"""
本地 PDF 转 Markdown 微服务，兼容 langchain-chat 中 file_converter.pdf_to_html 的调用约定：

POST /convert/
  Body: {"pdf_path": "<相对于知识库根目录的路径>"}
  成功: {"status": "success", "markdown_path": "<生成的 .md 绝对路径>"}
  失败: {"status": "error", "message": "..."}  + HTTP 4xx/5xx

环境变量:
  PDF_CONVERT_KB_ROOT  知识库根目录，须与 configs.kb_config.PDF_CONVERT_KB_ROOT 一致
  PDF_CONVERT_PORT     监听端口，默认 6006
"""
from __future__ import annotations

import logging
import os
from pathlib import Path

import fitz  # PyMuPDF
from fastapi import FastAPI, HTTPException
from pydantic import BaseModel, Field
import uvicorn

logger = logging.getLogger("pdf_convert_service")
logging.basicConfig(level=logging.INFO)

# 与 langchain-chat 默认知识库目录一致（本文件位于 langchain-chat/pdf_convert_service/app.py）
_LC_ROOT = Path(__file__).resolve().parent.parent
_DEFAULT_KB = _LC_ROOT / "knowledge_base"
KB_ROOT = Path(os.environ.get("PDF_CONVERT_KB_ROOT", str(_DEFAULT_KB))).resolve()

app = FastAPI(title="PDF Convert Service", version="1.0.0")


class ConvertRequest(BaseModel):
    pdf_path: str = Field(..., description="相对于知识库根的路径，如 kb_name/file.pdf")


def _under_kb_root(full: Path) -> bool:
    try:
        full.resolve().relative_to(KB_ROOT)
        return True
    except ValueError:
        return False


def _pdf_to_markdown_file(pdf_abs: Path, md_abs: Path) -> None:
    doc = fitz.open(pdf_abs)
    try:
        chunks: list[str] = []
        for i in range(len(doc)):
            page = doc.load_page(i)
            text = page.get_text()
            chunks.append(f"\n\n## 第 {i + 1} 页\n\n{text.strip()}\n")
        body = "".join(chunks).strip()
        if not body:
            body = "_（未能从 PDF 提取到文本，可能是扫描件或加密文档）_"
        md_abs.parent.mkdir(parents=True, exist_ok=True)
        md_abs.write_text(body, encoding="utf-8")
    finally:
        doc.close()


@app.get("/health")
def health():
    return {"status": "ok", "kb_root": str(KB_ROOT)}


@app.post("/convert/")
@app.post("/convert")
def convert(req: ConvertRequest):
    rel = req.pdf_path.replace("\\", "/").lstrip("/")
    if ".." in rel.split("/"):
        raise HTTPException(status_code=400, detail="invalid pdf_path")

    pdf_abs = (KB_ROOT / rel).resolve()
    if not _under_kb_root(pdf_abs):
        raise HTTPException(status_code=403, detail="pdf_path outside knowledge base root")
    if not pdf_abs.is_file():
        raise HTTPException(status_code=404, detail=f"file not found: {pdf_abs}")
    if pdf_abs.suffix.lower() != ".pdf":
        raise HTTPException(status_code=400, detail="not a pdf file")

    md_abs = pdf_abs.with_suffix(".md")
    try:
        _pdf_to_markdown_file(pdf_abs, md_abs)
    except Exception as e:
        logger.exception("pdf convert failed")
        raise HTTPException(status_code=500, detail=str(e)) from e

    return {"status": "success", "markdown_path": str(md_abs)}


def main():
    port = int(os.environ.get("PDF_CONVERT_PORT", "6006"))
    host = os.environ.get("PDF_CONVERT_HOST", "127.0.0.1")
    logger.info("KB_ROOT=%s listen=%s:%s", KB_ROOT, host, port)
    uvicorn.run(app, host=host, port=port, log_level="info")


if __name__ == "__main__":
    main()