import { useCallback, useEffect, useMemo, useState } from "react";
import { useParams } from "react-router-dom";
import { Alert, Badge, Button, Card, PageHeader, Select } from "@eden/ui";
import { useAuth } from "../../lib/auth/AuthContext.js";
import { hasPermission } from "../../lib/auth/permissions.js";
import { ApiError } from "../../lib/api/http.js";
import {
  cancelEnvelope,
  deleteEnvelope,
  downloadFinalPdf,
  finalizeEnvelope,
  getEnvelope,
  listAuditEvents,
  openDocumentPdf,
  sealCheckpoint,
  sendInvite,
  verifyAudit,
} from "../../lib/api/signatures.js";
import type {
  EnvelopeWithDetails,
  SendInviteTargets,
  SignatureAuditEvent,
  VerifyAuditResult,
} from "../../lib/api/signatures.js";
import { getCompany } from "../../lib/api/companies.js";
import type { Company } from "../../lib/api/companies.js";
import { formatDateTimeBR } from "../../lib/format.js";
import { Breadcrumb } from "../../components/Breadcrumb.js";
import {
  ENVELOPE_STATUS_LABEL,
  ENVELOPE_STATUS_VARIANT,
  SIGNER_STATUS_LABEL,
  SIGNER_STATUS_VARIANT,
  actorTypeLabel,
  auditEventLabel,
  partyRoleLabel,
} from "./signatureStatus.js";

const DELETE_BLOCKED_STATUSES = new Set(["SIGNED", "FINALIZING", "COMPLETED"]);
const SEND_INVITE_BLOCKED_STATUSES = new Set(["COMPLETED", "CANCELLED", "DECLINED", "EXPIRED", "SUPERSEDED", "ERROR"]);
/** Mirrors `ENVELOPE_TRANSITIONS` in `packages/database/src/repositories/signatures.ts` — `CANCELLED` is only a valid target from these pre-signing states; anything past `SIGNING` (inclusive) 409s server-side. UX-only gating, the backend is still the one enforcing it. */
const CANCEL_BLOCKED_STATUSES = new Set([
  "SIGNING",
  "SIGNED",
  "FINALIZING",
  "COMPLETED",
  "DECLINED",
  "EXPIRED",
  "CANCELLED",
  "SUPERSEDED",
  "ERROR",
]);

export function EnvelopeDetailPage() {
  const { id } = useParams<{ id: string }>();
  const { accessToken, permissions } = useAuth();

  const [envelope, setEnvelope] = useState<EnvelopeWithDetails | null>(null);
  const [company, setCompany] = useState<Company | null>(null);
  const [auditEvents, setAuditEvents] = useState<SignatureAuditEvent[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  const canEdit = hasPermission(permissions, "signatures", "edit");
  const canDelete = hasPermission(permissions, "signatures", "delete");

  const load = useCallback(() => {
    if (!id || !accessToken) return;
    setLoading(true);
    setError(null);
    getEnvelope(id, accessToken)
      .then(async (result) => {
        setEnvelope(result);
        const [companyResult, events] = await Promise.all([
          getCompany(result.company_id, accessToken).catch(() => null),
          listAuditEvents(id, accessToken).catch(() => []),
        ]);
        setCompany(companyResult);
        setAuditEvents(events);
      })
      .catch((err) => setError(err instanceof ApiError ? err.message : "Não foi possível carregar o envelope."))
      .finally(() => setLoading(false));
  }, [id, accessToken]);

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

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

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

  const verificationUrl = envelope.verification_id ? `${window.location.origin}/verificar/${envelope.verification_id}` : null;

  return (
    <div>
      <Breadcrumb items={[{ label: "Assinaturas", href: "/signatures" }, { label: envelope.envelope_number }]} />
      <PageHeader
        title={`Envelope ${envelope.envelope_number}`}
        actions={<Badge variant={ENVELOPE_STATUS_VARIANT[envelope.status]}>{ENVELOPE_STATUS_LABEL[envelope.status]}</Badge>}
      />

      <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 envelope">
            <dl className="space-y-3 text-sm">
              <Row label="Empresa (contratada)" value={company?.company_name ?? envelope.company_id} />
              <Row label="Cadastro de cliente" value={envelope.client_registration_id ?? "—"} />
              <Row label="Revenda" value={envelope.reseller_id ?? "—"} />
              <Row label="Criado em" value={formatDateTimeBR(envelope.created_at)} />
              <Row label="Enviado em" value={formatDateTimeBR(envelope.sent_at)} />
              <Row label="Assinado em" value={formatDateTimeBR(envelope.signed_at)} />
              <Row label="Concluído em" value={formatDateTimeBR(envelope.completed_at)} />
              <Row label="Cancelado em" value={formatDateTimeBR(envelope.cancelled_at)} />
            </dl>
          </Card>

          {envelope.status === "COMPLETED" ? (
            <Card title="Verificação pública">
              <p className="text-sm text-default">
                Qualquer pessoa com este link pode conferir a integridade do documento (sem autenticação):
              </p>
              {verificationUrl ? (
                <a
                  href={`/verificar/${envelope.verification_id}`}
                  target="_blank"
                  rel="noopener noreferrer"
                  className="mt-2 block break-all font-mono text-xs text-primary underline"
                >
                  {verificationUrl}
                </a>
              ) : null}
            </Card>
          ) : null}

          <EnvelopeActionsCard
            envelope={envelope}
            accessToken={accessToken}
            canEdit={canEdit}
            canDelete={canDelete}
            onChanged={load}
          />
        </div>

        <div className="space-y-4 lg:col-span-2">
          <Card title="Documentos">
            {envelope.documents.length === 0 ? (
              <p className="text-sm text-default">Nenhum documento neste envelope.</p>
            ) : (
              <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">Documento</th>
                      <th className="py-2 pe-3 font-semibold text-title">Versão</th>
                      <th className="py-2 pe-3 font-semibold text-title">Páginas</th>
                      <th className="py-2 font-semibold text-title" />
                    </tr>
                  </thead>
                  <tbody>
                    {envelope.documents
                      .slice()
                      .sort((a, b) => a.sort_order - b.sort_order)
                      .map((doc) => (
                        <DocumentRow key={doc.id} envelopeId={envelope.id} document={doc} accessToken={accessToken} />
                      ))}
                  </tbody>
                </table>
              </div>
            )}
          </Card>

          <Card title="Signatários">
            {envelope.signers.length === 0 ? (
              <p className="text-sm text-default">Nenhum signatário cadastrado.</p>
            ) : (
              <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">Papel</th>
                      <th className="py-2 pe-3 font-semibold text-title">Nome</th>
                      <th className="py-2 pe-3 font-semibold text-title">Contato</th>
                      <th className="py-2 pe-3 font-semibold text-title">Cargo</th>
                      <th className="py-2 font-semibold text-title">Status</th>
                    </tr>
                  </thead>
                  <tbody>
                    {envelope.signers
                      .slice()
                      .sort((a, b) => a.sort_order - b.sort_order)
                      .map((signer) => (
                        <tr key={signer.id} className="border-b border-border-color last:border-0">
                          <td className="py-2 pe-3">
                            <Badge variant={signer.party === "contratada" ? "primary" : "info"}>
                              {partyRoleLabel(signer.party)}
                            </Badge>
                          </td>
                          <td className="py-2 pe-3 font-semibold text-title">
                            {signer.full_name}
                            {signer.cpf ? <span className="block text-xs font-normal text-default">{signer.cpf}</span> : null}
                          </td>
                          <td className="py-2 pe-3 text-default">
                            {signer.email}
                            {signer.phone ? <span className="block text-xs">{signer.phone}</span> : null}
                          </td>
                          <td className="py-2 pe-3 text-default">{signer.role_title ?? "—"}</td>
                          <td className="py-2">
                            <Badge variant={SIGNER_STATUS_VARIANT[signer.status]}>{SIGNER_STATUS_LABEL[signer.status]}</Badge>
                          </td>
                        </tr>
                      ))}
                  </tbody>
                </table>
              </div>
            )}
          </Card>

          <AuditTrailCard events={auditEvents} />
        </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 DocumentRow({
  envelopeId,
  document,
  accessToken,
}: {
  envelopeId: string;
  document: EnvelopeWithDetails["documents"][number];
  accessToken: string | null;
}) {
  const [opening, setOpening] = useState(false);
  const [error, setError] = useState<string | null>(null);

  async function handleOpen() {
    if (!accessToken) return;
    setError(null);
    setOpening(true);
    try {
      await openDocumentPdf(envelopeId, document.id, accessToken);
    } catch {
      setError("Não foi possível abrir o PDF.");
    } finally {
      setOpening(false);
    }
  }

  return (
    <tr className="border-b border-border-color last:border-0">
      <td className="py-2 pe-3 font-semibold text-title">{document.title}</td>
      <td className="py-2 pe-3 text-default">v{document.document_version}</td>
      <td className="py-2 pe-3 text-default">{document.page_count ?? "—"}</td>
      <td className="py-2 text-right">
        <Button type="button" variant="secondary" size="sm" loading={opening} onClick={handleOpen}>
          Baixar PDF
        </Button>
        {error ? <p className="mt-1 text-xs text-danger">{error}</p> : null}
      </td>
    </tr>
  );
}

function EnvelopeActionsCard({
  envelope,
  accessToken,
  canEdit,
  canDelete,
  onChanged,
}: {
  envelope: EnvelopeWithDetails;
  accessToken: string | null;
  canEdit: boolean;
  canDelete: boolean;
  onChanged: () => void;
}) {
  const [targets, setTargets] = useState<SendInviteTargets>("both");
  const [sending, setSending] = useState(false);
  const [sealing, setSealing] = useState(false);
  const [finalizing, setFinalizing] = useState(false);
  const [downloadingFinal, setDownloadingFinal] = useState(false);
  const [verifying, setVerifying] = useState(false);
  const [verifyResult, setVerifyResult] = useState<VerifyAuditResult | null>(null);
  const [confirmCancel, setConfirmCancel] = useState(false);
  const [cancelReason, setCancelReason] = useState("");
  const [cancelling, setCancelling] = useState(false);
  const [confirmDelete, setConfirmDelete] = useState(false);
  const [deleting, setDeleting] = useState(false);
  const [actionError, setActionError] = useState<string | null>(null);

  const canSendInvite = canEdit && !SEND_INVITE_BLOCKED_STATUSES.has(envelope.status);
  const canCancel = canEdit && !CANCEL_BLOCKED_STATUSES.has(envelope.status);
  const canDeleteEnvelope = canDelete && !DELETE_BLOCKED_STATUSES.has(envelope.status);
  const canSeal = canEdit && envelope.status === "SIGNED";
  const canFinalize = canEdit && envelope.status === "FINALIZING";
  const canDownloadFinal = envelope.status === "COMPLETED";

  async function handleSend() {
    if (!accessToken) return;
    setActionError(null);
    setSending(true);
    try {
      await sendInvite(envelope.id, targets, accessToken);
      onChanged();
    } catch (err) {
      setActionError(err instanceof ApiError ? err.message : "Não foi possível enviar o convite.");
    } finally {
      setSending(false);
    }
  }

  async function handleCancelConfirm() {
    if (!accessToken) return;
    setActionError(null);
    setCancelling(true);
    try {
      await cancelEnvelope(envelope.id, cancelReason || undefined, accessToken);
      setConfirmCancel(false);
      setCancelReason("");
      onChanged();
    } catch (err) {
      setActionError(err instanceof ApiError ? err.message : "Não foi possível cancelar o envelope.");
    } finally {
      setCancelling(false);
    }
  }

  async function handleDeleteConfirm() {
    if (!accessToken) return;
    setActionError(null);
    setDeleting(true);
    try {
      await deleteEnvelope(envelope.id, accessToken);
      window.location.assign("/signatures");
    } catch (err) {
      setActionError(err instanceof ApiError ? err.message : "Não foi possível excluir o envelope.");
      setDeleting(false);
      setConfirmDelete(false);
    }
  }

  async function handleSeal() {
    if (!accessToken) return;
    setActionError(null);
    setSealing(true);
    try {
      await sealCheckpoint(envelope.id, accessToken);
      onChanged();
    } catch (err) {
      setActionError(err instanceof ApiError ? err.message : "Não foi possível selar o checkpoint.");
    } finally {
      setSealing(false);
    }
  }

  async function handleFinalize() {
    if (!accessToken) return;
    setActionError(null);
    setFinalizing(true);
    try {
      await finalizeEnvelope(envelope.id, accessToken);
      onChanged();
    } catch (err) {
      setActionError(err instanceof ApiError ? err.message : "Não foi possível finalizar o envelope.");
    } finally {
      setFinalizing(false);
    }
  }

  async function handleDownloadFinal() {
    if (!accessToken) return;
    setActionError(null);
    setDownloadingFinal(true);
    try {
      await downloadFinalPdf(envelope.id, envelope.envelope_number, accessToken);
    } catch {
      setActionError("Não foi possível baixar o PDF final.");
    } finally {
      setDownloadingFinal(false);
    }
  }

  async function handleVerify() {
    if (!accessToken) return;
    setActionError(null);
    setVerifying(true);
    setVerifyResult(null);
    try {
      const result = await verifyAudit(envelope.id, accessToken);
      setVerifyResult(result);
    } catch (err) {
      setActionError(err instanceof ApiError ? err.message : "Não foi possível verificar a integridade.");
    } finally {
      setVerifying(false);
    }
  }

  const hasAnyAction =
    canSendInvite || canCancel || canDeleteEnvelope || canSeal || canFinalize || canDownloadFinal;

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

      {!hasAnyAction ? <p className="text-sm text-default">Nenhuma ação disponível para este status.</p> : null}

      <div className="space-y-4">
        {canSendInvite ? (
          <div>
            <p className="mb-2 text-xs font-semibold uppercase text-default">Enviar convite</p>
            <div className="flex flex-col gap-2 sm:flex-row">
              <Select
                options={[
                  { value: "both", label: "Ambas as partes" },
                  { value: "contratada", label: "Só contratada" },
                  { value: "contratante", label: "Só contratante" },
                ]}
                value={targets}
                onChange={(e) => setTargets(e.target.value as SendInviteTargets)}
                aria-label="Destinatários do convite"
              />
              <Button type="button" loading={sending} onClick={handleSend}>
                Enviar
              </Button>
            </div>
            <p className="mt-1 text-xs text-default">Reenvia apenas para quem ainda não assinou.</p>
          </div>
        ) : null}

        {canSeal ? (
          <div>
            <p className="mb-2 text-xs font-semibold uppercase text-default">Finalização — passo 1</p>
            <Button type="button" loading={sealing} onClick={handleSeal}>
              Selar checkpoint
            </Button>
          </div>
        ) : null}

        {canFinalize ? (
          <div>
            <p className="mb-2 text-xs font-semibold uppercase text-default">Finalização — passo 2</p>
            <Button type="button" loading={finalizing} onClick={handleFinalize}>
              Finalizar
            </Button>
            <p className="mt-1 text-xs text-default">
              Pode levar alguns segundos — renderiza o certificado e consolida o PDF final no servidor.
            </p>
          </div>
        ) : null}

        {canDownloadFinal ? (
          <div>
            <p className="mb-2 text-xs font-semibold uppercase text-default">PDF final</p>
            <Button type="button" variant="secondary" loading={downloadingFinal} onClick={handleDownloadFinal}>
              Baixar PDF final
            </Button>
          </div>
        ) : null}

        <div>
          <p className="mb-2 text-xs font-semibold uppercase text-default">Auditoria</p>
          <Button type="button" variant="secondary" loading={verifying} onClick={handleVerify}>
            Verificar integridade da cadeia
          </Button>
          {verifyResult ? (
            <Alert variant={verifyResult.valid ? "success" : "error"} className="mt-2">
              {verifyResult.valid
                ? `Cadeia íntegra — ${verifyResult.eventsChecked} evento(s) verificado(s).`
                : `Integridade comprometida (${verifyResult.eventsChecked} evento(s) verificados antes da falha) — ${verifyResult.reason ?? "motivo não informado"}.`}
            </Alert>
          ) : null}
        </div>

        {canCancel ? (
          <div className="border-t border-border-color pt-4">
            {!confirmCancel ? (
              <Button type="button" variant="danger" size="sm" onClick={() => setConfirmCancel(true)}>
                Cancelar envelope
              </Button>
            ) : (
              <div className="space-y-2">
                <p className="text-sm font-semibold text-title">Confirma o cancelamento deste envelope?</p>
                <input
                  type="text"
                  placeholder="Motivo (opcional)"
                  value={cancelReason}
                  onChange={(e) => setCancelReason(e.target.value)}
                  className="w-full rounded-md border border-border-color px-3 py-2 text-sm"
                />
                <div className="flex gap-2">
                  <Button type="button" variant="danger" size="sm" loading={cancelling} onClick={handleCancelConfirm}>
                    Confirmar cancelamento
                  </Button>
                  <Button type="button" variant="secondary" size="sm" onClick={() => setConfirmCancel(false)}>
                    Voltar
                  </Button>
                </div>
              </div>
            )}
          </div>
        ) : null}

        {canDeleteEnvelope ? (
          <div className="border-t border-border-color pt-4">
            {!confirmDelete ? (
              <Button type="button" variant="danger" size="sm" onClick={() => setConfirmDelete(true)}>
                Excluir envelope
              </Button>
            ) : (
              <div className="space-y-2">
                <p className="text-sm font-semibold text-title">
                  Excluir permanentemente este envelope? Esta ação não pode ser desfeita.
                </p>
                <div className="flex gap-2">
                  <Button type="button" variant="danger" size="sm" loading={deleting} onClick={handleDeleteConfirm}>
                    Confirmar exclusão
                  </Button>
                  <Button type="button" variant="secondary" size="sm" onClick={() => setConfirmDelete(false)}>
                    Voltar
                  </Button>
                </div>
              </div>
            )}
          </div>
        ) : null}
      </div>
    </Card>
  );
}

function AuditTrailCard({ events }: { events: SignatureAuditEvent[] }) {
  const sorted = useMemo(() => events.slice().sort((a, b) => Number(a.seq) - Number(b.seq)), [events]);

  return (
    <Card title="Linha do tempo de auditoria">
      {sorted.length === 0 ? (
        <p className="text-sm text-default">Nenhum evento registrado ainda.</p>
      ) : (
        <ol className="max-h-[32rem] space-y-4 overflow-y-auto">
          {sorted.map((event) => (
            <li key={event.id} className="relative border-s-2 border-border-color ps-4">
              <span className="absolute -start-[5px] top-1 size-2 rounded-full bg-primary" aria-hidden="true" />
              <p className="text-sm font-semibold text-title">{auditEventLabel(event.event_type)}</p>
              <p className="text-xs text-default">
                {formatDateTimeBR(event.timestamp_utc)} · {actorTypeLabel(event.actor_type)}
                {event.actor_role ? ` (${event.actor_role})` : ""}
                {event.ip_address ? ` · ${event.ip_address}` : ""}
              </p>
              {Object.keys(event.metadata_json ?? {}).length > 0 ? (
                <p className="mt-1 font-mono text-xs text-default">{JSON.stringify(event.metadata_json)}</p>
              ) : null}
            </li>
          ))}
        </ol>
      )}
    </Card>
  );
}