import XLSX from "xlsx";
import { mkdir, readdir, writeFile } from "node:fs/promises";
import path from "node:path";

const INPUT_DIR = process.env.BIZMAX_OUTPUT_DIR ?? path.resolve(process.cwd(), "output");
const CSV_DIR = process.env.BIZMAX_CSV_DIR ?? path.join(INPUT_DIR, "csv");
const CSV_NAME = process.env.BIZMAX_CSV_NAME ?? "bizmax-all.csv";

function toText(value: unknown): string {
  if (value == null) {
    return "";
  }
  return String(value);
}

function escapeCsv(value: string): string {
  if (/[",\n\r]/.test(value)) {
    return `"${value.replace(/"/g, "\"\"")}"`;
  }
  return value;
}

function rowToCsv(row: string[]): string {
  return row.map(escapeCsv).join(",");
}

async function main(): Promise<void> {
  const entries = await readdir(INPUT_DIR, { withFileTypes: true });
  const xlsxFiles = entries
    .filter((entry) => entry.isFile() && entry.name.toLowerCase().endsWith(".xlsx"))
    .map((entry) => path.join(INPUT_DIR, entry.name))
    .sort();

  if (xlsxFiles.length === 0) {
    throw new Error(`No .xlsx files found in ${INPUT_DIR}`);
  }

  const outputRows: string[] = [];
  let wroteHeader = false;

  for (const xlsxFile of xlsxFiles) {
    const workbook = XLSX.readFile(xlsxFile, { cellDates: false });

    for (const sheetName of workbook.SheetNames) {
      const worksheet = workbook.Sheets[sheetName];
      const rows = XLSX.utils.sheet_to_json<unknown[]>(worksheet, {
        header: 1,
        raw: false,
        defval: "",
      });

      if (rows.length === 0) {
        continue;
      }

      const headerRow = (rows[0] ?? []).map(toText);
      if (!wroteHeader) {
        outputRows.push(
          rowToCsv(["source_file", "source_sheet", ...headerRow]),
        );
        wroteHeader = true;
      }

      for (const row of rows.slice(1)) {
        const values = (row as unknown[]).map(toText);
        outputRows.push(
          rowToCsv([
            path.basename(xlsxFile),
            sheetName,
            ...values,
          ]),
        );
      }
    }
  }

  if (!wroteHeader) {
    throw new Error(`No worksheet rows found in ${INPUT_DIR}`);
  }

  await mkdir(CSV_DIR, { recursive: true });
  const outputPath = path.join(CSV_DIR, CSV_NAME);
  await writeFile(outputPath, `${outputRows.join("\n")}\n`, "utf8");
  process.stdout.write(`${outputPath}\n`);
}

main().catch((error: unknown) => {
  const message = error instanceof Error ? error.message : String(error);
  process.stderr.write(`${message}\n`);
  process.exitCode = 1;
});