_width_override: Optional[int] = None,
    image_height_override: Optional[int] = None,
):
    width = height = hf_config.image_size
    if image_width_override is not None:
        width = image_width_override
    if image_height_override is not None:
        height = image_height_override

    image = Image.new("RGB", (width, height), color=0)
    return {"image": image if num_images == 1 else [image] * num_images}


def input_processor_for_blip(
    model_config: ModelConfig,
    hf_config: Union[BlipVisionConfig, Blip2VisionConfig],
    llm_inputs: LLMInputs,
    *,
    image_token_id: int,
    image_feature_size_override: Optional[int] = None,
):
    multi_modal_data = llm_inputs.get("multi_modal_data")
    if multi_modal_data is None or "image" not in multi_modal_data:
        return llm_inputs

    tokenizer = cached_get_tokenizer(model_config.tokenizer)

    if image_feature_size_override is None:
        image_feature_size = get_blip_image_feature_size(hf_config)
    else:
        image_feature_size = image_feature_size_override

    new_prompt, new_token_ids = repeat_and_pad_image_tokens(
        tokenizer,
        llm_inputs.get("prompt"),
        llm_inputs["prompt_token_ids"],
        image_token_id=image_token_id,
        repeat_count=image_feature_size,
    )

    # NOTE: Create a defensive copy of the original inputs
    return LLMInputs(prompt_token_ids=new_token_ids,
                     prompt=new_prompt,
                     multi_modal_data=multi_modal_data)


# Adapted from https://github.com/huggingface/transformers/blob/v4.39.0/src/transformers/models/blip/modeling_blip.py#L164 # noqa
class BlipVisionEmbeddings(nn.Module):

    def __init__(self, config: BlipVisionConfig):
        super().__init__()

        self.config = config
        self.embed_dim = config.hidden_size
        self.image_size = config.image_size
        self.patch_size = config.patch_size

        self.class_embedding = nn.Parameter(torch.randn(1, 1, self.embed_dim))

        self.patch_embedding = nn.Conv2d(
            in_channels=3,
            out_channels=self.embed_dim,
            kernel_size=self.patch_size,
            stride=self.patch_size,
        )

        self.num_patches = get_blip_num_patches(image_size=self.image_size,
                                                patch_size=self.patch_size)
        self.num_positions = self.num_patches + 1

        self.position_embedding = nn.Parameter(
            torch.randn(1, self.num_positions, self.embed_dim))

    def forward(self, pixel_values: torch.Tensor) -> torch.Tensor:
        batch_size = pixel_values.shape[0]
        target_dtype = self.patch_embedding.weight.dtype
        patch_embeds = self.patch_embedding(pixel_values.to(
            dtype=target_dtype))  # shape = [*, width, grid, grid]
        patch_embeds = patch_embeds.flatten(2).transpose(1, 2)

        class_embeds = self.class_embedding.expand(batch_size, 1, -1)
        embeddings = torch.cat([class_embeds, patch_embeds], dim=1)

        position_embeds = self.position_embedding.to(target_dtype)
        embeddings = embeddings + position_embeds[:, :embeddings.size(1), :]

        return embeddings


class BlipMLP(nn.Module):

    def __init__(self,
                 config: BlipVisionConfig,
                 quant_config: Optional[QuantizationConfig] = None):
        super().__init__()

        self.config = config

        self.activation_fn = get_act_fn(config.hidden_act)
        self.fc1 = ColumnParallelLinear(config.hidden_size,
                                        config.intermediate_size,
                                        bias=True,
                                        quant_config=quant_config)
        self.fc2 = RowParallelLinear(config.intermediate_size,
                                     config.hidden_size,
                                     bias=True,
                                     quant_config=quant_config)

    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 BlipEncoderLayer(nn.Module):

    def __init__(self,
                 config: BlipVisionConfig,
                 quant_config: Optional[QuantizationConfig] = None):
        super().__init__()

        self.self_attn = BlipAttention(config)
        self.layer_norm1 = nn.LayerNorm(config.hidden_size,
                                        eps=config.layer_norm_eps)
        self.mlp = BlipMLP(config, quant_config=quant_config)
        self.layer_norm2 = nn.LayerNorm(config.hidden_size,
                                        eps=config.layer_norm_eps)

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        residual = hidden_states

        hidden_states = self.layer_norm1(hidden_states)
        hidden_states, _ = self.self_attn(hidden_states=hidden_states)
        hidden_states = residual + hidden_states

        residual = hidden_states
        hidden_states = self.layer_norm2(hidden_states)
        hidden_states = self.mlp(hidden_states)
        hidden_states = residual + hidden_states

        return hidden_states


class BlipEncoder(nn.Module):
    """
    Transformer encoder consisting of `config.num_hidden_layers` self 
    attention layers. Each layer is a [`BlipEncoderLayer`].
    Args:
        config: BlipConfig
    """

    def __init__(self,
                 config: BlipVisionConfig,
                 quant_config: Optional[QuantizationConfig] = None,
                 num_hidden_layers_override: Optional[int] = None):
        super().__init__()

        self.config = config

        if num_hidden_layers_override is None:
            num_hidden_layers = config.num_hidden_layers
        else:
            num_hidden_layers = num_hidden_layers_override

        self.layers = nn.ModuleList([
            BlipEncoderLayer(config=config, quant_config=quant_config)
            for _ in range(num_hidden_layers)
        ])

    def forward(self, inputs_embeds: torch.Tensor):
        hidden_states = inputs_embeds
        for encoder_layer in self.layers:
            hidden_states = encoder_layer(hidden_states)

        return hidden_states


class BlipVisionModel(nn.Module):
    config_class = BlipVisionConfig
    main_input_name = "pixel_values"

    def __init__(self,
                 config: BlipVisionConfig,
                 quant_config: Optional[QuantizationConfig] = None,
                 num_hidden_layers_override: Optional[int] = None):
        super().__init__()

        self.config = config

        self.embeddings = BlipVisionEmbeddings(config)
        self.encoder = BlipEncoder(
            config=config,
            quant_config=quant_config,
            num_hidden_layers_override=num_hidden_layers_override,
        )
        self.post_layernorm = nn.LayerNorm(config.hidden_size,
                                           eps=config.layer_norm_eps)

    def forward(self, pixel_values: torch.Tensor) -> torch.Tensor:
        hidden_states = self.embeddings(pixel_values)
        hidden_states = self.encoder(inputs_embeds=hidden_states)

        return self.post_layernorm(hidden_states)