app.py

import gradio as gr
import os
import tempfile
import shutil
import re
import json
import datetime
from pathlib import Path
from huggingface_hub import HfApi, hf_hub_download
from safetensors.torch import load_file, save_file
import torch
import torch.nn.functional as F
import traceback
import math
try:
    from modelscope.hub.file_download import model_file_download as ms_file_download
    from modelscope.hub.api import HubApi as ModelScopeApi
    MODELScope_AVAILABLE = True
except ImportError:
    MODELScope_AVAILABLE = False

def get_fp8_dtype(fp8_format):
    """Get torch FP8 dtype."""
    if fp8_format == "e5m2":
        return torch.float8_e5m2
    else:
        return torch.float8_e4m3fn

def quantize_and_get_error(weight, fp8_dtype):
    """Quantize weight to FP8 and return both quantized weight and error."""
    weight_fp8 = weight.to(fp8_dtype)
    weight_dequantized = weight_fp8.to(weight.dtype)
    error = weight - weight_dequantized
    return weight_fp8, error

def low_rank_decomposition_error(error_tensor, rank=32, min_error_threshold=1e-6):
    """Decompose error tensor with proper rank reduction."""
    if error_tensor.ndim not in [2, 4]:
        return None, None
    
    try:
        # Calculate error magnitude
        error_norm = torch.norm(error_tensor.float())
        if error_norm < min_error_threshold:
            return None, None
        
        # For 2D tensors (linear layers)
        if error_tensor.ndim == 2:
            U, S, Vh = torch.linalg.svd(error_tensor.float(), full_matrices=False)
            
            # Calculate rank based on variance explained (keep 95% of error)
            total_variance = torch.sum(S ** 2)
            cumulative = torch.cumsum(S ** 2, dim=0)
            keep_components = torch.sum(cumulative <= 0.95 * total_variance).item() + 1
            
            # Limit rank to much smaller than original
            max_rank = min(error_tensor.shape)
            actual_rank = min(rank, keep_components, max_rank // 2)
            
            if actual_rank < 2:
                return None, None
                
            A = Vh[:actual_rank, :].contiguous()
            B = U[:, :actual_rank] @ torch.diag(S[:actual_rank]).contiguous()
            
            return A, B
        
        # For 4D convolutions
        elif error_tensor.ndim == 4:
            out_ch, in_ch, kH, kW = error_tensor.shape
            
            # Reshape to 2D for decomposition
            error_2d = error_tensor.view(out_ch, in_ch * kH * kW)
            U, S, Vh = torch.linalg.svd(error_2d.float(), full_matrices=False)
            
            # Calculate rank based on variance explained (90% for conv)
            total_variance = torch.sum(S ** 2)
            cumulative = torch.cumsum(S ** 2, dim=0)
            keep_components = torch.sum(cumulative <= 0.90 * total_variance).item() + 1
            
            # Use even lower rank for conv
            max_rank = min(error_2d.shape)
            actual_rank = min(rank // 2, keep_components, max_rank // 4)
            
            if actual_rank < 2:
                return None, None
                
            A = Vh[:actual_rank, :].contiguous()
            B = U[:, :actual_rank] @ torch.diag(S[:actual_rank]).contiguous()
            
            # Reshape back for convolutional format
            if kH == 1 and kW == 1:
                B = B.view(out_ch, actual_rank, 1, 1)
                A = A.view(actual_rank, in_ch, 1, 1)
            else:
                B = B.view(out_ch, actual_rank, 1, 1)
                A = A.view(actual_rank, in_ch, kH, kW)
                
            return A, B
            
    except Exception as e:
        print(f"Error decomposition failed: {e}")
    
    return None, None

def extract_correction_factors(original_weight, fp8_weight):
    """Extract simple correction factors for VAE."""
    with torch.no_grad():
        orig = original_weight.float()
        quant = fp8_weight.float()
        error = orig - quant
        
        error_norm = torch.norm(error)
        orig_norm = torch.norm(orig)
        if orig_norm > 1e-6 and error_norm / orig_norm < 0.001:
            return None
            
        # For 4D tensors (VAE), compute per-channel correction
        if orig.ndim == 4:
            channel_mean = error.mean(dim=tuple(i for i in range(1, orig.ndim)), keepdim=True)
            return channel_mean.to(original_weight.dtype)
        elif orig.ndim == 2:
            row_mean = error.mean(dim=1, keepdim=True)
            return row_mean.to(original_weight.dtype)
        else:
            return error.mean().to(original_weight.dtype)

def get_architecture_settings(architecture, base_rank):
    """Get optimal settings for different architectures."""
    settings = {
        "text_encoder": {
            "rank": base_rank,
            "error_threshold": 5e-5,
            "min_rank": 8,
            "max_rank_factor": 0.4,
            "method": "lora"
        },
        "transformer": {
            "rank": base_rank,
            "error_threshold": 1e-5,
            "min_rank": 12,
            "max_rank_factor": 0.35,
            "method": "lora"
        },
        "vae": {
            "rank": base_rank // 2,
            "error_threshold": 1e-4,
            "min_rank": 4,
            "max_rank_factor": 0.3,
            "method": "correction"
        },
        "unet_conv": {
            "rank": base_rank // 3,
            "error_threshold": 2e-5,
            "min_rank": 8,
            "max_rank_factor": 0.25,
            "method": "lora"
        },
        "auto": {
            "rank": base_rank,
            "error_threshold": 1e-5,
            "min_rank": 8,
            "max_rank_factor": 0.3,
            "method": "lora"
        },
        "all": {
            "rank": base_rank,
            "error_threshold": 1e-5,
            "min_rank": 8,
            "max_rank_factor": 0.3,
            "method": "lora"
        }
    }
    
    return settings.get(architecture, settings["auto"])

def should_process_layer(key, weight, architecture):
    """Determine if layer should be processed for LoRA/correction."""
    lower_key = key.lower()
    
    # Skip biases and normalization layers
    if 'bias' in key or 'norm' in key.lower() or 'bn' in key.lower():
        return False
    
    if weight.numel() < 100:
        return False
    
    # Architecture-specific filtering
    if architecture == "text_encoder":
        return ('text' in lower_key or 'emb' in lower_key or 
                'encoder' in lower_key or 'attn' in lower_key)
    elif architecture == "transformer":
        return ('attn' in lower_key or 'transformer' in lower_key or 
                'mlp' in lower_key or 'to_out' in lower_key)
    elif architecture == "vae":
        return ('vae' in lower_key or 'encoder' in lower_key or 
                'decoder' in lower_key or 'conv' in lower_key)
    elif architecture == "unet_conv":
        return ('conv' in lower_key or 'resnet' in lower_key or 
                'downsample' in lower_key or 'upsample' in lower_key)
    elif architecture in ["all", "auto"]:
        return True
    
    return False

def convert_safetensors_to_fp8_with_lora(safetensors_path, output_dir, fp8_format, lora_rank=128, architecture="auto", progress=gr.Progress()):
    progress(0.1, desc="Starting FP8 conversion with error recovery...")
    try:
        def read_safetensors_metadata(path):
            with open(path, 'rb') as f:
                header_size = int.from_bytes(f.read(8), 'little')
                header_json = f.read(header_size).decode('utf-8')
                header = json.loads(header_json)
                return header.get('__metadata__', {})
        
        metadata = read_safetensors_metadata(safetensors_path)
        progress(0.2, desc="Loaded metadata.")
        
        state_dict = load_file(safetensors_path)
        progress(0.4, desc="Loaded weights.")
        
        # Auto-detect architecture if needed
        if architecture == "auto":
            model_keys = " ".join(state_dict.keys()).lower()
            if "vae" in model_keys or ("encoder" in model_keys and "decoder" in model_keys):
                architecture = "vae"
            elif "text" in model_keys or "emb" in model_keys:
                architecture = "text_encoder"
            elif "attn" in model_keys or "transformer" in model_keys:
                architecture = "transformer"
            elif "conv" in model_keys or "resnet" in model_keys:
                architecture = "unet_conv"
            else:
                architecture = "all"
        
        settings = get_architecture_settings(architecture, lora_rank)
        fp8_dtype = get_fp8_dtype(fp8_format)
        
        sd_fp8 = {}
        lora_weights = {}
        correction_factors = {}
        stats = {
            "total_layers": len(state_dict),
            "eligible_layers": 0,
            "layers_with_error": 0,
            "processed_layers": 0,
            "correction_layers": 0,
            "skipped_layers": [],
            "architecture": architecture,
            "method": settings["method"],
            "error_magnitudes": []
        }
        
        total = len(state_dict)
        
        for i, key in enumerate(state_dict):
            progress(0.4 + 0.4 * (i / total), desc=f"Processing {i+1}/{total}...")
            weight = state_dict[key]
            
            if weight.dtype in [torch.float16, torch.float32, torch.bfloat16]:
                # Quantize to FP8 and calculate error
                weight_fp8, error = quantize_and_get_error(weight, fp8_dtype)
                sd_fp8[key] = weight_fp8
                
                # Calculate error magnitude
                error_norm = torch.norm(error.float())
                weight_norm = torch.norm(weight.float())
                relative_error = (error_norm / weight_norm).item() if weight_norm > 0 else 0
                
                stats["error_magnitudes"].append({
                    "key": key,
                    "relative_error": relative_error
                })
                
                # Check if layer should be processed
                should_process = should_process_layer(key, weight, architecture)
                
                if should_process:
                    stats["eligible_layers"] += 1
                    
                    # Only process if error is significant
                    if relative_error > settings["error_threshold"]:
                        stats["layers_with_error"] += 1
                        
                        if settings["method"] == "correction":
                            # Use correction factors for VAE
                            correction = extract_correction_factors(weight, weight_fp8)
                            if correction is not None:
                                correction_factors[f"correction.{key}"] = correction
                                stats["correction_layers"] += 1
                                stats["processed_layers"] += 1
                        else:
                            # Use LoRA decomposition for other architectures
                            try:
                                A, B = low_rank_decomposition_error(
                                    error,
                                    rank=settings["rank"],
                                    min_error_threshold=settings["error_threshold"]
                                )
                                
                                if A is not None and B is not None:
                                    lora_weights[f"lora_A.{key}"] = A.to(torch.float16)
                                    lora_weights[f"lora_B.{key}"] = B.to(torch.float16)
                                    stats["processed_layers"] += 1
                                else:
                                    stats["skipped_layers"].append(f"{key}: decomposition failed")
                            except Exception as e:
                                stats["skipped_layers"].append(f"{key}: error - {str(e)}")
                    else:
                        stats["skipped_layers"].append(f"{key}: error too small ({relative_error:.6f})")
            else:
                sd_fp8[key] = weight
                stats["skipped_layers"].append(f"{key}: non-float dtype")
        
        # Calculate average error
        if stats["error_magnitudes"]:
            errors = [e["relative_error"] for e in stats["error_magnitudes"]]
            stats["avg_error"] = sum(errors) / len(errors) if errors else 0
            stats["max_error"] = max(errors) if errors else 0
        
        base_name = os.path.splitext(os.path.basename(safetensors_path))[0]
        fp8_path = os.path.join(output_dir, f"{base_name}-fp8-{fp8_format}.safetensors")
        
        save_file(sd_fp8, fp8_path, metadata={"format": "pt", "fp8_format": fp8_format, **metadata})
        
        # Save precision recovery weights
        if lora_weights:
            lora_path = os.path.join(output_dir, f"{base_name}-lora-r{lora_rank}-{architecture}.safetensors")
            lora_metadata = {
                "format": "pt", 
                "lora_rank": str(lora_rank),
                "architecture": architecture,
                "stats": json.dumps(stats),
                "method": "lora"
            }
            save_file(lora_weights, lora_path, metadata=lora_metadata)
        
        if correction_factors:
            correction_path = os.path.join(output_dir, f"{base_name}-correction-{architecture}.safetensors")
            correction_metadata = {
                "format": "pt",
                "architecture": architecture,
                "stats": json.dumps(stats),
                "method": "correction"
            }
            save_file(correction_factors, correction_path, metadata=correction_metadata)
        
        progress(0.9, desc="Saved FP8 and precision recovery files.")
        progress(1.0, desc="✅ FP8 + precision recovery extraction complete!")
        
        stats_msg = f"FP8 ({fp8_format}) with precision recovery saved.\n"
        stats_msg += f"Architecture: {architecture}\n"
        stats_msg += f"Method: {settings['method']}\n"
        stats_msg += f"Average quantization error: {stats.get('avg_error', 0):.6f}\n"
        
        if settings["method"] == "correction":
            stats_msg += f"Correction factors generated for {stats['correction_layers']} layers."
        else:
            stats_msg += f"LoRA generated for {stats['processed_layers']}/{stats['eligible_layers']} eligible layers (rank {lora_rank})."
        
        if stats['processed_layers'] == 0 and stats['correction_layers'] == 0:
            stats_msg += "\n⚠️ No precision recovery weights were generated. FP8 quantization error may be too small."
        
        return True, stats_msg, stats

    except Exception as e:
        error_msg = f"Error: {str(e)}\n{traceback.format_exc()}"
        return False, error_msg, None

def parse_hf_url(url):
    url = url.strip().rstrip("/")
    if not url.startswith("https://huggingface.co/"):
        raise ValueError("URL must start with https://huggingface.co/")
    path = url.replace("https://huggingface.co/", "")
    parts = path.split("/")
    if len(parts) < 2:
        raise ValueError("Invalid repo format")
    repo_id = "/".join(parts[:2])
    subfolder = ""
    if len(parts) > 3 and parts[2] == "tree":
        subfolder = "/".join(parts[4:]) if len(parts) > 4 else ""
    elif len(parts) > 2:
        subfolder = "/".join(parts[2:])
    return repo_id, subfolder

def download_safetensors_file(source_type, repo_url, filename, hf_token=None, progress=gr.Progress()):
    temp_dir = tempfile.mkdtemp()
    try:
        if source_type == "huggingface":
            repo_id, subfolder = parse_hf_url(repo_url)
            safetensors_path = hf_hub_download(
                repo_id=repo_id,
                filename=filename,
                subfolder=subfolder or None,
                cache_dir=temp_dir,
                token=hf_token,
                resume_download=True
            )
        elif source_type == "modelscope":
            if not MODELScope_AVAILABLE:
                raise ImportError("ModelScope not installed")
            repo_id = repo_url.strip()
            safetensors_path = ms_file_download(model_id=repo_id, file_path=filename)
        else:
            raise ValueError("Unknown source")
        return safetensors_path, temp_dir
    except Exception as e:
        shutil.rmtree(temp_dir, ignore_errors=True)
        raise e

def upload_to_target(target_type, new_repo_id, output_dir, fp8_format, hf_token=None, modelscope_token=None, private_repo=False):
    if target_type == "huggingface":
        api = HfApi(token=hf_token)
        api.create_repo(repo_id=new_repo_id, private=private_repo, repo_type="model", exist_ok=True)
        api.upload_folder(repo_id=new_repo_id, folder_path=output_dir, repo_type="model", token=hf_token)
        return f"https://huggingface.co/{new_repo_id}"
    elif target_type == "modelscope":
        api = ModelScopeApi()
        if modelscope_token:
            api.login(modelscope_token)
        api.push_model(model_id=new_repo_id, model_dir=output_dir)
        return f"https://modelscope.cn/models/{new_repo_id}"
    else:
        raise ValueError("Unknown target")

def process_and_upload_fp8(
    source_type,
    repo_url,
    safetensors_filename,
    fp8_format,
    lora_rank,
    architecture,
    target_type,
    new_repo_id,
    hf_token,
    modelscope_token,
    private_repo,
    progress=gr.Progress()
):
    if not re.match(r"^[a-zA-Z0-9._-]+/[a-zA-Z0-9._-]+$", new_repo_id):
        return None, "❌ Invalid repo ID format. Use 'username/model-name'.", ""
    if source_type == "huggingface" and not hf_token:
        return None, "❌ Hugging Face token required for source.", ""
    if target_type == "huggingface" and not hf_token:
        return None, "❌ Hugging Face token required for target.", ""
    if lora_rank < 8:
        return None, "❌ LoRA rank must be at least 8.", ""
    
    temp_dir = None
    output_dir = tempfile.mkdtemp()
    try:
        progress(0.05, desc="Downloading model...")
        safetensors_path, temp_dir = download_safetensors_file(
            source_type, repo_url, safetensors_filename, hf_token, progress
        )
        
        progress(0.25, desc="Converting to FP8 with precision recovery...")
        success, msg, stats = convert_safetensors_to_fp8_with_lora(
            safetensors_path, output_dir, fp8_format, lora_rank, architecture, progress
        )
        
        if not success:
            return None, f"❌ Conversion failed: {msg}", ""
        
        progress(0.9, desc="Uploading...")
        repo_url_final = upload_to_target(
            target_type, new_repo_id, output_dir, fp8_format, hf_token, modelscope_token, private_repo
        )
        
        base_name = os.path.splitext(safetensors_filename)[0]
        fp8_filename = f"{base_name}-fp8-{fp8_format}.safetensors"
        
        # Determine which precision recovery file was generated
        precision_recovery_file = ""
        precision_recovery_type = ""
        if stats.get("method") == "correction" and stats.get("correction_layers", 0) > 0:
            precision_recovery_file = f"{base_name}-correction-{architecture}.safetensors"
            precision_recovery_type = "Correction Factors"
        elif stats.get("method") == "lora" and stats.get("processed_layers", 0) > 0:
            precision_recovery_file = f"{base_name}-lora-r{lora_rank}-{architecture}.safetensors"
            precision_recovery_type = "LoRA"
        
        readme = f"""---
library_name: diffusers
tags:
- fp8
- safetensors
- precision-recovery
- diffusion
- converted-by-gradio
---
# FP8 Model with Precision Recovery
- **Source**: `{repo_url}`
- **File**: `{safetensors_filename}`
- **FP8 Format**: `{fp8_format.upper()}`
- **Architecture**: {architecture}
- **Precision Recovery Type**: {precision_recovery_type}
- **Precision Recovery File**: `{precision_recovery_file}` if available
- **FP8 File**: `{fp8_filename}`

## Usage (Inference)
```python
from safetensors.torch import load_file
import torch

# Load FP8 model
fp8_state = load_file("{fp8_filename}")

# Load precision recovery file if available
recovery_state = {{}}
if "{precision_recovery_file}":
    recovery_state = load_file("{precision_recovery_file}")

# Reconstruct high-precision weights
reconstructed = {{}}
for key in fp8_state:
    # Dequantize FP8 to target precision
    fp_weight = fp8_state[key].to(torch.float32)
    
    if recovery_state:
        # For LoRA approach
        if f"lora_A.{{key}}" in recovery_state and f"lora_B.{{key}}" in recovery_state:
            A = recovery_state[f"lora_A.{{key}}"].to(torch.float32)
            B = recovery_state[f"lora_B.{{key}}"].to(torch.float32)
            error_correction = B @ A
            reconstructed[key] = fp_weight + error_correction
        # For correction factor approach
        elif f"correction.{{key}}" in recovery_state:
            correction = recovery_state[f"correction.{{key}}"].to(torch.float32)
            reconstructed[key] = fp_weight + correction
        else:
            reconstructed[key] = fp_weight
    else:
        reconstructed[key] = fp_weight

print("Model reconstructed with FP8 error recovery")
```

> **Note**: This precision recovery targets FP8 quantization errors.
> Average quantization error: {stats.get('avg_error', 0):.6f}
"""

        with open(os.path.join(output_dir, "README.md"), "w") as f:
            f.write(readme)
        
        if target_type == "huggingface":
            HfApi(token=hf_token).upload_file(
                path_or_fileobj=os.path.join(output_dir, "README.md"),
                path_in_repo="README.md",
                repo_id=new_repo_id,
                repo_type="model",
                token=hf_token
            )
        
        progress(1.0, desc="✅ Done!")
        
        result_html = f"""
✅ Success!  
Model uploaded to: <a href="{repo_url_final}" target="_blank">{new_repo_id}</a>  
Includes: FP8 model + precision recovery ({precision_recovery_type}).  
Average quantization error: {stats.get('avg_error', 0):.6f}
"""
        
        if stats['processed_layers'] > 0 or stats['correction_layers'] > 0:
            result_html += f"<br>Precision recovery applied to {stats['processed_layers'] + stats['correction_layers']} layers."
        
        return gr.HTML(result_html), "✅ FP8 + precision recovery upload successful!", msg
    
    except Exception as e:
        error_msg = f"❌ Error: {str(e)}\n{traceback.format_exc()}"
        return None, error_msg, ""
    
    finally:
        if temp_dir:
            shutil.rmtree(temp_dir, ignore_errors=True)
        shutil.rmtree(output_dir, ignore_errors=True)

with gr.Blocks(title="FP8 + Precision Recovery Extractor") as demo:
    gr.Markdown("# 🔄 FP8 Converter with Architecture-Specific Precision Recovery")
    gr.Markdown("Convert models to **FP8** with **error-based precision recovery**.")
    
    with gr.Row():
        with gr.Column():
            source_type = gr.Radio(["huggingface", "modelscope"], value="huggingface", label="Source")
            repo_url = gr.Textbox(label="Repo URL or ID", placeholder="https://huggingface.co/... or modelscope-id")
            safetensors_filename = gr.Textbox(label="Filename", placeholder="model.safetensors")
            
            with gr.Accordion("Advanced Settings", open=True):
                fp8_format = gr.Radio(["e4m3fn", "e5m2"], value="e5m2", label="FP8 Format")
                lora_rank = gr.Slider(minimum=8, maximum=256, step=8, value=128, 
                                     label="LoRA Rank (for text/transformers)")
                architecture = gr.Dropdown(
                    choices=[
                        ("Auto-detect architecture", "auto"),
                        ("Text Encoder (LoRA)", "text_encoder"),
                        ("Transformer blocks (LoRA)", "transformer"),
                        ("VAE (Correction Factors)", "vae"),
                        ("UNet Convolutions (LoRA)", "unet_conv"),
                        ("All layers (LoRA where applicable)", "all")
                    ],
                    value="auto",
                    label="Target Architecture"
                )
            
            with gr.Accordion("Authentication", open=False):
                hf_token = gr.Textbox(label="Hugging Face Token", type="password")
                modelscope_token = gr.Textbox(label="ModelScope Token (optional)", type="password", 
                                              visible=MODELScope_AVAILABLE)
        
        with gr.Column():
            target_type = gr.Radio(["huggingface", "modelscope"], value="huggingface", label="Target")
            new_repo_id = gr.Textbox(label="New Repo ID", placeholder="user/model-fp8-precision")
            private_repo = gr.Checkbox(label="Private Repository (HF only)", value=False)
            
            status_output = gr.Markdown()
            detailed_log = gr.Textbox(label="Processing Log", interactive=False, lines=10)
    
    convert_btn = gr.Button("🚀 Convert & Upload", variant="primary")
    repo_link_output = gr.HTML()
    
    convert_btn.click(
        fn=process_and_upload_fp8,
        inputs=[
            source_type,
            repo_url,
            safetensors_filename,
            fp8_format,
            lora_rank,
            architecture,
            target_type,
            new_repo_id,
            hf_token,
            modelscope_token,
            private_repo
        ],
        outputs=[repo_link_output, status_output, detailed_log],
        show_progress=True
    )
    
    gr.Examples(
        examples=[
            ["huggingface", "https://huggingface.co/runwayml/stable-diffusion-v1-5/tree/main/text_encoder", 
             "model.safetensors", "e5m2", 96, "text_encoder"],
            ["huggingface", "https://huggingface.co/stabilityai/sdxl-vae", 
             "diffusion_pytorch_model.safetensors", "e4m3fn", 64, "vae"],
            ["huggingface", "https://huggingface.co/Yabo/FramePainter/tree/main", 
             "unet_diffusion_pytorch_model.safetensors", "e5m2", 128, "transformer"]
        ],
        inputs=[source_type, repo_url, safetensors_filename, fp8_format, lora_rank, architecture],
        label="Example Conversions"
    )
    
    gr.Markdown("""
    ## 🎯 What This Tool Does
    
    Unlike traditional LoRA fine-tuning, this tool:
    
    1. **Quantizes** the model to FP8 (loses precision)
    2. **Measures** the quantization error for each weight
    3. **Extracts recovery weights** that specifically recover this error
    4. **Only applies** recovery where error is significant (>0.001%)
    
    ## 💡 Recommended Settings
    
    - **Text Encoders**: rank 64-96 (text is sensitive)
    - **Transformers**: rank 96-128 
    - **VAE**: Uses correction factors (no rank needed)
    - **UNet Convolutions**: rank 32-64
    
    ## ⚠️ Important Notes
    
    - This recovers **FP8 quantization errors**, not fine-tuning changes
    - If FP8 error is tiny (<0.0001%), recovery may not be generated
    - Higher rank ≠ better for error recovery (use recommended ranges)
    """)

demo.launch()