/**
 * Copyright since 2025 Mifos Initiative
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

// Shared "Export to Excel" builder for Cashier reports (mirrors ../investment/investment-export.ts)
// — centralised so the ExcelJS boilerplate (title/meta/header rows, number formatting, safe sheet
// names, Blob download) is written once and every cashier report's export behaves the same way.

import * as ExcelJS from 'exceljs';

export interface ExportSheetSpec {
  /** Worksheet tab name — sanitised for Excel's forbidden characters (\ / ? * [ ]) and length. */
  sheetName: string;
  /** Bold title row, merged across all columns. */
  title: string;
  /** Optional italic subtitle row (e.g. scope/date), merged across all columns. */
  subtitle?: string;
  headers: string[];
  rows: (string | number | null)[][];
  widths?: number[];
}

/** Excel worksheet names can't contain \ / ? * [ ] or exceed 31 chars. */
function safeSheetName(name: string): string {
  return name.replace(/[\\/?*[\]]/g, '-').slice(0, 31);
}

function buildSheet(wb: ExcelJS.Workbook, spec: ExportSheetSpec): void {
  const sheet = wb.addWorksheet(safeSheetName(spec.sheetName));
  sheet.columns = (spec.widths || spec.headers.map(() => 18)).map((w) => ({ width: w }));

  const title = sheet.addRow([spec.title]);
  sheet.mergeCells(title.number, 1, title.number, spec.headers.length);
  title.font = { bold: true, size: 14, color: { argb: 'FFFFFFFF' } };
  title.alignment = { horizontal: 'center', vertical: 'middle' };
  title.height = 24;
  title.getCell(1).fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FF0F4F3C' } };

  if (spec.subtitle) {
    const meta = sheet.addRow([spec.subtitle]);
    sheet.mergeCells(meta.number, 1, meta.number, spec.headers.length);
    meta.font = { italic: true, size: 10 };
  }
  sheet.addRow([]);

  const head = sheet.addRow(spec.headers);
  head.font = { bold: true };
  head.alignment = { wrapText: true, horizontal: 'center' };
  head.eachCell((c) => {
    c.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFE2E8F0' } };
    c.border = { bottom: { style: 'thin' } };
  });

  for (const r of spec.rows) {
    const row = sheet.addRow(r);
    r.forEach((v, idx) => {
      if (typeof v === 'number') {
        row.getCell(idx + 1).numFmt = '#,##0.00';
      }
    });
  }
  sheet.views = [{ state: 'frozen', ySplit: spec.subtitle ? 4 : 3 }];
}

/** Builds a (possibly multi-sheet) workbook and triggers a browser download. */
export async function exportWorkbook(sheets: ExportSheetSpec[], fileName: string): Promise<void> {
  const wb = new ExcelJS.Workbook();
  wb.creator = 'CBSNexora';
  wb.created = new Date();
  sheets.forEach((s) => buildSheet(wb, s));

  const buffer = await wb.xlsx.writeBuffer();
  const blob = new Blob([buffer], {
    type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
  });
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = `${fileName.replace(/[^\w]+/g, '-')}.xlsx`;
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  URL.revokeObjectURL(url);
}