import { CommonModule, CurrencyPipe, DatePipe } from '@angular/common';
import { AfterViewChecked, Component, OnDestroy, OnInit, effect, inject } from '@angular/core';
import { Chart, ArcElement, CategoryScale, DoughnutController, Legend, LineController, LineElement, LinearScale, PointElement, Tooltip } from 'chart.js';
import { AuthService } from '../../core/services/auth.service';
import { ExpensesService } from '../../core/services/expenses.service';
import { ShoppingListIntegrationService } from '../../core/services/shopping-list-integration.service';
import { StatsService } from '../../core/services/stats.service';
import { UiService } from '../../core/services/ui.service';
import type { CashflowResponse, Expense, ShoppingListSummary, StatsResponse } from '../../shared/models';

Chart.register(DoughnutController, ArcElement, Tooltip, Legend, LineController, LineElement, PointElement, CategoryScale, LinearScale);

const DASHBOARD_CACHE_KEY = 'expense-control-dashboard-v7';
const chartPalette = ['#206bc4', '#2fb344', '#f59f00', '#d63939', '#9b4dca', '#4263eb', '#0ca678', '#e8590c'];
type TimelineRangeKey = '1m' | '2m' | '3m' | 'q' | '6m' | '12m';

type TimelineRangeOption = {
  value: TimelineRangeKey;
  labelKey: string;
};

const formatLocalDate = (date: Date) => {
  const year = date.getFullYear();
  const month = `${date.getMonth() + 1}`.padStart(2, '0');
  const day = `${date.getDate()}`.padStart(2, '0');
  return `${year}-${month}-${day}`;
};

const startOfMonth = (date: Date) => new Date(date.getFullYear(), date.getMonth(), 1);

const addMonths = (date: Date, amount: number) => {
  const next = new Date(date);
  next.setMonth(next.getMonth() + amount, 1);
  return next;
};

const getMonthRange = () => {
  const today = new Date();
  return {
    start: formatLocalDate(startOfMonth(today)),
    end: formatLocalDate(today)
  };
};

const getTimelineRange = (range: TimelineRangeKey) => {
  const today = new Date();
  const monthsBack = ({ '1m': 0, '2m': 1, '3m': 2, q: 2, '6m': 5, '12m': 11 } as Record<TimelineRangeKey, number>)[range] ?? 0;
  return {
    start: formatLocalDate(startOfMonth(addMonths(today, -monthsBack))),
    end: formatLocalDate(today)
  };
};

@Component({
  selector: 'app-dashboard',
  standalone: true,
  imports: [CommonModule, CurrencyPipe, DatePipe],
  template: `
    <div class="page-header d-print-none mb-3 ec-page-header">
      <div class="row align-items-center g-3">
        <div class="col">
          <h2 class="page-title mb-1">{{ ui.t('nav.dashboard') }}</h2>
          <div class="text-secondary">{{ ui.t('dashboard.cashflowHint') }}</div>
        </div>
      </div>
    </div>

    <div class="row row-cards">
      <div class="col-md-3"><div class="card pv-card overflow-hidden"><div class="card-body"><div class="text-secondary">{{ ui.t('dashboard.total') }}</div><div class="display-6">{{ (stats?.total || 0) | currency:'PLN':'symbol':'1.2-2' }}</div></div></div></div>
      <div class="col-md-3"><div class="card pv-card overflow-hidden"><div class="card-body"><div class="text-secondary">{{ ui.t('dashboard.count') }}</div><div class="display-6">{{ stats?.count || 0 }}</div></div></div></div>
      <div class="col-md-3"><div class="card pv-card overflow-hidden"><div class="card-body"><div class="text-secondary">{{ ui.t('dashboard.budgetUsage') }}</div><div class="display-6">{{ cashflow?.budgetUsagePercent || 0 }}%</div></div></div></div>
      <div class="col-md-3"><div class="card pv-card overflow-hidden"><div class="card-body"><div class="text-secondary">{{ ui.t('cashflow.forecast') }}</div><div class="display-6">{{ (cashflow?.forecastCurrentMonth || 0) | currency:'PLN':'symbol':'1.2-2' }}</div></div></div></div>

      @if (canShowExternalStats()) {
        <div class="col-md-6"><div class="card pv-card overflow-hidden"><div class="card-body"><div class="text-secondary">{{ ui.t('dashboard.externalSpend') }}</div><div class="display-6">{{ externalAmount() | currency:'PLN':'symbol':'1.2-2' }}</div></div></div></div>
        <div class="col-md-6"><div class="card pv-card overflow-hidden"><div class="card-body"><div class="text-secondary">{{ ui.t('dashboard.externalRecords') }}</div><div class="display-6">{{ externalCount() }}</div></div></div></div>
      }

      <div class="col-12 d-flex align-items-stretch">
        <div class="card pv-card h-100 w-100 overflow-hidden">
          <div class="card-header d-flex justify-content-between align-items-center gap-2 flex-wrap">
            <h3 class="card-title mb-0">{{ ui.t('dashboard.trend') }}</h3>
            <div class="btn-list">
              @for (option of timelineRangeOptions; track option.value) {
                <button class="btn btn-sm"
                        type="button"
                        [class.btn-primary]="selectedTimelineRange === option.value"
                        [class.btn-outline-secondary]="selectedTimelineRange !== option.value"
                        (click)="changeTimelineRange(option.value)">
                  {{ ui.t(option.labelKey) }}
                </button>
              }
            </div>
          </div>
          <div class="card-body">
            @if (timelineStats?.timeline?.length) {
              <div class="ec-chart-wrap"><canvas id="dashboardTimelineChart"></canvas></div>
            } @else {
              <div class="alert alert-info mb-0">{{ ui.t('dashboard.noTrendData') }}</div>
            }
          </div>
        </div>
      </div>

      <div class="col-lg-7 d-flex align-items-stretch">
        <div class="card pv-card h-100 w-100 overflow-hidden">
          <div class="card-header"><h3 class="card-title">{{ ui.t('dashboard.share') }}</h3></div>
          <div class="card-body">
            @if (stats?.byCategory?.length) {
              <div class="ec-chart-wrap"><canvas id="dashboardCategoryChart"></canvas></div>
            } @else {
              <div class="alert alert-info mb-0">{{ ui.t('dashboard.noChartData') }}</div>
            }
          </div>
        </div>
      </div>

      <div class="col-lg-5 d-flex align-items-stretch">
        <div class="card pv-card h-100 w-100 overflow-hidden">
          <div class="card-header"><h3 class="card-title">{{ ui.t('nav.cashflow') }}</h3></div>
          <div class="card-body d-grid gap-3">
            <div class="d-flex justify-content-between"><span class="text-secondary">{{ ui.t('cashflow.actual') }}</span><strong>{{ (cashflow?.actualCurrent || 0) | currency:'PLN':'symbol':'1.2-2' }}</strong></div>
            <div class="d-flex justify-content-between"><span class="text-secondary">{{ ui.t('cashflow.budget') }}</span><strong>{{ (cashflow?.totalBudget || 0) | currency:'PLN':'symbol':'1.2-2' }}</strong></div>
            <div class="d-flex justify-content-between"><span class="text-secondary">{{ ui.t('cashflow.pending') }}</span><strong>{{ cashflow?.pendingApproval || 0 }}</strong></div>
            <div class="d-flex justify-content-between"><span class="text-secondary">{{ ui.t('cashflow.duplicates') }}</span><strong>{{ cashflow?.duplicateCount || 0 }}</strong></div>
            <div>
              <div class="form-label mb-2">{{ ui.t('budget.alerts') }}</div>
              <div class="d-grid gap-2">
                @for (alert of cashflow?.alerts || []; track alert.id) {
                  <div class="alert alert-warning mb-0 py-2 px-3">{{ alert.name }} · {{ alert.usagePercent }}%</div>
                } @empty {
                  <div class="text-secondary">{{ ui.t('common.noData') }}</div>
                }
              </div>
            </div>
          </div>
        </div>
      </div>

      <div class="col-lg-6">
        <div class="card overflow-hidden">
          <div class="card-header"><h3 class="card-title">{{ ui.t('dashboard.recent') }}</h3></div>
          <div class="table-responsive">
            <table class="table table-vcenter card-table mb-0">
              <thead><tr><th>{{ ui.t('table.title') }}</th><th>{{ ui.t('table.category') }}</th><th>{{ ui.t('expenses.field.status') }}</th><th class="text-end">{{ ui.t('table.amount') }}</th></tr></thead>
              <tbody>
                @for (item of recentExpenses; track item.id) {
                  <tr>
                    <td>
                      <div class="fw-semibold">{{ item.title }}</div>
                      <div class="text-secondary small">{{ item.merchant || ui.t('expenses.noMerchant') }}</div>
                    </td>
                    <td>{{ item.category.name }}</td>
                    <td><span class="badge" [ngClass]="statusBadgeClass(item.status)">{{ ui.t('status.' + item.status.toLowerCase()) }}</span></td>
                    <td class="text-end">{{ item.amount | currency:'PLN':'symbol':'1.2-2' }}</td>
                  </tr>
                } @empty {
                  <tr><td colspan="4" class="text-secondary">{{ ui.t('common.noExpenses') }}</td></tr>
                }
              </tbody>
            </table>
          </div>
        </div>
      </div>

      <div class="col-lg-6">
        <div class="card overflow-hidden">
          <div class="card-header"><h3 class="card-title">{{ ui.t('cashflow.upcomingRecurring') }}</h3></div>
          <div class="table-responsive">
            <table class="table table-vcenter card-table mb-0">
              <thead><tr><th>{{ ui.t('table.title') }}</th><th>{{ ui.t('table.date') }}</th><th class="text-end">{{ ui.t('table.amount') }}</th></tr></thead>
              <tbody>
                @for (item of cashflow?.upcomingRecurring || []; track item.id) {
                  <tr><td>{{ item.title }}</td><td>{{ item.nextRunDate | date:'yyyy-MM-dd' }}</td><td class="text-end">{{ item.amount | currency:'PLN':'symbol':'1.2-2' }}</td></tr>
                } @empty {
                  <tr><td colspan="3" class="text-secondary">{{ ui.t('common.noData') }}</td></tr>
                }
              </tbody>
            </table>
          </div>
        </div>
      </div>
    </div>
  `
})
export class DashboardComponent implements OnInit, AfterViewChecked, OnDestroy {
  readonly ui = inject(UiService);
  readonly auth = inject(AuthService);
  private readonly expensesService = inject(ExpensesService);
  private readonly statsService = inject(StatsService);
  private readonly shoppingIntegration = inject(ShoppingListIntegrationService);
  readonly timelineRangeOptions: TimelineRangeOption[] = [
    { value: '1m', labelKey: 'dashboard.range.1m' },
    { value: '2m', labelKey: 'dashboard.range.2m' },
    { value: '3m', labelKey: 'dashboard.range.3m' },
    { value: 'q', labelKey: 'dashboard.range.q' },
    { value: '6m', labelKey: 'dashboard.range.6m' },
    { value: '12m', labelKey: 'dashboard.range.12m' }
  ];

  recentExpenses: Expense[] = [];
  stats: StatsResponse | null = null;
  timelineStats: StatsResponse | null = null;
  cashflow: CashflowResponse | null = null;
  externalSummary: ShoppingListSummary | null = null;
  selectedTimelineRange: TimelineRangeKey = '3m';
  private categoryChart?: Chart;
  private timelineChart?: Chart;
  private categoryChartPending = false;
  private timelineChartPending = false;

  constructor() {
    effect(() => {
      if (this.canShowExternalStats()) this.loadExternalSummary();
      else {
        this.externalSummary = null;
        this.persistCache();
      }
    });
  }

  ngOnInit() {
    this.restoreCache();
    this.loadDashboard();
    this.loadTimeline();
  }

  ngAfterViewChecked() {
    if (this.categoryChartPending) {
      this.categoryChartPending = false;
      this.renderCategoryChart();
    }

    if (this.timelineChartPending) {
      this.timelineChartPending = false;
      this.renderTimelineChart();
    }
  }

  ngOnDestroy() {
    this.categoryChart?.destroy();
    this.timelineChart?.destroy();
  }

  canShowExternalStats() {
    return Boolean(this.auth.currentUser()?.integrationsEnabled);
  }

  loadDashboard() {
    const range = getMonthRange();
    this.expensesService.list().subscribe({
      next: (response) => {
        this.recentExpenses = response.items.slice(0, 8);
        this.persistCache();
      }
    });
    this.statsService.overview({ startDate: range.start, endDate: range.end, bucket: 'month' }).subscribe({
      next: (response) => {
        this.stats = response;
        this.categoryChartPending = true;
        this.persistCache();
      }
    });
    this.statsService.cashflow().subscribe({
      next: (response) => {
        this.cashflow = response;
        this.persistCache();
      }
    });
  }

  changeTimelineRange(range: TimelineRangeKey) {
    if (this.selectedTimelineRange === range) return;
    this.selectedTimelineRange = range;
    this.loadTimeline();
  }

  loadTimeline() {
    const range = getTimelineRange(this.selectedTimelineRange);
    this.statsService.overview({ startDate: range.start, endDate: range.end, bucket: 'month' }).subscribe({
      next: (response) => {
        this.timelineStats = response;
        this.timelineChartPending = true;
        this.persistCache();
      }
    });
  }

  private loadExternalSummary() {
    const range = getMonthRange();
    this.shoppingIntegration.summary({ start_date: range.start, end_date: range.end }).subscribe({
      next: (response) => {
        this.externalSummary = response;
        this.persistCache();
      },
      error: () => {
        this.externalSummary = this.externalSummary ?? null;
      }
    });
  }

  externalAmount() { return Number(this.externalSummary?.total ?? this.externalSummary?.amount ?? this.externalSummary?.meta?.total_amount ?? 0); }
  externalCount() { return Number(this.externalSummary?.count ?? this.externalSummary?.records ?? this.externalSummary?.meta?.total_count ?? 0); }

  statusBadgeClass(status: string) {
    return {
      DRAFT: 'text-bg-secondary',
      PENDING: 'text-bg-warning',
      APPROVED: 'text-bg-success',
      REJECTED: 'text-bg-danger'
    }[status] || 'text-bg-secondary';
  }

  private renderCategoryChart() {
    const canvas = document.getElementById('dashboardCategoryChart') as HTMLCanvasElement | null;
    if (!canvas || !this.stats?.byCategory?.length) {
      this.categoryChart?.destroy();
      return;
    }

    const colors = this.stats.byCategory.map((_, index) => chartPalette[index % chartPalette.length]);
    this.categoryChart?.destroy();
    this.categoryChart = new Chart(canvas, {
      type: 'doughnut',
      data: {
        labels: this.stats.byCategory.map((item) => item.categoryName),
        datasets: [{ data: this.stats.byCategory.map((item) => item.total), backgroundColor: colors, borderColor: '#ffffff', hoverOffset: 10 }]
      },
      options: {
        responsive: true,
        maintainAspectRatio: false,
        cutout: '66%',
        plugins: { legend: { position: 'bottom', labels: { usePointStyle: true, boxWidth: 10, color: '#9ca3af' } } }
      }
    });
  }

  private renderTimelineChart() {
    const canvas = document.getElementById('dashboardTimelineChart') as HTMLCanvasElement | null;
    if (!canvas || !this.timelineStats?.timeline?.length) {
      this.timelineChart?.destroy();
      return;
    }

    this.timelineChart?.destroy();
    this.timelineChart = new Chart(canvas, {
      type: 'line',
      data: {
        labels: this.timelineStats.timeline.map((item) => item.label),
        datasets: [{
          label: this.ui.t('stats.expensesLabel'),
          data: this.timelineStats.timeline.map((item) => item.total),
          borderColor: '#206bc4',
          backgroundColor: '#206bc4',
          tension: 0.25,
          fill: false
        }]
      },
      options: {
        responsive: true,
        maintainAspectRatio: false,
        plugins: { legend: { display: false } },
        scales: { x: { ticks: { color: '#9ca3af' } }, y: { ticks: { color: '#9ca3af' } } }
      }
    });
  }

  private restoreCache() {
    try {
      const raw = localStorage.getItem(DASHBOARD_CACHE_KEY);
      if (!raw) return;
      const parsed = JSON.parse(raw) as {
        recentExpenses?: Expense[];
        stats?: StatsResponse | null;
        timelineStats?: StatsResponse | null;
        cashflow?: CashflowResponse | null;
        externalSummary?: ShoppingListSummary | null;
        selectedTimelineRange?: TimelineRangeKey;
      };
      this.recentExpenses = parsed.recentExpenses ?? [];
      this.stats = parsed.stats ?? null;
      this.timelineStats = parsed.timelineStats ?? null;
      this.cashflow = parsed.cashflow ?? null;
      this.externalSummary = parsed.externalSummary ?? null;
      this.selectedTimelineRange = parsed.selectedTimelineRange ?? '3m';
      this.categoryChartPending = Boolean(this.stats?.byCategory?.length);
      this.timelineChartPending = Boolean(this.timelineStats?.timeline?.length);
    } catch {}
  }

  private persistCache() {
    try {
      localStorage.setItem(DASHBOARD_CACHE_KEY, JSON.stringify({
        recentExpenses: this.recentExpenses,
        stats: this.stats,
        timelineStats: this.timelineStats,
        cashflow: this.cashflow,
        externalSummary: this.externalSummary,
        selectedTimelineRange: this.selectedTimelineRange
      }));
    } catch {}
  }
}