"""
Excel / PDF 抽出纯文本。

本文件职责：把允许的附件字节变成可见原文，供千问整理、再走文字询价。
属于 policy 包。禁止在这里猜港口/箱型/缺项；禁止写六态。
识别槽与 H5 都只调用本模块的纯函数。
"""

from __future__ import annotations

import io
import logging
from typing import Any

logger = logging.getLogger(__name__)

_ALLOWED_EXT = {".xls", ".xlsx", ".pdf"}
_REJECT_HINT = "only_xlsx_xls_pdf"


def attachment_ext(filename: str) -> str:
    """小写后缀，含点。无后缀返回空。"""
    name = (filename or "").strip().rsplit("/", 1)[-1].rsplit("\\", 1)[-1]
    if "." not in name:
        return ""
    return "." + name.rsplit(".", 1)[-1].lower()


def allowed_attachment(filename: str) -> bool:
    """H5 只收 xls / xlsx / pdf。"""
    return attachment_ext(filename) in _ALLOWED_EXT


def extract_attachment_text(filename: str, raw: bytes) -> dict[str, Any]:
    """
    抽出单元格或 PDF 可见字。

    返回 ok/text/error/empty。失败时 text 为空，由上层走「没看清 / 暂时没认出」。
    """
    ext = attachment_ext(filename)
    if ext not in _ALLOWED_EXT:
        return {"ok": False, "text": "", "empty": True, "error": _REJECT_HINT}
    blob = raw or b""
    if not blob:
        return {"ok": False, "text": "", "empty": True, "error": "empty_bytes"}
    try:
        if ext == ".pdf":
            text = _pdf_text(blob)
        elif ext == ".xlsx":
            text = _xlsx_text(blob)
        else:
            text = _xls_text(blob)
    except Exception as exc:  # noqa: BLE001
        logger.exception("抽附件文本失败 name=%s", filename)
        return {"ok": False, "text": "", "empty": True, "error": f"extract_fail:{type(exc).__name__}"}
    body = (text or "").strip()
    return {"ok": True, "text": body, "empty": not bool(body), "error": ""}


def _xlsx_text(raw: bytes) -> str:
    from openpyxl import load_workbook

    wb = load_workbook(io.BytesIO(raw), read_only=True, data_only=True)
    parts: list[str] = []
    try:
        for sheet in wb.worksheets:
            title = str(sheet.title or "").strip()
            if title:
                parts.append(f"# {title}")
            for row in sheet.iter_rows(values_only=True):
                cells = [str(c).strip() for c in row if c is not None and str(c).strip()]
                if cells:
                    parts.append("\t".join(cells))
    finally:
        wb.close()
    return "\n".join(parts)


def _xls_text(raw: bytes) -> str:
    try:
        import xlrd
    except ImportError:
        return ""
    book = xlrd.open_workbook(file_contents=raw)
    parts: list[str] = []
    for sheet in book.sheets():
        title = str(sheet.name or "").strip()
        if title:
            parts.append(f"# {title}")
        for r in range(sheet.nrows):
            cells = [
                str(sheet.cell_value(r, c)).strip()
                for c in range(sheet.ncols)
                if str(sheet.cell_value(r, c)).strip()
            ]
            if cells:
                parts.append("\t".join(cells))
    return "\n".join(parts)


def _pdf_text(raw: bytes) -> str:
    from pypdf import PdfReader

    reader = PdfReader(io.BytesIO(raw))
    parts: list[str] = []
    for page in reader.pages:
        piece = page.extract_text() or ""
        if piece.strip():
            parts.append(piece.strip())
    return "\n".join(parts)