# -*- coding: utf-8 -*-
import streamlit as st
from docx import Document
from config import APP_CONFIG

try:
    import pandas as pd
    PANDAS_AVAILABLE = True
except ImportError:
    PANDAS_AVAILABLE = False

try:
    import fitz  # PyMuPDF 的导入名称是 fitz
    PYMUPDF_AVAILABLE = True
except ImportError:
    PYMUPDF_AVAILABLE = False

def extract_text_from_files(uploaded_files, max_chars=None):
    if max_chars is None:
        max_chars = APP_CONFIG.get("max_extract_chars", 150000)
        
    extracted_text = ""
    for file in uploaded_files:
        try:
            file.seek(0)
            if file.name.lower().endswith('.pdf') and PYMUPDF_AVAILABLE:
                # 从内存中读取文件字节流
                pdf_bytes = file.read()
                # 使用上下文管理器确保内存被及时释放
                with fitz.open(stream=pdf_bytes, filetype="pdf") as pdf_doc:
                    for page in pdf_doc:
                        text = page.get_text()
                        if text: 
                            extracted_text += text + "\n"
                        if len(extracted_text) > max_chars: 
                            break
            elif file.name.lower().endswith(('.docx', '.doc')):
                doc = Document(file)
                for para in doc.paragraphs:
                    extracted_text += para.text + "\n"
                    if len(extracted_text) > max_chars: 
                        break
            else:
                content = file.getvalue().decode('utf-8', errors='ignore')
                extracted_text += content + "\n"
            
            if len(extracted_text) > max_chars:
                st.warning(f"⚠️ 文件 {file.name} 已安全截断至 {max_chars} 字符。")
                break
        except Exception as e:
            st.warning(f"⚠️ 解析失败: {e}")
        finally:
            file.seek(0)
    return extracted_text[:max_chars]

def extract_data_from_files(uploaded_file, max_chars=20000):
    if not uploaded_file: 
        return ""
        
    try:
        uploaded_file.seek(0)
        if PANDAS_AVAILABLE:
            df = pd.read_csv(uploaded_file) if uploaded_file.name.lower().endswith('.csv') else pd.read_excel(uploaded_file)
            if len(df) > 100:
                st.warning(f"⚠️ 数据表超长，安全截取前100行。")
                df = df.head(100)
            return df.to_markdown(index=False)
        else:
            return uploaded_file.getvalue().decode('utf-8', errors='ignore')[:max_chars]
    except Exception as e:
        st.warning(f"⚠️ 解析失败: {e}")
        return ""
    finally:
        uploaded_file.seek(0)