# Copyright (c) 2024 Black Forest Labs.
# Copyright (c) 2025 Bytedance Ltd. and/or its affiliates.
# SPDX-License-Identifier: Apache-2.0
#
# This file has been modified by ByteDance Ltd. and/or its affiliates. on 2025-05-20.
#
# Original file was released under Apache-2.0, with the full license text
# available at https://github.com/black-forest-labs/flux/blob/main/LICENSE.
#
# This modified file is released under the same license.

from dataclasses import dataclass

import torch
from einops import rearrange
from torch import Tensor, nn
from vllm.logger import init_logger

from vllm_omni.diffusion.distributed.autoencoders.distributed_vae_executor import (
    DistributedOperator,
    DistributedVaeMixin,
    GridSpec,
    TileTask,
)

logger = init_logger(__name__)


@dataclass
class AutoEncoderParams:
    resolution: int
    in_channels: int
    downsample: int
    ch: int
    out_ch: int
    ch_mult: list[int]
    num_res_blocks: int
    z_channels: int
    scale_factor: float
    shift_factor: float


def swish(x: Tensor) -> Tensor:
    return x * torch.sigmoid(x)


class AttnBlock(nn.Module):
    def __init__(self, in_channels: int):
        super().__init__()
        self.in_channels = in_channels

        self.norm = nn.GroupNorm(num_groups=32, num_channels=in_channels, eps=1e-6, affine=True)

        self.q = nn.Conv2d(in_channels, in_channels, kernel_size=1)
        self.k = nn.Conv2d(in_channels, in_channels, kernel_size=1)
        self.v = nn.Conv2d(in_channels, in_channels, kernel_size=1)
        self.proj_out = nn.Conv2d(in_channels, in_channels, kernel_size=1)

    def attention(self, h_: Tensor) -> Tensor:
        h_ = self.norm(h_)
        q = self.q(h_)
        k = self.k(h_)
        v = self.v(h_)

        b, c, h, w = q.shape
        q = rearrange(q, "b c h w -> b 1 (h w) c").contiguous()
        k = rearrange(k, "b c h w -> b 1 (h w) c").contiguous()
        v = rearrange(v, "b c h w -> b 1 (h w) c").contiguous()
        h_ = nn.functional.scaled_dot_product_attention(q, k, v)

        return rearrange(h_, "b 1 (h w) c -> b c h w", h=h, w=w, c=c, b=b)

    def forward(self, x: Tensor) -> Tensor:
        return x + self.proj_out(self.attention(x))


class ResnetBlock(nn.Module):
    def __init__(self, in_channels: int, out_channels: int):
        super().__init__()
        self.in_channels = in_channels
        out_channels = in_channels if out_channels is None else out_channels
        self.out_channels = out_channels

        self.norm1 = nn.GroupNorm(num_groups=32, num_channels=in_channels, eps=1e-6, affine=True)
        self.conv1 = nn.Conv2d(in_channels, out_channels, kernel_size=3, stride=1, padding=1)
        self.norm2 = nn.GroupNorm(num_groups=32, num_channels=out_channels, eps=1e-6, affine=True)
        self.conv2 = nn.Conv2d(out_channels, out_channels, kernel_size=3, stride=1, padding=1)
        if self.in_channels != self.out_channels:
            self.nin_shortcut = nn.Conv2d(in_channels, out_channels, kernel_size=1, stride=1, padding=0)

    def forward(self, x):
        h = x
        h = self.norm1(h)
        h = swish(h)
        h = self.conv1(h)

        h = self.norm2(h)
        h = swish(h)
        h = self.conv2(h)

        if self.in_channels != self.out_channels:
            x = self.nin_shortcut(x)

        return x + h


class Downsample(nn.Module):
    def __init__(self, in_channels: int):
        super().__init__()
        # no asymmetric padding in torch conv, must do it ourselves
        self.conv = nn.Conv2d(in_channels, in_channels, kernel_size=3, stride=2, padding=0)

    def forward(self, x: Tensor):
        pad = (0, 1, 0, 1)
        x = nn.functional.pad(x, pad, mode="constant", value=0)
        x = self.conv(x)
        return x


class Upsample(nn.Module):
    def __init__(self, in_channels: int):
        super().__init__()
        self.conv = nn.Conv2d(in_channels, in_channels, kernel_size=3, stride=1, padding=1)

    def forward(self, x: Tensor):
        x = nn.functional.interpolate(x, scale_factor=2.0, mode="nearest")
        x = self.conv(x)
        return x


class Encoder(nn.Module):
    def __init__(
        self,
        resolution: int,
        in_channels: int,
        ch: int,
        ch_mult: list[int],
        num_res_blocks: int,
        z_channels: int,
    ):
        super().__init__()
        self.ch = ch
        self.num_resolutions = len(ch_mult)
        self.num_res_blocks = num_res_blocks
        self.resolution = resolution
        self.in_channels = in_channels
        # downsampling
        self.conv_in = nn.Conv2d(in_channels, self.ch, kernel_size=3, stride=1, padding=1)

        curr_res = resolution
        in_ch_mult = (1,) + tuple(ch_mult)
        self.in_ch_mult = in_ch_mult
        self.down = nn.ModuleList()
        block_in = self.ch
        for i_level in range(self.num_resolutions):
            block = nn.ModuleList()
            attn = nn.ModuleList()
            block_in = ch * in_ch_mult[i_level]
            block_out = ch * ch_mult[i_level]
            for _ in range(self.num_res_blocks):
                block.append(ResnetBlock(in_channels=block_in, out_channels=block_out))
                block_in = block_out
            down = nn.Module()
            down.block = block
            down.attn = attn
            if i_level != self.num_resolutions - 1:
                down.downsample = Downsample(block_in)
                curr_res = curr_res // 2
            self.down.append(down)

        # middle
        self.mid = nn.Module()
        self.mid.block_1 = ResnetBlock(in_channels=block_in, out_channels=block_in)
        self.mid.attn_1 = AttnBlock(block_in)
        self.mid.block_2 = ResnetBlock(in_channels=block_in, out_channels=block_in)

        # end
        self.norm_out = nn.GroupNorm(num_groups=32, num_channels=block_in, eps=1e-6, affine=True)
        self.conv_out = nn.Conv2d(block_in, 2 * z_channels, kernel_size=3, stride=1, padding=1)

    def forward(self, x: Tensor) -> Tensor:
        # downsampling
        hs = [self.conv_in(x)]
        for i_level in range(self.num_resolutions):
            for i_block in range(self.num_res_blocks):
                h = self.down[i_level].block[i_block](hs[-1])
                if len(self.down[i_level].attn) > 0:
                    h = self.down[i_level].attn[i_block](h)
                hs.append(h)
            if i_level != self.num_resolutions - 1:
                hs.append(self.down[i_level].downsample(hs[-1]))

        # middle
        h = hs[-1]
        h = self.mid.block_1(h)
        h = self.mid.attn_1(h)
        h = self.mid.block_2(h)
        # end
        h = self.norm_out(h)
        h = swish(h)
        h = self.conv_out(h)
        return h


class Decoder(nn.Module):
    def __init__(
        self,
        ch: int,
        out_ch: int,
        ch_mult: list[int],
        num_res_blocks: int,
        in_channels: int,
        resolution: int,
        z_channels: int,
    ):
        super().__init__()
        self.ch = ch
        self.num_resolutions = len(ch_mult)
        self.num_res_blocks = num_res_blocks
        self.resolution = resolution
        self.in_channels = in_channels
        self.ffactor = 2 ** (self.num_resolutions - 1)

        # compute in_ch_mult, block_in and curr_res at lowest res
        block_in = ch * ch_mult[self.num_resolutions - 1]
        curr_res = resolution // 2 ** (self.num_resolutions - 1)
        self.z_shape = (1, z_channels, curr_res, curr_res)

        # z to block_in
        self.conv_in = nn.Conv2d(z_channels, block_in, kernel_size=3, stride=1, padding=1)

        # middle
        self.mid = nn.Module()
        self.mid.block_1 = ResnetBlock(in_channels=block_in, out_channels=block_in)
        self.mid.attn_1 = AttnBlock(block_in)
        self.mid.block_2 = ResnetBlock(in_channels=block_in, out_channels=block_in)

        # upsampling
        self.up = nn.ModuleList()
        for i_level in reversed(range(self.num_resolutions)):
            block = nn.ModuleList()
            attn = nn.ModuleList()
            block_out = ch * ch_mult[i_level]
            for _ in range(self.num_res_blocks + 1):
                block.append(ResnetBlock(in_channels=block_in, out_channels=block_out))
                block_in = block_out
            up = nn.Module()
            up.block = block
            up.attn = attn
            if i_level != 0:
                up.upsample = Upsample(block_in)
                curr_res = curr_res * 2
            self.up.insert(0, up)  # prepend to get consistent order

        # end
        self.norm_out = nn.GroupNorm(num_groups=32, num_channels=block_in, eps=1e-6, affine=True)
        self.conv_out = nn.Conv2d(block_in, out_ch, kernel_size=3, stride=1, padding=1)

    def forward(self, z: Tensor) -> Tensor:
        # z to block_in
        h = self.conv_in(z)

        # middle
        h = self.mid.block_1(h)
        h = self.mid.attn_1(h)
        h = self.mid.block_2(h)

        # upsampling
        for i_level in reversed(range(self.num_resolutions)):
            for i_block in range(self.num_res_blocks + 1):
                h = self.up[i_level].block[i_block](h)
                if len(self.up[i_level].attn) > 0:
                    h = self.up[i_level].attn[i_block](h)
            if i_level != 0:
                h = self.up[i_level].upsample(h)

        # end
        h = self.norm_out(h)
        h = swish(h)
        h = self.conv_out(h)
        return h


class DiagonalGaussian(nn.Module):
    def __init__(self, sample: bool = True, chunk_dim: int = 1):
        super().__init__()
        self.sample = sample
        self.chunk_dim = chunk_dim

    def forward(self, z: Tensor) -> Tensor:
        mean, logvar = torch.chunk(z, 2, dim=self.chunk_dim)
        if self.sample:
            std = torch.exp(0.5 * logvar)
            return mean + std * torch.randn_like(mean)
        else:
            return mean


class AutoEncoder(nn.Module):
    def __init__(self, params: AutoEncoderParams):
        super().__init__()
        self.encoder = Encoder(
            resolution=params.resolution,
            in_channels=params.in_channels,
            ch=params.ch,
            ch_mult=params.ch_mult,
            num_res_blocks=params.num_res_blocks,
            z_channels=params.z_channels,
        )
        self.decoder = Decoder(
            resolution=params.resolution,
            in_channels=params.in_channels,
            ch=params.ch,
            out_ch=params.out_ch,
            ch_mult=params.ch_mult,
            num_res_blocks=params.num_res_blocks,
            z_channels=params.z_channels,
        )
        self.reg = DiagonalGaussian()

        self.scale_factor = params.scale_factor
        self.shift_factor = params.shift_factor

    def encode(self, x: Tensor) -> Tensor:
        z = self.reg(self.encoder(x))
        z = self.scale_factor * (z - self.shift_factor)
        return z

    def decode(self, z: Tensor) -> Tensor:
        z = z / self.scale_factor + self.shift_factor
        return self.decoder(z)

    def forward(self, x: Tensor) -> Tensor:
        return self.decode(self.encode(x))


class DistributedAutoEncoder(AutoEncoder, DistributedVaeMixin):
    def __init__(self, params: AutoEncoderParams):
        super().__init__(params)
        self.init_distributed()

        self.use_tiling = False
        self.tile_sample_min_height = 512
        self.tile_sample_min_width = 512
        self.tile_sample_stride_height = 448
        self.tile_sample_stride_width = 448
        self.spatial_compression_ratio = params.downsample

    def blend_v(self, above: Tensor, current: Tensor, blend_extent: int) -> Tensor:
        blend_extent = min(above.shape[-2], current.shape[-2], blend_extent)
        if blend_extent <= 0:
            return current

        for y in range(blend_extent):
            alpha = y / blend_extent
            current[:, :, y, :] = above[:, :, -blend_extent + y, :] * (1 - alpha) + current[:, :, y, :] * alpha
        return current

    def blend_h(self, left: Tensor, current: Tensor, blend_extent: int) -> Tensor:
        blend_extent = min(left.shape[-1], current.shape[-1], blend_extent)
        if blend_extent <= 0:
            return current

        for x in range(blend_extent):
            alpha = x / blend_extent
            current[:, :, :, x] = left[:, :, :, -blend_extent + x] * (1 - alpha) + current[:, :, :, x] * alpha
        return current

    def decode_tile_split(self, z: Tensor) -> tuple[list[TileTask], GridSpec]:
        _, _, latent_height, latent_width = z.shape

        sample_height = latent_height * self.spatial_compression_ratio
        sample_width = latent_width * self.spatial_compression_ratio

        tile_latent_min_height = self.tile_sample_min_height // self.spatial_compression_ratio
        tile_latent_min_width = self.tile_sample_min_width // self.spatial_compression_ratio
        tile_latent_stride_height = self.tile_sample_stride_height // self.spatial_compression_ratio
        tile_latent_stride_width = self.tile_sample_stride_width // self.spatial_compression_ratio

        blend_height = self.tile_sample_min_height - self.tile_sample_stride_height
        blend_width = self.tile_sample_min_width - self.tile_sample_stride_width

        tiletask_list = []
        for i in range(0, latent_height, tile_latent_stride_height):
            for j in range(0, latent_width, tile_latent_stride_width):
                tile = z[
                    :,
                    :,
                    i : i + tile_latent_min_height,
                    j : j + tile_latent_min_width,
                ]
                tiletask_list.append(
                    TileTask(
                        tile_id=len(tiletask_list),
                        grid_coord=(i // tile_latent_stride_height, j // tile_latent_stride_width),
                        tensor=tile,
                        workload=tile.shape[-2] * tile.shape[-1],
                    )
                )
        grid_spec = GridSpec(
            split_dims=(2, 3),
            grid_shape=(tiletask_list[-1].grid_coord[0] + 1, tiletask_list[-1].grid_coord[1] + 1),
            tile_spec={
                "sample_height": sample_height,
                "sample_width": sample_width,
                "blend_height": blend_height,
                "blend_width": blend_width,
            },
            output_dtype=z.dtype,
        )
        return tiletask_list, grid_spec

    def decode_tile_exec(self, task: TileTask) -> Tensor:
        tile = task.tensor
        tile = tile / self.scale_factor + self.shift_factor
        return self.decoder(tile)

    def decode_tile_merge(self, coord_tensor_map: dict[tuple[int, ...], Tensor], grid_spec: GridSpec) -> Tensor:
        grid_h, grid_w = grid_spec.grid_shape
        result_rows = []

        for i in range(grid_h):
            result_row = []
            for j in range(grid_w):
                tile = coord_tensor_map[(i, j)]
                if i > 0:
                    tile = self.blend_v(coord_tensor_map[(i - 1, j)], tile, grid_spec.tile_spec["blend_height"])
                if j > 0:
                    tile = self.blend_h(coord_tensor_map[(i, j - 1)], tile, grid_spec.tile_spec["blend_width"])

                result_row.append(
                    tile[
                        :,
                        :,
                        : self.tile_sample_stride_height,
                        : self.tile_sample_stride_width,
                    ]
                )
            result_rows.append(torch.cat(result_row, dim=-1))

        dec = torch.cat(result_rows, dim=-2)[
            :,
            :,
            : grid_spec.tile_spec["sample_height"],
            : grid_spec.tile_spec["sample_width"],
        ]
        return dec

    def decode(self, z: Tensor) -> Tensor:
        if not self.is_distributed_enabled():
            return super().decode(z)

        logger.debug("Bagel VAE decode running with distributed executor")
        return self.distributed_executor.execute(
            z,
            DistributedOperator(
                split=self.decode_tile_split,
                exec=self.decode_tile_exec,
                merge=self.decode_tile_merge,
            ),
            broadcast_result=True,
        )

    def encode_tile_split(self, x: Tensor) -> tuple[list[TileTask], GridSpec]:
        _, _, height, width = x.shape

        latent_height = height // self.spatial_compression_ratio
        latent_width = width // self.spatial_compression_ratio

        tile_latent_min_height = self.tile_sample_min_height // self.spatial_compression_ratio
        tile_latent_min_width = self.tile_sample_min_width // self.spatial_compression_ratio

        tile_latent_stride_height = self.tile_sample_stride_height // self.spatial_compression_ratio
        tile_latent_stride_width = self.tile_sample_stride_width // self.spatial_compression_ratio

        blend_height = tile_latent_min_height - tile_latent_stride_height
        blend_width = tile_latent_min_width - tile_latent_stride_width

        tiletask_list = []
        for i in range(0, height, self.tile_sample_stride_height):
            for j in range(0, width, self.tile_sample_stride_width):
                tile = x[
                    :,
                    :,
                    i : i + self.tile_sample_min_height,
                    j : j + self.tile_sample_min_width,
                ]
                tiletask_list.append(
                    TileTask(
                        tile_id=len(tiletask_list),
                        grid_coord=(i // self.tile_sample_stride_height, j // self.tile_sample_stride_width),
                        tensor=tile,
                        workload=tile.shape[-2] * tile.shape[-1],
                    )
                )
        grid_spec = GridSpec(
            split_dims=(2, 3),
            grid_shape=(tiletask_list[-1].grid_coord[0] + 1, tiletask_list[-1].grid_coord[1] + 1),
            tile_spec={
                "latent_height": latent_height,
                "latent_width": latent_width,
                "blend_height": blend_height,
                "blend_width": blend_width,
                "tile_latent_stride_height": tile_latent_stride_height,
                "tile_latent_stride_width": tile_latent_stride_width,
            },
            output_dtype=next(self.parameters()).dtype,
        )
        return tiletask_list, grid_spec

    def encode_tile_exec(self, task: TileTask) -> Tensor:
        tile = task.tensor
        z = self.reg(self.encoder(tile))
        z = self.scale_factor * (z - self.shift_factor)
        return z

    def encode_tile_merge(self, coord_tensor_map: dict[tuple[int, ...], Tensor], grid_spec: GridSpec) -> Tensor:
        grid_h, grid_w = grid_spec.grid_shape
        result_rows = []

        for i in range(grid_h):
            result_row = []
            for j in range(grid_w):
                tile = coord_tensor_map[(i, j)]
                if i > 0:
                    tile = self.blend_v(coord_tensor_map[(i - 1, j)], tile, grid_spec.tile_spec["blend_height"])
                if j > 0:
                    tile = self.blend_h(coord_tensor_map[(i, j - 1)], tile, grid_spec.tile_spec["blend_width"])

                result_row.append(
                    tile[
                        :,
                        :,
                        : grid_spec.tile_spec["tile_latent_stride_height"],
                        : grid_spec.tile_spec["tile_latent_stride_width"],
                    ]
                )
            result_rows.append(torch.cat(result_row, dim=-1))

        enc = torch.cat(result_rows, dim=-2)[
            :,
            :,
            : grid_spec.tile_spec["latent_height"],
            : grid_spec.tile_spec["latent_width"],
        ]
        return enc

    def encode(self, x: Tensor) -> Tensor:
        if not self.is_distributed_enabled():
            return super().encode(x)
        logger.debug("Bagel VAE encode running with distributed executor")
        return self.distributed_executor.execute(
            x,
            DistributedOperator(
                split=self.encode_tile_split,
                exec=self.encode_tile_exec,
                merge=self.encode_tile_merge,
            ),
            broadcast_result=True,
        )