import { useState, useMemo, useCallback } from 'react';
import { useParams } from 'react-router';
import { useGlobalFilters } from '@cameleer/design-system';
import { useSearchExecutions, useExecutionDetail } from '../../api/queries/executions';
import { useDiagramByRoute } from '../../api/queries/diagrams';
import { useRouteCatalog } from '../../api/queries/catalog';
import type { ExecutionSummary } from '../../api/types';
import { ExchangeList } from './ExchangeList';
import { ExchangeHeader } from './ExchangeHeader';
import { ExecutionDiagram } from '../../components/ExecutionDiagram/ExecutionDiagram';
import { ProcessDiagram } from '../../components/ProcessDiagram';
import styles from './ExchangesPage.module.css';

// Lazy-import the full-width Dashboard for the no-route-scope view
import Dashboard from '../Dashboard/Dashboard';

export default function ExchangesPage() {
  const { appId, routeId, exchangeId } = useParams<{
    appId?: string; routeId?: string; exchangeId?: string;
  }>();

  // If no route is scoped, render the existing full-width Dashboard table
  if (!routeId) {
    return <Dashboard />;
  }

  // Route is scoped: render 3-column layout
  return (
    <RouteExchangeView appId={appId!} routeId={routeId} initialExchangeId={exchangeId} />
  );
}

// ─── 3-column view when route is scoped ─────────────────────────────────────

interface RouteExchangeViewProps {
  appId: string;
  routeId: string;
  initialExchangeId?: string;
}

function RouteExchangeView({ appId, routeId, initialExchangeId }: RouteExchangeViewProps) {
  const [selectedExchangeId, setSelectedExchangeId] = useState<string | undefined>(initialExchangeId);
  const { timeRange } = useGlobalFilters();
  const timeFrom = timeRange.start.toISOString();
  const timeTo = timeRange.end.toISOString();

  // Fetch exchanges for this route
  const { data: searchResult } = useSearchExecutions(
    { timeFrom, timeTo, routeId, application: appId, sortField: 'startTime', sortDir: 'desc', offset: 0, limit: 50 },
    true,
  );
  const exchanges: ExecutionSummary[] = searchResult?.data || [];

  // Fetch execution detail for selected exchange
  const { data: detail } = useExecutionDetail(selectedExchangeId ?? null);

  // Fetch diagram for topology-only view (when no exchange selected)
  const diagramQuery = useDiagramByRoute(appId, routeId);

  // Known route IDs for drill-down resolution
  const { data: catalog } = useRouteCatalog(timeFrom, timeTo);
  const knownRouteIds = useMemo(() => {
    const ids = new Set<string>();
    if (catalog) {
      for (const app of catalog as any[]) {
        for (const r of app.routes || []) {
          ids.add(r.routeId);
        }
      }
    }
    return ids;
  }, [catalog]);

  const handleExchangeSelect = useCallback((ex: ExecutionSummary) => {
    setSelectedExchangeId(ex.executionId);
  }, []);

  return (
    <div className={styles.threeColumn}>
      <ExchangeList
        exchanges={exchanges}
        selectedId={selectedExchangeId}
        onSelect={handleExchangeSelect}
      />

      <div className={styles.rightPanel}>
        {selectedExchangeId && detail ? (
          <>
            <ExchangeHeader detail={detail} />
            <ExecutionDiagram
              executionId={selectedExchangeId}
              executionDetail={detail}
              knownRouteIds={knownRouteIds}
            />
          </>
        ) : (
          diagramQuery.data ? (
            <ProcessDiagram
              application={appId}
              routeId={routeId}
              diagramLayout={diagramQuery.data}
              knownRouteIds={knownRouteIds}
            />
          ) : (
            <div className={styles.emptyRight}>
              Select an exchange to view execution details
            </div>
          )
        )}
      </div>
    </div>
  );
}