import { useCallback, useEffect, useMemo, useState } from "react";
import { useTranslation } from "react-i18next";
import { api, ApiError } from "../api/client";
import type { AutomationRun, IntegrationStatus, KnowledgeHealth } from "../api/types";
import { StatusBadge } from "../components/Badge";
import { useAuth } from "../context/AuthContext";
import { useLocaleFormat } from "../i18n/format";
import { ErrorState, IntegrationMark, LoadingState, PageHeader, SectionHeading } from "../components/PageChrome";
import { N8N_STATE_META, MCP_STATE_META } from "../data/integrationLabels";

type ViewFilter = "attention" | "recent" | "succeeded" | "all";

function deriveDisplayRef(run: AutomationRun): string {
  const digits = run.aggregate_ref.match(/(\d+)$/)?.[1];
  if (digits) return `AUT-RET-${digits}`;
  return `AUT-${run.event_id.slice(0, 4).toUpperCase()}`;
}

export function Automation() {
  const { t } = useTranslation(["integrations", "common"]);
  const { formatDateTime } = useLocaleFormat();
  const { user } = useAuth();
  const [runs, setRuns] = useState<AutomationRun[] | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [status, setStatus] = useState("");
  const [view, setView] = useState<ViewFilter>("attention");
  const [expandSucceeded, setExpandSucceeded] = useState(false);
  const [retryError, setRetryError] = useState<string | null>(null);
  const [retrying, setRetrying] = useState<string | null>(null);
  const [knowledge, setKnowledge] = useState<KnowledgeHealth | null>(null);
  const [integrationStatus, setIntegrationStatus] = useState<IntegrationStatus | null>(null);

  const load = useCallback(() => {
    setRuns(null);
    setError(null);
    const params = new URLSearchParams();
    if (status) params.set("status", status);
    api
      .get<AutomationRun[]>(`/api/v1/workflows?${params.toString()}`)
      .then(setRuns)
      .catch(() =>
        setError(user?.role === "operations_manager" ? t("ledger.unavailable") : t("ledger.managerOnly")),
      );
  }, [status, user, t]);

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

  useEffect(() => {
    api.get<KnowledgeHealth>("/api/v1/knowledge/status").then(setKnowledge).catch(() => setKnowledge(null));
  }, []);

  const loadIntegrationStatus = useCallback(() => {
    api
      .get<IntegrationStatus>("/api/v1/integrations/status")
      .then(setIntegrationStatus)
      .catch(() => setIntegrationStatus(null));
  }, []);

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

  async function handleRetry(eventId: string) {
    setRetryError(null);
    setRetrying(eventId);
    try {
      await api.post(`/api/v1/workflows/${eventId}/retry`);
      load();
      loadIntegrationStatus();
    } catch (err) {
      setRetryError(err instanceof ApiError ? err.message : t("ledger.retryFailed"));
    } finally {
      setRetrying(null);
    }
  }

  const visibleRuns = useMemo(() => {
    if (!runs) return null;
    switch (view) {
      case "attention":
        return runs.filter((r) => r.status === "failed" || r.status === "pending" || r.status === "delivering");
      case "recent":
        return runs.slice(0, 5);
      case "succeeded":
        return runs.filter((r) => r.status === "succeeded");
      default:
        return runs;
    }
  }, [runs, view]);

  const succeededRuns = useMemo(() => (visibleRuns ?? []).filter((r) => r.status === "succeeded"), [visibleRuns]);
  const otherRuns = useMemo(() => (visibleRuns ?? []).filter((r) => r.status !== "succeeded"), [visibleRuns]);
  const groupSucceeded = view !== "succeeded" && succeededRuns.length > 3;

  if (user?.role !== "operations_manager") {
    return (
      <div className="page">
        <PageHeader eyebrow={t("eyebrow")} title={t("title")} description={t("ledger.managerOnly")} />
        <p>{t("ledger.managerOnly")}</p>
      </div>
    );
  }

  function renderRow(r: AutomationRun) {
    return (
      <tr key={r.event_id}>
        <td className="mono" data-label={t("ledger.columns.event")}>
          <details>
            <summary>{deriveDisplayRef(r)}</summary>
            <span className="table-subtext">{r.event_id}</span>
          </details>
        </td>
        <td data-label={t("ledger.columns.type")}>{t(`ledger.eventTypes.${r.event_type}`, { defaultValue: r.event_type })}</td>
        <td data-label={t("ledger.columns.booking")}>{r.aggregate_ref}</td>
        <td data-label={t("ledger.columns.status")}>
          <StatusBadge status={r.status} label={t(`ledger.status${r.status.charAt(0).toUpperCase()}${r.status.slice(1)}`)} />
        </td>
        <td data-label={t("ledger.columns.attempts")}>{r.attempts}</td>
        <td data-label={t("ledger.columns.lastError")}>
          {r.last_error_code ? (
            <>
              <span>{t(`ledger.errorCodes.${r.last_error_code}`, { defaultValue: r.last_error ?? r.last_error_code })}</span>
              {r.last_error && (
                <details className="evidence-disclosure">
                  <summary>{t("common:actions.technicalDetails")}</summary>
                  <pre className="evidence-block">{r.last_error}</pre>
                </details>
              )}
            </>
          ) : (
            "—"
          )}
        </td>
        <td data-label={t("ledger.columns.when")}>
          <time dateTime={r.occurred_at}>{formatDateTime(r.occurred_at)}</time>
        </td>
        <td data-label={t("ledger.columns.action")}>
          {r.status === "failed" ? (
            <button type="button" onClick={() => handleRetry(r.event_id)} disabled={retrying === r.event_id}>
              {retrying === r.event_id ? t("ledger.retrying") : t("ledger.retry")}
            </button>
          ) : (
            t("ledger.noAction")
          )}
        </td>
      </tr>
    );
  }

  return (
    <div className="page">
      <PageHeader eyebrow={t("eyebrow")} title={t("title")} description={t("description")} />

      <section className="integration-cards" aria-label={t("title")}>
        <article>
          <IntegrationMark kind="n8n" />
          <div>
            <span className="integration-kicker">{t("cards.orchestrationKicker")}</span>
            <h2>{t("cards.n8nTitle")}</h2>
            <p>
              {integrationStatus
                ? t("cards.n8nSummary", {
                    succeeded: integrationStatus.n8n.succeeded,
                    failed: integrationStatus.n8n.failed,
                    pending: integrationStatus.n8n.pending,
                    delivering: integrationStatus.n8n.delivering,
                  })
                : t("cards.n8nFallback")}
            </p>
          </div>
          {(() => {
            const meta = integrationStatus ? N8N_STATE_META[integrationStatus.n8n.state] : null;
            return (
              <StatusBadge
                status={meta?.statusClass ?? (runs?.[0]?.status ?? "no_events")}
                label={meta ? t(`statusLabels.${meta.labelKey}`) : undefined}
              />
            );
          })()}
        </article>
        <article>
          <IntegrationMark kind="rag" />
          <div>
            <span className="integration-kicker">{t("cards.knowledgeKicker")}</span>
            <h2>{t("cards.knowledgeTitle")}</h2>
            <p>
              {knowledge
                ? t(knowledge.provider === "ragcore" ? "cards.knowledgeSummaryRagcore" : "cards.knowledgeSummaryDemo", {
                    count: knowledge.document_count,
                    collection: knowledge.collection,
                  })
                : t("cards.knowledgeUnavailable")}
            </p>
          </div>
          <StatusBadge
            status={knowledge?.available ? "available" : "unavailable"}
            label={
              knowledge?.available
                ? t(`statusLabels.${knowledge.provider === "ragcore" ? "operational" : "demoMode"}`)
                : t("statusLabels.unavailable")
            }
          />
        </article>
        <article>
          <IntegrationMark kind="mcp" />
          <div>
            <span className="integration-kicker">{t("cards.gatewayKicker")}</span>
            <h2>{t("cards.mcpTitle")}</h2>
            <p>{integrationStatus?.mcp_hub.registration_enabled ? t("cards.mcpEnabled") : t("cards.mcpNotConnected")}</p>
          </div>
          {(() => {
            const meta = integrationStatus ? MCP_STATE_META[integrationStatus.mcp_hub.state] : null;
            return <StatusBadge status={meta?.statusClass ?? "not_configured"} label={meta ? t(`statusLabels.${meta.labelKey}`) : undefined} />;
          })()}
        </article>
      </section>

      <SectionHeading title={t("ledger.title")} description={t("ledger.description")} />

      <form className="filters" aria-label={t("ledger.title")}>
        <label>
          {t("ledger.filterLabel")}
          <select value={view} onChange={(e) => setView(e.target.value as ViewFilter)}>
            <option value="attention">{t("ledger.filterNeedsAttention")}</option>
            <option value="recent">{t("ledger.filterRecent")}</option>
            <option value="succeeded">{t("ledger.filterSucceeded")}</option>
            <option value="all">{t("ledger.filterAll")}</option>
          </select>
        </label>
        <label>
          {t("ledger.statusFilterLabel")}
          <select value={status} onChange={(e) => setStatus(e.target.value)}>
            <option value="">{t("ledger.statusAll")}</option>
            <option value="pending">{t("ledger.statusPending")}</option>
            <option value="delivering">{t("ledger.statusDelivering")}</option>
            <option value="succeeded">{t("ledger.statusSucceeded")}</option>
            <option value="failed">{t("ledger.statusFailed")}</option>
          </select>
        </label>
      </form>

      {error && <ErrorState message={error} />}
      {retryError && <p className="error" role="alert">{retryError}</p>}
      {!error && !runs && <LoadingState label={t("ledger.loading")} />}
      {visibleRuns && visibleRuns.length === 0 && <p>{t("ledger.empty")}</p>}

      {visibleRuns && visibleRuns.length > 0 && (
        <div className="table-shell">
          <div className="table-meta"><span>{t("ledger.count", { count: visibleRuns.length })}</span><span>{t("ledger.boundedRetries")}</span></div>
          <table className="data-table">
            <caption className="visually-hidden">{t("ledger.title")}</caption>
            <thead>
              <tr>
                <th scope="col">{t("ledger.columns.event")}</th>
                <th scope="col">{t("ledger.columns.type")}</th>
                <th scope="col">{t("ledger.columns.booking")}</th>
                <th scope="col">{t("ledger.columns.status")}</th>
                <th scope="col">{t("ledger.columns.attempts")}</th>
                <th scope="col">{t("ledger.columns.lastError")}</th>
                <th scope="col">{t("ledger.columns.when")}</th>
                <th scope="col">{t("ledger.columns.action")}</th>
              </tr>
            </thead>
            <tbody>
              {otherRuns.map(renderRow)}
              {groupSucceeded ? (
                <>
                  <tr>
                    <td colSpan={8}>
                      <button type="button" className="link-button" onClick={() => setExpandSucceeded((v) => !v)}>
                        {expandSucceeded
                          ? t("ledger.hideIndividually")
                          : t("ledger.groupedSucceeded", { count: succeededRuns.length })}
                      </button>
                    </td>
                  </tr>
                  {expandSucceeded && succeededRuns.map(renderRow)}
                </>
              ) : (
                succeededRuns.map(renderRow)
              )}
            </tbody>
          </table>
        </div>
      )}
    </div>
  );
}