import React, { useEffect, useMemo, useRef, useState } from 'react';
import {
  Bot,
  Compass,
  Crosshair,
  Maximize2,
  Megaphone,
  Minus,
  Plus,
  RotateCcw,
  ScrollText,
  Target,
  TrendingUp,
  UserCheck,
  X,
  Zap,
} from 'lucide-react';
import { useTheme } from '../../contexts/ThemeContext';
import type { ExpertCard, SixStepMessage } from './types';
import {
  CURRENT_PAIR_BY_STAGE,
  EDGE_COLOR,
  EDGE_LABEL,
  STATUS_TITLE,
  VARIANT_ABBREV,
  VARIANT_LABEL,
  buildEdgePath,
  buildLayout,
  type LayoutEdge,
  type LayoutNode,
} from './flowLayout';

interface SixStepFlowSandboxProps {
  message?: SixStepMessage;
  width: number;
  onResizeStart: (e: React.MouseEvent) => void;
  onClose: () => void;
  onOpenFullscreen: () => void;
}

const COMPACT_OPTIONS = {
  nodeWidth: 120,
  nodeHeight: 60,
  levelGap: 80,
  nodeGap: 24,
  paddingX: 32,
  paddingY: 28,
};

const VARIANT_GRADIENT: Record<LayoutNode['variant'], { dark: string; light: string }> = {
  agent: { dark: 'from-slate-700/80 to-slate-900/80 border-slate-500/60', light: 'from-white to-slate-50 border-slate-300' },
  purpose: { dark: 'from-violet-700/40 to-violet-900/40 border-violet-400/50', light: 'from-orange-50 to-white border-orange-300' },
  actor: { dark: 'from-cyan-700/40 to-cyan-900/40 border-cyan-400/50', light: 'from-red-50 to-white border-red-300' },
  behavior: { dark: 'from-emerald-700/40 to-emerald-900/40 border-emerald-400/50', light: 'from-emerald-50 to-white border-emerald-300' },
  driver: { dark: 'from-emerald-800/40 to-teal-900/40 border-teal-400/50', light: 'from-teal-50 to-white border-teal-300' },
  narrative: { dark: 'from-amber-700/40 to-amber-900/40 border-amber-400/50', light: 'from-amber-50 to-white border-amber-300' },
};

const VARIANT_ICON: Record<LayoutNode['variant'], React.ComponentType<{ className?: string }>> = {
  agent: Bot,
  purpose: Target,
  actor: UserCheck,
  behavior: TrendingUp,
  driver: Zap,
  narrative: ScrollText,
};

// Colored icon wrapper per variant (dark / light)
const VARIANT_ICON_CLS: Record<LayoutNode['variant'], { dark: string; light: string }> = {
  agent:     { dark: 'bg-slate-600/60 text-slate-200',      light: 'bg-slate-100 text-slate-600' },
  purpose:   { dark: 'bg-violet-500/25 text-violet-200',    light: 'bg-orange-100 text-orange-600' },
  actor:     { dark: 'bg-cyan-500/25 text-cyan-200',        light: 'bg-red-100 text-red-600' },
  behavior:  { dark: 'bg-emerald-500/25 text-emerald-200',  light: 'bg-emerald-100 text-emerald-700' },
  driver:    { dark: 'bg-teal-500/25 text-teal-200',        light: 'bg-teal-100 text-teal-700' },
  narrative: { dark: 'bg-amber-500/25 text-amber-200',      light: 'bg-amber-100 text-amber-600' },
};

const SCALE_MIN = 0.3;
const SCALE_MAX = 2.5;

const buildExpertRootDetail = (expert: ExpertCard): string => {
  const segments = [expert.title, expert.detail].filter((item): item is string => Boolean(item && item.trim()));
  return segments.join(' · ') || '已确认专家';
};

const CompactNode: React.FC<{
  node: LayoutNode;
  isDark: boolean;
  appearing: boolean;
  collapsible: boolean;
  collapsed: boolean;
  onToggleCollapse?: (nodeId: string) => void;
}> = ({ node, isDark, appearing, collapsible, collapsed, onToggleCollapse }) => {
  const Icon = VARIANT_ICON[node.variant];
  const grad = VARIANT_GRADIENT[node.variant][isDark ? 'dark' : 'light'];
  const canToggle = collapsible && Boolean(onToggleCollapse);
  const handleClick = (e: React.MouseEvent<SVGGElement>) => {
    if (!canToggle) return;
    e.stopPropagation();
    onToggleCollapse(node.id);
  };
  const handleMouseDown = (e: React.MouseEvent<SVGGElement>) => {
    if (canToggle) e.stopPropagation();
  };
  return (
    <g
      className={appearing ? 'sixstep-node-pop' : ''}
      onMouseDown={handleMouseDown}
      onClick={handleClick}
      style={canToggle ? { cursor: 'pointer' } : undefined}
    >
      {appearing && (
        <circle
          cx={node.x + node.width / 2}
          cy={node.y + node.height / 2}
          r={0}
          stroke={isDark ? '#22d3ee' : '#ef4444'}
          className="sixstep-ring-burst"
        />
      )}
      <foreignObject x={node.x} y={node.y} width={node.width} height={node.height}>
        <div className={`relative w-full h-full rounded-2xl border bg-gradient-to-br ${grad} backdrop-blur-sm flex items-center justify-center gap-1.5 px-2 shadow-sm`}>
          {collapsible && (
            <div
              className={`absolute right-1.5 top-1.5 w-4 h-4 rounded-full flex items-center justify-center text-[10px] font-bold ${
                isDark ? 'bg-slate-800/75 text-slate-200' : 'bg-white text-slate-600 border border-slate-200'
              }`}
              title={collapsed ? '展开子节点' : '收起子节点'}
            >
              {collapsed ? '+' : '-'}
            </div>
          )}
          <div className={`w-7 h-7 rounded-lg flex items-center justify-center ${VARIANT_ICON_CLS[node.variant][isDark ? 'dark' : 'light']}`}>
            <Icon className="w-3.5 h-3.5" />
          </div>
          <span className={`text-sm font-bold tracking-wider ${isDark ? 'text-white' : 'text-slate-800'}`}>
            {VARIANT_ABBREV[node.variant]}
          </span>
        </div>
      </foreignObject>
    </g>
  );
};

const ToolbarButton: React.FC<{ title: string; onClick: () => void; isDark: boolean; children: React.ReactNode }> = ({ title, onClick, isDark, children }) => (
  <button
    type="button"
    title={title}
    onClick={onClick}
    className={`sixstep-toolbar-btn ${
      isDark ? 'text-slate-300 hover:bg-slate-700/70 hover:text-white' : 'text-gray-600 hover:bg-gray-100 hover:text-gray-900'
    }`}
  >
    {children}
  </button>
);

const SixStepFlowSandbox: React.FC<SixStepFlowSandboxProps> = ({ message, width, onResizeStart, onClose, onOpenFullscreen }) => {
  const { theme } = useTheme();
  const isDark = theme === 'dark';

  const purposes = message?.stages?.purpose?.cards ?? [];
  const actors = message?.stages?.actor?.cards ?? [];
  const behaviors = message?.stages?.behavior?.cards ?? [];
  const narratives = message?.stages?.narrative?.cards ?? [];
  const selectedExpert = message?.selectedExpert;

  const layout = useMemo(
    () => buildLayout(purposes, actors, behaviors, narratives, {
      ...COMPACT_OPTIONS,
      rootTitle: selectedExpert?.name,
      rootDetail: selectedExpert ? buildExpertRootDetail(selectedExpert) : undefined,
    }),
    [purposes, actors, behaviors, narratives, selectedExpert],
  );

  const currentSub = message?.currentSubStep;
  const activePair = currentSub ? CURRENT_PAIR_BY_STAGE[currentSub] : null;
  const statusTitle = currentSub ? STATUS_TITLE[currentSub] : '推演结果可视化';
  const generating = Boolean(currentSub);

  const [transform, setTransform] = useState({ tx: 0, ty: 0, scale: 1 });
  const [isPanning, setIsPanning] = useState(false);
  const [collapsedNodeIds, setCollapsedNodeIds] = useState<Set<string>>(new Set());
  const containerRef = useRef<HTMLDivElement>(null);
  const panStart = useRef<{ x: number; y: number; tx: number; ty: number } | null>(null);

  // Track newly appearing nodes for animation
  const seenIdsRef = useRef<Set<string>>(new Set());
  const [appearingIds, setAppearingIds] = useState<Set<string>>(new Set());

  const nodeMap = useMemo(() => {
    return new Map(layout.nodes.map((node) => [node.id, node]));
  }, [layout.nodes]);

  const visibleNodeSet = useMemo(() => {
    const visible = new Set<string>();
    layout.nodes.forEach((node) => {
      let parentId = node.parent;
      let hidden = false;
      while (parentId) {
        if (collapsedNodeIds.has(parentId)) {
          hidden = true;
          break;
        }
        parentId = nodeMap.get(parentId)?.parent;
      }
      if (!hidden) visible.add(node.id);
    });
    return visible;
  }, [collapsedNodeIds, layout.nodes, nodeMap]);

  const visibleNodes = useMemo(
    () => layout.nodes.filter((node) => visibleNodeSet.has(node.id)),
    [layout.nodes, visibleNodeSet],
  );

  const visibleEdges = useMemo(
    () => layout.edges.filter((edge) => visibleNodeSet.has(edge.fromId) && visibleNodeSet.has(edge.toId)),
    [layout.edges, visibleNodeSet],
  );

  const toggleNodeCollapse = (nodeId: string) => {
    const targetNode = nodeMap.get(nodeId);
    if (!targetNode || targetNode.children.length === 0) return;
    setCollapsedNodeIds((prev) => {
      const next = new Set(prev);
      if (next.has(nodeId)) next.delete(nodeId);
      else next.add(nodeId);
      return next;
    });
  };

  useEffect(() => {
    const validIds = new Set(
      layout.nodes.filter((node) => node.children.length > 0).map((node) => node.id),
    );
    setCollapsedNodeIds((prev) => {
      let changed = false;
      const next = new Set<string>();
      prev.forEach((id) => {
        if (validIds.has(id)) next.add(id);
        else changed = true;
      });
      return changed ? next : prev;
    });
  }, [layout.nodes]);

  useEffect(() => {
    const newIds: string[] = [];
    visibleNodes.forEach((n) => {
      if (!seenIdsRef.current.has(n.id)) {
        seenIdsRef.current.add(n.id);
        newIds.push(n.id);
      }
    });
    if (newIds.length > 0) {
      setAppearingIds((prev) => {
        const next = new Set(prev);
        newIds.forEach((id) => next.add(id));
        return next;
      });
      const timer = window.setTimeout(() => {
        setAppearingIds((prev) => {
          const next = new Set(prev);
          newIds.forEach((id) => next.delete(id));
          return next;
        });
      }, 700);
      return () => window.clearTimeout(timer);
    }
  }, [visibleNodes]);

  // Native wheel listener with passive:false so preventDefault actually blocks browser zoom
  useEffect(() => {
    const container = containerRef.current;
    if (!container) return;
    const onWheel = (e: WheelEvent) => {
      e.preventDefault();
      const rect = container.getBoundingClientRect();
      const mx = e.clientX - rect.left;
      const my = e.clientY - rect.top;
      const delta = -e.deltaY * 0.0015;
      setTransform((prev) => {
        const nextScale = Math.max(SCALE_MIN, Math.min(SCALE_MAX, prev.scale * (1 + delta)));
        const ratio = nextScale / prev.scale;
        return { tx: mx - (mx - prev.tx) * ratio, ty: my - (my - prev.ty) * ratio, scale: nextScale };
      });
    };
    container.addEventListener('wheel', onWheel, { passive: false });
    return () => container.removeEventListener('wheel', onWheel);
  }, []);

  const handlePanStart = (e: React.MouseEvent) => {
    if (e.button !== 0) return;
    panStart.current = { x: e.clientX, y: e.clientY, tx: transform.tx, ty: transform.ty };
    setIsPanning(true);
  };

  useEffect(() => {
    if (!isPanning) return;
    const move = (e: MouseEvent) => {
      const start = panStart.current;
      if (!start) return;
      setTransform((prev) => ({ ...prev, tx: start.tx + (e.clientX - start.x), ty: start.ty + (e.clientY - start.y) }));
    };
    const up = () => {
      panStart.current = null;
      setIsPanning(false);
    };
    window.addEventListener('mousemove', move);
    window.addEventListener('mouseup', up);
    return () => {
      window.removeEventListener('mousemove', move);
      window.removeEventListener('mouseup', up);
    };
  }, [isPanning]);

  const fitToView = () => {
    const container = containerRef.current;
    if (!container || layout.width <= 0 || layout.height <= 0) {
      setTransform({ tx: 0, ty: 0, scale: 1 });
      return;
    }
    const rect = container.getBoundingClientRect();
    const scale = Math.min((rect.width - 40) / layout.width, (rect.height - 40) / layout.height, 1);
    const tx = (rect.width - layout.width * scale) / 2;
    const ty = (rect.height - layout.height * scale) / 2;
    setTransform({ tx, ty, scale });
  };

  const centerView = () => {
    const container = containerRef.current;
    if (!container) return;
    const rect = container.getBoundingClientRect();
    setTransform((prev) => ({
      ...prev,
      tx: (rect.width - layout.width * prev.scale) / 2,
      ty: (rect.height - layout.height * prev.scale) / 2,
    }));
  };

  const zoomIn = () => setTransform((prev) => ({ ...prev, scale: Math.min(SCALE_MAX, prev.scale * 1.2) }));
  const zoomOut = () => setTransform((prev) => ({ ...prev, scale: Math.max(SCALE_MIN, prev.scale / 1.2) }));
  const reset = () => setTransform({ tx: 0, ty: 0, scale: 1 });

  // Auto-fit on first render with content
  const fitAppliedRef = useRef(false);
  useEffect(() => {
    if (!fitAppliedRef.current && layout.nodes.length > 1) {
      fitToView();
      fitAppliedRef.current = true;
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [layout.nodes.length]);

  return (
    <div
      className={`relative h-full flex flex-col border-l ${
        isDark ? 'border-slate-700/60 bg-slate-900/60' : 'border-red-100 bg-white'
      }`}
      style={{ width }}
    >
      <div className="sixstep-resize-handle" onMouseDown={onResizeStart} />

      <div className={`flex items-center justify-between gap-3 px-4 py-3 border-b ${
        isDark ? 'border-slate-700/60 bg-slate-900/40' : 'border-red-100 bg-gradient-to-r from-red-50/60 to-orange-50/40'
      }`}>
        <div className="flex items-center gap-2 min-w-0">
          <div className={`w-8 h-8 rounded-2xl flex items-center justify-center ${
            isDark ? 'bg-cyan-500/15 text-cyan-300' : 'bg-red-50 text-red-500'
          } ${generating ? 'sixstep-pulse' : ''}`}>
            <Compass className="w-4 h-4" />
          </div>
          <div className="min-w-0">
            <div className={`text-sm font-semibold truncate ${
              generating ? (isDark ? 'sixstep-shimmer-text' : 'sixstep-shimmer-text-light') : (isDark ? 'text-white' : 'text-gray-900')
            }`}>
              {statusTitle}
            </div>
            <div className={`text-[11px] ${isDark ? 'text-slate-400' : 'text-gray-500'}`}>
              简化视图 · 节点缩写显示
            </div>
          </div>
        </div>
        <button
          type="button"
          onClick={onClose}
          className={`p-1.5 rounded-lg transition-colors ${
            isDark ? 'text-slate-400 hover:text-white hover:bg-slate-700/60' : 'text-gray-500 hover:text-gray-800 hover:bg-gray-100'
          }`}
          title="关闭沙箱"
        >
          <X className="w-4 h-4" />
        </button>
      </div>

      <div className={`flex items-center gap-1 px-3 py-2 border-b ${
        isDark ? 'border-slate-700/60 bg-slate-900/30' : 'border-red-100 bg-white'
      }`}>
        <ToolbarButton title="放大" onClick={zoomIn} isDark={isDark}><Plus className="w-4 h-4" /></ToolbarButton>
        <ToolbarButton title="缩小" onClick={zoomOut} isDark={isDark}><Minus className="w-4 h-4" /></ToolbarButton>
        <ToolbarButton title="恢复 1:1" onClick={reset} isDark={isDark}><RotateCcw className="w-4 h-4" /></ToolbarButton>
        <ToolbarButton title="定位到画布中央" onClick={centerView} isDark={isDark}><Crosshair className="w-4 h-4" /></ToolbarButton>
        <span className={`mx-2 h-5 w-px ${isDark ? 'bg-slate-700' : 'bg-gray-200'}`} />
        <span className={`text-[11px] tabular-nums ${isDark ? 'text-slate-400' : 'text-gray-500'}`}>
          {Math.round(transform.scale * 100)}%
        </span>
        <div className="flex-1" />
        <ToolbarButton title="全屏查看完整流程图" onClick={onOpenFullscreen} isDark={isDark}>
          <Maximize2 className="w-4 h-4" />
        </ToolbarButton>
      </div>

      <div className={`flex items-center gap-3 px-3 py-1.5 border-b text-[11px] flex-wrap ${
        isDark ? 'border-slate-700/60 text-slate-400 bg-slate-900/30' : 'border-red-100 text-gray-500 bg-white'
      }`}>
        {(Object.keys(EDGE_COLOR) as LayoutEdge['pair'][]).map((pair) => {
          const color = EDGE_COLOR[pair][isDark ? 'dark' : 'light'];
          const active = activePair === pair;
          return (
            <span key={pair} className="inline-flex items-center gap-1.5">
              <span className={`inline-block w-5 h-0.5 rounded-full ${active ? 'sixstep-ant-line' : ''}`} style={{ background: color, stroke: color }} />
              <span className={active ? (isDark ? 'text-cyan-200' : 'text-red-600') : ''}>{EDGE_LABEL[pair]}</span>
            </span>
          );
        })}
      </div>

      <div
        ref={containerRef}
        className={`flex-1 overflow-hidden relative ${isPanning ? 'sixstep-canvas-grabbing' : 'sixstep-canvas-grab'}`}
        onMouseDown={handlePanStart}
      >
        {visibleNodes.length <= 1 ? (
          <div className={`h-full flex flex-col items-center justify-center text-center ${
            isDark ? 'text-slate-500' : 'text-gray-400'
          }`}>
            <Megaphone className="w-10 h-10 opacity-40 mb-3" />
            <div className={`text-sm font-medium ${isDark ? 'text-slate-300' : 'text-gray-600'}`}>等待推演开始</div>
            <div className="text-xs mt-1">推演产出将以流程图形式呈现</div>
          </div>
        ) : (
          <svg
            width="100%"
            height="100%"
            className="block select-none"
          >
            <defs>
              {(Object.keys(EDGE_COLOR) as LayoutEdge['pair'][]).map((pair) => {
                const color = EDGE_COLOR[pair][isDark ? 'dark' : 'light'];
                return (
                  <marker
                    key={pair}
                    id={`sixstep-sandbox-arrow-${pair}`}
                    viewBox="0 0 8 8"
                    refX="7"
                    refY="4"
                    markerWidth="6"
                    markerHeight="6"
                    orient="auto-start-reverse"
                  >
                    <path d="M 0 0 L 8 4 L 0 8 z" fill={color} />
                  </marker>
                );
              })}
            </defs>

            <g transform={`translate(${transform.tx}, ${transform.ty}) scale(${transform.scale})`}>
              {visibleEdges.map((edge) => {
                const from = nodeMap.get(edge.fromId);
                const to = nodeMap.get(edge.toId);
                if (!from || !to) return null;
                const color = EDGE_COLOR[edge.pair][isDark ? 'dark' : 'light'];
                const isActive = activePair === edge.pair;
                return (
                  <path
                    key={edge.id}
                    d={buildEdgePath(from, to)}
                    fill="none"
                    stroke={color}
                    strokeWidth={isActive ? 2.2 : 1.6}
                    strokeOpacity={isActive ? 1 : 0.7}
                    className={isActive ? 'sixstep-ant-line' : ''}
                    markerEnd={`url(#sixstep-sandbox-arrow-${edge.pair})`}
                  />
                );
              })}

              {visibleNodes.map((node) => (
                <CompactNode
                  key={node.id}
                  node={node}
                  isDark={isDark}
                  appearing={appearingIds.has(node.id)}
                  collapsible={node.children.length > 0}
                  collapsed={collapsedNodeIds.has(node.id)}
                  onToggleCollapse={toggleNodeCollapse}
                />
              ))}
            </g>
          </svg>
        )}

        <div className={`absolute bottom-3 left-3 px-2 py-1 rounded-md text-[10px] backdrop-blur-md ${
          isDark ? 'bg-slate-800/70 text-slate-400 border border-slate-700/50' : 'bg-white/90 text-gray-500 border border-gray-200'
        }`}>
          {VARIANT_LABEL.purpose}=md · {VARIANT_LABEL.actor}=xwt · {VARIANT_LABEL.behavior}=yqxw · {VARIANT_LABEL.driver}=qdys · {VARIANT_LABEL.narrative}=xs
        </div>
        <div className={`absolute bottom-3 right-3 px-2 py-1 rounded-md text-[10px] backdrop-blur-md ${
          isDark ? 'bg-slate-800/70 text-slate-400 border border-slate-700/50' : 'bg-white/90 text-gray-500 border border-gray-200'
        }`}>
          点击父节点可收起/展开子节点
        </div>
      </div>
    </div>
  );
};

export default SixStepFlowSandbox;