"""PDF 解析器（PyMuPDF fallback）。"""

from app.core.logging import get_logger

logger = get_logger(__name__)


def parse_pdf_with_pymupdf(file_content: bytes) -> str | None:
    """用 PyMuPDF 解析 PDF，返回 Markdown 或 None（失败时）。"""
    try:
        import pymupdf  # PyMuPDF >= 1.24

        doc = pymupdf.open(stream=file_content, filetype="pdf")
        pages = []
        for page_num in range(len(doc)):
            page = doc.load_page(page_num)
            text = page.get_text()
            if text.strip():
                pages.append(text)
        doc.close()

        if not pages:
            return None

        # 组合成 Markdown（每页一个段落）
        markdown = "\n\n".join(pages)
        return markdown
    except Exception as e:
        logger.warning("PyMuPDF 解析失败: %s", e)
        return None


def has_text_layer(file_content: bytes) -> bool:
    """检查 PDF 是否有文本层。"""
    try:
        import pymupdf

        doc = pymupdf.open(stream=file_content, filetype="pdf")
        for page_num in range(min(3, len(doc))):  # 检查前 3 页
            page = doc.load_page(page_num)
            if page.get_text().strip():
                doc.close()
                return True
        doc.close()
        return False
    except Exception:
        return False