/**
 * 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, OnInit, inject } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { AccountingService } from '../accounting.service';
import { OrganizationService } from '../../organization/organization.service';
import { buildBalanceSheetPdf } from './balance-sheet-pdf';

interface BalanceSheetNode {
  id: number;
  name: string;
  glCode: string;
  usage: 'HEADER' | 'DETAIL';
  balance: number;
  children: BalanceSheetNode[];
}

interface BalanceSheetGroup {
  classification: string;
  total: number;
  nodes: BalanceSheetNode[];
}

interface BalanceSheetSide {
  label: string;
  total: number;
  groups: BalanceSheetGroup[];
}

/**
 * Consolidated Balance Sheet (sub-group wise), laid out the way the bank's own printed balance
 * sheet reads: liabilities on the left, assets on the right, each top-level Header account a named
 * block whose Detail accounts are listed under it and subtotalled in the TOTAL column.
 *
 * Balances come from BalanceSheetApiResource, which reads the live ledger - a Detail account's own
 * postings, and a Header's as the recursive sum of its children (a Header never carries a posting
 * of its own). A Detail account that sits under no Header at all is shown as its own one-line block
 * rather than being dropped.
 */
@Component({
  selector: 'mifosx-balance-sheet',
  standalone: true,
  imports: [
    CommonModule,
    FormsModule
  ],
  templateUrl: './balance-sheet.component.html',
  styleUrl: './balance-sheet.component.scss'
})
export class BalanceSheetComponent implements OnInit {
  private accountingService = inject(AccountingService);
  private organizationService = inject(OrganizationService);

  /** Printed at the head of the PDF. Falls back to a neutral title if the profile is not set up. */
  bankName = 'Bank';

  asOnDate: string = new Date().toISOString().slice(0, 10);
  officeId: number | null = null;
  offices: { id: number; name: string }[] = [];

  loading = false;
  error = '';
  asOnDateLoaded = '';

  /** What the server returned, kept whole so the zero-balance toggle never needs a refetch. */
  private rawDebitSide: BalanceSheetSide | null = null;
  private rawCreditSide: BalanceSheetSide | null = null;

  debitSide: BalanceSheetSide | null = null;
  creditSide: BalanceSheetSide | null = null;

  /**
   * A working chart of accounts carries far more accounts than a bank actually operates, and a
   * printed balance sheet lists only the ones carrying a balance — leaving every nil line in makes
   * the sheet unreadable. On by default for that reason; switch it off to audit the full chart.
   */
  hideZeroBalances = true;

  /** Both sides are derived from the same double-entry ledger, so they can only disagree if a
   *  posting is missing a leg — worth surfacing rather than hiding. */
  get tallied(): boolean {
    if (!this.debitSide || !this.creditSide) {
      return true;
    }
    return Math.abs(this.debitSide.total - this.creditSide.total) < 0.01;
  }

  get difference(): number {
    if (!this.debitSide || !this.creditSide) {
      return 0;
    }
    return Math.abs(this.debitSide.total - this.creditSide.total);
  }

  get officeLabel(): string {
    if (this.officeId == null) {
      return 'ALL BRANCHES';
    }
    return (this.offices.find((o) => o.id === this.officeId)?.name ?? '').toUpperCase();
  }

  ngOnInit(): void {
    this.accountingService.getOffices().subscribe({
      next: (offices) => (this.offices = offices || []),
      error: () => (this.offices = [])
    });
    this.organizationService.getInstitutionProfile().subscribe({
      next: (profile: any) => {
        this.bankName = profile?.statementHeaderName || profile?.bankName || this.bankName;
      },
      // A missing institution profile must not stop the sheet from loading — the PDF just carries
      // the fallback title.
      error: () => undefined
    });
    this.load();
  }

  load(): void {
    this.loading = true;
    this.error = '';
    this.accountingService.getBalanceSheet(this.asOnDate, this.officeId ?? undefined).subscribe({
      next: (res: any) => {
        this.rawDebitSide = res.debitSide;
        this.rawCreditSide = res.creditSide;
        this.asOnDateLoaded = res.asOnDate;
        this.applyZeroFilter();
        this.loading = false;
      },
      error: () => {
        this.error = 'Could not load the balance sheet for this date.';
        this.loading = false;
      }
    });
  }

  /**
   * Rebuilds the displayed sides from what the server sent, dropping nil lines when asked. The
   * totals are deliberately left as the server computed them — hiding a nil line must never change
   * a figure, and a group total is unaffected by removing children that summed to nothing.
   */
  applyZeroFilter(): void {
    this.debitSide = this.filterSide(this.rawDebitSide);
    this.creditSide = this.filterSide(this.rawCreditSide);
  }

  private filterSide(side: BalanceSheetSide | null): BalanceSheetSide | null {
    if (!side) {
      return null;
    }
    if (!this.hideZeroBalances) {
      return side;
    }
    const groups = side.groups
      .map((group) => ({
        ...group,
        nodes: group.nodes
          .map((node) => this.pruneZeros(node))
          .filter((node): node is BalanceSheetNode => node !== null)
      }))
      .filter((group) => group.nodes.length > 0);
    return { ...side, groups };
  }

  /** Drops a node whose balance is nil, and any Header left with nothing under it. */
  private pruneZeros(node: BalanceSheetNode): BalanceSheetNode | null {
    if (Math.abs(node.balance) < 0.005) {
      return null;
    }
    const children = node.children
      .map((child) => this.pruneZeros(child))
      .filter((child): child is BalanceSheetNode => child !== null);
    return { ...node, children };
  }

  /** Indian grouping with two decimals, matching the printed report (2,76,92,608.00). */
  fmt(value: number): string {
    return new Intl.NumberFormat('en-IN', { minimumFractionDigits: 2, maximumFractionDigits: 2 }).format(value ?? 0);
  }

  /** dd/MM/yyyy, as the printed report dates it. */
  displayDate(iso: string): string {
    if (!iso) {
      return '';
    }
    const [
      y,
      m,
      d
    ] = iso.split('-');
    return `${d}/${m}/${y}`;
  }

  /**
   * Builds the report as a real PDF rather than printing the page: window.print() takes the whole
   * app shell with it and breaks pages wherever they happen to fall, which is what made the earlier
   * output unusable.
   */
  downloadPdf(): void {
    if (!this.debitSide || !this.creditSide) {
      return;
    }
    const doc = buildBalanceSheetPdf({
      bankName: this.bankName,
      officeLabel: this.officeLabel,
      asOnDate: this.asOnDateLoaded || this.asOnDate,
      creditSide: this.creditSide,
      debitSide: this.debitSide
    });
    doc.save(`balance-sheet-${this.asOnDateLoaded || this.asOnDate}.pdf`);
  }
}