import { useEffect, useState } from 'react';
import { supabase } from '../supabaseClient';
import { ExternalLink, Search, CheckCircle, XCircle, ArrowLeft, RefreshCw, Star, Info } from 'lucide-react';

const JOURNEY_SEQUENCE = [
  217, 242, 1, 49, 347, 271, 238, 36, 128, 125, 167, 15, 11, 42, 121, 3, 424, 567, 76, 239, 20, 
  155, 150, 739, 853, 84, 704, 74, 875, 153, 33, 981, 4, 206, 21, 141, 143, 19, 138, 2, 287, 
  146, 23, 25, 226, 104, 543, 110, 100, 572, 235, 102, 199, 1448, 98, 230, 105, 124, 297, 703, 
  1046, 973, 215, 621, 355, 295, 78, 39, 40, 46, 90, 22, 79, 131, 17, 51, 208, 211, 212, 200, 
  695, 133, 286, 994, 417, 130, 207, 210, 261, 323, 684, 127, 743, 332, 1584, 778, 269, 787, 
  70, 746, 198, 213, 5, 647, 91, 322, 152, 139, 300, 416, 62, 1143, 309, 518, 494, 97, 329, 
  115, 72, 312, 10, 53, 55, 45, 134, 846, 1899, 763, 678, 57, 56, 435, 252, 253, 1851, 48, 
  54, 73, 202, 66, 50, 43, 2013, 136, 191, 338, 190, 268, 371, 7
];

interface JourneyPathProps {
  onSelectProblemForReview: (problemId: string) => void;
}

export default function JourneyPath({ onSelectProblemForReview }: JourneyPathProps) {
  const [completions, setCompletions] = useState<Set<number>>(new Set());
  const [titles, setTitles] = useState<Record<number, string>>({});
  const [loading, setLoading] = useState(true);
  const [selectedNum, setSelectedNum] = useState<number | null>(null);
  const [details, setDetails] = useState<any[]>([]);
  const [modalLoading, setModalLoading] = useState(false);
  const [toggleLoading, setToggleLoading] = useState(false);

  const fetchData = async () => {
    try {
      const { data: { session } } = await supabase.auth.getSession();
      if (!session) return;

      const headers = { 'Authorization': `Bearer ${session.access_token}` };
      
      const [progRes, titlesRes] = await Promise.all([
        fetch(`${import.meta.env.VITE_API_BASE_URL}/api/journey-progress`, { headers }),
        fetch(`${import.meta.env.VITE_API_BASE_URL}/api/journey-progress/titles`, { headers })
      ]);

      if (progRes.ok && titlesRes.ok) {
        const progData = await progRes.json();
        const titlesData = await titlesRes.json();
        setCompletions(new Set(progData));
        setTitles(titlesData);
      }
    } catch (err) {
      console.error('Error fetching journey data:', err);
    } finally {
      setLoading(false);
    }
  };

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

  const handleNodeClick = async (num: number) => {
    setSelectedNum(num);
    setDetails([]);
    setModalLoading(true);
    try {
      const { data: { session } } = await supabase.auth.getSession();
      if (!session) return;

      const res = await fetch(`${import.meta.env.VITE_API_BASE_URL}/api/reviews/problems/${num}`, {
        headers: { 'Authorization': `Bearer ${session.access_token}` }
      });
      if (res.ok) {
        const data = await res.json();
        setDetails(data);
      }
    } catch (err) {
      console.error('Error fetching problem details:', err);
    } finally {
      setModalLoading(false);
    }
  };

  const handleToggleCompletion = async (num: number) => {
    setToggleLoading(true);
    try {
      const { data: { session } } = await supabase.auth.getSession();
      if (!session) return;

      const res = await fetch(`${import.meta.env.VITE_API_BASE_URL}/api/journey-progress/toggle`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'Authorization': `Bearer ${session.access_token}`
        },
        body: JSON.stringify({ problem_number: num })
      });

      if (res.ok) {
        const updated = new Set(completions);
        if (updated.has(num)) {
          updated.delete(num);
        } else {
          updated.add(num);
        }
        setCompletions(updated);
      }
    } catch (err) {
      console.error('Error toggling progress:', err);
    } finally {
      setToggleLoading(false);
    }
  };

  // Compute stats
  const total = JOURNEY_SEQUENCE.length;
  const completedCount = JOURNEY_SEQUENCE.filter(num => completions.has(num)).length;
  const percentage = total > 0 ? Math.round((completedCount / total) * 100) : 0;

  if (loading) {
    return (
      <div className="w-full h-full flex items-center justify-center bg-[#fdf8e1] text-ink-black">
        <div className="flex flex-col items-center gap-3">
          <RefreshCw className="w-8 h-8 text-primary animate-spin" />
          <span className="font-arcade text-[10px] tracking-wide">COMPILING MAP...</span>
        </div>
      </div>
    );
  }

  // Determine active node: first node in sequence that is not completed
  const activeNode = JOURNEY_SEQUENCE.find(num => !completions.has(num)) || JOURNEY_SEQUENCE[0];

  return (
    <div className="w-full h-full bg-[#fdf8e1] p-6 overflow-y-auto custom-scrollbar flex flex-col relative">
      <div className="flex flex-col gap-4">
        {/* Header progress info */}
        <div className="flex flex-col md:flex-row items-center justify-between p-4 bg-white border-[3px] border-ink-black shadow-[4px_4px_0px_0px_rgba(30,41,59,1)] gap-4 select-none">
          <div>
            <h3 className="font-headline-md font-bold text-ink-black text-sm m-0">MAP PROGRESS STATUS</h3>
            <span className="text-[10px] font-arcade text-trash-gray font-bold uppercase mt-1 block">Leitner path completion metrics</span>
          </div>
          <div className="flex items-center gap-4">
            <span className="font-arcade text-[10px] font-bold text-ink-black">{percentage}% DONE</span>
            <div className="w-48 h-6 bg-slate-100 border-[3px] border-ink-black relative overflow-hidden">
              <div 
                className="absolute inset-y-0 left-0 bg-[#0ea5e9] border-r-[3px] border-ink-black transition-all duration-500"
                style={{ width: `${percentage}%` }}
              />
            </div>
          </div>
        </div>

        {/* Milestone path visualization */}
        <div className="bg-white border-[3px] border-ink-black shadow-[4px_4px_0px_0px_rgba(30,41,59,1)] relative p-8 mt-4 overflow-hidden min-h-[700px] flex flex-col items-center">
          {/* Timeline Center Sine Path via SVG */}
          <svg className="absolute inset-y-0 w-full h-full pointer-events-none" preserveAspectRatio="none" viewBox="0 0 100 1000">
            <path 
              d="M 50,0 Q 70,50 30,100 T 50,200 T 70,300 T 30,400 T 50,500 T 70,600 T 30,700 T 50,800 T 70,900 T 50,1000" 
              fill="none" 
              opacity="0.3" 
              stroke="#1E293B" 
              strokeDasharray="5,15" 
              strokeLinecap="round" 
              strokeWidth="6"
            />
          </svg>

          {/* Nodes Container */}
          <div className="relative z-10 flex flex-col items-center gap-10 w-full max-w-sm">
            {JOURNEY_SEQUENCE.map((num, index) => {
              const isCompleted = completions.has(num);
              const isSynced = num in titles;
              const title = titles[num] || 'Unsynced Note';
              const isActive = num === activeNode;
              
              // Sine wave displacement
              const xOffset = Math.sin(index * 0.8) * 75;

              return (
                <div
                  key={num}
                  className="relative group flex items-center justify-center"
                  style={{ transform: `translateX(${xOffset}px)` }}
                >
                  {/* Tooltip */}
                  <div className="absolute bottom-[115%] left-1/2 -translate-x-1/2 bg-paper-white text-ink-black border-[3px] border-ink-black text-[9px] font-arcade px-3 py-2 rounded-xl whitespace-nowrap shadow-[4px_4px_0px_0px_#1E293B] opacity-0 group-hover:opacity-100 transition-all duration-200 scale-90 group-hover:scale-100 pointer-events-none z-30">
                    <span className="font-bold text-primary mr-1">#{num}</span>
                    <span>{title.toUpperCase()}</span>
                    {!isSynced && <span className="ml-2 text-red-500 font-bold">(LOCKED)</span>}
                  </div>

                  {/* Circular / Rounded Square Node */}
                  <button
                    onClick={() => handleNodeClick(num)}
                    className={`w-14 h-14 border-[3px] border-ink-black flex items-center justify-center font-arcade font-bold text-xs cursor-pointer transition-all duration-200 hover:scale-110 active:scale-95 ${
                      isCompleted
                        ? 'bg-grass-green text-ink-black shadow-[3px_3px_0px_0px_#1E293B] rounded-lg'
                        : isActive
                        ? 'bg-[#ffe24c] text-ink-black shadow-[4px_4px_0px_0px_#F472B6] rounded-xl animate-bounce border-dashed'
                        : isSynced
                        ? 'bg-[#c0e8ff] text-ink-black shadow-[3px_3px_0px_0px_#1E293B] rounded-lg'
                        : 'bg-slate-200 text-trash-gray opacity-60 shadow-[1px_1px_0px_0px_#1E293B] rounded-lg'
                    }`}
                  >
                    {isCompleted ? '✓' : isActive ? '▶' : num}
                  </button>
                </div>
              );
            })}
          </div>
        </div>
      </div>

      {/* Modal Dialog (Styled as a Retro OS System Dialog) */}
      {selectedNum !== null && (
        <div className="fixed inset-0 bg-black/50 backdrop-blur-xs flex items-center justify-center z-[100] p-4 animate-fade-in">
          <div className="w-full max-w-md bg-paper-white border-[4px] border-ink-black p-0 shadow-[8px_8px_0px_0px_rgba(30,41,59,1)] relative select-none">
            {/* Title Bar */}
            <div className="bg-[#0ea5e9] border-b-[4px] border-ink-black px-4 py-2 flex justify-between items-center text-white font-bold text-sm">
              <div className="flex items-center gap-2">
                <span className="material-symbols-outlined text-sm font-bold">info</span>
                <span>Problem_Detail.sys</span>
              </div>
              <button
                onClick={() => setSelectedNum(null)}
                className="w-6 h-6 bg-highlight-pink text-white border-2 border-ink-black flex items-center justify-center hover:bg-rose-600 active:translate-y-0.5 shadow-[1px_1px_0px_0px_rgba(30,41,59,1)] active:shadow-none transition-all cursor-pointer font-bold"
              >
                &times;
              </button>
            </div>

            {/* Dialog Content */}
            <div className="p-6 bg-[#fdf8e1] space-y-4">
              <div className="pb-3 border-b-2 border-dashed border-ink-black">
                <span className="text-[8px] font-arcade font-bold text-trash-gray uppercase block">Milestone Index</span>
                <h3 className="text-xl font-bold font-headline-md text-ink-black mt-1">LeetCode Problem #{selectedNum}</h3>
              </div>

              {modalLoading ? (
                <div className="py-8 flex flex-col items-center justify-center gap-3">
                  <RefreshCw className="w-6 h-6 text-primary animate-spin" />
                  <span className="text-[8px] font-arcade font-bold text-trash-gray uppercase">FETCHING DATA...</span>
                </div>
              ) : details.length > 0 ? (
                <div className="space-y-4">
                  {details.map((prob) => (
                    <div key={prob.id} className="p-4 bg-white border-[3px] border-ink-black shadow-[3px_3px_0px_0px_rgba(30,41,59,1)] space-y-3">
                      <div className="flex justify-between items-start gap-2">
                        <div>
                          <h4 className="font-bold text-ink-black text-sm font-headline-md leading-tight m-0">{prob.name}</h4>
                          <span className="text-[8px] font-arcade text-trash-gray font-bold uppercase mt-1 block">Pattern: {prob.pattern}</span>
                        </div>
                        <span className={`text-[8px] font-arcade font-bold px-2 py-0.5 border-2 border-ink-black ${
                          prob.difficulty === 'Easy' ? 'bg-grass-green text-ink-black' :
                          prob.difficulty === 'Medium' ? 'bg-secondary-container text-ink-black' :
                          'bg-highlight-pink text-white'
                        }`}>
                          {prob.difficulty.toUpperCase()}
                        </span>
                      </div>

                      <div className="flex gap-4 text-xs font-bold text-ink-black">
                        <div>Time: <code className="bg-[#1E293B] text-[#4ADE80] font-code-mono px-1.5 py-0.5 border border-ink-black">{prob.optimal_time}</code></div>
                        <div>Space: <code className="bg-[#1E293B] text-[#4ADE80] font-code-mono px-1.5 py-0.5 border border-ink-black">{prob.optimal_space}</code></div>
                      </div>

                      <div className="flex flex-col sm:flex-row gap-2 pt-2 border-t border-slate-200">
                        <a
                          href={prob.google_doc_url}
                          target="_blank"
                          rel="noreferrer"
                          className="flex-1 flex items-center justify-center gap-1.5 py-2 border-[3px] border-ink-black bg-white hover:bg-slate-100 text-xs font-bold text-ink-black shadow-[2px_2px_0px_0px_#1E293B] active:translate-y-0.5 active:shadow-none transition-all cursor-pointer text-center"
                        >
                          <ExternalLink className="w-3.5 h-3.5" />
                          Google Doc
                        </a>
                        <button
                          onClick={() => {
                            onSelectProblemForReview(prob.id);
                            setSelectedNum(null);
                          }}
                          className="flex-1 flex items-center justify-center gap-1.5 py-2 border-[3px] border-ink-black bg-[#ffe24c] hover:bg-yellow-300 text-xs font-bold text-ink-black shadow-[2px_2px_0px_0px_#1E293B] active:translate-y-0.5 active:shadow-none transition-all cursor-pointer text-center"
                        >
                          <Star className="w-3.5 h-3.5" />
                          Review Problem
                        </button>
                      </div>
                    </div>
                  ))}
                </div>
              ) : (
                <div className="p-4 bg-white border-[3px] border-ink-black shadow-[3px_3px_0px_0px_rgba(30,41,59,1)] space-y-4">
                  <div className="flex items-start gap-3 text-xs font-bold text-ink-black leading-relaxed">
                    <Info className="w-5 h-5 text-amber-500 shrink-0 mt-0.5" />
                    <div>
                      <h4 className="font-bold text-ink-black m-0">No Local Note Synced</h4>
                      <p className="text-[10px] text-trash-gray mt-1 leading-normal font-semibold">
                        You haven't synced notes for LeetCode #{selectedNum} yet. Click "Sync Google Drive" to import your progress notes.
                      </p>
                    </div>
                  </div>

                  <div className="space-y-2 pt-2 border-t border-slate-200">
                    <span className="text-[8px] font-arcade text-trash-gray uppercase font-bold block">External Search Shortcuts:</span>
                    <a
                      href={`https://leetcode.com/problemset/?search=${selectedNum}`}
                      target="_blank"
                      rel="noreferrer"
                      className="w-full flex items-center justify-between p-2.5 bg-white border-[3px] border-ink-black text-xs font-bold text-ink-black hover:bg-slate-100 shadow-[2px_2px_0px_0px_#1E293B] active:translate-y-0.5 active:shadow-none transition-all cursor-pointer"
                    >
                      <span className="flex items-center gap-2">
                        <ExternalLink className="w-4 h-4 text-emerald-500" />
                        Search LeetCode
                      </span>
                      <ArrowLeft className="w-3.5 h-3.5 rotate-180 text-trash-gray" />
                    </a>
                    <a
                      href={`https://www.google.com/search?q=leetcode+${selectedNum}`}
                      target="_blank"
                      rel="noreferrer"
                      className="w-full flex items-center justify-between p-2.5 bg-white border-[3px] border-ink-black text-xs font-bold text-ink-black hover:bg-slate-100 shadow-[2px_2px_0px_0px_#1E293B] active:translate-y-0.5 active:shadow-none transition-all cursor-pointer"
                    >
                      <span className="flex items-center gap-2">
                        <Search className="w-4 h-4 text-primary" />
                        Search Google
                      </span>
                      <ArrowLeft className="w-3.5 h-3.5 rotate-180 text-trash-gray" />
                    </a>
                  </div>
                </div>
              )}

              {/* Completion Toggle */}
              <div className="mt-4 pt-3 border-t-2 border-dashed border-ink-black flex flex-col gap-2">
                <span className="text-[8px] font-arcade text-trash-gray font-bold uppercase block">Quick Action</span>
                
                <button
                  onClick={() => handleToggleCompletion(selectedNum)}
                  disabled={toggleLoading}
                  className={`w-full py-3 border-[3px] border-ink-black font-arcade text-[10px] font-bold tracking-wide uppercase flex items-center justify-center gap-2 cursor-pointer transition-all shadow-[3px_3px_0px_0px_#1E293B] active:translate-y-0.5 active:shadow-none disabled:opacity-50 ${
                    completions.has(selectedNum)
                      ? 'bg-red-100 text-red-600 hover:bg-red-200'
                      : 'bg-emerald-100 text-emerald-700 hover:bg-emerald-200'
                  }`}
                >
                  {completions.has(selectedNum) ? (
                    <>
                      <XCircle className="w-4.5 h-4.5" />
                      UNMARK AS COMPLETED
                    </>
                  ) : (
                    <>
                      <CheckCircle className="w-4.5 h-4.5" />
                      MARK AS COMPLETED
                    </>
                  )}
                </button>
              </div>
            </div>
          </div>
        </div>
      )}
    </div>
  );
}