import { useCallback, useEffect, useState } from "react";
import { useParams } from "react-router-dom";
import { Alert, Badge, Button, Card, PageHeader } from "@eden/ui";
import { useAuth } from "../../lib/auth/AuthContext.js";
import { ApiError } from "../../lib/api/http.js";
import { consolidateBillingRun, getBillingRun } from "../../lib/api/billing.js";
import type { BillingRunWithInvoices } from "../../lib/api/billing.js";
import { formatCurrencyBRL, formatDateBR } from "../../lib/format.js";
import { Breadcrumb } from "../../components/Breadcrumb.js";
import { INVOICE_STATUS_LABEL, INVOICE_STATUS_VARIANT, RUN_STATUS_LABEL, RUN_STATUS_VARIANT, periodLabel } from "./billingStatus.js";

/**
 * Layout reference: DreamsERP theme `.tmp/theme-reference/recurringInvoiceDetails.tsx`
 * (breadcrumb + title with a status pill, a two-column summary block, an
 * item table, right-aligned total below it) — same shape as
 * `ContractDetailPage`'s financial summary + items sections. Rebuilt with
 * `@eden/ui` + plain Tailwind, no theme JSX copied.
 */
export function BillingRunDetailPage() {
  const { id } = useParams<{ id: string }>();
  const { accessToken } = useAuth();

  const [run, setRun] = useState<BillingRunWithInvoices | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  const load = useCallback(() => {
    if (!id || !accessToken) return;
    setLoading(true);
    setError(null);
    getBillingRun(id, accessToken)
      .then(setRun)
      .catch((err) => setError(err instanceof ApiError ? err.message : "Não foi possível carregar o fechamento."))
      .finally(() => setLoading(false));
  }, [id, accessToken]);

  useEffect(() => {
    load();
  }, [load]);

  if (loading) {
    return (
      <div>
        <PageHeader title="Fechamento" />
        <p className="text-sm text-default">Carregando fechamento…</p>
      </div>
    );
  }

  if (error || !run) {
    return (
      <div>
        <PageHeader title="Fechamento" />
        <Alert variant="error">{error ?? "Fechamento não encontrado."}</Alert>
      </div>
    );
  }

  return (
    <div>
      <Breadcrumb
        items={[{ label: "Fechamentos", href: "/billing/runs" }, { label: periodLabel(run.reference_year, run.reference_month) }]}
      />
      <PageHeader
        title={`Fechamento ${periodLabel(run.reference_year, run.reference_month)}`}
        actions={<Badge variant={RUN_STATUS_VARIANT[run.status]}>{RUN_STATUS_LABEL[run.status]}</Badge>}
      />

      {run.status === "draft" ? (
        <Alert variant="info" className="mb-4" title="Ainda em rascunho">
          Rodar o formulário de fechamento de novo com o MESMO ano, mês e dia de cobrança reaproveita este fechamento
          e regenera suas faturas — seguro para repetir. Consolidar é a única ação irreversível.
        </Alert>
      ) : null}

      <div className="grid grid-cols-1 gap-4 lg:grid-cols-3">
        <div className="space-y-4 lg:col-span-1">
          <Card title="Dados do fechamento">
            <dl className="space-y-3 text-sm">
              <Row label="Período" value={periodLabel(run.reference_year, run.reference_month)} />
              <Row label="Dia de cobrança" value={String(run.billing_day)} />
              <Row label="Faturas geradas" value={String(run.invoices.length)} />
              <Row label="Total" value={formatCurrencyBRL(run.totalAmount)} />
              <Row label="Criado em" value={formatDateBR(run.created_at)} />
              <Row label="Consolidado em" value={formatDateBR(run.consolidated_at)} />
            </dl>
          </Card>

          <ConsolidateCard run={run} accessToken={accessToken} onConsolidated={load} />
        </div>

        <div className="lg:col-span-2">
          <Card title="Faturas geradas">
            <div className="overflow-x-auto">
              <table className="w-full text-sm">
                <thead>
                  <tr className="border-b border-border-color text-left">
                    <th className="py-2 pe-3 font-semibold text-title">Fatura</th>
                    <th className="py-2 pe-3 font-semibold text-title">Assinatura</th>
                    <th className="py-2 pe-3 font-semibold text-title">Vencimento</th>
                    <th className="py-2 pe-3 text-right font-semibold text-title">Valor</th>
                    <th className="py-2 font-semibold text-title">Status</th>
                  </tr>
                </thead>
                <tbody>
                  {run.invoices.length === 0 ? (
                    <tr>
                      <td colSpan={5} className="py-4 text-center text-sm text-default">
                        Nenhuma fatura gerada — nenhuma assinatura ativa bate com este dia de cobrança.
                      </td>
                    </tr>
                  ) : (
                    run.invoices.map((invoice) => (
                      <tr key={invoice.id} className="border-b border-border-color last:border-0">
                        <td className="py-2 pe-3 font-mono text-xs text-title">{invoice.id.slice(0, 8)}</td>
                        <td className="py-2 pe-3 font-mono text-xs text-default">
                          {invoice.billing_subscription_id.slice(0, 8)}
                        </td>
                        <td className="py-2 pe-3 text-default">{formatDateBR(invoice.due_date)}</td>
                        <td className="py-2 pe-3 text-right text-default">{formatCurrencyBRL(invoice.amount)}</td>
                        <td className="py-2">
                          <Badge variant={INVOICE_STATUS_VARIANT[invoice.status]}>
                            {INVOICE_STATUS_LABEL[invoice.status]}
                          </Badge>
                        </td>
                      </tr>
                    ))
                  )}
                </tbody>
                {run.invoices.length > 0 ? (
                  <tfoot>
                    <tr>
                      <td colSpan={3} className="pt-3 text-right text-sm font-bold text-title">
                        Total
                      </td>
                      <td className="pt-3 text-right text-sm font-bold text-primary">
                        {formatCurrencyBRL(run.totalAmount)}
                      </td>
                      <td className="pt-3" />
                    </tr>
                  </tfoot>
                ) : null}
              </table>
            </div>
          </Card>
        </div>
      </div>
    </div>
  );
}

function Row({ label, value }: { label: string; value: string }) {
  return (
    <div className="flex items-start justify-between gap-3">
      <dt className="text-default">{label}</dt>
      <dd className="text-right font-semibold text-title">{value}</dd>
    </div>
  );
}

function ConsolidateCard({
  run,
  accessToken,
  onConsolidated,
}: {
  run: BillingRunWithInvoices;
  accessToken: string | null;
  onConsolidated: () => void;
}) {
  const [confirming, setConfirming] = useState(false);
  const [submitting, setSubmitting] = useState(false);
  const [error, setError] = useState<string | null>(null);

  if (run.status !== "draft") {
    return (
      <Card title="Consolidação">
        <p className="text-sm text-default">
          Status <strong>{RUN_STATUS_LABEL[run.status]}</strong> é final — este fechamento não pode mais ser alterado.
        </p>
      </Card>
    );
  }

  async function handleConfirm() {
    if (!accessToken) return;
    setError(null);
    setSubmitting(true);
    try {
      await consolidateBillingRun(run.id, accessToken);
      setConfirming(false);
      onConsolidated();
    } catch (err) {
      setError(err instanceof ApiError ? err.message : "Não foi possível consolidar o fechamento.");
    } finally {
      setSubmitting(false);
    }
  }

  return (
    <Card title="Consolidação">
      {error ? (
        <Alert variant="error" className="mb-3">
          {error}
        </Alert>
      ) : null}

      {confirming ? (
        <div className="space-y-3">
          <Alert variant="warning" title="Ação irreversível">
            Consolidar trava o fechamento e todas as suas faturas — não será mais possível regenerá-las.
          </Alert>
          <div className="flex gap-2">
            <Button variant="danger" size="sm" loading={submitting} onClick={handleConfirm}>
              Sim, consolidar
            </Button>
            <Button variant="secondary" size="sm" type="button" onClick={() => setConfirming(false)}>
              Cancelar
            </Button>
          </div>
        </div>
      ) : (
        <Button onClick={() => setConfirming(true)}>Consolidar</Button>
      )}
    </Card>
  );
}