'use client';

import { isApiError, type DeclarationDto } from '@impuestos/contracts';
import { formatDateLong, formatGs, formatGsAmount, type Locale } from '@impuestos/i18n';
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
import { useRef, useState } from 'react';
import { FormPreview } from '@/components/form-preview';
import { Button } from '@/components/ui/button';
import { Card } from '@/components/ui/card';
import { Skeleton } from '@/components/ui/skeleton';
import { useT } from '@/i18n/t';
import { api } from '@/lib/api';
import { FilingChecklist } from './filing-checklist';

/**
 * Flow D2 and D3. The human summary first, the official layout underneath, and one
 * primary action. Nothing here files anything: the checklist that follows approval is how
 * the user presents it themselves.
 */
export function DeclarationDetail({ id, locale }: { id: string; locale: string }) {
  const t = useT();
  const queryClient = useQueryClient();
  const confirmDialog = useRef<HTMLDialogElement>(null);
  const [staleWarning, setStaleWarning] = useState<string | null>(null);

  const declaration = useQuery({
    queryKey: ['declarations', id],
    queryFn: ({ signal }) => api.getDeclaration(id, signal),
    retry: (count, error) => !isApiError(error) && count < 1,
  });

  const approve = useMutation({
    mutationFn: () => api.approveDeclaration(id),
    onSuccess: async () => {
      setStaleWarning(null);
      confirmDialog.current?.close();
      await queryClient.invalidateQueries({ queryKey: ['declarations'] });
      await queryClient.invalidateQueries({ queryKey: ['dashboard'] });
    },
    onError: (error) => {
      confirmDialog.current?.close();
      // A 409 means the documents moved: the numbers on screen are stale, not wrong.
      setStaleWarning(isApiError(error) ? error.message : t('common.error.generic'));
      void queryClient.invalidateQueries({ queryKey: ['declarations', id] });
    },
  });

  if (declaration.isPending) {
    return (
      <Card className="my-4">
        <Skeleton name="declaration-summary" />
      </Card>
    );
  }

  if (declaration.isError || !declaration.data) {
    const missing = isApiError(declaration.error) && declaration.error.code === 'not_found';
    return (
      <Card className="my-4 space-y-3">
        <p role="alert" className="text-sm">
          {missing ? t('error.not_found') : t('common.error.generic')}
        </p>
        {!missing ? (
          <Button type="button" onClick={() => void declaration.refetch()}>
            {t('common.retry')}
          </Button>
        ) : null}
      </Card>
    );
  }

  const data = declaration.data;
  const approved = data.status === 'approved';
  // Spanish in every locale, like the form it names (COPY.md multi-language policy).
  const officialTitle = `Formulario ${data.formCode}`;

  return (
    <div className="space-y-4 py-4 pb-28">
      <div>
        <h1 className="text-2xl font-semibold tracking-tight">{officialTitle}</h1>
        <p className="tnum text-sm text-[var(--text-muted)]">{data.period}</p>
      </div>

      {staleWarning ? (
        <Card className="border-attention">
          <p role="alert" className="text-sm text-attention text-pretty">
            {staleWarning}
          </p>
        </Card>
      ) : null}

      <Card className="space-y-3">
        <h2 className="font-semibold tracking-tight">{t('decl.summary.title')}</h2>
        <p className="text-lg text-pretty">{humanSummary(data, t)}</p>
        <Breakdown declaration={data} />
      </Card>

      <FormPreview
        formCode={data.formCode}
        period={data.period}
        values={data.values}
        draft={!approved}
        labels={{
          title: t('decl.preview.title'),
          spanishNote: t('decl.preview.spanishNote'),
          casilla: t('decl.preview.casilla'),
          concept: t('decl.preview.concept'),
          amount: t('decl.amount'),
          draftMark: t('decl.preview.draftMark'),
        }}
      />

      {approved ? (
        <FilingChecklist declaration={data} locale={locale as Locale} />
      ) : (
        <>
          {/* Sticky footer: the primary action stays reachable however long the form is. */}
          <div className="fixed inset-x-0 bottom-16 z-10 border-t bg-[var(--surface-raised)] px-5 py-3">
            <div className="mx-auto flex max-w-2xl gap-2">
              <a
                href={api.declarationPdfUrl(data.id)}
                download
                className="flex h-11 flex-1 items-center justify-center rounded-full border text-sm font-medium"
              >
                {t('decl.downloadPdf')}
              </a>
              <Button
                type="button"
                className="flex-1"
                onClick={() => confirmDialog.current?.showModal()}
              >
                {t('decl.approve')}
              </Button>
            </div>
          </div>

          <dialog
            ref={confirmDialog}
            aria-label={t('decl.approve.confirmTitle')}
            className="m-auto w-[min(28rem,calc(100vw-2rem))] rounded-2xl border bg-[var(--surface-raised)] p-6 text-[var(--text)] backdrop:bg-black/40"
          >
            <div className="space-y-4">
              <h2 className="text-lg font-semibold tracking-tight">
                {t('decl.approve.confirmTitle')}
              </h2>
              <p className="text-sm text-[var(--text-muted)] text-pretty">
                {t('decl.approve.confirmBody', {
                  form: data.formCode,
                  period: data.period,
                  amount: formatGsAmount(payable(data)),
                })}
              </p>
              <div className="flex justify-end gap-2">
                <Button
                  type="button"
                  variant="ghost"
                  onClick={() => confirmDialog.current?.close()}
                >
                  {t('common.cancel')}
                </Button>
                <Button type="button" disabled={approve.isPending} onClick={() => approve.mutate()}>
                  {approve.isPending ? t('common.saving') : t('decl.approve')}
                </Button>
              </div>
            </div>
          </dialog>
        </>
      )}

      {approved && data.approvedAt ? (
        <p className="text-center text-xs text-[var(--text-muted)]">
          {t('decl.approvedAt', { date: formatDateLong(locale as Locale, data.approvedAt.slice(0, 10)) })}
        </p>
      ) : null}
    </div>
  );
}

type Translate = ReturnType<typeof useT>;

/** FLOWS.md D2: the sentence comes before the form, always. */
function humanSummary(declaration: DeclarationDto, t: Translate): string {
  const summary = declaration.summary;

  if (declaration.formCode === '120') {
    const aPagar = Number(summary['aPagar'] ?? 0);
    const result =
      aPagar > 0
        ? t('decl.f120.toPay', { amount: formatGsAmount(aPagar) })
        : t('decl.f120.inFavor', { amount: formatGsAmount(Number(summary['saldoAFavor'] ?? 0)) });

    return t('decl.f120.summary', {
      sales: formatGsAmount(Number(summary['sales'] ?? 0)),
      purchases: formatGsAmount(Number(summary['purchases'] ?? 0)),
      result,
    });
  }

  return t('decl.f515.summary', {
    income: formatGsAmount(Number(summary['grossIncome'] ?? 0)),
    deductions: formatGsAmount(Number(summary['totalDeductions'] ?? 0)),
    tax: formatGsAmount(Number(summary['tax'] ?? 0)),
  });
}

function Breakdown({ declaration }: { declaration: DeclarationDto }) {
  const t = useT();
  const summary = declaration.summary;

  const rows: [string, number][] =
    declaration.formCode === '120'
      ? [
          [t('decl.breakdown.debito'), Number(summary['debito'] ?? 0)],
          [t('decl.breakdown.credito'), Number(summary['credito'] ?? 0)],
          [t('decl.breakdown.saldoAnterior'), Number(summary['saldoAnterior'] ?? 0)],
        ]
      : [
          [t('profile.income'), Number(summary['grossIncome'] ?? 0)],
          [t('docs.detail.deductible'), Number(summary['totalDeductions'] ?? 0)],
          [t('decl.f515.netIncome'), Number(summary['netIncome'] ?? 0)],
        ];

  const capExcess = Number(summary['capExcess'] ?? 0);

  return (
    <dl className="space-y-2 text-sm">
      {rows.map(([label, amount]) => (
        <div key={label} className="flex items-baseline justify-between gap-4">
          <dt className="text-[var(--text-muted)]">{label}</dt>
          <dd className="tnum font-medium">{formatGs(amount)}</dd>
        </div>
      ))}

      {capExcess > 0 ? (
        <p className="pt-2 text-[var(--text-muted)] text-pretty">
          {t('decl.f515.capNote', { amount: formatGsAmount(capExcess) })}
        </p>
      ) : null}
    </dl>
  );
}

function payable(declaration: DeclarationDto): number {
  const summary = declaration.summary;
  return declaration.formCode === '120'
    ? Number(summary['aPagar'] ?? 0) || Number(summary['saldoAFavor'] ?? 0)
    : Number(summary['tax'] ?? 0);
}