import XLSXModule from "xlsx";

const XLSX =
  (
    XLSXModule as typeof import("xlsx") & {
      default?: typeof import("xlsx");
    }
  ).default ?? (XLSXModule as typeof import("xlsx"));

export type WorksheetCellValue = boolean | Date | number | string | null;
export type WorksheetMatrix = WorksheetCellValue[][];

function normalizeWorksheetCellValue(value: unknown): WorksheetCellValue {
  if (value === undefined || value === null) {
    return null;
  }

  if (typeof value === "string" || typeof value === "number" || typeof value === "boolean") {
    return value;
  }

  if (value instanceof Date) {
    return value;
  }

  return String(value);
}

export async function readWorksheetMatrix(
  workbookPath: string,
  sheetName: string,
): Promise<WorksheetMatrix> {
  const workbook = XLSX.readFile(workbookPath, {
    cellDates: true,
    dense: true,
  });
  const worksheet = workbook.Sheets[sheetName];
  if (!worksheet) {
    throw new Error(`Worksheet "${sheetName}" not found in workbook "${workbookPath}"`);
  }

  const rows = XLSX.utils.sheet_to_json<(WorksheetCellValue | null)[]>(worksheet, {
    header: 1,
    raw: true,
    defval: null,
  });

  return rows.map((row) => row.map((value) => normalizeWorksheetCellValue(value)));
}

export function getCellString(
  rows: WorksheetMatrix,
  rowNumber: number,
  columnNumber: number,
): string | null {
  const value = rows[rowNumber - 1]?.[columnNumber - 1];
  if (value === null || value === undefined) {
    return null;
  }

  if (value instanceof Date) {
    return value.toISOString();
  }

  return String(value);
}

export function toColumnLetter(columnNumber: number): string {
  let current = columnNumber;
  let result = "";

  while (current > 0) {
    const remainder = (current - 1) % 26;
    result = String.fromCharCode(65 + remainder) + result;
    current = Math.floor((current - 1) / 26);
  }

  return result;
}