import os
import json
from docx import Document
from PyPDF2 import PdfReader
from app.services.file_storage import get_file_content


async def parse_reference_file(file_path: str) -> str:
    ext = os.path.splitext(file_path)[1].lower()
    content = await get_file_content(file_path)

    if ext == ".txt":
        return content.decode("utf-8", errors="ignore")
    if ext == ".docx":
        from io import BytesIO
        doc = Document(BytesIO(content))
        return "\n".join(p.text for p in doc.paragraphs if p.text.strip())
    if ext == ".pdf":
        from io import BytesIO
        reader = PdfReader(BytesIO(content))
        return "\n".join(page.extract_text() or "" for page in reader.pages)

    raise ValueError(f"不支持的文件格式: {ext}")


async def parse_reference_files(ref_file_path: str | None) -> str:
    if not ref_file_path:
        return ""

    try:
        paths = json.loads(ref_file_path)
        if isinstance(paths, list):
            texts = []
            for path in paths:
                try:
                    texts.append(await parse_reference_file(path))
                except Exception:
                    texts.append(f"[无法解析文件: {path}]")
            return "\n\n".join(texts)
    except json.JSONDecodeError:
        pass

    try:
        return await parse_reference_file(ref_file_path)
    except Exception:
        return f"[无法解析文件: {ref_file_path}]"