import * as XLSX from "xlsx";
import type { WordImportInput, WordRecord } from "@/lib/db";

export const wordExcelHeaders = ["词库英语", "中文", "图标/图片"] as const;

type WordExcelHeader = (typeof wordExcelHeaders)[number];

type WordExcelRow = Record<WordExcelHeader, string>;

export function parseWordExcel(buffer: Buffer): WordImportInput[] {
  const workbook = XLSX.read(buffer, { type: "buffer" });
  const sheetName = workbook.SheetNames[0];
  if (!sheetName) {
    throw new Error("表格中没有可导入的工作表");
  }

  const sheet = workbook.Sheets[sheetName];
  const rows = XLSX.utils.sheet_to_json<Record<string, unknown>>(sheet, {
    defval: "",
    raw: false,
  });

  return rows.map((row) => ({
    english: readCell(row, "词库英语"),
    chinese: readCell(row, "中文"),
    image: readCell(row, "图标/图片"),
  }));
}

export function buildWordExcel(words: WordRecord[]) {
  const rows: WordExcelRow[] =
    words.length > 0
      ? words.map((word) => ({
          词库英语: word.english,
          中文: word.chinese,
          "图标/图片": word.image,
        }))
      : [
          {
            词库英语: "apple",
            中文: "苹果",
            "图标/图片": "🍎",
          },
        ];

  const worksheet = XLSX.utils.json_to_sheet(rows, { header: [...wordExcelHeaders] });
  worksheet["!cols"] = [{ wch: 24 }, { wch: 18 }, { wch: 28 }];

  const workbook = XLSX.utils.book_new();
  XLSX.utils.book_append_sheet(workbook, worksheet, "词库导入");
  return XLSX.write(workbook, { bookType: "xlsx", type: "buffer" }) as Buffer;
}

function readCell(row: Record<string, unknown>, header: string) {
  const value = row[header];
  return value == null ? "" : String(value).trim();
}