combine_peft_weights.py

"""
将 PEFT LoRA 权重合并到基础 Flux Transformer 模型中

功能：
1. 加载基础 Flux Fill 模型的 Transformer
2. 加载 RL 训练的 PEFT LoRA 权重
3. 将 LoRA 权重合并到基础模型
4. 保存合并后的完整模型

使用方法：
python combine_peft_weights.py \
    --base_model_path /path/to/base/model \
    --lora_weights_path /path/to/lora/weights \
    --output_path /path/to/output \
    --save_full_pipeline  # 可选：保存完整 pipeline 而不只是 transformer
"""

import torch
import argparse
import os
from pathlib import Path
from diffusers import FluxFillPipeline
from peft import PeftModel


def merge_and_save_transformer(
    base_model_path: str,
    lora_weights_path: str,
    output_path: str,
    dtype: torch.dtype = torch.bfloat16,
    device: str = "cpu"
):
    """
    合并 LoRA 权重到 Transformer 并保存
    
    Args:
        base_model_path: 基础 Flux Fill 模型路径
        lora_weights_path: PEFT LoRA 权重路径
        output_path: 输出路径（保存合并后的 transformer）
        dtype: 数据类型
        device: 加载设备（建议用 CPU 以节省显存）
    """
    print("=" * 80)
    print("Step 1: 加载基础 Flux Fill 模型...")
    print("=" * 80)
    
    # 加载基础模型（只加载 transformer 部分以节省内存）
    pipe = FluxFillPipeline.from_pretrained(
        base_model_path,
        torch_dtype=dtype,
        low_cpu_mem_usage=True
    )
    
    print(f"✓ 基础模型加载完成: {base_model_path}")
    print(f"  Transformer 参数量: {sum(p.numel() for p in pipe.transformer.parameters()) / 1e9:.2f}B")
    
    # 移动到指定设备
    if device != "cpu":
        print(f"  移动 transformer 到 {device}...")
        pipe.transformer = pipe.transformer.to(device)
    
    print("\n" + "=" * 80)
    print("Step 2: 加载 PEFT LoRA 权重...")
    print("=" * 80)
    
    # 加载 PEFT 模型
    print(f"  从 {lora_weights_path} 加载 LoRA 权重...")
    peft_model = PeftModel.from_pretrained(
        pipe.transformer,
        lora_weights_path,
        is_trainable=False
    )
    peft_model.set_adapter("default")
    
    print(f"✓ PEFT 模型加载完成")
    
    # 检查 LoRA 配置
    lora_config = peft_model.peft_config.get("default", None)
    if lora_config:
        print(f"  LoRA 配置:")
        print(f"    - Rank (r): {lora_config.r}")
        print(f"    - Alpha: {lora_config.lora_alpha}")
        print(f"    - Dropout: {lora_config.lora_dropout}")
        print(f"    - Target modules: {lora_config.target_modules}")
    
    print("\n" + "=" * 80)
    print("Step 3: 合并 LoRA 权重到基础模型...")
    print("=" * 80)
    
    # 合并权重
    merged_model = peft_model.merge_and_unload()
    
    print(f"✓ 权重合并完成")
    print(f"  合并后模型参数量: {sum(p.numel() for p in merged_model.parameters()) / 1e9:.2f}B")
    
    print("\n" + "=" * 80)
    print("Step 4: 保存合并后的模型...")
    print("=" * 80)
    
    # 创建输出目录
    os.makedirs(output_path, exist_ok=True)
    
    # 保存合并后的 transformer
    print(f"  保存到 {output_path}...")
    merged_model.save_pretrained(
        output_path,
        safe_serialization=True,  # 使用 safetensors 格式
        max_shard_size="5GB"  # 分片大小
    )
    
    print(f"✓ 模型保存完成: {output_path}")
    
    # 保存模型配置信息
    info_path = os.path.join(output_path, "merge_info.txt")
    with open(info_path, "w") as f:
        f.write(f"Base model: {base_model_path}\n")
        f.write(f"LoRA weights: {lora_weights_path}\n")
        f.write(f"Merged model: {output_path}\n")
        f.write(f"Data type: {dtype}\n")
        if lora_config:
            f.write(f"\nLoRA Configuration:\n")
            f.write(f"  Rank (r): {lora_config.r}\n")
            f.write(f"  Alpha: {lora_config.lora_alpha}\n")
            f.write(f"  Dropout: {lora_config.lora_dropout}\n")
            f.write(f"  Target modules: {lora_config.target_modules}\n")
    
    print(f"✓ 合并信息保存到: {info_path}")
    
    return merged_model


def merge_and_save_full_pipeline(
    base_model_path: str,
    lora_weights_path: str,
    output_path: str,
    dtype: torch.dtype = torch.bfloat16,
    device: str = "cpu"
):
    """
    合并 LoRA 权重并保存完整的 FluxFillPipeline
    
    Args:
        base_model_path: 基础 Flux Fill 模型路径
        lora_weights_path: PEFT LoRA 权重路径
        output_path: 输出路径（保存完整 pipeline）
        dtype: 数据类型
        device: 加载设备
    """
    print("=" * 80)
    print("Step 1: 加载基础 Flux Fill Pipeline...")
    print("=" * 80)
    
    # 加载完整 pipeline
    pipe = FluxFillPipeline.from_pretrained(
        base_model_path,
        torch_dtype=dtype,
        low_cpu_mem_usage=True
    )
    
    print(f"✓ Pipeline 加载完成: {base_model_path}")
    
    # 移动到指定设备
    if device != "cpu":
        print(f"  移动 transformer 到 {device}...")
        pipe.transformer = pipe.transformer.to(device)
    
    print("\n" + "=" * 80)
    print("Step 2: 加载并合并 PEFT LoRA 权重...")
    print("=" * 80)
    
    # 加载 PEFT 模型
    peft_model = PeftModel.from_pretrained(
        pipe.transformer,
        lora_weights_path,
        is_trainable=False
    )
    peft_model.set_adapter("default")
    
    # 合并权重
    merged_transformer = peft_model.merge_and_unload()
    
    # 替换 pipeline 中的 transformer
    pipe.transformer = merged_transformer
    
    print(f"✓ 权重合并完成")
    
    print("\n" + "=" * 80)
    print("Step 3: 保存完整 Pipeline...")
    print("=" * 80)
    
    # 创建输出目录
    os.makedirs(output_path, exist_ok=True)
    
    # 保存完整 pipeline
    print(f"  保存到 {output_path}...")
    pipe.save_pretrained(
        output_path,
        safe_serialization=True,
        max_shard_size="5GB"
    )
    
    print(f"✓ 完整 Pipeline 保存完成: {output_path}")
    
    # 保存合并信息
    info_path = os.path.join(output_path, "merge_info.txt")
    with open(info_path, "w") as f:
        f.write(f"Base model: {base_model_path}\n")
        f.write(f"LoRA weights: {lora_weights_path}\n")
        f.write(f"Merged pipeline: {output_path}\n")
        f.write(f"Data type: {dtype}\n")
        f.write(f"Components saved:\n")
        f.write(f"  - Transformer (merged with LoRA)\n")
        f.write(f"  - VAE\n")
        f.write(f"  - Text Encoder\n")
        f.write(f"  - Scheduler\n")
        f.write(f"  - Other components\n")
    
    print(f"✓ 合并信息保存到: {info_path}")
    
    return pipe


def main():
    parser = argparse.ArgumentParser(
        description="将 PEFT LoRA 权重合并到基础 Flux Transformer 模型中"
    )
    
    parser.add_argument(
        "--base_model_path",
        type=str,
        default="/home/tione/notebook/research/retofan/ckpt/FLUX.1-Fill-dev-UDG-1121_e4",
        help="基础 Flux Fill 模型路径"
    )
    
    parser.add_argument(
        "--lora_weights_path",
        type=str,
        default="/home/tione/notebook2/research/retofan/code/RL/flow_grpo/logs/defectgen_det/flux_fill_redux/checkpoints/checkpoint-60/lora",
        help="PEFT LoRA 权重路径"
    )
    
    parser.add_argument(
        "--output_path",
        type=str,
        default="/home/tione/notebook/research/retofan/ckpt/FLUX.1-Fill-dev-UDG-1121_e4_defect_gen_det_e60",
        help="输出路径（保存合并后的模型）"
    )
    
    parser.add_argument(
        "--save_full_pipeline",
        action="store_true",
        help="保存完整 FluxFillPipeline（包含 VAE、Text Encoder 等），而不只是 Transformer"
    )
    
    parser.add_argument(
        "--dtype",
        type=str,
        default="bfloat16",
        choices=["float32", "float16", "bfloat16"],
        help="数据类型"
    )
    
    parser.add_argument(
        "--device",
        type=str,
        default="cpu",
        help="加载设备（cpu 或 cuda:0 等）。建议使用 cpu 以节省显存"
    )
    
    args = parser.parse_args()
    
    # 转换 dtype
    dtype_map = {
        "float32": torch.float32,
        "float16": torch.float16,
        "bfloat16": torch.bfloat16
    }
    dtype = dtype_map[args.dtype]
    
    # 检查路径
    if not os.path.exists(args.base_model_path):
        print(f"错误: 基础模型路径不存在: {args.base_model_path}")
        return
    
    if not os.path.exists(args.lora_weights_path):
        print(f"错误: LoRA 权重路径不存在: {args.lora_weights_path}")
        return
    
    print("\n" + "=" * 80)
    print("PEFT LoRA 权重合并工具")
    print("=" * 80)
    print(f"基础模型: {args.base_model_path}")
    print(f"LoRA 权重: {args.lora_weights_path}")
    print(f"输出路径: {args.output_path}")
    print(f"保存类型: {'完整 Pipeline' if args.save_full_pipeline else '仅 Transformer'}")
    print(f"数据类型: {args.dtype}")
    print(f"加载设备: {args.device}")
    print("=" * 80 + "\n")
    
    try:
        if args.save_full_pipeline:
            # 保存完整 pipeline
            merge_and_save_full_pipeline(
                base_model_path=args.base_model_path,
                lora_weights_path=args.lora_weights_path,
                output_path=args.output_path,
                dtype=dtype,
                device=args.device
            )
        else:
            # 只保存 transformer
            merge_and_save_transformer(
                base_model_path=args.base_model_path,
                lora_weights_path=args.lora_weights_path,
                output_path=args.output_path,
                dtype=dtype,
                device=args.device
            )
        
        print("\n" + "=" * 80)
        print("✅ 合并完成！")
        print("=" * 80)
        print(f"\n合并后的模型已保存到: {args.output_path}")
        print("\n使用方法:")
        
        if args.save_full_pipeline:
            print("  # 直接加载合并后的完整 pipeline")
            print("  from diffusers import FluxFillPipeline")
            print(f"  pipe = FluxFillPipeline.from_pretrained('{args.output_path}')")
        else:
            print("  # 加载基础 pipeline，然后替换 transformer")
            print("  from diffusers import FluxFillPipeline")
            print("  from diffusers.models import FluxTransformer2DModel")
            print(f"  pipe = FluxFillPipeline.from_pretrained('{args.base_model_path}')")
            print(f"  pipe.transformer = FluxTransformer2DModel.from_pretrained('{args.output_path}')")
        
        print("\n" + "=" * 80)
        
    except Exception as e:
        print(f"\n❌ 错误: {e}")
        import traceback
        traceback.print_exc()
        return 1
    
    return 0


if __name__ == "__main__":
    exit(main())