import React, { useState, useMemo } from 'react';
import { useParams, useNavigate } from 'react-router';
import {
  Badge, StatusDot, MonoText, CodeBlock, InfoCallout,
  ProcessorTimeline, Breadcrumb, Spinner, SegmentedTabs, RouteFlow,
} from '@cameleer/design-system';
import { useExecutionDetail, useProcessorSnapshot } from '../../api/queries/executions';
import { useCorrelationChain } from '../../api/queries/correlation';
import { useDiagramByRoute } from '../../api/queries/diagrams';
import { mapDiagramToRouteNodes } from '../../utils/diagram-mapping';
import styles from './ExchangeDetail.module.css';

function countProcessors(nodes: any[]): number {
  return nodes.reduce((sum, n) => sum + 1 + countProcessors(n.children || []), 0);
}

export default function ExchangeDetail() {
  const { id } = useParams();
  const navigate = useNavigate();
  const { data: detail, isLoading } = useExecutionDetail(id ?? null);
  const [selectedProcessor, setSelectedProcessor] = useState<number | null>(null);
  const [viewMode, setViewMode] = useState<'timeline' | 'flow'>('timeline');
  const { data: snapshot } = useProcessorSnapshot(id ?? null, selectedProcessor);
  const { data: correlationData } = useCorrelationChain(detail?.correlationId ?? null);
  const { data: diagram } = useDiagramByRoute(detail?.groupName, detail?.routeId);

  const processors = useMemo(() => {
    if (!detail?.children) return [];
    const result: any[] = [];
    let offset = 0;
    function walk(node: any) {
      result.push({
        name: node.processorId || node.processorType,
        type: node.processorType,
        durationMs: node.durationMs ?? 0,
        status: node.status === 'COMPLETED' ? 'ok' : node.status === 'FAILED' ? 'fail' : 'ok',
        startMs: offset,
      });
      offset += node.durationMs ?? 0;
      if (node.children) node.children.forEach(walk);
    }
    detail.children.forEach(walk);
    return result;
  }, [detail]);

  if (isLoading) return <div style={{ display: 'flex', justifyContent: 'center', padding: '4rem' }}><Spinner size="lg" /></div>;
  if (!detail) return <InfoCallout variant="warning">Exchange not found</InfoCallout>;

  return (
    <div>
      <Breadcrumb items={[
        { label: 'Dashboard', href: '/apps' },
        { label: detail.groupName || 'App', href: `/apps/${detail.groupName}` },
        { label: id?.slice(0, 12) || '' },
      ]} />

      <div className={styles.exchangeHeader}>
        <div className={styles.headerRow}>
          <div className={styles.headerLeft}>
            <StatusDot variant={detail.status === 'COMPLETED' ? 'success' : detail.status === 'FAILED' ? 'error' : 'running'} />
            <div>
              <Badge label={detail.status} color={detail.status === 'COMPLETED' ? 'success' : 'error'} />
              <MonoText>{id}</MonoText>
            </div>
          </div>
          <div className={styles.headerRight}>
            <div className={styles.headerStat}>
              <div className={styles.headerStatLabel}>Duration</div>
              <div className={styles.headerStatValue}>{detail.durationMs}ms</div>
            </div>
            <div className={styles.headerStat}>
              <div className={styles.headerStatLabel}>Agent</div>
              <div className={styles.headerStatValue}>{detail.agentId}</div>
            </div>
            <div className={styles.headerStat}>
              <div className={styles.headerStatLabel}>Processors</div>
              <div className={styles.headerStatValue}>{countProcessors(detail.processors || detail.children || [])}</div>
            </div>
            <div className={styles.headerStat}>
              <div className={styles.headerStatLabel}>Route</div>
              <div className={styles.headerStatValue}>{detail.routeId}</div>
            </div>
            <div className={styles.headerStat}>
              <div className={styles.headerStatLabel}>Application</div>
              <div className={styles.headerStatValue}>{detail.groupName || 'unknown'}</div>
            </div>
          </div>
        </div>
      </div>

      {correlationData?.data && correlationData.data.length > 1 && (
        <div className={styles.correlationChain}>
          <div className={styles.panelHeader}>
            <span className={styles.panelTitle}>Correlation Chain</span>
          </div>
          <div className={styles.chainRow}>
            {correlationData.data.map((exec, i) => (
              <React.Fragment key={exec.executionId}>
                {i > 0 && <span className={styles.chainArrow}>→</span>}
                <a
                  href={`/exchanges/${exec.executionId}`}
                  className={`${styles.chainCard} ${exec.executionId === id ? styles.chainCardActive : ''}`}
                  onClick={(e) => { e.preventDefault(); navigate(`/exchanges/${exec.executionId}`); }}
                >
                  <StatusDot variant={exec.status === 'COMPLETED' ? 'success' : exec.status === 'FAILED' ? 'error' : 'warning'} />
                  <span className={styles.chainRoute}>{exec.routeId}</span>
                  <span className={styles.chainDuration}>{exec.durationMs}ms</span>
                </a>
              </React.Fragment>
            ))}
            {correlationData.total > 20 && (
              <span className={styles.chainMore}>+{correlationData.total - 20} more</span>
            )}
          </div>
        </div>
      )}

      {detail.errorMessage && (
        <InfoCallout variant="error">
          {detail.errorMessage}
        </InfoCallout>
      )}

      <div className={styles.timelineSection}>
        <div className={styles.timelineHeader}>
          <span className={styles.timelineTitle}>Processors</span>
          <SegmentedTabs
            tabs={[
              { label: 'Timeline', value: 'timeline' },
              { label: 'Flow', value: 'flow' },
            ]}
            active={viewMode}
            onChange={(v) => setViewMode(v as 'timeline' | 'flow')}
          />
        </div>
        <div className={styles.timelineBody}>
          {viewMode === 'timeline' ? (
            processors.length > 0 ? (
              <ProcessorTimeline
                processors={processors}
                totalMs={detail.durationMs}
                onProcessorClick={(_p, i) => setSelectedProcessor(i)}
                selectedIndex={selectedProcessor ?? undefined}
              />
            ) : (
              <InfoCallout>No processor data available</InfoCallout>
            )
          ) : (
            diagram ? (
              <RouteFlow
                nodes={mapDiagramToRouteNodes(diagram.nodes || [], detail.processors || detail.children || [])}
                onNodeClick={(_node, i) => setSelectedProcessor(i)}
                selectedIndex={selectedProcessor ?? undefined}
              />
            ) : (
              <Spinner />
            )
          )}
        </div>
      </div>

      {snapshot && (
        <>
          <div className={styles.sectionLabel}>Exchange Snapshot</div>
          <div className={styles.detailSplit}>
            <div className={styles.detailPanel}>
              <div className={styles.panelHeader}>
                <span className={styles.panelTitle}>Input Body</span>
              </div>
              <div className={styles.panelBody}>
                <CodeBlock content={String(snapshot.inputBody ?? 'null')} />
              </div>
            </div>
            <div className={styles.detailPanel}>
              <div className={styles.panelHeader}>
                <span className={styles.panelTitle}>Output Body</span>
              </div>
              <div className={styles.panelBody}>
                <CodeBlock content={String(snapshot.outputBody ?? 'null')} />
              </div>
            </div>
          </div>
          <div className={styles.detailSplit}>
            <div className={styles.detailPanel}>
              <div className={styles.panelHeader}>
                <span className={styles.panelTitle}>Input Headers</span>
              </div>
              <div className={styles.panelBody}>
                <CodeBlock content={JSON.stringify(snapshot.inputHeaders ?? {}, null, 2)} />
              </div>
            </div>
            <div className={styles.detailPanel}>
              <div className={styles.panelHeader}>
                <span className={styles.panelTitle}>Output Headers</span>
              </div>
              <div className={styles.panelBody}>
                <CodeBlock content={JSON.stringify(snapshot.outputHeaders ?? {}, null, 2)} />
              </div>
            </div>
          </div>
        </>
      )}
    </div>
  );
}