import { RATINGS, actionColumns, goalCount } from './helpers';

function fileStamp(now = new Date()) {
  const day = String(now.getDate()).padStart(2, '0');
  const month = String(now.getMonth() + 1).padStart(2, '0');
  const year = String(now.getFullYear()).slice(2);
  return `${day}-${month}-${year}`;
}

function countCell(value) {
  if (value == null || value === '') return 0;
  const number = Number(value);
  return Number.isFinite(number) ? number : value;
}

function exportHeader(key) {
  if (key === 'total') return 'Total';
  return String(key).replaceAll('_', ' ').replace(/\b[a-z]/g, (letter) => letter.toUpperCase());
}

function exportMonth(month) {
  if (!/^\d{4}-\d{2}$/.test(month)) return month;
  const [year, mon] = month.split('-');
  const label = new Date(Number(year), Number(mon) - 1, 1).toLocaleString('en-US', { month: 'short' });
  return `${label}-${year}`;
}

async function downloadXlsx(filename, lines) {
  const { default: ExcelJS } = await import('exceljs');
  const workbook = new ExcelJS.Workbook();
  const sheet = workbook.addWorksheet('Worksheet');
  lines.forEach((line) => sheet.addRow(line));
  const buffer = await workbook.xlsx.writeBuffer();
  const blob = new Blob([buffer], { type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' });
  const anchor = document.createElement('a');
  anchor.href = URL.createObjectURL(blob);
  anchor.download = filename;
  document.body.appendChild(anchor);
  anchor.click();
  document.body.removeChild(anchor);
  URL.revokeObjectURL(anchor.href);
}

export async function exportActionPlan(report, rows) {
  const columns = actionColumns();
  const lines = [
    [report.columnTitle, ...columns.map((column) => exportHeader(column))],
    ...rows.map((row) => [row.label, ...columns.map((column) => countCell(row[column]))]),
  ];
  await downloadXlsx(`${report.exportFile}_${fileStamp()}.xlsx`, lines);
}

export async function exportGoalReport(report, grid) {
  const header = [report.columnTitle];
  const ratings = [''];
  grid.months.forEach((month) => {
    const label = exportMonth(month);
    RATINGS.forEach(() => header.push(label));
    RATINGS.forEach((rating) => ratings.push(rating));
  });
  const lines = [
    header,
    ratings,
    ...grid.goals.map((goalName) => [
      goalName,
      ...grid.months.flatMap((month) => RATINGS.map((rating) => countCell(goalCount(grid.byMonth, month, goalName, rating)))),
    ]),
  ];
  await downloadXlsx(`${report.exportFile}_${fileStamp()}.xlsx`, lines);
}