import os
import tempfile
import pypandoc
from typing import Optional
from fastapi import APIRouter, HTTPException, Depends
from fastapi.responses import FileResponse
from pydantic import BaseModel
from starlette.background import BackgroundTask
import auth
import db
from formula_processor import preprocess_formulas

router = APIRouter()

class DocRequest(BaseModel):
    markdown: str

def remove_file(path: str):
    try:
        os.remove(path)
    except Exception:
        pass

@router.post("/api/convert")
async def convert_md_to_docx(req: DocRequest, current_user: Optional[dict] = Depends(auth.get_optional_user)):
    try:
        # 如果带有合法登录 token，则记录历史
        if current_user:
            db.add_history_record(current_user["id"], req.markdown)

        try:
            pypandoc.get_pandoc_version()
        except OSError:
            pypandoc.download_pandoc()

        # ====== 公式预处理：统一各种定界符格式 ======
        # 将 GPT/AI 生成内容中 \(...\)、\[...\]、缺失反斜杠的 [...] 和 (...)
        # 全部转换为 Pandoc 可识别的标准 $...$ 和 $$...$$ 格式
        processed_markdown = preprocess_formulas(req.markdown)

        fd, tmp_path = tempfile.mkstemp(suffix=".docx")
        os.close(fd)
        
        md_fd, md_tmp_path = tempfile.mkstemp(suffix=".md")
        with os.fdopen(md_fd, 'w', encoding='utf-8') as f:
            f.write(processed_markdown)
        
        pypandoc.convert_file(
            md_tmp_path, 
            'docx', 
            format='markdown+tex_math_dollars', 
            outputfile=tmp_path
        )
        os.remove(md_tmp_path)
        
        return FileResponse(
            tmp_path, 
            media_type='application/vnd.openxmlformats-officedocument.wordprocessingml.document', 
            filename='document.docx',
            background=BackgroundTask(remove_file, tmp_path)
        )
    except Exception as e:
        print(f"Error during conversion: {e}")
        raise HTTPException(status_code=500, detail=str(e))

@router.get("/api/history")
async def get_history(current_user: dict = Depends(auth.get_current_user)):
    history = db.get_history_records(current_user["id"])
    return {"history": history}