app.py

import os
import spaces

import time
import gradio as gr
import torch
from PIL import Image
from torchvision import transforms
from dataclasses import dataclass, field
import math
from typing import Callable

from tqdm import tqdm
import bitsandbytes as bnb
from bitsandbytes.nn.modules import Params4bit, QuantState

import torch
import random
from einops import rearrange, repeat
from diffusers import AutoencoderKL
from torch import Tensor, nn
from transformers import CLIPTextModel, CLIPTokenizer
from transformers import T5EncoderModel, T5Tokenizer

# ---------------- Encoders ----------------

class HFEmbedder(nn.Module):
    def __init__(self, version: str, max_length: int, **hf_kwargs):
        super().__init__()
        self.is_clip = version.startswith("openai")
        self.max_length = max_length
        self.output_key = "pooler_output" if self.is_clip else "last_hidden_state"

        if self.is_clip:
            self.tokenizer: CLIPTokenizer = CLIPTokenizer.from_pretrained(version, max_length=max_length)
            self.hf_module: CLIPTextModel = CLIPTextModel.from_pretrained(version, **hf_kwargs)
        else:
            self.tokenizer: T5Tokenizer = T5Tokenizer.from_pretrained(version, max_length=max_length)
            self.hf_module: T5EncoderModel = T5EncoderModel.from_pretrained(version, **hf_kwargs)

        self.hf_module = self.hf_module.eval().requires_grad_(False)

    def forward(self, text: list[str]) -> Tensor:
        batch_encoding = self.tokenizer(
            text,
            truncation=True,
            max_length=self.max_length,
            return_length=False,
            return_overflowing_tokens=False,
            padding="max_length",
            return_tensors="pt",
        )

        outputs = self.hf_module(
            input_ids=batch_encoding["input_ids"].to(self.hf_module.device),
            attention_mask=None,
            output_hidden_states=False,
        )
        return outputs[self.output_key]

device = "cuda"
t5 = HFEmbedder("DeepFloyd/t5-v1_1-xxl", max_length=512, torch_dtype=torch.bfloat16).to(device)
clip = HFEmbedder("openai/clip-vit-large-patch14", max_length=77, torch_dtype=torch.bfloat16).to(device)
ae = AutoencoderKL.from_pretrained("black-forest-labs/FLUX.1-dev", subfolder="vae", torch_dtype=torch.bfloat16).to(device)

# ---------------- NF4 ----------------

def functional_linear_4bits(x, weight, bias):
    out = bnb.matmul_4bit(x, weight.t(), bias=bias, quant_state=weight.quant_state)
    out = out.to(x)
    return out

def copy_quant_state(state: QuantState, device: torch.device = None) -> QuantState:
    if state is None:
        return None

    device = device or state.absmax.device

    state2 = (
        QuantState(
            absmax=state.state2.absmax.to(device),
            shape=state.state2.shape,
            code=state.state2.code.to(device),
            blocksize=state.state2.blocksize,
            quant_type=state.state2.quant_type,
            dtype=state.state2.dtype,
        )
        if state.nested
        else None
    )

    return QuantState(
        absmax=state.absmax.to(device),
        shape=state.shape,
        code=state.code.to(device),
        blocksize=state.blocksize,
        quant_type=state.quant_type,
        dtype=state.dtype,
        offset=state.offset.to(device) if state.nested else None,
        state2=state2,
    )

class ForgeParams4bit(Params4bit):
    def to(self, *args, **kwargs):
        device, dtype, non_blocking, convert_to_format = torch._C._nn._parse_to(*args, **kwargs)
        if device is not None and device.type == "cuda" and not self.bnb_quantized:
            return self._quantize(device)
        else:
            n = ForgeParams4bit(
                torch.nn.Parameter.to(self, device=device, dtype=dtype, non_blocking=non_blocking),
                requires_grad=self.requires_grad,
                quant_state=copy_quant_state(self.quant_state, device),
                compress_statistics=False,
                blocksize=64,
                quant_type=self.quant_type,
                quant_storage=self.quant_storage,
                bnb_quantized=self.bnb_quantized,
                module=self.module
            )
            self.module.quant_state = n.quant_state
            self.data = n.data
            self.quant_state = n.quant_state
            return n

class ForgeLoader4Bit(torch.nn.Module):
    def __init__(self, *, device, dtype, quant_type, **kwargs):
        super().__init__()
        self.dummy = torch.nn.Parameter(torch.empty(1, device=device, dtype=dtype))
        self.weight = None
        self.quant_state = None
        self.bias = None
        self.quant_type = quant_type

    def _save_to_state_dict(self, destination, prefix, keep_vars):
        super()._save_to_state_dict(destination, prefix, keep_vars)
        quant_state = getattr(self.weight, "quant_state", None)
        if quant_state is not None:
            for k, v in quant_state.as_dict(packed=True).items():
                destination[prefix + "weight." + k] = v if keep_vars else v.detach()
        return

    def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs):
        quant_state_keys = {k[len(prefix + "weight."):] for k in state_dict.keys() if k.startswith(prefix + "weight.")}

        if any('bitsandbytes' in k for k in quant_state_keys):
            quant_state_dict = {k: state_dict[prefix + "weight." + k] for k in quant_state_keys}

            self.weight = ForgeParams4bit.from_prequantized(
                data=state_dict[prefix + 'weight'],
                quantized_stats=quant_state_dict,
                requires_grad=False,
                device=torch.device('cuda'),
                module=self
            )
            self.quant_state = self.weight.quant_state

            if prefix + 'bias' in state_dict:
                self.bias = torch.nn.Parameter(state_dict[prefix + 'bias'].to(self.dummy))

            del self.dummy
        elif hasattr(self, 'dummy'):
            if prefix + 'weight' in state_dict:
                self.weight = ForgeParams4bit(
                    state_dict[prefix + 'weight'].to(self.dummy),
                    requires_grad=False,
                    compress_statistics=True,
                    quant_type=self.quant_type,
                    quant_storage=torch.uint8,
                    module=self,
                )
                self.quant_state = self.weight.quant_state

            if prefix + 'bias' in state_dict:
                self.bias = torch.nn.Parameter(state_dict[prefix + 'bias'].to(self.dummy))

            del self.dummy
        else:
            super()._load_from_state_dict(state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs)

class Linear(ForgeLoader4Bit):
    def __init__(self, *args, device=None, dtype=None, **kwargs):
        super().__init__(device=device, dtype=dtype, quant_type='nf4')

    def forward(self, x):
        self.weight.quant_state = self.quant_state

        if self.bias is not None and self.bias.dtype != x.dtype:
            self.bias.data = self.bias.data.to(x.dtype)

        return functional_linear_4bits(x, self.weight, self.bias)

nn.Linear = Linear

# ---------------- Model ----------------

def attention(q: Tensor, k: Tensor, v: Tensor, pe: Tensor) -> Tensor:
    q, k = apply_rope(q, k, pe)
    x = torch.nn.functional.scaled_dot_product_attention(q, k, v)
    x = x.permute(0, 2, 1, 3).reshape(x.size(0), x.size(2), -1)
    return x

def rope(pos, dim, theta):
    scale = torch.arange(0, dim, 2, dtype=torch.float64, device=pos.device) / dim
    omega = 1.0 / (theta ** scale)
    out = pos.unsqueeze(-1) * omega.unsqueeze(0)
    cos_out = torch.cos(out)
    sin_out = torch.sin(out)
    out = torch.stack([cos_out, -sin_out, sin_out, cos_out], dim=-1)
    b, n, d, _ = out.shape
    out = out.view(b, n, d, 2, 2)
    return out.float()

def apply_rope(xq: Tensor, xk: Tensor, freqs_cis: Tensor) -> tuple[Tensor, Tensor]:
    xq_ = xq.float().reshape(*xq.shape[:-1], -1, 1, 2)
    xk_ = xk.float().reshape(*xk.shape[:-1], -1, 1, 2)
    xq_out = freqs_cis[..., 0] * xq_[..., 0] + freqs_cis[..., 1] * xq_[..., 1]
    xk_out = freqs_cis[..., 0] * xk_[..., 0] + freqs_cis[..., 1] * xk_[..., 1]
    return xq_out.reshape(*xq.shape).type_as(xq), xk_out.reshape(*xk.shape).type_as(xk)

class EmbedND(nn.Module):
    def __init__(self, dim: int, theta: int, axes_dim: list[int]):
        super().__init__()
        self.dim = dim
        self.theta = theta
        self.axes_dim = axes_dim

    def forward(self, ids: Tensor) -> Tensor:
        n_axes = ids.shape[-1]
        emb = torch.cat(
            [rope(ids[..., i], self.axes_dim[i], self.theta) for i in range(n_axes)],
            dim=-3,
        )
        return emb.unsqueeze(1)

def timestep_embedding(t: Tensor, dim, max_period=10000, time_factor: float = 1000.0):
    t = time_factor * t
    half = dim // 2
    freqs = torch.exp(-math.log(max_period) * torch.arange(start=0, end=half, dtype=torch.float32) / half).to(t.device)
    args = t[:, None].float() * freqs[None]
    embedding = torch.cat([torch.cos(args), torch.sin(args)], dim=-1)
    if dim % 2:
        embedding = torch.cat([embedding, torch.zeros_like(embedding[:, :1])], dim=-1)
    if torch.is_floating_point(t):
        embedding = embedding.to(t)
    return embedding

class MLPEmbedder(nn.Module):
    def __init__(self, in_dim: int, hidden_dim: int):
        super().__init__()
        self.in_layer = nn.Linear(in_dim, hidden_dim, bias=True)
        self.silu = nn.SiLU()
        self.out_layer = nn.Linear(hidden_dim, hidden_dim, bias=True)

    def forward(self, x: Tensor) -> Tensor:
        return self.out_layer(self.silu(self.in_layer(x)))

class RMSNorm(torch.nn.Module):
    def __init__(self, dim: int):
        super().__init__()
        self.scale = nn.Parameter(torch.ones(dim))

    def forward(self, x: Tensor):
        x_dtype = x.dtype
        x = x.float()
        rrms = torch.rsqrt(torch.mean(x**2, dim=-1, keepdim=True) + 1e-6)
        return (x * rrms).to(dtype=x_dtype) * self.scale

class QKNorm(torch.nn.Module):
    def __init__(self, dim: int):
        super().__init__()
        self.query_norm = RMSNorm(dim)
        self.key_norm = RMSNorm(dim)

    def forward(self, q: Tensor, k: Tensor, v: Tensor) -> tuple[Tensor, Tensor]:
        q = self.query_norm(q)
        k = self.key_norm(k)
        return q.to(v), k.to(v)

class SelfAttention(nn.Module):
    def __init__(self, dim: int, num_heads: int = 8, qkv_bias: bool = False):
        super().__init__()
        self.num_heads = num_heads
        self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)
        head_dim = dim // num_heads
        self.norm = QKNorm(head_dim)
        self.proj = nn.Linear(dim, dim)

    def forward(self, x: Tensor, pe: Tensor) -> Tensor:
        qkv = self.qkv(x)
        B, L, _ = qkv.shape
        qkv = qkv.view(B, L, 3, self.num_heads, -1)
        q, k, v = qkv.permute(2, 0, 3, 1, 4)
        q, k = self.norm(q, k, v)
        x = attention(q, k, v, pe=pe)
        x = self.proj(x)
        return x

@dataclass
class ModulationOut:
    shift: Tensor
    scale: Tensor
    gate: Tensor

class Modulation(nn.Module):
    def __init__(self, dim: int, double: bool):
        super().__init__()
        self.is_double = double
        self.multiplier = 6 if double else 3
        self.lin = nn.Linear(dim, self.multiplier * dim, bias=True)

    def forward(self, vec: Tensor) -> tuple[ModulationOut, ModulationOut | None]:
        out = self.lin(nn.functional.silu(vec))[:, None, :].chunk(self.multiplier, dim=-1)
        return (
            ModulationOut(*out[:3]),
            ModulationOut(*out[3:]) if self.is_double else None,
        )

class DoubleStreamBlock(nn.Module):
    def __init__(self, hidden_size: int, num_heads: int, mlp_ratio: float, qkv_bias: bool = False):
        super().__init__()
        mlp_hidden_dim = int(hidden_size * mlp_ratio)
        self.num_heads = num_heads
        self.hidden_size = hidden_size
        self.img_mod = Modulation(hidden_size, double=True)
        self.img_norm1 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
        self.img_attn = SelfAttention(dim=hidden_size, num_heads=num_heads, qkv_bias=qkv_bias)
        self.img_norm2 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
        self.img_mlp = nn.Sequential(
            nn.Linear(hidden_size, mlp_hidden_dim, bias=True),
            nn.GELU(approximate="tanh"),
            nn.Linear(mlp_hidden_dim, hidden_size, bias=True),
        )
        self.txt_mod = Modulation(hidden_size, double=True)
        self.txt_norm1 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
        self.txt_attn = SelfAttention(dim=hidden_size, num_heads=num_heads, qkv_bias=qkv_bias)
        self.txt_norm2 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
        self.txt_mlp = nn.Sequential(
            nn.Linear(hidden_size, mlp_hidden_dim, bias=True),
            nn.GELU(approximate="tanh"),
            nn.Linear(mlp_hidden_dim, hidden_size, bias=True),
        )

    def forward(self, img: Tensor, txt: Tensor, vec: Tensor, pe: Tensor) -> tuple[Tensor, Tensor]:
        img_mod1, img_mod2 = self.img_mod(vec)
        txt_mod1, txt_mod2 = self.txt_mod(vec)

        # Image attention
        img_modulated = self.img_norm1(img)
        img_modulated = (1 + img_mod1.scale) * img_modulated + img_mod1.shift
        img_qkv = self.img_attn.qkv(img_modulated)
        B, L, _ = img_qkv.shape
        H = self.num_heads
        D = img_qkv.shape[-1] // (3 * H)
        img_q, img_k, img_v = img_qkv.view(B, L, 3, H, D).permute(2, 0, 3, 1, 4)
        img_q, img_k = self.img_attn.norm(img_q, img_k, img_v)

        # Text attention
        txt_modulated = self.txt_norm1(txt)
        txt_modulated = (1 + txt_mod1.scale) * txt_modulated + txt_mod1.shift
        txt_qkv = self.txt_attn.qkv(txt_modulated)
        B, L, _ = txt_qkv.shape
        txt_q, txt_k, txt_v = txt_qkv.view(B, L, 3, H, D).permute(2, 0, 3, 1, 4)
        txt_q, txt_k = self.txt_attn.norm(txt_q, txt_k, txt_v)

        # Combined attention
        q = torch.cat((txt_q, img_q), dim=2)
        k = torch.cat((txt_k, img_k), dim=2)
        v = torch.cat((txt_v, img_v), dim=2)
        attn = attention(q, k, v, pe=pe)
        txt_attn, img_attn = attn[:, : txt.shape[1]], attn[:, txt.shape[1] :]

        # Img final
        img = img + img_mod1.gate * self.img_attn.proj(img_attn)
        img = img + img_mod2.gate * self.img_mlp((1 + img_mod2.scale) * self.img_norm2(img) + img_mod2.shift)

        # Text final
        txt = txt + txt_mod1.gate * self.txt_attn.proj(txt_attn)
        txt = txt + txt_mod2.gate * self.txt_mlp((1 + txt_mod2.scale) * self.txt_norm2(txt) + txt_mod2.shift)
        return img, txt

class SingleStreamBlock(nn.Module):
    def __init__(
        self,
        hidden_size: int,
        num_heads: int,
        mlp_ratio: float = 4.0,
        qk_scale: float | None = None,
    ):
        super().__init__()
        self.hidden_dim = hidden_size
        self.num_heads = num_heads
        head_dim = hidden_size // num_heads
        self.scale = qk_scale or head_dim**-0.5
        self.mlp_hidden_dim = int(hidden_size * mlp_ratio)
        self.linear1 = nn.Linear(hidden_size, hidden_size * 3 + self.mlp_hidden_dim)
        self.linear2 = nn.Linear(hidden_size + self.mlp_hidden_dim, hidden_size)
        self.norm = QKNorm(head_dim)
        self.hidden_size = hidden_size
        self.pre_norm = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
        self.mlp_act = nn.GELU(approximate="tanh")
        self.modulation = Modulation(hidden_size, double=False)

    def forward(self, x: Tensor, vec: Tensor, pe: Tensor) -> Tensor:
        mod, _ = self.modulation(vec)
        x_mod = (1 + mod.scale) * self.pre_norm(x) + mod.shift
        qkv, mlp = torch.split(self.linear1(x_mod), [3 * self.hidden_size, self.mlp_hidden_dim], dim=-1)
        qkv = qkv.view(qkv.size(0), qkv.size(1), 3, self.num_heads, self.hidden_size // self.num_heads)
        q, k, v = qkv.permute(2, 0, 3, 1, 4)
        q, k = self.norm(q, k, v)
        attn = attention(q, k, v, pe=pe)
        output = self.linear2(torch.cat((attn, self.mlp_act(mlp)), 2))
        return x + mod.gate * output

class LastLayer(nn.Module):
    def __init__(self, hidden_size: int, patch_size: int, out_channels: int):
        super().__init__()
        self.norm_final = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
        self.linear = nn.Linear(hidden_size, patch_size * patch_size * out_channels, bias=True)
        self.adaLN_modulation = nn.Sequential(nn.SiLU(), nn.Linear(hidden_size, 2 * hidden_size, bias=True))

    def forward(self, x: Tensor, vec: Tensor) -> Tensor:
        shift, scale = self.adaLN_modulation(vec).chunk(2, dim=1)
        x = (1 + scale[:, None, :]) * self.norm_final(x) + shift[:, None, :]
        x = self.linear(x)
        return x

@dataclass
class FluxParams:
    in_channels: int = 64
    vec_in_dim: int = 768
    context_in_dim: int = 4096
    hidden_size: int = 3072
    mlp_ratio: float = 4.0
    num_heads: int = 24
    depth: int = 19
    depth_single_blocks: int = 38
    axes_dim: list[int] = field(default_factory=lambda: [16, 56, 56])
    theta: int = 10000
    qkv_bias: bool = True
    guidance_embed: bool = True

class Flux(nn.Module):
    def __init__(self, params = FluxParams()):
        super().__init__()
        self.params = params
        self.in_channels = params.in_channels
        self.out_channels = self.in_channels
        if params.hidden_size % params.num_heads != 0:
            raise ValueError(
                f"Hidden size {params.hidden_size} must be divisible by num_heads {params.num_heads}"
            )
        pe_dim = params.hidden_size // params.num_heads
        if sum(params.axes_dim) != pe_dim:
            raise ValueError(f"Got {params.axes_dim} but expected positional dim {pe_dim}")
        self.hidden_size = params.hidden_size
        self.num_heads = params.num_heads
        self.pe_embedder = EmbedND(dim=pe_dim, theta=params.theta, axes_dim=params.axes_dim)
        self.img_in = nn.Linear(self.in_channels, self.hidden_size, bias=True)
        self.time_in = MLPEmbedder(in_dim=256, hidden_dim=self.hidden_size)
        self.vector_in = MLPEmbedder(params.vec_in_dim, self.hidden_size)
        self.guidance_in = (
            MLPEmbedder(in_dim=256, hidden_dim=self.hidden_size) if params.guidance_embed else nn.Identity()
        )
        self.txt_in = nn.Linear(params.context_in_dim, self.hidden_size)

        self.double_blocks = nn.ModuleList(
            [
                DoubleStreamBlock(
                    self.hidden_size,
                    self.num_heads,
                    mlp_ratio=params.mlp_ratio,
                    qkv_bias=params.qkv_bias,
                )
                for _ in range(params.depth)
            ]
        )

        self.single_blocks = nn.ModuleList(
            [
                SingleStreamBlock(self.hidden_size, self.num_heads, mlp_ratio=params.mlp_ratio)
                for _ in range(params.depth_single_blocks)
            ]
        )

        self.final_layer = LastLayer(self.hidden_size, 1, self.out_channels)

    def forward(
        self,
        img: Tensor,
        img_ids: Tensor,
        txt: Tensor,
        txt_ids: Tensor,
        timesteps: Tensor,
        y: Tensor,
        guidance: Tensor | None = None,
    ) -> Tensor:
        if img.ndim != 3 or txt.ndim != 3:
            raise ValueError("Input img and txt tensors must have 3 dimensions.")
        img = self.img_in(img)
        vec = self.time_in(timestep_embedding(timesteps, 256))
        if self.params.guidance_embed:
            if guidance is None:
                raise ValueError("No guidance strength provided for guidance-distilled model.")
            vec = vec + self.guidance_in(timestep_embedding(guidance, 256))
        vec = vec + self.vector_in(y)
        txt = self.txt_in(txt)
        ids = torch.cat((txt_ids, img_ids), dim=1)
        pe = self.pe_embedder(ids)
        for block in self.double_blocks:
            img, txt = block(img=img, txt=txt, vec=vec, pe=pe)
        img = torch.cat((txt, img), 1)
        for block in self.single_blocks:
            img = block(img, vec=vec, pe=pe)
        img = img[:, txt.shape[1] :, ...]
        img = self.final_layer(img, vec)
        return img

def prepare(t5: HFEmbedder, clip: HFEmbedder, img: Tensor, prompt: str | list[str]) -> dict[str, Tensor]:
    bs, c, h, w = img.shape
    if bs == 1 and not isinstance(prompt, str):
        bs = len(prompt)
    img = rearrange(img, "b c (h ph) (w pw) -> b (h w) (c ph pw)", ph=2, pw=2)
    if img.shape[0] == 1 and bs > 1:
        img = repeat(img, "1 ... -> bs ...", bs=bs)
    img_ids = torch.zeros(h // 2, w // 2, 3)
    img_ids[..., 1] = img_ids[..., 1] + torch.arange(h // 2)[:, None]
    img_ids[..., 2] = img_ids[..., 2] + torch.arange(w // 2)[None, :]
    img_ids = repeat(img_ids, "h w c -> b (h w) c", b=bs)
    if isinstance(prompt, str):
        prompt = [prompt]
    txt = t5(prompt)
    if txt.shape[0] == 1 and bs > 1:
        txt = repeat(txt, "1 ... -> bs ...", bs=bs)
    txt_ids = torch.zeros(bs, txt.shape[1], 3)
    vec = clip(prompt)
    if vec.shape[0] == 1 and bs > 1:
        vec = repeat(vec, "1 ... -> bs ...", bs=bs)
    return {
        "img": img,
        "img_ids": img_ids.to(img.device),
        "txt": txt.to(img.device),
        "txt_ids": txt_ids.to(img.device),
        "vec": vec.to(img.device),
    }

def time_shift(mu: float, sigma: float, t: Tensor):
    return math.exp(mu) / (math.exp(mu) + (1 / t - 1) ** sigma)

def get_lin_function(
    x1: float = 256, y1: float = 0.5, x2: float = 4096, y2: float = 1.15
) -> Callable[[float], float]:
    m = (y2 - y1) / (x2 - x1)
    b = y1 - m * x1
    return lambda x: m * x + b

def get_schedule(
    num_steps: int,
    image_seq_len: int,
    base_shift: float = 0.5,
    max_shift: float = 1.15,
    shift: bool = True,
) -> list[float]:
    timesteps = torch.linspace(1, 0, num_steps + 1)
    if shift:
        mu = get_lin_function(y1=base_shift, y2=max_shift)(image_seq_len)
        timesteps = time_shift(mu, 1.0, timesteps)
    return timesteps.tolist()

def denoise(
    model: "Flux",
    img: Tensor,
    img_ids: Tensor,
    txt: Tensor,
    txt_ids: Tensor,
    vec: Tensor,
    timesteps: list[float],
    guidance: float = 4.0,
):
    guidance_vec = torch.full((img.shape[0],), guidance, device=img.device, dtype=img.dtype)
    for t_curr, t_prev in tqdm(zip(timesteps[:-1], timesteps[1:]), total=len(timesteps) - 1):
        t_vec = torch.full((img.shape[0],), t_curr, dtype=img.dtype, device=img.device)
        pred = model(
            img=img,
            img_ids=img_ids,
            txt=txt,
            txt_ids=txt_ids,
            y=vec,
            timesteps=t_vec,
            guidance=guidance_vec,
        )
        img = img + (t_prev - t_curr) * pred
    return img

def unpack(x: Tensor, height: int, width: int) -> Tensor:
    return rearrange(
        x,
        "b (h w) (c ph pw) -> b c (h ph) (w pw)",
        h=math.ceil(height / 16),
        w=math.ceil(width / 16),
        ph=2,
        pw=2,
    )

@dataclass
class SamplingOptions:
    prompt: str
    width: int
    height: int
    guidance: float
    seed: int | None

def get_image(image) -> torch.Tensor | None:
    if image is None:
        return None
    image = Image.fromarray(image).convert("RGB")
    transform = transforms.Compose([
        transforms.ToTensor(),
        transforms.Lambda(lambda x: 2.0 * x - 1.0),
    ])
    img: torch.Tensor = transform(image)
    return img[None, ...]

from huggingface_hub import hf_hub_download
from safetensors.torch import load_file

sd = load_file(hf_hub_download(repo_id="lllyasviel/flux1-dev-bnb-nf4", filename="flux1-dev-bnb-nf4-v2.safetensors"))
sd = {k.replace("model.diffusion_model.", ""): v for k, v in sd.items() if "model.diffusion_model" in k}
model = Flux().to(dtype=torch.bfloat16, device="cuda")
result = model.load_state_dict(sd)
model_zero_init = False

@spaces.GPU
@torch.no_grad()
def generate_image(
    prompt, width, height, guidance, inference_steps, seed,
    do_img2img, init_image, image2image_strength, resize_img,
    progress=gr.Progress(track_tqdm=True),
):
    if seed == 0:
        seed = int(random.random() * 1000000)
        
    device = "cuda" if torch.cuda.is_available() else "cpu"
    torch_device = torch.device(device)
    
    global model, model_zero_init
    if not model_zero_init:
        model = model.to(torch_device)
        model_zero_init = True
    
    if do_img2img and init_image is not None:
        init_image = get_image(init_image)
        if resize_img:
            init_image = torch.nn.functional.interpolate(init_image, (height, width))
        else:
            h, w = init_image.shape[-2:]
            init_image = init_image[..., : 16 * (h // 16), : 16 * (w // 16)]
            height = init_image.shape[-2]
            width = init_image.shape[-1]
        init_image = ae.encode(init_image.to(torch_device).to(torch.bfloat16)).latent_dist.sample()
        init_image = (init_image - ae.config.shift_factor) * ae.config.scaling_factor

    generator = torch.Generator(device=device).manual_seed(seed)
    x = torch.randn(
        1,
        16,
        2 * math.ceil(height / 16),
        2 * math.ceil(width / 16),
        device=device,
        dtype=torch.bfloat16,
        generator=generator
    )

    num_steps = inference_steps
    timesteps = get_schedule(num_steps, (x.shape[-1] * x.shape[-2]) // 4, shift=True)

    if do_img2img and init_image is not None:
        t_idx = int((1 - image2image_strength) * num_steps)
        t = timesteps[t_idx]
        timesteps = timesteps[t_idx:]
        x = t * x + (1.0 - t) * init_image.to(x.dtype)

    inp = prepare(t5=t5, clip=clip, img=x, prompt=prompt)
    x = denoise(model, **inp, timesteps=timesteps, guidance=guidance)
    x = unpack(x.float(), height, width)
    with torch.autocast(device_type=torch_device.type, dtype=torch.bfloat16):
        x = (x / ae.config.scaling_factor) + ae.config.shift_factor
        x = ae.decode(x).sample
    x = x.clamp(-1, 1)
    x = rearrange(x[0], "c h w -> h w c")
    img = Image.fromarray((127.5 * (x + 1.0)).cpu().byte().numpy())
    return img, seed

def create_demo():
    with gr.Blocks(css=".gradio-container {background-color: #282828 !important;}") as demo:
        gr.HTML(
            """
            <div style="text-align: center; margin: 0 auto;">
                <h1 style="color: #ffffff; font-weight: 900;">
                    FluxLLama
                </h1>
            </div>
            """
        )
        with gr.Row():
            with gr.Column():
                prompt = gr.Textbox(label="Prompt", value="A majestic castle on top of a floating island")
                width = gr.Slider(minimum=128, maximum=2048, step=64, label="Width", value=640)
                height = gr.Slider(minimum=128, maximum=2048, step=64, label="Height", value=640)
                guidance = gr.Slider(minimum=1.0, maximum=5.0, step=0.1, label="Guidance", value=3.5)
                inference_steps = gr.Slider(
                    label="Inference steps",
                    minimum=1,
                    maximum=30,
                    step=1,
                    value=16,
                )
                seed = gr.Number(label="Seed", precision=-1)
                do_img2img = gr.Checkbox(label="Image to Image", value=False)
                init_image = gr.Image(label="Initial Image", visible=False)
                image2image_strength = gr.Slider(minimum=0.0, maximum=1.0, step=0.01, label="Noising Strength", value=0.8, visible=False)
                resize_img = gr.Checkbox(label="Resize Initial Image", value=True, visible=False)
                generate_button = gr.Button("Generate", variant="primary")
            with gr.Column():
                output_image = gr.Image(label="Result")
                output_seed = gr.Text(label="Seed Used")

        do_img2img.change(
            fn=lambda x: [gr.update(visible=x), gr.update(visible=x), gr.update(visible=x)],
            inputs=[do_img2img],
            outputs=[init_image, image2image_strength, resize_img]
        )

        generate_button.click(
            fn=generate_image,
            inputs=[prompt, width, height, guidance, inference_steps, seed, do_img2img, init_image, image2image_strength, resize_img],
            outputs=[output_image, output_seed]
        )
    return demo

if __name__ == "__main__":
    demo = create_demo()
    demo.launch()