import json
import Levenshtein

def compute_edit_distance(pred: str, gt: str) -> float:
    """
    计算两个字符串的归一化编辑距离 (Normalized Edit Distance, NED)
    值域为 [0, 1]，越小表示越相似。
    """
    pred = pred.replace("\n", "").replace(" ", "")
    gt = gt.replace("\n", "").replace(" ", "")
    if not pred and not gt:
        return 0.0
    dist = Levenshtein.distance(pred, gt)
    return round(dist / max(len(pred), len(gt)), 4)


def compute_accuracy(json_path: str):
    """从 JSON 文件批量计算平均 NED 及每条样本的编辑距离"""
    with open(json_path, 'r', encoding='utf-8') as f:
        data = json.load(f)

    total_ned = 0
    sample_accuracies = []

    for sample in data:
        # Ground truth 选择逻辑
        if "normal" in json_path:
            gt = sample.get("content", "")
        elif "tiny_shuffled" in json_path:
            gt = sample.get("tiny_shuffled_content", "")
        elif "shuffled" in json_path:
            gt = sample.get("shuffled_content", "")
        else:
            raise ValueError("无法确定使用哪个字段作为 ground truth")

        pred = sample.get("ocr", "")
        ned = compute_edit_distance(pred, gt)
        total_ned += ned

        sample_accuracies.append({
            "id": sample["id"],
            "image_path": sample["image_path"],
            "content": gt,
            "ocr": sample["ocr"],
            "NED": ned
        })

    overall_ned = round(total_ned / len(data), 4)
    print(f"共 {len(data)} 条样本, 平均 NED = {overall_ned}")

    return overall_ned, sample_accuracies


if __name__ == "__main__":

    # json_path = "/vol/zhaoy/ds-ocr/data/CCI3-Data/sample200_len1.0-1.2k/tiny_shuffled/input_small_ocr.json"
    # overall_ned, sample_accuracies = compute_accuracy(json_path)
    # # 保存每条样本的编辑距离
    # out_path = json_path.replace(".json", "_acc.json")
    # with open(out_path, "w", encoding="utf-8") as f:
    #     json.dump(sample_accuracies, f, ensure_ascii=False, indent=2)
    # print(f"结果已保存至：{out_path}")


    origin = "四月飞雪《四月飞雪》是四月菲雪创作的网络小说，发表于起点网。作品简介大千世界，两亿年前究竟发生了什么，在我们身边，好似缺少着什么，，一个生活在这个世界的小孩，究竟经历了什么，一步步走上了永无止境的通天大道。。接下来就让我们一起见证。。。。。"
    mod = "四月飞雪《四月飞雪雪》是四月菲雪作创作的网络小说，发表于起点网。作作品简大简介世大千世界，两两亿年前究竟发竟发什生了什么，在我们身身边，好似缺什少着什么，，一个生活活在这个世世小界的小孩，经究竟经历了什么，一步步步上走上了永止无止天境的通天大道。。接下来就让我们一起见见证。。。。。"
    ned = compute_edit_distance(origin, mod)
    print(ned)