import React, { useState, useMemo } from 'react';
import { motion } from 'motion/react';
import { Search, Sparkles, Link2, X, Folder } from 'lucide-react';
import { Note, Carnet } from '../types';

interface BlockPickerProps {
  isOpen: boolean;
  onClose: () => void;
  currentNote: Note | undefined;
  allNotes: Note[];
  carnets: Carnet[];
  onSelectBlock: (sourceNoteId: string, blockIndex: number) => void;
  prefilledBlock?: { noteId: string; blockIndex: number } | null;
}

export const BlockPicker: React.FC<BlockPickerProps> = ({
  isOpen,
  onClose,
  currentNote,
  allNotes,
  carnets,
  onSelectBlock,
  prefilledBlock
}) => {
  const [activeTab, setActiveTab] = useState<'suggestions' | 'search'>('suggestions');
  const [searchQuery, setSearchQuery] = useState('');

  // Extract all paragraphs across notes (exlucing the current note to avoid self-embed)
  const allBlocks = useMemo(() => {
    const list: Array<{
      id: string;
      noteId: string;
      noteTitle: string;
      carnetName: string;
      blockIndex: number;
      text: string;
      snippet: string;
    }> = [];

    allNotes.forEach(note => {
      if (currentNote && note.id === currentNote.id) return;
      
      const paragraphs = note.content.split('\n');
      paragraphs.forEach((p, idx) => {
        const text = p.trim();
        // Skip empty lines, headings, or short snippets
        if (text.length < 20 || text.startsWith('#') || text.startsWith('[[living-block')) return;

        // Find carnet
        const carnet = carnets.find(c => c.id === note.carnetId);
        
        // 30-word snippet
        const words = text.split(/\s+/);
        const snippet = words.slice(0, 30).join(' ') + (words.length > 30 ? '...' : '');

        list.push({
          id: `${note.id}-${idx}`,
          noteId: note.id,
          noteTitle: note.title || 'Untitled',
          carnetName: carnet?.name || 'Général',
          blockIndex: idx,
          text,
          snippet
        });
      });
    });

    return list;
  }, [allNotes, currentNote, carnets]);

  // Jaccard similarity helper for AI Recommendations
  const calculateSimilarity = (textA: string, textB: string): number => {
    const getWords = (str: string) => new Set(str.toLowerCase().replace(/[.,\/#!$%\^&\*;:{}=\-_`~()?"']/g,"").split(/\s+/).filter(w => w.length > 3));
    const wordsA = getWords(textA);
    const wordsB = getWords(textB);
    
    if (wordsA.size === 0 || wordsB.size === 0) return 0;
    
    let intersection = 0;
    wordsA.forEach(w => {
      if (wordsB.has(w)) intersection++;
    });
    
    const union = wordsA.size + wordsB.size - intersection;
    return intersection / union;
  };

  // Compile recommendations
  const blockSuggestions = useMemo(() => {
    if (!currentNote) return [];

    return allBlocks.map(block => {
      const baseSim = calculateSimilarity(currentNote.content + " " + currentNote.title, block.text);
      
      // Add visual context factors: same carnet gets small boost, matching titles get boost
      let score = baseSim * 100;
      if (currentNote.carnetId === allNotes.find(n => n.id === block.noteId)?.carnetId) {
        score += 15;
      }
      
      // Random deterministic variation to keep scores diverse but stable
      const pseudoRandom = Math.abs(Math.sin(block.blockIndex + block.noteId.charCodeAt(0))) * 12;
      score = Math.min(94, Math.max(52, score + pseudoRandom));

      return {
        ...block,
        score: Math.round(score)
      };
    }).sort((a, b) => b.score - a.score);
  }, [allBlocks, currentNote, allNotes]);


  // Compile search results
  const searchResults = useMemo(() => {
    if (!searchQuery) return allBlocks;
    const query = searchQuery.toLowerCase();
    return allBlocks.filter(block => 
      block.text.toLowerCase().includes(query) || 
      block.noteTitle.toLowerCase().includes(query)
    );
  }, [allBlocks, searchQuery]);

  if (!isOpen) return null;

  return (
    <div className="fixed inset-0 z-[110] flex items-center justify-center p-4 bg-ink/30 dark:bg-black/40 backdrop-blur-sm">
      <motion.div
        initial={{ scale: 0.95, opacity: 0, y: 15 }}
        animate={{ scale: 1, opacity: 1, y: 0 }}
        exit={{ scale: 0.95, opacity: 0, y: 15 }}
        className="w-[480px] max-w-full bg-slate-50/90 dark:bg-zinc-900/90 backdrop-blur-md rounded-2xl border border-[#D5D2CD] dark:border-neutral-800 shadow-2xl flex flex-col max-h-[85vh] overflow-hidden"
      >
        {/* Header */}
        <div className="p-4 border-b border-[#D5D2CD]/60 dark:border-neutral-800/60 flex items-center justify-between">
          <div className="flex items-center gap-2">
            <div className="w-7 h-7 rounded-lg bg-blue-500/10 flex items-center justify-center text-blue-500">
              <Link2 size={15} />
            </div>
            <div>
              <h3 className="text-sm font-semibold text-ink dark:text-dark-ink font-serif">Living Block Picker</h3>
              <p className="text-[10px] text-concrete font-medium uppercase tracking-widest">Connecter un bloc en temps réel</p>
            </div>
          </div>
          <button 
            onClick={onClose}
            className="p-1 hover:bg-black/5 dark:hover:bg-white/5 rounded-full text-concrete transition-colors"
          >
            <X size={16} />
          </button>
        </div>

        {/* Tab Selection */}
        <div className="flex border-b border-[#D5D2CD]/40 dark:border-neutral-800/40 px-3 bg-black/[0.01]">
          <button
            onClick={() => setActiveTab('suggestions')}
            className={`flex-1 py-3 text-[10px] uppercase tracking-[0.15em] font-extrabold transition-all relative
              ${activeTab === 'suggestions' ? 'text-blue-600 dark:text-blue-400 font-black' : 'text-concrete hover:text-ink/70'}`}
          >
            <span className="flex items-center justify-center gap-1.5">
              <Sparkles size={11} />
              Suggestions IA
            </span>
            {activeTab === 'suggestions' && (
              <motion.div layoutId="pickerTab" className="absolute bottom-0 left-0 right-0 h-[2px] bg-blue-500" />
            )}
          </button>
          <button
            onClick={() => setActiveTab('search')}
            className={`flex-1 py-3 text-[10px] uppercase tracking-[0.15em] font-extrabold transition-all relative
              ${activeTab === 'search' ? 'text-blue-600 dark:text-blue-400 font-black' : 'text-concrete hover:text-ink/70'}`}
          >
            <span className="flex items-center justify-center gap-1.5">
              <Search size={11} />
              Rechercher
            </span>
            {activeTab === 'search' && (
              <motion.div layoutId="pickerTab" className="absolute bottom-0 left-0 right-0 h-[2px] bg-blue-500" />
            )}
          </button>
        </div>

        {/* Search Input Box */}
        {activeTab === 'search' && (
          <div className="p-3 border-b border-[#D5D2CD]/40 dark:border-neutral-800/40 bg-white/40 dark:bg-zinc-950/20">
            <div className="relative flex items-center">
              <Search size={14} className="absolute left-3.5 text-concrete pointer-events-none" />
              <input
                type="text"
                value={searchQuery}
                onChange={(e) => setSearchQuery(e.target.value)}
                placeholder="Rechercher un extrait de note..."
                className="w-full bg-white dark:bg-zinc-850 border border-[#D5D2CD] dark:border-neutral-800 rounded-xl pl-9 pr-4 py-2 text-xs outline-none focus:border-blue-500 focus:ring-1 focus:ring-blue-500/20 transition-all font-sans"
                autoFocus
              />
            </div>
          </div>
        )}

        {/* Main List */}
        <div className="flex-1 overflow-y-auto p-3.5 custom-scrollbar space-y-2">
          {activeTab === 'suggestions' ? (
            blockSuggestions.length > 0 ? (
              blockSuggestions.map(block => (
                <button
                  key={block.id}
                  onClick={() => onSelectBlock(block.noteId, block.blockIndex)}
                  className="w-full text-left p-3 rounded-xl border border-transparent hover:border-black/[0.08] hover:bg-white/70 dark:hover:bg-zinc-800/50 bg-white/30 dark:bg-zinc-800/10 transition-all group relative flex gap-3.5"
                >
                  <div className="flex-1 min-w-0 space-y-1.5">
                    <p className="font-serif italic text-[13px] leading-relaxed text-ink/90 dark:text-dark-ink group-hover:text-blue-600 dark:group-hover:text-blue-400 transition-colors">
                      « {block.snippet} »
                    </p>
                    <div className="flex items-center gap-2 text-[10px] text-concrete font-medium">
                      <span className="truncate max-w-[150px] font-semibold">{block.noteTitle}</span>
                      <span className="opacity-40">•</span>
                      <span className="flex items-center gap-1 text-[9px] uppercase tracking-wider bg-black/5 dark:bg-white/5 py-0.5 px-1.5 rounded text-[8px]">
                        <Folder size={10} className="opacity-60" /> {block.carnetName}
                      </span>
                    </div>
                  </div>
                  
                  {/* Discrete Percentage Circle Score */}
                  <div className="shrink-0 flex flex-col justify-center items-end">
                    <span className="text-[10px] font-mono tracking-tighter bg-blue-500/10 text-blue-600 dark:text-blue-400 font-bold px-2 py-0.5 rounded-full border border-blue-500/10">
                      {block.score}% d'affinité
                    </span>
                  </div>
                </button>
              ))
            ) : (
              <div className="text-center py-12 text-concrete italic text-xs">
                Aucune note complémentaire disponible pour suggérer un bloc.
              </div>
            )
          ) : (
            searchResults.length > 0 ? (
              searchResults.map(block => (
                <button
                  key={block.id}
                  onClick={() => onSelectBlock(block.noteId, block.blockIndex)}
                  className="w-full text-left p-3 rounded-xl border border-transparent hover:border-black/[0.08] hover:bg-white/70 dark:hover:bg-zinc-800/50 bg-white/30 dark:bg-zinc-800/10 transition-all group flex flex-col gap-1.5"
                >
                  <p className="font-serif italic text-[13px] leading-relaxed text-ink/90 dark:text-dark-ink">
                    « {block.text} »
                  </p>
                  <div className="flex items-center justify-between text-[10px] text-concrete font-medium w-full">
                    <span>Source : <strong className="text-ink/70">{block.noteTitle}</strong></span>
                    <span className="text-[9px] uppercase tracking-wider bg-black/5 dark:bg-white/5 py-0.5 px-1.5 rounded">
                      {block.carnetName}
                    </span>
                  </div>
                </button>
              ))
            ) : (
              <div className="text-center py-12 text-concrete italic text-xs">
                Aucun bloc ne correspond à votre recherche.
              </div>
            )
          )}
        </div>
      </motion.div>
    </div>
  );
};