from __future__ import annotations

from dataclasses import dataclass
from pathlib import Path


SUPPORTED_EXTENSIONS = {"pdf", "doc", "docx", "xls", "xlsx", "ppt", "pptx"}


@dataclass(frozen=True)
class PageCountResult:
    status: str
    page_count: int | None = None
    error_message: str = ""


def count_document_pages(path: str | Path) -> PageCountResult:
    file_path = Path(path)
    ext = file_path.suffix.lower().lstrip(".")
    if ext not in SUPPORTED_EXTENSIONS:
        return PageCountResult(status="unsupported")

    try:
        if ext == "pdf":
            from pypdf import PdfReader

            return PageCountResult(status="success", page_count=len(PdfReader(str(file_path)).pages))
        if ext == "docx":
            from docx import Document

            properties = Document(str(file_path)).core_properties
            pages = getattr(properties, "pages", None)
            if pages:
                return PageCountResult(status="success", page_count=pages)
            return PageCountResult(status="uncertain")
        if ext == "xlsx":
            from openpyxl import load_workbook

            workbook = load_workbook(str(file_path), read_only=True, data_only=True)
            return PageCountResult(status="success", page_count=len(workbook.sheetnames))
        if ext == "xls":
            import xlrd

            workbook = xlrd.open_workbook(str(file_path), on_demand=True)
            return PageCountResult(status="success", page_count=workbook.nsheets)
        if ext == "pptx":
            from pptx import Presentation

            return PageCountResult(status="success", page_count=len(Presentation(str(file_path)).slides))
        if ext in {"doc", "ppt"}:
            import olefile

            if olefile.isOleFile(str(file_path)):
                return PageCountResult(status="uncertain")
            return PageCountResult(status="failed", error_message="不是有效的 OLE 文件。")
    except Exception as exc:
        return PageCountResult(status="failed", error_message=str(exc))

    return PageCountResult(status="uncertain")