"""CMS 导入 / 导出通用工具（基于 openpyxl）。"""
import io

from django.http import HttpResponse
from openpyxl import Workbook, load_workbook

XLSX_CONTENT_TYPE = (
    'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
)


def xlsx_response(filename, headers, rows):
    """生成 .xlsx 下载响应。

    Args:
        filename: 下载文件名（含 .xlsx）
        headers: 表头列表
        rows: 二维数据（list[list]）；空则只导出表头（可作模板）
    """
    wb = Workbook()
    ws = wb.active
    ws.append(list(headers))
    for row in rows:
        ws.append(list(row))
    buf = io.BytesIO()
    wb.save(buf)
    buf.seek(0)
    resp = HttpResponse(buf.getvalue(), content_type=XLSX_CONTENT_TYPE)
    resp['Content-Disposition'] = f'attachment; filename="{filename}"'
    return resp


def rows_from_xlsx(file):
    """解析上传的 .xlsx，首行为表头，返回 list[dict]（表头→单元格字符串）。

    空行跳过；单元格统一转为去空格字符串（None → ''）。
    """
    wb = load_workbook(file, read_only=True, data_only=True)
    ws = wb.active
    it = ws.iter_rows(values_only=True)
    try:
        header_cells = next(it)
    except StopIteration:
        return []
    headers = [str(h).strip() if h is not None else '' for h in header_cells]

    result = []
    for raw in it:
        if raw is None or all(c is None or str(c).strip() == '' for c in raw):
            continue
        row = {}
        for i, h in enumerate(headers):
            if not h:
                continue
            val = raw[i] if i < len(raw) else None
            row[h] = '' if val is None else str(val).strip()
        result.append(row)
    return result