import json

input_file = "/home/DataProcess/data/val_filtered_by_length2048_turns20_p2r.json"
output_file = "/home/DataProcess/data/val_filtered_by_length2048_turns20_restored.json"

with open(input_file, 'r', encoding='utf-8') as f:
    data = json.load(f)

processed_data = []

for item in data:
    chosen = item.get("chosen", [])
    rejected = item.get("rejected", [])

    if len(chosen) < 1 or len(rejected) < 1:
        continue  # 防御性跳过

    # 公共 history（去掉最后一条）
    history = chosen[:-1]

    new_item = {
        "messages": history,
        "chosen": [chosen[-1]],
        "rejected": [rejected[-1]]
    }

    processed_data.append(new_item)

with open(output_file, 'w', encoding='utf-8') as f:
    json.dump(processed_data, f, ensure_ascii=False, indent=2)

print(f"done, restored {len(processed_data)} items")