app.py

import gradio as gr
import torch
from transformers import AutoTokenizer, AutoModelForMultipleChoice, AutoModelForQuestionAnswering
import json
import collections # 如果您的 postprocess_qa_predictions 需要

# 假設 utils_qa.py 在同一目錄下 (或者您需要將其函數複製過來或確保可導入)
# from utils_qa import postprocess_qa_predictions # 您可能需要完整路徑或將其放入 requirements.txt

# --- 模型和分詞器加載 ---
# 建議從 Hugging Face Hub 加載您已經上傳的模型
# 這樣您的 Space 就不需要包含模型文件本身，保持輕量
TOKENIZER_PATH = "bert-base-chinese" # 或者您上傳的分詞器路徑
SELECTOR_MODEL_PATH = "TheWeeeed/chinese-paragraph-selector" # 替換為您上傳的段落選擇模型 ID
QA_MODEL_PATH = "TheWeeeed/chinese-extractive-qa" # 替換為您上傳的答案抽取模型 ID

try:
    tokenizer = AutoTokenizer.from_pretrained(TOKENIZER_PATH)
    selector_model = AutoModelForMultipleChoice.from_pretrained(SELECTOR_MODEL_PATH)
    qa_model = AutoModelForQuestionAnswering.from_pretrained(QA_MODEL_PATH)

    device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
    selector_model.to(device)
    selector_model.eval()
    qa_model.to(device)
    qa_model.eval()
    models_loaded_successfully = True
    print(f"模型和分詞器加載成功，使用設備: {device}")
except Exception as e:
    models_loaded_successfully = False
    error_message = f"加載模型或分詞器時出錯: {e}"
    print(error_message)
    # 在 Gradio 界面中，我們可以顯示這個錯誤信息


# --- 從您的 inference_pipeline.py 中提取並調整以下函數 ---
def select_relevant_paragraph_gradio(question_text, candidate_paragraph_texts_str, model, tokenizer, device, max_seq_len):
    # candidate_paragraph_texts_str 是一個由換行符分隔的字符串
    candidate_paragraph_texts = [p.strip() for p in candidate_paragraph_texts_str.split('\n') if p.strip()]
    if not candidate_paragraph_texts:
        return "請至少提供一個候選段落。", -1

    model.eval()
    inputs_mc = []
    for p_text in candidate_paragraph_texts:
        inputs_mc.append(
            tokenizer(
                question_text, p_text, add_special_tokens=True, max_length=max_seq_len,
                padding="max_length", truncation=True, return_tensors="pt"
            )
        )
    input_ids = torch.stack([inp["input_ids"].squeeze(0) for inp in inputs_mc]).unsqueeze(0).to(device)
    attention_mask = torch.stack([inp["attention_mask"].squeeze(0) for inp in inputs_mc]).unsqueeze(0).to(device)
    token_type_ids = None
    if "token_type_ids" in inputs_mc[0]:
        token_type_ids = torch.stack([inp["token_type_ids"].squeeze(0) for inp in inputs_mc]).unsqueeze(0).to(device)

    with torch.no_grad():
        if token_type_ids is not None:
            outputs = model(input_ids=input_ids, attention_mask=attention_mask, token_type_ids=token_type_ids)
        else:
            outputs = model(input_ids=input_ids, attention_mask=attention_mask)
    predicted_index = torch.argmax(outputs.logits, dim=1).item()
    if predicted_index < len(candidate_paragraph_texts):
        return candidate_paragraph_texts[predicted_index], predicted_index
    else:
        return "段落選擇索引錯誤。", -1


def prepare_features_for_qa_inference_gradio(question_id, question_text, selected_context, tokenizer, max_seq_len, doc_stride):
    # 這個函數需要從您的 inference_pipeline.py 中提取並適當修改
    # 它需要返回一個可以被 QA 模型使用的 Dataset 或 features 列表
    # 簡化版:
    from datasets import Dataset # 需要在 requirements.txt 中

    qa_example_for_processing = {"id": [question_id], "question": [question_text], "context": [selected_context]}
    temp_dataset = Dataset.from_dict(qa_example_for_processing)

    pad_on_right = tokenizer.padding_side == "right"

    qa_features = temp_dataset.map(
        lambda examples: prepare_features_for_qa_inference( # 這是您 inference_pipeline.py 中的函數
            examples, tokenizer, pad_on_right, max_seq_len, doc_stride
        ),
        batched=True,
        remove_columns=temp_dataset.column_names
    )
    return qa_features # 返回 Dataset 對象

# 您 inference_pipeline.py 中的 prepare_features_for_qa_inference 函數需要被複製到這裡
# 或者確保它可以被導入
def prepare_features_for_qa_inference(examples, tokenizer, pad_on_right, max_seq_len, doc_stride):
    examples["question"] = [q.lstrip() if isinstance(q, str) else "" for q in examples["question"]]
    questions = examples["question" if pad_on_right else "context"]
    contexts = examples["context" if pad_on_right else "question"]

    # Ensure questions and contexts are lists of strings, handle None by converting to empty string
    questions = [q if isinstance(q, str) else "" for q in questions]
    contexts = [c if isinstance(c, str) else "" for c in contexts]

    tokenized_output = tokenizer(
        questions,
        contexts,
        truncation="only_second" if pad_on_right else "only_first",
        max_length=max_seq_len,
        stride=doc_stride,
        return_overflowing_tokens=True,
        return_offsets_mapping=True,
        padding="max_length", # This ensures all primary outputs are lists of numbers of fixed length
    )

    # The tokenizer with padding="max_length" should already produce lists of integers
    # for input_ids, attention_mask, token_type_ids.
    # The main risk of 'None' would be if the input strings were so problematic
    # that the tokenizer failed internally in a way not producing standard padded output.
    # However, standard tokenizers are quite robust with empty strings when padding is enabled.

    # Let's directly create the structure we need for the output Dataset.
    # `tokenized_output` is a BatchEncoding (dict-like).
    # If `return_overflowing_tokens=True` and N features are generated from one example,
    # then `tokenized_output['input_ids']` is a list of N lists.

    processed_features = []
    num_generated_features = len(tokenized_output["input_ids"]) # Number of features due to overflow

    # `sample_mapping` maps each generated feature back to its original example index in the input `examples`
    sample_mapping = tokenized_output.pop("overflow_to_sample_mapping", list(range(len(examples["id"]))))


    for i in range(num_generated_features):
        feature = {}
        original_example_index = sample_mapping[i] # Index of the original example this feature came from

        # These should always be lists of integers due to padding="max_length"
        feature["input_ids"] = tokenized_output["input_ids"][i]
        if "attention_mask" in tokenized_output:
            feature["attention_mask"] = tokenized_output["attention_mask"][i]
        if "token_type_ids" in tokenized_output:
            feature["token_type_ids"] = tokenized_output["token_type_ids"][i]
        
        # These might not be strictly needed by the model's forward pass but are used by postprocessing
        feature["example_id"] = examples["id"][original_example_index]
        
        current_offset_mapping = tokenized_output["offset_mapping"][i]
        sequence_ids = tokenized_output.sequence_ids(i) # Pass the index of the feature
        context_idx_in_pair = 1 if pad_on_right else 0
        
        feature["offset_mapping"] = [
            offset if sequence_ids[k] == context_idx_in_pair else None
            for k, offset in enumerate(current_offset_mapping)
        ]
        processed_features.append(feature)

    # The .map function expects a dictionary where keys are column names
    # and values are lists of features for those columns.
    # Since we are processing one original example at a time (batched=True on a Dataset of 1 row),
    # and this one example can produce multiple features, `processed_features` is a list of dicts.
    # We need to return a dictionary of lists.
    if not processed_features: # Should not happen if tokenizer works, but as a safeguard
        # Return structure with empty lists to match expected features by .map()
        # This case indicates an issue with tokenizing the input example.
        logger.error(f"No features generated for example ID {examples['id'][0]}. Input q: {examples['question'][0]}, c: {examples['context'][0]}")
        return {
            "input_ids": [], "token_type_ids": [], "attention_mask": [],
            "offset_mapping": [], "example_id": []
        }

    # Transpose the list of feature dictionaries into a dictionary of feature lists
    # This is what the .map(batched=True) function expects as a return value
    final_batch = {}
    for key in processed_features[0].keys():
        final_batch[key] = [feature[key] for feature in processed_features]
    
    for key_to_check in ["input_ids", "attention_mask", "token_type_ids"]:
        if key_to_check in final_batch:
            for i, lst in enumerate(final_batch[key_to_check]):
                if lst is None:
                    raise ValueError(f"在 prepare_features_for_qa_inference 中，{key_to_check} 的第 {i} 個特徵列表為 None！")
                if any(x is None for x in lst):
                    raise ValueError(f"在 prepare_features_for_qa_inference 中，{key_to_check} 的第 {i} 個特徵列表內部包含 None！內容: {lst[:20]}")
                    
    return final_batch

# postprocess_qa_predictions 函數也需要從 utils_qa.py 複製或導入
# from utils_qa import postprocess_qa_predictions # 確保 utils_qa.py 在 Space 的環境中可用

# --- Gradio 界面函數 ---
def two_stage_qa(question, candidate_paragraphs_str, max_seq_len_mc=512, max_seq_len_qa=384, doc_stride_qa=128, n_best_size=20, max_answer_length=100):
    if not models_loaded_successfully:
        return f"錯誤: {error_message}", "N/A", "N/A"

    if not question.strip() or not candidate_paragraphs_str.strip():
        return "錯誤: 問題和候選段落不能為空。", "N/A", "N/A"

    # 階段一
    selected_paragraph, selected_idx = select_relevant_paragraph_gradio(
        question, candidate_paragraphs_str, selector_model, tokenizer, device, max_seq_len_mc
    )
    if selected_idx == -1: # 段落選擇出錯
        return f"段落選擇出錯: {selected_paragraph}", "N/A", selected_paragraph

    # 階段二
    # 準備 QA 特徵
    qa_features_dataset = prepare_features_for_qa_inference_gradio(
        "temp_id", question, selected_paragraph, tokenizer, max_seq_len_qa, doc_stride_qa
    )

    if len(qa_features_dataset) == 0:
        return "錯誤: 無法為選定段落生成QA特徵 (可能段落太短或內容問題)。", f"選中的段落 (索引 {selected_idx}):\n{selected_paragraph}", "N/A"

    # 創建 DataLoader
    from transformers import default_data_collator # 需要導入
    qa_dataloader = DataLoader(
        qa_features_dataset, collate_fn=default_data_collator, batch_size=8 # batch_size可以小一些
    )

    all_start_logits = []
    all_end_logits = []
    for batch in qa_dataloader:
        batch = {k: v.to(device) for k, v in batch.items()}
        with torch.no_grad():
            outputs_qa = qa_model(**batch)
        all_start_logits.append(outputs_qa.start_logits.cpu().numpy())
        all_end_logits.append(outputs_qa.end_logits.cpu().numpy())

    if not all_start_logits:
         return "錯誤: QA模型沒有產生logits。", f"選中的段落 (索引 {selected_idx}):\n{selected_paragraph}", "N/A"

    start_logits_np = np.concatenate(all_start_logits, axis=0)
    end_logits_np = np.concatenate(all_end_logits, axis=0)

    # 為了 postprocess_qa_predictions，我們需要原始的 example 數據
    # 它期望一個包含 "answers" 字段的 Dataset
    def add_empty_answers(example):
        example["answers"] = {"text": [], "answer_start": []}
        return example

    # temp_dataset 用於 postprocessing
    original_example_for_postproc = {"id": ["temp_id"], "question": [question], "context": [selected_paragraph]}
    original_dataset_for_postproc = Dataset.from_dict(original_example_for_postproc).map(add_empty_answers)


    # 後處理
    # 確保 postprocess_qa_predictions 可用
    predictions_dict = postprocess_qa_predictions(
        examples=original_dataset_for_postproc, # 原始的、包含 context 和空 answers 的 Dataset
        features=qa_features_dataset,      # 包含 offset_mapping 和 example_id 的 Dataset
        predictions=(start_logits_np, end_logits_np),
        version_2_with_negative=False,
        n_best_size=n_best_size,
        max_answer_length=max_answer_length,
        null_score_diff_threshold=0.0,
        output_dir=None,
        prefix="gradio_predict",
        is_world_process_zero=True
    )

    final_answer = predictions_dict.get("temp_id", "未能提取答案。")

    return final_answer, f"選中的段落 (索引 {selected_idx}):\n{selected_paragraph}", predictions_dict

# --- 創建 Gradio 界面 ---
# 定義預設的問題和段落內容
DEFAULT_QUESTION = "世界最高峰是什麼？"
DEFAULT_PARAGRAPHS = (
    "珠穆朗瑪峰是喜馬拉雅山脈的主峰，位於中國與尼泊爾邊界上，是世界海拔最高的山峰。\n"
    "喬戈里峰，又稱K2，是喀喇崑崙山脈的主峰，海拔8611米，是世界第二高峰，位於中國與巴基斯坦邊界。\n"
    "干城章嘉峰位於喜馬拉雅山脈中段尼泊爾和印度邊界線上，海拔8586米，為世界第三高峰。\n"
    "洛子峰，海拔8516米，為世界第四高峰，位於珠穆朗瑪峰以南約3公里處，同屬喜馬拉雅山脈。"
)

iface = gr.Interface(
    fn=two_stage_qa, # 您的兩階段問答處理函數
    inputs=[
        gr.Textbox(
            lines=2, 
            placeholder="輸入您的問題...", 
            label="問題 (Question)", 
            value=DEFAULT_QUESTION  # <--- 為問題設置預設值
        ),
        gr.Textbox(
            lines=10, 
            placeholder="在此處輸入候選段落，每段一行...", 
            label="候選段落 (Candidate Paragraphs - One per line)", 
            value=DEFAULT_PARAGRAPHS # <--- 為段落設置預設值
        )
    ],
    outputs=[
        gr.Textbox(label="預測答案 (Predicted Answer)"),
        gr.Textbox(label="選中的相關段落 (Selected Relevant Paragraph)"),
        gr.JSON(label="原始預測字典 (Raw Predictions Dict - for debugging)") 
    ],
    title="兩階段中文抽取式問答系統",
    description="輸入一個問題和多個候選段落（每行一個段落）。系統會先選擇最相關的段落，然後從中抽取答案。",
    allow_flagging="never" # 或者您希望的標記設置
)

if __name__ == "__main__":
    if models_loaded_successfully: # 確保模型已加載才啟動
        iface.launch()
    else:
        print(f"Gradio 應用無法啟動，因為模型加載失敗: {error_message if 'error_message' in locals() else '未知錯誤'}")