'use client';

import dynamic from 'next/dynamic';
import clsx from 'clsx';
import {
  BanknotesIcon, ShoppingBagIcon, ArrowTrendingUpIcon, ArrowTrendingDownIcon, ScaleIcon, EyeSlashIcon,
  ExclamationTriangleIcon, CheckCircleIcon, ChevronDownIcon, PlusIcon,
} from '@heroicons/react/24/outline';
import { useLanguage } from '@/context/LanguageContext';
import { usePrivacy } from '@/context/PrivacyContext';
import { useMoney } from '@/lib/useMoney';
import type { EventFinance } from '@/lib/api';
import Button from '@/components/ui/Button';
import { Skeleton } from '@/components/ui/Skeleton';
import { Money, EmptyState, Pill } from './ui';
import { breakEvenState, detailChartsAvailable } from './derive';
import type { FinanceSection } from './FinanceTab';

// Recharts only loads when someone opens the Finance tab.
const FinanceCharts = dynamic(() => import('./FinanceCharts'), {
  ssr: false,
  loading: () => <Skeleton className="h-64" />,
});

function Kpi({ label, tag, value, detail, icon: Icon, tone, children }: {
  label: string; tag?: React.ReactNode; value: React.ReactNode; detail?: React.ReactNode; icon: typeof BanknotesIcon;
  tone: 'blue' | 'orange' | 'green' | 'red' | 'purple' | 'gray'; children?: React.ReactNode;
}) {
  const tones = {
    blue: 'bg-blue-50 text-blue-600', orange: 'bg-orange-50 text-orange-600', green: 'bg-green-50 text-green-600',
    red: 'bg-red-50 text-red-600', purple: 'bg-purple-50 text-purple-600', gray: 'bg-gray-100 text-gray-600',
  };
  return (
    <div className="bg-white rounded-card shadow-card p-3 md:p-4 min-w-0 flex flex-col">
      <div className="flex items-center gap-2 min-w-0">
        <span className={clsx('w-7 h-7 rounded-full flex items-center justify-center flex-shrink-0', tones[tone])}><Icon className="w-4 h-4" aria-hidden /></span>
        <p className="text-xs md:text-sm text-gray-500 truncate">{label}</p>
        {tag}
      </div>
      <div className="mt-2 text-lg md:text-2xl font-bold leading-tight break-words">{value}</div>
      {detail && <div className="mt-1 text-xs text-gray-500 space-y-0.5">{detail}</div>}
      {children}
    </div>
  );
}

/** The P&L as a compact statement under the waterfall, in the same order as its bars. */
function Breakdown({ data, finalized }: { data: EventFinance; finalized: boolean }) {
  const { t, locale } = useLanguage();
  const { num } = useMoney();
  const s = data.summary;
  const catName = (id: string | null) => {
    const c = data.categories.find((x) => x.id === id);
    return c ? (locale === 'es' ? c.nameEs : c.nameEn) : t('admin.finance.charts.uncategorized');
  };
  const resultTone = (v: number | null) => (finalized && v !== null ? (v < 0 ? 'text-red-600' : 'text-green-700') : undefined);
  const Row = ({ label, value, sign, strong, muted, className }: {
    label: React.ReactNode; value: number | null; sign?: '+' | '−'; strong?: boolean; muted?: boolean; className?: string;
  }) => (
    <div className={clsx('flex items-baseline justify-between gap-3 py-1', strong && 'font-semibold', muted && 'text-gray-500')}>
      <span className="min-w-0">{sign && <span className="inline-block w-4 text-gray-400" aria-hidden>{sign}</span>}{label}</span>
      <Money value={value} className={clsx('whitespace-nowrap', className)} />
    </div>
  );
  const partners = s.split.partners;
  const showSplit = partners.length > 0 && s.split.organization !== null;

  return (
    <div className="text-sm">
      <h3 className="text-sm font-semibold text-primary-dark mb-1">{t('admin.finance.statement.title')}</h3>
      <Row label={t('admin.finance.statement.ticketSales', { count: num(s.counts.ticketsSold) })} value={s.revenue.gross} />
      {s.revenue.refunds > 0 && <Row sign="−" label={t('admin.finance.waterfall.refunds')} value={s.revenue.refunds} muted />}
      {s.revenue.fees > 0 && <Row sign="−" label={t('admin.finance.waterfall.fees')} value={s.revenue.fees} muted />}
      {s.expenses.total > 0 && (
        <details className="group">
          <summary className="list-none cursor-pointer flex items-baseline justify-between gap-3 py-1 text-gray-500 [&::-webkit-details-marker]:hidden">
            <span className="inline-flex items-center gap-1">
              <span className="inline-block w-4 text-gray-400" aria-hidden>−</span>
              {t('admin.finance.waterfall.expenses')}
              <ChevronDownIcon className="w-3.5 h-3.5 transition-transform group-open:rotate-180" aria-hidden />
            </span>
            <Money value={s.expenses.total} className="whitespace-nowrap" />
          </summary>
          <div className="pl-5 pb-1">
            {s.expenses.byCategory.map((c) => (
              <div key={c.categoryId || 'none'} className="flex justify-between gap-3 py-0.5 text-xs text-gray-500">
                <span className="truncate">{catName(c.categoryId)}</span>
                <Money value={c.total} className="whitespace-nowrap" />
              </div>
            ))}
          </div>
        </details>
      )}
      {s.revenue.otherIncome > 0 && <Row sign="+" label={t('admin.finance.waterfall.otherIncome')} value={s.revenue.otherIncome} muted />}
      <div className="border-t border-gray-200 mt-1" />
      <Row label={t(s.profit < 0 ? 'admin.finance.kpi.loss' : 'admin.finance.kpi.profit')} value={s.profit} strong className={resultTone(s.profit)} />

      {showSplit && (
        <>
          {partners.map((p) => (
            <Row
              key={p.partnerId}
              sign={p.share < 0 ? '+' : '−'}
              label={<>{p.name}{p.share < 0 && <span className="block text-xs text-gray-400 pl-4">{t('admin.finance.statement.carriesLoss')}</span>}</>}
              value={Math.abs(p.share)}
              muted
            />
          ))}
          <div className="border-t border-gray-200 mt-1" />
          <Row label={t('admin.finance.split.organization')} value={s.split.organization} strong className={resultTone(s.split.organization)} />
        </>
      )}
    </div>
  );
}

export function SummaryView({ data, goTo }: { data: EventFinance; goTo: (s: FinanceSection) => void }) {
  const { t, locale } = useLanguage();
  const { privacyMode } = usePrivacy();
  const { num } = useMoney();
  const s = data.summary;
  const finalized = data.status !== 'open';
  const loss = s.profit < 0;
  const capacity = data.event.capacity;
  const canAdd = data.status === 'open' && (data.viewer.canEditExpenses || data.viewer.canEditOwnExpenses);

  const nothingYet = s.revenue.gross === 0 && s.expenses.total === 0 && s.revenue.otherIncome === 0;
  if (nothingYet) {
    return (
      <EmptyState icon={<BanknotesIcon className="w-5 h-5" />} title={t('admin.finance.empty.title')} body={t('admin.finance.empty.body')}>
        {canAdd && <Button onClick={() => goTo('expenses')}><PlusIcon className="w-4 h-4 mr-1" />{t('admin.finance.expenses.add')}</Button>}
      </EmptyState>
    );
  }

  const sold = s.counts.ticketsSold;
  const be = breakEvenState(s);
  let breakEvenValue: React.ReactNode;
  let breakEvenDetail: React.ReactNode;
  let breakEvenBar: number | null = null;
  if (be.kind === 'noCosts') {
    breakEvenValue = <span className="text-sm md:text-base font-semibold leading-snug text-gray-500">{t('admin.finance.breakEven.noCosts')}</span>;
    breakEvenDetail = t('admin.finance.breakEven.noCostsHint');
  } else if (be.kind === 'unreachable') {
    breakEvenValue = <span className="text-sm md:text-base font-semibold leading-snug">{t('admin.finance.kpi.breakEvenNever')}</span>;
  } else if (privacyMode) {
    breakEvenValue = '••••';
  } else if (be.kind === 'reached') {
    breakEvenValue = (
      <span className="text-sm md:text-base font-semibold leading-snug inline-flex items-start gap-1.5 text-green-700">
        <CheckCircleIcon className="w-5 h-5 flex-shrink-0 mt-0.5" aria-hidden />
        {be.at === 0
          ? t('admin.finance.breakEven.coveredWithoutTickets')
          : t('admin.finance.breakEven.reached', { at: num(be.at), sold: num(be.sold) })}
      </span>
    );
  } else {
    breakEvenValue = <span className="text-sm md:text-base font-semibold leading-snug">{t('admin.finance.breakEven.needed', { count: num(be.remaining) })}</span>;
    breakEvenBar = be.pct;
    breakEvenDetail = be.needed > capacity
      ? <span className="inline-flex items-start gap-1 text-amber-700"><ExclamationTriangleIcon className="w-4 h-4 flex-shrink-0" aria-hidden />{t('admin.finance.kpi.beyondCapacity', { capacity: num(capacity) })}</span>
      : t('admin.finance.kpi.breakEvenProgress', { sold: num(be.sold), total: num(be.needed) });
  }

  const show = detailChartsAvailable(s);

  return (
    <div className="space-y-4">
      <div className="grid grid-cols-1 min-[420px]:grid-cols-2 lg:grid-cols-4 gap-3">
        <Kpi
          label={t('admin.finance.kpi.ticketRevenue')}
          value={<Money value={s.revenue.sales} />}
          detail={privacyMode ? undefined : (
            <>
              <p>{t('admin.finance.kpi.revenueDetail', { count: num(sold) })}</p>
              {s.revenue.gross > 0 && (
                <p>{t('admin.finance.kpi.presale')} <Money value={s.revenue.presale} /> · {t('admin.finance.kpi.door')} <Money value={s.revenue.door} /></p>
              )}
            </>
          )}
          icon={BanknotesIcon}
          tone="blue"
        />
        <Kpi
          label={t('admin.finance.kpi.expenses')}
          value={<Money value={s.expenses.total} />}
          detail={privacyMode || s.expenses.total === 0 ? undefined : (
            <span>{t('admin.finance.charts.paid')} <Money value={s.expenses.paid} /> · {t('admin.finance.charts.planned')} <Money value={s.expenses.planned} /></span>
          )}
          icon={ShoppingBagIcon}
          tone="orange"
        />
        <Kpi
          label={t(loss ? 'admin.finance.kpi.loss' : 'admin.finance.kpi.profit')}
          tag={!finalized && <Pill>{t('admin.finance.kpi.estimated')}</Pill>}
          value={<Money value={s.profit} className={clsx(finalized && !privacyMode && (loss ? 'text-red-600' : 'text-green-700'))} />}
          detail={t(finalized ? 'admin.finance.kpi.afterFees' : 'admin.finance.kpi.estimatedHint')}
          icon={loss ? ArrowTrendingDownIcon : ArrowTrendingUpIcon}
          tone={finalized ? (loss ? 'red' : 'green') : 'gray'}
        />
        <Kpi label={t('admin.finance.kpi.breakEven')} value={breakEvenValue} detail={breakEvenDetail} icon={ScaleIcon} tone="purple">
          {breakEvenBar !== null && (
            <div className="mt-2 h-1.5 rounded-full bg-gray-100 overflow-hidden" role="progressbar" aria-valuenow={breakEvenBar} aria-valuemin={0} aria-valuemax={100}>
              <div className="h-full rounded-full bg-purple-500" style={{ width: `${Math.max(breakEvenBar, 2)}%` }} />
            </div>
          )}
        </Kpi>
      </div>

      {privacyMode ? (
        <div className="bg-white rounded-card shadow-card p-8 text-center text-sm text-gray-500 flex flex-col items-center gap-2">
          <EyeSlashIcon className="w-6 h-6 text-gray-400" aria-hidden />
          {t('admin.finance.hiddenStats')}
        </div>
      ) : (
        <>
          <div className="bg-white rounded-card shadow-card p-4 grid grid-cols-1 lg:grid-cols-5 gap-4 lg:gap-6">
            <div className="lg:col-span-3 min-w-0">
              <FinanceCharts part="waterfall" summary={s} categories={data.categories} locale={locale} t={t} estimated={!finalized} />
            </div>
            <div className="lg:col-span-2 min-w-0 border-t lg:border-t-0 lg:border-l border-gray-100 pt-4 lg:pt-0 lg:pl-6">
              <Breakdown data={data} finalized={finalized} />
            </div>
          </div>
          <FinanceCharts part="details" summary={s} categories={data.categories} locale={locale} t={t} />
          {!show.costs && (
            <p className="text-sm text-gray-400 text-center py-2">
              {canAdd ? (
                <button onClick={() => goTo('expenses')} className="hover:underline cursor-pointer">{t('admin.finance.charts.addExpensesHint')}</button>
              ) : t('admin.finance.charts.addExpensesHint')}
            </p>
          )}
        </>
      )}
    </div>
  );
}