/**
 * 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/.
 */

import { Component, inject } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { FaIconComponent } from '@fortawesome/angular-fontawesome';
import { STANDALONE_SHARED_IMPORTS } from 'app/standalone-shared.module';
import * as ExcelJS from 'exceljs';

import { BranchScopeService } from '../core/branch-scope.service';
import { FY_TAX_CONFIG, QUARTER_LABEL } from '../letter-mgmt/certificates/form-15gh/tds-15gh.compute';
import { TDS_AS_AT, TDS_FYS } from './tds-reports-data';
import { Tds26qSummary, TdsRemittanceRow, tds26qSummary, tdsRemittanceRows } from './tds-reports.compute';

@Component({
  selector: 'mifosx-tds-remittance-report',
  templateUrl: './tds-remittance-report.component.html',
  styleUrls: ['./tds-reports.shared.scss'],
  imports: [
    ...STANDALONE_SHARED_IMPORTS,
    FaIconComponent,
    FormsModule
  ]
})
export class TdsRemittanceReportComponent {
  private scope = inject(BranchScopeService);

  readonly financialYears = TDS_FYS;
  readonly quarterLabel = QUARTER_LABEL;
  readonly asAt = TDS_AS_AT;

  fy = TDS_FYS[0];
  exporting = false;

  /**
   * Provision and return references for the selected year. The quarterly return
   * became Form 140 under the 2025 Act, so the labels are read from the config
   * rather than written into the template.
   */
  get statute(): { section: string; statement: string; frequency: string } {
    const cfg = FY_TAX_CONFIG[this.fy];
    return {
      section: cfg?.interestTdsSection ?? '—',
      statement: cfg?.tdsStatementForm ?? '—',
      frequency: cfg?.declarationStatementFrequency === 'MONTHLY' ? 'monthly' : 'quarterly'
    };
  }

  get scopeLabel(): string {
    return this.scope.isHeadOffice ? 'Bank as a whole' : this.scope.officeName;
  }

  get rows(): TdsRemittanceRow[] {
    return tdsRemittanceRows(this.fy, this.asAt);
  }

  get summary(): Tds26qSummary {
    return tds26qSummary(this.fy, this.asAt);
  }

  /**
   * The control that matters. Tax deducted must equal tax deposited plus tax
   * still within its due date. Anything else means something has gone missing
   * and must be found before the return is filed.
   */
  get reconciled(): boolean {
    return this.summary.difference === 0;
  }

  get totalDefaultInterest(): number {
    return this.summary.defaultInterest;
  }

  trackRow(_: number, row: TdsRemittanceRow): string {
    return `${row.fy}-${row.quarter}`;
  }

  async exportWorkbook(): Promise<void> {
    this.exporting = true;
    try {
      const s = this.summary;
      const wb = new ExcelJS.Workbook();

      const challan = wb.addWorksheet('Challans');
      challan.addRow([`TDS remitted to Government — FY ${this.fy}`]);
      challan.addRow([`Scope: ${this.scopeLabel} · as at ${this.asAt}`]);
      challan.addRow([]);
      challan.addRow([
        'Quarter',
        'Deduction month',
        'Amount deducted',
        'Due date',
        'Deposited on',
        'Challan no.',
        'BSR code',
        'Status',
        'Delay (months)',
        'Late-deposit interest',
        `${this.statute.statement} due`
      ]);
      for (const r of this.rows) {
        challan.addRow([
          `Q${r.quarter}`,
          r.month,
          r.amount,
          r.dueDate,
          r.depositedOn ?? 'PENDING',
          r.challanNo ?? '',
          r.bsrCode ?? '',
          r.overdue ? 'OVERDUE' : r.late ? 'LATE' : r.depositedOn ? 'On time' : 'Within due date',
          r.delayMonths || '',
          r.defaultInterest || '',
          r.returnDueDate
        ]);
      }
      challan.getRow(1).font = { bold: true, size: 13 };
      challan.getRow(4).font = { bold: true };
      challan.columns.forEach((c) => (c.width = 18));

      const recon = wb.addWorksheet('Return Summary');
      recon.addRow([`${this.statute.statement} year-end position — FY ${this.fy}`]);
      recon.addRow([]);
      const lines: [string, number | string][] = [
        [
          'Deductees',
          s.deductees
        ],
        [
          'Total interest paid on time deposits',
          s.totalInterestPaid
        ],
        [
          '  — with tax deducted',
          s.interestWithDeduction
        ],
        [
          '  — without deduction (declaration on record)',
          s.interestWithoutDeduction
        ],
        [
          'TDS at standard rate (PAN on record)',
          s.tdsAtStandardRate
        ],
        [
          'TDS at higher rate (no PAN)',
          s.tdsAtHigherRate
        ],
        [
          'Total TDS deducted',
          s.totalDeducted
        ],
        [
          'Total deposited with Government',
          s.totalDeposited
        ],
        [
          'Still within due date',
          s.pendingDeposit
        ],
        [
          'DIFFERENCE (must be zero)',
          s.difference
        ],
        [
          'Interest payable for late deposit',
          s.defaultInterest
        ],
        [
          'Challans deposited late',
          s.lateChallans
        ],
        [
          'Challans overdue',
          s.overdueChallans
        ]
      ];
      for (const line of lines) {
        recon.addRow(line);
      }
      recon.getRow(1).font = { bold: true, size: 13 };
      recon.columns.forEach((c) => (c.width = 42));
      recon.getColumn(2).width = 20;

      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 = `TDS-Remittance-FY${this.fy}.xlsx`;
      a.click();
      URL.revokeObjectURL(url);
    } finally {
      this.exporting = false;
    }
  }
}