import React, { useState } from 'react';
import { motion } from 'framer-motion';
import { Resource, Agent, GridPosition, Polyline } from '../types';
import { BookOpen, Play, FileText, PenTool, RefreshCw, MapPin, Sparkles, Search, X, ChevronRight, ZoomIn, ZoomOut } from 'lucide-react';
import { nlpApi } from '../services/nlpApi';
const avatar = "https://api.dicebear.com/7.x/avataaars/svg?seed=Felix&backgroundColor=f1f5f9";

interface GridVisualizationProps {
  resources: Resource[];
  agent: Agent;
  polylines: Polyline[];
  onResourceClick: (resource: Resource) => void;
  onAgentMove: (position: GridPosition) => void;
  isSimulationRunning: boolean;
  dqnPathInfo: { resource: Resource | null, reward: number } | null;
  onRefreshDQNPath: () => void;
  isPlaying?: boolean;
  playbackPath?: GridPosition[];
  onPlaybackComplete?: () => void;
}

const GRID_SIZE = 20;

const ResourceIcon = ({ type }: { type: Resource['type'] }) => {
  const iconProps = { size: 14, className: "text-white drop-shadow-sm" };

  switch (type) {
    case 'book':
      return <BookOpen {...iconProps} />;
    case 'video':
      return <Play {...iconProps} />;
    case 'quiz':
      return <FileText {...iconProps} />;
    case 'assignment':
      return <PenTool {...iconProps} />;
    default:
      return <BookOpen {...iconProps} />;
  }
};

const SocialAgent: React.FC<{ isMoving: boolean }> = ({ isMoving }) => {
  return (
    <motion.div
      className="relative flex flex-col items-center justify-center -translate-y-4"
      animate={isMoving ? { 
        scale: [1, 1.1, 1],
        rotateY: 0
      } : { rotateY: 0 }}
      transition={{ duration: 0.3 }}
    >
      {/* Tooltip */}
      <div className="absolute -bottom-8 bg-[#1A1F2E] text-white text-[10px] font-medium px-2 py-0.5 rounded shadow-lg whitespace-nowrap z-50">
          You are here
          <div className="absolute -top-1 left-1/2 -translate-x-1/2 w-0 h-0 border-l-4 border-l-transparent border-r-4 border-r-transparent border-b-4 border-b-[#1A1F2E]" />
      </div>

      {/* Main Avatar Container */}
      <div className="relative w-12 h-12 rounded-full border-2 border-white shadow-xl overflow-visible p-0.5 bg-white">
        <img 
          src={avatar} 
          alt="User Profile" 
          className="w-full h-full rounded-full object-cover"
        />
        {/* Online Indicator */}
        <div className="absolute top-0 right-0 w-3 h-3 bg-green-500 border-2 border-white rounded-full shadow-sm animate-pulse" />
      </div>
    </motion.div>
  );
};

export const GridVisualization: React.FC<GridVisualizationProps> = ({
  resources,
  agent,
  polylines,
  onResourceClick,
  onAgentMove,
  isSimulationRunning,
  dqnPathInfo,
  onRefreshDQNPath,
  isPlaying = false,
  playbackPath = [],
  onPlaybackComplete
}) => {
  const [selectedResource, setSelectedResource] = useState<Resource | null>(null);
  const [hoveredResource, setHoveredResource] = useState<string | null>(null);
  const hoverTimeout = React.useRef<NodeJS.Timeout | null>(null);
  const [pathProgress, setPathProgress] = useState(0);
  const [isSearching, setIsSearching] = useState(false);
  const [searchQuery, setSearchQuery] = useState('');
  const [zoomLevel, setZoomLevel] = useState(1.5);
  const gridRef = React.useRef<HTMLDivElement>(null);

  // Auto-scroll to agent on load or movement
  React.useEffect(() => {
    if (gridRef.current && agent.position) {
      const scrollY = (agent.position.y * (1000 / GRID_SIZE) * zoomLevel) - (gridRef.current.clientHeight / 2);
      const scrollX = (agent.position.x * (1000 / GRID_SIZE) * zoomLevel) - (gridRef.current.clientWidth / 2);
      
      gridRef.current.scrollTo({
        top: scrollY,
        left: scrollX,
        behavior: 'smooth'
      });
    }
  }, [agent.position.x, agent.position.y, zoomLevel]);
  const [videoResource, setVideoResource] = useState<Resource | null>(null);
  const [chatMessages, setChatMessages] = useState<{ role: string; content: string }[]>([]);
  const [chatInput, setChatInput] = useState('');
  const [chatLoading, setChatLoading] = useState(false);
  // @ts-ignore
  const chatEndRef = React.useRef<HTMLDivElement | null>(null);

  // Tracking agent movement for animation
  const [prevPosition, setPrevPosition] = useState<GridPosition>(agent.position);
  const [showTravelArrow, setShowTravelArrow] = useState(false);

  React.useEffect(() => {
    if (agent.position.x !== prevPosition.x || agent.position.y !== prevPosition.y) {
      setShowTravelArrow(true);
      const timer = setTimeout(() => {
        setShowTravelArrow(false);
        setPrevPosition(agent.position);
      }, 1500); // Duration of arrow visibility
      return () => clearTimeout(timer);
    }
  }, [agent.position, prevPosition]);

  // Convert YouTube URL to embed URL
  const getYouTubeEmbedUrl = (url: string): string | null => {
    if (!url) return null;
    // Handle youtu.be/ID and youtube.com/watch?v=ID formats
    let videoId = '';
    if (url.includes('youtu.be/')) {
      videoId = url.split('youtu.be/')[1]?.split(/[?&#]/)[0] || '';
    } else if (url.includes('watch?v=')) {
      videoId = url.split('watch?v=')[1]?.split(/[?&#]/)[0] || '';
    } else if (url.includes('youtube.com/embed/')) {
      return url; // Already embed URL
    }
    return videoId ? `https://www.youtube.com/embed/${videoId}?autoplay=1&rel=0` : null;
  };

  const handleMouseEnter = (id: string) => {
    if (hoverTimeout.current) clearTimeout(hoverTimeout.current);
    setHoveredResource(id);
  };

  const handleMouseLeave = () => {
    hoverTimeout.current = setTimeout(() => {
      setHoveredResource(null);
    }, 200);
  };

  // Handle Playback Animation
  React.useEffect(() => {
    if (isPlaying && playbackPath.length > 1) {
      setPathProgress(0);
      const totalDuration = playbackPath.length * 800; // 800ms per segment
      const startTime = Date.now();

      const interval = setInterval(() => {
        const elapsed = Date.now() - startTime;
        const progress = Math.min(elapsed / totalDuration, 1);
        setPathProgress(progress);

        if (progress >= 1) {
          clearInterval(interval);
          if (onPlaybackComplete) onPlaybackComplete();
        }
      }, 16);

      return () => clearInterval(interval);
    }
  }, [isPlaying, playbackPath, onPlaybackComplete]);

  const handleCellClick = (x: number, y: number) => {
    const resource = resources.find(r => r.position.x === x && r.position.y === y);
    if (resource) {
      setSelectedResource(resource);
      onResourceClick(resource);
    } else {
      onAgentMove({ x, y });
    }
  };

  const renderNeuralRoad = () => {
    return polylines.filter(p => p.isActive).map(polyline => (
        <svg key={polyline.id} className="absolute inset-0 w-full h-full pointer-events-none z-10">
            <path
                d={polyline.path.map((pos, i) => 
                    `${i === 0 ? 'M' : 'L'} ${(pos.x + 0.5) * 50} ${(pos.y + 0.5) * 50}`
                ).join(' ')}
                fill="none"
                stroke={polyline.color}
                strokeWidth="12"
                strokeLinecap="round"
                strokeLinejoin="round"
                className="opacity-20 filter blur-[2px]"
            />
            <path
                d={polyline.path.map((pos, i) => 
                    `${i === 0 ? 'M' : 'L'} ${(pos.x + 0.5) * 50} ${(pos.y + 0.5) * 50}`
                ).join(' ')}
                fill="none"
                stroke={polyline.color}
                strokeWidth="4"
                strokeLinecap="round"
                strokeLinejoin="round"
                strokeDasharray="1 8"
                className="opacity-40"
            />
        </svg>
    ));
  };

  const renderPlaybackOverlay = () => {
    if (!isPlaying || playbackPath.length < 2) return null;

    // Convert grid coordinates to percentages (assuming 1fr grid)
    // Grid matches 1000x1000px container
    const CELL_SIZE = 1000 / GRID_SIZE;
    const HALF_CELL = CELL_SIZE / 2;

    const pathSegments = [];
    for (let i = 0; i < playbackPath.length - 1; i++) {
      const start = playbackPath[i];
      const end = playbackPath[i + 1];

      const x1 = start.x * CELL_SIZE + HALF_CELL;
      const y1 = start.y * CELL_SIZE + HALF_CELL;
      const x2 = end.x * CELL_SIZE + HALF_CELL;
      const y2 = end.y * CELL_SIZE + HALF_CELL;

      // Calculate control point for arc
      // Midpoint
      const mx = (x1 + x2) / 2;
      const my = (y1 + y2) / 2;
      // Vector
      const dx = x2 - x1;
      const dy = y2 - y1;
      // Perpendicular vector (scaled) - Fixed arc height
      const arcHeight = 30;
      // Normalize
      const len = Math.sqrt(dx * dx + dy * dy) || 1;
      const px = -dy / len * arcHeight;
      const py = dx / len * arcHeight;

      const cx = mx + px;
      const cy = my + py;

      const d = `M ${x1} ${y1} Q ${cx} ${cy} ${x2} ${y2}`;
      pathSegments.push({ d, id: i }); // Add index to stagger animation
    }

    return (
      <div className="absolute inset-0 z-50 pointer-events-none">
        <svg width="100%" height="100%" viewBox="0 0 1000 1000" className="overflow-visible">
          <defs>
            <filter id="glow" x="-20%" y="-20%" width="140%" height="140%">
              <feGaussianBlur stdDeviation="2" result="blur" />
              <feComposite in="SourceGraphic" in2="blur" operator="over" />
            </filter>
            <linearGradient id="pathGradient" x1="0%" y1="0%" x2="100%" y2="0%">
              <stop offset="0%" stopColor="#3b82f6" />
              <stop offset="50%" stopColor="#8b5cf6" />
              <stop offset="100%" stopColor="#d946ef" />
            </linearGradient>
            <marker id="arrowhead-swallowtail" markerWidth="6" markerHeight="6" refX="5" refY="3" orient="auto">
              <path d="M 0 0 L 6 3 L 0 6 L 2 3 z" fill="#d946ef" />
            </marker>
          </defs>
          {pathSegments.map((seg, idx) => {
            const segmentProgress = Math.max(0, Math.min(1, (pathProgress * playbackPath.length) - idx));
            const dashLen = 1000;

            if (segmentProgress <= 0) return null;

            return (
              <g key={idx}>
                {/* Background trace */}
                <path d={seg.d} fill="none" stroke="rgba(139, 92, 246, 0.1)" strokeWidth="4" strokeLinecap="round" />

                {/* Animated Glowing Line */}
                <path
                  d={seg.d}
                  fill="none"
                  stroke="url(#pathGradient)"
                  strokeWidth="3"
                  strokeLinecap="round"
                  strokeDasharray="8 6"
                  markerEnd="url(#arrowhead-swallowtail)"
                  filter="url(#glow)"
                  strokeDashoffset={dashLen * (1 - segmentProgress)}
                />
              </g>
            );
          })}
        </svg>
      </div>
    );
  };

  const renderGrid = () => {
    const cells = [];

    for (let y = 0; y < GRID_SIZE; y++) {
      for (let x = 0; x < GRID_SIZE; x++) {
        const resource = resources.find(r => r.position.x === x && r.position.y === y);
        const isAgent = agent.position.x === x && agent.position.y === y;

        // Dynamic Tooltip Positioning
        let tooltipClass = "absolute bottom-full left-1/2 -translate-x-1/2 mb-2";
        let arrowClass = "absolute left-1/2 -translate-x-1/2 -bottom-2";

        if (x < 4) {
          tooltipClass = "absolute bottom-full left-0 mb-2";
          arrowClass = "absolute left-4 -bottom-2";
        } else if (x > 15) {
          tooltipClass = "absolute bottom-full right-0 mb-2";
          arrowClass = "absolute right-4 -bottom-2";
        }

        if (y < 4) {
          if (x < 4) {
            tooltipClass = "absolute top-full left-0 mt-2";
            arrowClass = "absolute left-4 -top-2";
          } else if (x > 15) {
            tooltipClass = "absolute top-full right-0 mt-2";
            arrowClass = "absolute right-4 -top-2";
          } else {
            tooltipClass = "absolute top-full left-1/2 -translate-x-1/2 mt-2";
            arrowClass = "absolute left-1/2 -translate-x-1/2 -top-2";
          }
        }

        const showTooltip = resource && hoveredResource === resource.id;

        cells.push(
            <div
            key={`${x}-${y}`}
            className={`
              relative transition-all duration-300
              ${isAgent ? 'z-40' : 'z-30'}
              ${showTooltip ? 'z-[100]' : ''}
            `}
            style={{
              gridColumn: x + 1,
              gridRow: y + 1,
            }}
            onClick={() => handleCellClick(x, y)}
          >
            {resource && (
              <div
                className="absolute inset-0 m-auto flex items-center justify-center w-full h-full"
                onMouseEnter={() => handleMouseEnter(resource.id)}
                onMouseLeave={handleMouseLeave}
              >
                {/* Circular Reference Marker */}
                <div className={`
                  relative flex items-center justify-center
                  w-10 h-10 transform transition-all duration-300
                  ${selectedResource?.id === resource.id ? 'scale-110' : 'hover:scale-110 hover:-translate-y-1'}
                `}>
                  {/* Outer Glow */}
                  <div className={`absolute inset-0 rounded-full blur-[8px] opacity-25 ${
                    resource.visited ? 'bg-green-400' :
                    resource.difficulty <= 2 ? 'bg-purple-400' : 
                    resource.difficulty <= 4 ? 'bg-blue-400' : 
                    resource.difficulty <= 6 ? 'bg-amber-400' : 'bg-red-400'
                  }`} />
                  
                  {/* Pin Head — green when visited */}
                  <div className={`
                    w-8 h-8 rounded-full shadow-lg flex items-center justify-center border-2 border-white
                    transition-colors duration-500
                    ${resource.visited ? 'bg-emerald-500' :
                      resource.difficulty <= 2 ? 'bg-[#A855F7]' :
                      resource.difficulty <= 4 ? 'bg-[#3B82F6]' :
                      resource.difficulty <= 6 ? 'bg-[#F59E0B]' : 'bg-[#EF4444]'}
                  `}>
                    <ResourceIcon type={resource.type} />
                  </div>

                  <div
                    className={`${tooltipClass} w-72 transition-opacity duration-200 z-50 ${showTooltip ? 'opacity-100 pointer-events-auto' : 'opacity-0 pointer-events-none'}`}
                    onMouseEnter={() => handleMouseEnter(resource.id)}
                    onMouseLeave={handleMouseLeave}
                  >
                    <div className="bg-white rounded-xl shadow-2xl border border-gray-100 overflow-hidden cursor-default" onClick={(e) => e.stopPropagation()}>
                      <div className={`h-32 w-full relative ${resource.visited ? 'bg-gradient-to-tr from-emerald-500 to-teal-400' : 'bg-gradient-to-tr from-blue-600 to-indigo-500'}`}>
                        <div className="absolute inset-0 opacity-20" style={{ backgroundImage: 'radial-gradient(circle at 2px 2px, white 1px, transparent 0)', backgroundSize: '16px 16px' }}></div>
                        <div className="absolute inset-0 flex items-center justify-center">
                          <ResourceIcon type={resource.type} />
                          <div className="absolute transform scale-[5] opacity-10"><ResourceIcon type={resource.type} /></div>
                        </div>
                      </div>

                      <div className="p-4 text-left">
                        <div className="flex justify-between items-start mb-2">
                          <h4 className="font-bold text-gray-900 text-lg leading-tight line-clamp-2">{resource.title}</h4>
                          {resource.visited && (
                            <span className="bg-green-100 text-green-700 text-[10px] font-bold px-2 py-0.5 rounded uppercase tracking-wide shrink-0 ml-2">
                              Completed
                            </span>
                          )}
                        </div>

                        <div className="flex items-center gap-2 text-xs text-gray-500 mb-3">
                          <span className="capitalize">{resource.type} Lesson</span>
                          <span>•</span>
                          <span>{['Beginner', 'Intermediate', 'Advanced', 'Expert', 'Master'][resource.difficulty - 1] || 'Intermediate'}</span>
                        </div>

                        <div className="flex items-center gap-4 text-xs text-gray-500 font-medium mb-4">
                          <div className="flex items-center gap-1">
                            <span className="text-gray-400">⏱</span>
                            <span>{10 + (resource.title.length % 20)} mins</span>
                          </div>
                          <div className="flex items-center gap-1">
                            <span className="text-emerald-400">🎯</span>
                            <span>Target: {(resource.high_line ? resource.high_line * 100 : 80).toFixed(0)}%</span>
                          </div>
                          <div className="flex items-center gap-1">
                            <span className="text-amber-400">★</span>
                            <span>{resource.base_points ?? 50} pts</span>
                          </div>
                        </div>

                        <button
                          onClick={(e) => {
                            e.stopPropagation();
                            if (isAgent && resource.youtube_url) {
                              setVideoResource(resource);
                              setHoveredResource(null);
                            } else {
                              handleCellClick(x, y);
                            }
                          }}
                          className={`w-full py-2.5 ${isAgent ? 'bg-indigo-600 hover:bg-indigo-700 border-indigo-500/20 shadow-indigo-500/20' : 'bg-blue-600 hover:bg-blue-700 border-blue-500/20 shadow-blue-500/10'} text-white text-sm font-semibold rounded-xl transition-all flex items-center justify-center gap-2 shadow-lg active:scale-95 transform duration-100 border`}
                        >
                          {isAgent ? '▶ Start Lesson' : 'Travel to Lesson'}
                          <span className="text-lg leading-none">→</span>
                        </button>
                      </div>
                    </div>
                    <div className={`w-4 h-4 bg-white transform rotate-45 shadow-lg z-[-1] ${arrowClass}`}></div>
                  </div>
                </div>
              </div>
            )}

            {/* Resource cell placeholder */}
          </div>
        );
      }
    }
    return cells;
  };

  const handleChatSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!chatInput.trim() || !videoResource || chatLoading) return;

    const userMessage = chatInput;
    setChatInput('');
    setChatMessages(prev => [...prev, { role: 'user', content: userMessage }]);
    setChatLoading(true);

    try {
      const data = await nlpApi.chat(videoResource.title, userMessage, chatMessages);
      setChatMessages(prev => [...prev, { role: 'ai', content: data.answer }]);
    } catch (error) {
      console.error('Chat error:', error);
      setChatMessages(prev => [...prev, { role: 'ai', content: 'Sorry, I failed to process your request.' }]);
    } finally {
      setChatLoading(false);
    }
  };

  return (
    <div className="flex flex-col h-full bg-gray-50/30 overflow-hidden">
      <div className="flex-none px-6 py-4 bg-white/90 backdrop-blur-sm border-b border-gray-100 flex justify-between items-center z-10">
        <div>
          <h2 className="text-lg font-bold text-gray-900 flex items-center gap-2">
            <MapPin className="w-5 h-5 text-blue-600" />
            Learning Environment
          </h2>
          <p className="text-xs text-gray-500 mt-0.5">Explore resources and track your journey</p>
        </div>

        <div className="flex items-center gap-4">
          <div className="flex items-center bg-white border border-gray-100 rounded-lg shadow-sm p-1">
             <button 
              onClick={() => setZoomLevel(prev => Math.max(1, prev - 0.25))}
              className="p-1.5 hover:bg-gray-50 text-gray-500 transition-colors rounded-md"
              title="Zoom Out"
             >
                <ZoomOut size={16} />
             </button>
             <div className="w-px h-4 bg-gray-100 mx-1"></div>
             <button 
              onClick={() => setZoomLevel(1.5)}
              className="px-2 py-1 hover:bg-gray-50 text-gray-400 text-[10px] font-bold transition-colors rounded-md"
              title="Reset Zoom"
             >
                {Math.round(zoomLevel * 100)}%
             </button>
             <div className="w-px h-4 bg-gray-100 mx-1"></div>
             <button 
              onClick={() => setZoomLevel(prev => Math.min(3, prev + 0.25))}
              className="p-1.5 hover:bg-gray-50 text-gray-500 transition-colors rounded-md"
              title="Zoom In"
             >
                <ZoomIn size={16} />
             </button>
          </div>

          <button
            onClick={() => setIsSearching(true)}
            className="flex items-center gap-2 px-3 py-1.5 bg-white border border-blue-200 hover:bg-blue-50 text-blue-600 text-xs font-semibold rounded-lg transition-all shadow-sm"
          >
            <Search className="w-3.5 h-3.5" />
            <span>Search</span>
          </button>
          
          {isSimulationRunning && (
            <button
              onClick={onRefreshDQNPath}
              className="flex items-center gap-2 px-3 py-1.5 bg-white border border-red-200 hover:bg-red-50 text-red-600 text-xs font-semibold rounded-lg transition-all shadow-sm group"
            >
              <RefreshCw className="w-3.5 h-3.5 group-hover:rotate-180 transition-transform duration-500" />
              <span>Optimize Path</span>
            </button>
          )}

          <div className="flex items-center gap-3 bg-gray-50 px-3 py-1.5 rounded-lg border border-gray-100">
                  <div className="flex items-center gap-2">
                    <div className="w-5 h-5 rounded-full border border-blue-200 overflow-hidden bg-white shadow-sm">
                        <img src={avatar} alt="Avatar" className="w-full h-full object-cover" />
                    </div>
                    <span className="text-xs font-medium text-gray-600">You (Agent)</span>
                  </div>
            <div className="w-px h-3 bg-gray-200"></div>
            <div className="flex items-center gap-1.5">
              <div className="w-2.5 h-2.5 bg-[#A855F7] rounded-full"></div>
              <span className="text-xs font-medium text-gray-600">Resource</span>
            </div>
          </div>
        </div>
      </div>

      {isSimulationRunning && dqnPathInfo?.resource && (
        <div className="absolute top-20 right-6 z-20 animate-in slide-in-from-top-4 fade-in duration-300 pointer-events-none">
          <div className="bg-white/95 backdrop-blur-md px-4 py-3 rounded-xl shadow-lg border border-red-100 ring-1 ring-red-50 w-64 pointer-events-auto">
            <div className="flex items-start justify-between gap-3">
              <div>
                <span className="text-[10px] font-bold tracking-wider text-red-500 uppercase">Recommendation</span>
                <h3 className="text-sm font-semibold text-gray-900 mt-0.5 line-clamp-1">{dqnPathInfo.resource.title}</h3>
              </div>
              <div className="flex flex-col items-end">
                <span className="text-lg font-bold text-red-600 leading-none">+{dqnPathInfo.reward}</span>
              </div>
            </div>
          </div>
        </div>
      )}

      <div className="flex-1 w-full relative overflow-auto bg-gray-50/30" ref={gridRef}>
        <div className="min-w-full min-h-full flex items-center justify-center p-8">
          <div
            className="grid gap-0 bg-[#F8FAFC] rounded-3xl shadow-2xl p-4 shrink-0 relative overflow-hidden"
            style={{
              width: `${1000 * zoomLevel}px`,
              height: `${1000 * zoomLevel}px`,
              gridTemplateColumns: `repeat(${GRID_SIZE}, 1fr)`,
              gridTemplateRows: `repeat(${GRID_SIZE}, 1fr)`,
              backgroundImage: `radial-gradient(#E2E8F0 1.5px, transparent 1.5px)`,
              backgroundSize: `${24 * zoomLevel}px ${24 * zoomLevel}px`,
              transition: 'width 0.3s ease-out, height 0.3s ease-out'
            }}
          >
            {/* Map Terrain: color-coded 0°-90° quarter-circle arcs with hover tooltips */}
            <div className="absolute inset-0 pointer-events-none z-0">
              <svg className="absolute inset-0 w-full h-full" viewBox="0 0 1000 1000" preserveAspectRatio="none">
                {/* Color-coded concentric arcs — each arc belongs to a tier */}
                {(() => {
                  // Tier boundaries based on radii 3,7,11,15 grid units × 50px/unit
                  // Boundaries (midpoints between radii): 0-250, 250-450, 450-650, 650-900
                  const tierDefs = [
                    { name: 'Fundamentals', color: '#A855F7', from: 0,   to: 250 },
                    { name: 'Intermediate', color: '#3B82F6', from: 250, to: 450 },
                    { name: 'Advance',      color: '#F59E0B', from: 450, to: 650 },
                    { name: 'Mastery',      color: '#EF4444', from: 650, to: 900 },
                  ];
                  const allArcs = [100,200,300,400,500,600,700,800,900];
                  return allArcs.map((r) => {
                    const tier = tierDefs.find(t => r > t.from && r <= t.to) || tierDefs[tierDefs.length - 1];
                    return (
                      <path key={`arc-${r}`}
                        d={`M ${r} 1000 A ${r} ${r} 0 0 0 0 ${1000 - r}`}
                        fill="none"
                        stroke={tier.color}
                        strokeWidth="1.5"
                        strokeDasharray="5 7"
                        opacity="0.5"
                        style={{ pointerEvents: 'stroke', cursor: 'default' }}
                      >
                        <title>{tier.name}</title>
                      </path>
                    );
                  });
                })()}
                {/* Radial spokes every 10° */}
                {[10,20,30,40,50,60,70,80].map((deg) => {
                  const rad = (deg * Math.PI) / 180;
                  return <line key={`sp-${deg}`}
                    x1={0} y1={1000}
                    x2={950 * Math.cos(rad)}
                    y2={1000 - 950 * Math.sin(rad)}
                    stroke="#94A3B8" strokeWidth="0.8"
                    strokeDasharray="4 7" opacity="0.35"
                  />;
                })}
                {/* X-axis (bottom) and Y-axis (left) */}
                <line x1="0" y1="999" x2="980" y2="999" stroke="#94A3B8" strokeWidth="1.5"/>
                <line x1="1" y1="1000" x2="1" y2="20" stroke="#94A3B8" strokeWidth="1.5"/>
                {/* Tier boundary tick marks */}
                {[250,450,650].map(x => (
                  <line key={`tick-${x}`} x1={x} y1={992} x2={x} y2={1000} stroke="#94A3B8" strokeWidth="1.5"/>
                ))}
              </svg>
              {/* Bottom tier labels aligned to arc radii */}
              <div className="absolute bottom-1 left-0 w-full pointer-events-none">
                {[
                  { label: 'FUNDAMENTALS', pct: '12.5%', color: 'text-purple-400' },
                  { label: 'INTERMEDIATE', pct: '35%',   color: 'text-blue-400'   },
                  { label: 'ADVANCE',      pct: '55%',   color: 'text-amber-400'  },
                  { label: 'MASTERY',      pct: '77.5%', color: 'text-red-400'    },
                ].map((t) => (
                  <span key={t.label}
                    className={`absolute text-[9px] font-black uppercase tracking-[0.15em] -translate-x-1/2 ${t.color}`}
                    style={{ left: t.pct, bottom: 0 }}>
                    {t.label}
                  </span>
                ))}
              </div>
            </div>


            {renderGrid()}
            {renderPlaybackOverlay()}

            {/* Animated Student Agent Marker */}
            <motion.div
              key={`agent-at-${agent.position.x}-${agent.position.y}`}
              className="absolute pointer-events-none z-40 flex items-center justify-center"
              initial={false}
              transition={{
                left: { type: "spring", damping: 25, stiffness: 120 },
                top: { type: "spring", damping: 25, stiffness: 120 },
                scale: { duration: 0.4 },
                rotate: { duration: 0.4 }
              }}
              animate={{
                left: `${(agent.position.x + 0.5) * (100 / GRID_SIZE)}%`,
                top: `${(agent.position.y + 0.5) * (100 / GRID_SIZE)}%`,
                scale: isPlaying ? [1, 1.15, 1] : 1, // Subtle bounce effect during playback
                rotateY: 0 // Force orientation reset to clear potential mirrored state
              }}
              style={{
                width: `${100 / GRID_SIZE}%`,
                height: `${100 / GRID_SIZE}%`,
                x: '-50%',
                y: '-50%',
              }}
            >
              <SocialAgent isMoving={isPlaying} />
            </motion.div>

            {showTravelArrow && (
              <svg className="absolute inset-0 w-full h-full pointer-events-none z-30">
                <defs>
                  <linearGradient id="travelGradient" x1="0%" y1="0%" x2="100%" y2="100%">
                    <stop offset="0%" stopColor="#ef4444" stopOpacity="0.8" />
                    <stop offset="100%" stopColor="#ec4899" stopOpacity="0.8" />
                  </linearGradient>
                  <marker id="travel-arrowhead" markerWidth="12" markerHeight="8" refX="10" refY="4" orient="auto">
                    <path d="M0,0 L12,4 L0,8 Z" fill="#ef4444" />
                  </marker>
                </defs>
                <line
                  x1={`${(prevPosition.x + 0.5) * (100 / GRID_SIZE)}%`}
                  y1={`${(prevPosition.y + 0.5) * (100 / GRID_SIZE)}%`}
                  x2={`${(agent.position.x + 0.5) * (100 / GRID_SIZE)}%`}
                  y2={`${(agent.position.y + 0.5) * (100 / GRID_SIZE)}%`}
                  stroke="url(#travelGradient)"
                  strokeWidth="4"
                  strokeDasharray="12 6"
                  className="animate-pulse"
                  markerEnd="url(#travel-arrowhead)"
                  opacity="0.8"
                >
                  <animate attributeName="stroke-dashoffset" from="100" to="0" dur="2s" repeatCount="indefinite" />
                </line>
              </svg>
            )}
          </div>
        </div>
      </div>

      {selectedResource && (
        <div className="flex-none w-full bg-white/95 backdrop-blur-md p-4 border-t border-blue-100 z-10 animate-in slide-in-from-bottom-4 fade-in duration-300">
          <div className="max-w-4xl mx-auto flex items-center gap-4">
            <div className={`p-3 rounded-lg ${selectedResource.visited ? 'bg-green-100 text-green-600' : 'bg-blue-100 text-blue-600'}`}>
              <ResourceIcon type={selectedResource.type} />
            </div>
            <div className="flex-1">
              <h3 className="font-semibold text-gray-900">{selectedResource.title}</h3>
              <div className="flex items-center gap-3 mt-1 text-sm text-gray-500">
                <span className="px-2 py-0.5 bg-gray-100 rounded text-xs font-medium uppercase tracking-wide">{selectedResource.type}</span>
              </div>
            </div>
            <div className="flex flex-col items-end border-l border-gray-100 pl-4">
              <span className="text-xs text-gray-400 uppercase font-semibold">Reward</span>
              <span className="text-xl font-bold text-gray-900">+{selectedResource.reward}</span>
            </div>
          </div>
        </div>
      )}

      {isSearching && (
        <div className="fixed inset-0 bg-gray-950/40 backdrop-blur-md flex items-center justify-center z-[250] p-4 animate-in fade-in duration-300">
          <div className="bg-white/95 backdrop-blur-2xl rounded-[2rem] shadow-2xl w-full max-w-lg overflow-hidden border border-white/20 animate-in zoom-in-95 duration-300 flex flex-col max-h-[80vh]">
            <div className="px-6 py-5 border-b border-gray-100 flex items-center justify-between bg-white/50">
              <div className="flex items-center gap-3">
                <div className="w-10 h-10 rounded-xl bg-blue-600 flex items-center justify-center text-white shadow-lg shadow-blue-500/20">
                  <Search className="w-5 h-5" />
                </div>
                <div>
                  <h3 className="text-lg font-bold text-gray-900">Resource Navigator</h3>
                </div>
              </div>
              <button 
                onClick={() => setIsSearching(false)}
                className="p-2 rounded-full hover:bg-gray-100 text-gray-400 hover:text-gray-600 transition-colors"
              >
                <X className="w-5 h-5" />
              </button>
            </div>

            <div className="p-4 border-b border-gray-100 bg-gray-50/50">
              <div className="relative">
                <Search className="absolute left-4 top-1/2 -translate-y-1/2 w-4 h-4 text-gray-400" />
                <input
                  autoFocus
                  type="text"
                  placeholder="Filter resources..."
                  value={searchQuery}
                  onChange={(e) => setSearchQuery(e.target.value)}
                  className="w-full pl-11 pr-4 py-3 bg-white border border-gray-200 rounded-2xl outline-none focus:ring-2 focus:ring-blue-500/20 focus:border-blue-500 transition-all font-medium text-gray-800"
                />
              </div>
            </div>

            <div className="flex-1 overflow-y-auto p-4 space-y-2">
              {resources
                .filter(r => r.title.toLowerCase().includes(searchQuery.toLowerCase()))
                .map(resource => (
                  <button
                    key={resource.id}
                    onClick={() => {
                      onAgentMove(resource.position);
                      onResourceClick(resource);
                      setIsSearching(false);
                      setSearchQuery('');
                    }}
                    className="w-full flex items-center gap-4 p-3 rounded-2xl hover:bg-blue-50/50 border border-transparent hover:border-blue-100 transition-all group text-left"
                  >
                    <div className={`p-2.5 rounded-xl ${resource.visited ? 'bg-green-100 text-green-600' : 'bg-blue-100 text-blue-600'} group-hover:scale-110 transition-transform`}>
                      <ResourceIcon type={resource.type} />
                    </div>
                    <div className="flex-1 min-w-0">
                      <h4 className="font-semibold text-gray-900 text-sm truncate">{resource.title}</h4>
                    </div>
                    <ChevronRight className="w-4 h-4 text-gray-300 group-hover:text-blue-500 group-hover:translate-x-1 transition-all" />
                  </button>
                ))}
            </div>
          </div>
        </div>
      )}

      {videoResource && videoResource.youtube_url && (
        <div
          className="fixed inset-0 bg-gray-950/80 backdrop-blur-3xl flex items-center justify-center z-[200] p-4 sm:p-8"
          onClick={() => { setVideoResource(null); setChatMessages([]); setChatInput(''); }}
        >
          <div
            className="bg-[#0f111a]/95 backdrop-blur-md rounded-[2.5rem] shadow-[0_0_80px_-15px_rgba(79,70,229,0.25)] w-full max-w-7xl h-[90vh] overflow-hidden flex flex-col border border-white/10 animate-in zoom-in-90 fade-in duration-500 ease-out relative z-10"
            onClick={(e) => e.stopPropagation()}
          >
            <div className="bg-[#131620]/80 backdrop-blur-3xl px-8 py-5 flex items-center justify-between border-b border-white/5 flex-shrink-0 relative z-20">
              <div className="flex items-center gap-5 text-white min-w-0">
                <div className="w-12 h-12 rounded-2xl bg-gradient-to-br from-red-500 via-rose-500 to-pink-600 flex items-center justify-center flex-shrink-0 shadow-lg shadow-red-500/30 border border-white/10">
                  <Play size={20} className="text-white fill-current ml-0.5" />
                </div>
                <div className="min-w-0">
                  <h3 className="font-bold text-lg truncate text-white tracking-tight drop-shadow-sm">{videoResource.title}</h3>
                </div>
              </div>
              <button
                onClick={() => { setVideoResource(null); setChatMessages([]); setChatInput(''); }}
                className="w-12 h-12 rounded-full bg-white/5 hover:bg-red-500/20 hover:border-red-500/30 text-gray-400 hover:text-red-400 transition-all flex items-center justify-center border border-white/5 group"
              >
                <X size={22} className="group-hover:rotate-90 transition-transform duration-300" />
              </button>
            </div>

            <div className="flex flex-1 min-h-0 bg-[#090b10]">
              <div className="flex-[65] relative bg-black overflow-hidden z-10">
                <iframe
                  className="w-full h-full"
                  src={getYouTubeEmbedUrl(videoResource.youtube_url) || ''}
                  title={videoResource.title}
                  frameBorder="0"
                  allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share"
                  allowFullScreen
                />
              </div>

              <div className="flex-[35] flex flex-col bg-[#0f111a] border-l border-white/5 relative overflow-hidden z-20">
                <div className="bg-gradient-to-r from-indigo-500/10 to-purple-500/10 backdrop-blur-2xl px-6 py-5 flex items-center gap-4 border-b border-white/5 flex-shrink-0 relative z-30">
                  <div className="w-10 h-10 rounded-[14px] bg-gradient-to-tr from-indigo-500 via-purple-500 to-fuchsia-500 flex items-center justify-center shadow-lg border border-white/10 ring-2 ring-white/5">
                    <Sparkles size={18} className="text-white" />
                  </div>
                  <div>
                    <h4 className="font-extrabold text-white text-[15px] tracking-tight">Learning Assistant</h4>
                  </div>
                </div>

                <div className="flex-1 overflow-y-auto p-6 space-y-5 relative z-20">
                  {chatMessages.map((msg, i) => (
                    <div key={i} className={`flex ${msg.role === 'user' ? 'justify-end' : 'justify-start'}`}>
                      <div className={`max-w-[85%] px-5 py-3.5 rounded-2xl text-[15px] leading-relaxed relative ${msg.role === 'user'
                        ? 'bg-indigo-600 text-white rounded-br-sm'
                        : 'bg-white/5 border border-white/10 text-gray-200 rounded-bl-sm'
                        }`}>
                        {msg.content}
                      </div>
                    </div>
                  ))}
                  {chatLoading && <div className="text-gray-500 text-xs animate-pulse">Thinking...</div>}
                </div>

                <form onSubmit={handleChatSubmit} className="p-4 border-t border-white/5 relative z-30">
                  <div className="relative">
                    <input
                      type="text"
                      value={chatInput}
                      onChange={(e) => setChatInput(e.target.value)}
                      placeholder="Ask Sider AI..."
                      className="w-full bg-white/5 border border-white/10 rounded-xl px-4 py-3 text-white text-sm outline-none focus:border-indigo-500/50 transition-all"
                    />
                    <button type="submit" className="absolute right-2 top-1/2 -translate-y-1/2 p-1.5 text-indigo-400 hover:text-indigo-300">
                      <ChevronRight size={18} />
                    </button>
                  </div>
                </form>
              </div>
            </div>
          </div>
        </div>
      )}
    </div>
  );
};