import React, { useState, useEffect, useRef } from 'react';
import { motion, AnimatePresence } from 'framer-motion';
import { useTranslation } from 'react-i18next';
import { Sparkles, X, Send, Lightbulb, Compass, Award, AlertCircle, Pencil, Loader2 } from 'lucide-react';

const AIHintOverlay = ({ 
  isAIActive, 
  setIsAIActive, 
  aiLoading, 
  submitAICanvasPrompt, 
  chatMessages = [], 
  setChatMessages,
  chatThreads = [],
  activeThreadId = 'default',
  setActiveThreadId,
  createNewThread,
  deleteThread,
  renameThread
}) => {
  const { t } = useTranslation();
  const [prompt, setPrompt] = useState('');
  const [loadingStepIndex, setLoadingStepIndex] = useState(0);
  const [isEditingThreadTitle, setIsEditingThreadTitle] = useState(false);
  const [editTitleVal, setEditTitleVal] = useState('');
  const messagesEndRef = useRef(null);

  const activeThread = chatThreads.find(t => t.id === activeThreadId) || chatThreads[0] || { title: '' };

  const handleStartRename = () => {
    setEditTitleVal(activeThread.title);
    setIsEditingThreadTitle(true);
  };

  const handleFinishRename = () => {
    if (editTitleVal.trim()) {
      renameThread(activeThreadId, editTitleVal.trim());
    }
    setIsEditingThreadTitle(false);
  };

  const loadingSteps = [
    "Гостримо графітові олівці...",
    "Відкриваємо чистий пергамент...",
    "Калібруємо творчий компас...",
    "Консультуємось з цифровим оракулом...",
    "Малюємо контури вузлів...",
    "Накладаємо зв'язки...",
    "Задуваємо свіже чорнило..."
  ];

  const suggestions = [
    {
      text: t('canvas.ai_suggest_details', 'Розпиши поточний крок на підзадачі'),
      icon: <Lightbulb size={14} className="text-amber-600" />,
      tag: t('canvas.ai_suggest_details_tag', 'Деталізація')
    },
    {
      text: t('canvas.ai_suggest_route', 'Запропонуй альтернативний шлях на випадок сбою'),
      icon: <Compass size={14} className="text-emerald-600" />,
      tag: t('canvas.ai_suggest_route_tag', 'Альтернатива')
    },
    {
      text: t('canvas.ai_suggest_habits', 'Створи щоденні звички для підкріплення цієї цілі'),
      icon: <Award size={14} className="text-indigo-600" />,
      tag: t('canvas.ai_suggest_habits_tag', 'Звички')
    }
  ];

  useEffect(() => {
    let interval;
    if (aiLoading) {
      setLoadingStepIndex(0);
      interval = setInterval(() => {
        setLoadingStepIndex((prev) => (prev + 1) % loadingSteps.length);
      }, 3000);
    }
    return () => clearInterval(interval);
  }, [aiLoading]);

  // Auto scroll to bottom
  useEffect(() => {
    if (isAIActive) {
      const timer = setTimeout(() => {
        messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
      }, 100);
      return () => clearTimeout(timer);
    }
  }, [chatMessages, aiLoading, isAIActive, activeThreadId]);

  const handleSubmit = async (e) => {
    if (e) e.preventDefault();
    if (!prompt.trim() || aiLoading) return;
    const promptToSend = prompt;
    setPrompt('');
    await submitAICanvasPrompt(promptToSend);
  };

  const handleKeyDown = (e) => {
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault();
      handleSubmit();
    }
  };

  const parseInlineMarkdown = (text) => {
    const parts = [];
    let remaining = text;
    const boldRegex = /\*\*([^*]+)\*\*/g;
    let match;
    let lastIndex = 0;
    
    while ((match = boldRegex.exec(text)) !== null) {
      const textBefore = text.substring(lastIndex, match.index);
      if (textBefore) parts.push(textBefore);
      parts.push(<strong key={match.index} className="font-extrabold text-primary">{match[1]}</strong>);
      lastIndex = boldRegex.lastIndex;
    }
    
    const textAfter = text.substring(lastIndex);
    if (textAfter) parts.push(textAfter);
    
    return parts.length > 0 ? parts : text;
  };

  const renderMarkdown = (text) => {
    if (!text) return null;
    return text.split('\n').map((line, idx) => {
      const cleanLine = line.trim();
      if (!cleanLine) return <div key={idx} className="h-2" />;
      
      const listMatch = cleanLine.match(/^[\*\-\u2022]\s+(.*)/);
      if (listMatch) {
        return (
          <li key={idx} className="ml-4 list-disc pl-1 text-sm text-primary/80 font-body my-1">
            {parseInlineMarkdown(listMatch[1])}
          </li>
        );
      }
      
      const numListMatch = cleanLine.match(/^\d+\.\s+(.*)/);
      if (numListMatch) {
        return (
          <li key={idx} className="ml-4 list-decimal pl-1 text-sm text-primary/80 font-body my-1">
            {parseInlineMarkdown(numListMatch[1])}
          </li>
        );
      }

      const headingMatch = cleanLine.match(/^(#{1,6})\s+(.*)/);
      if (headingMatch) {
        const level = headingMatch[1].length;
        const headingText = headingMatch[2];
        const classes = level === 1 ? "text-xl font-bold font-display mt-3 mb-1.5" :
                        level === 2 ? "text-lg font-bold font-display mt-2.5 mb-1.5" :
                                      "text-base font-bold font-display mt-2 mb-1";
        return <div key={idx} className={`${classes} text-primary`}>{parseInlineMarkdown(headingText)}</div>;
      }
      
      return (
        <p key={idx} className="text-sm text-primary/85 font-body leading-relaxed mb-1.5 break-words">
          {parseInlineMarkdown(cleanLine)}
        </p>
      );
    });
  };

  return (
    <AnimatePresence>
      {isAIActive && (
        <>
          {/* Backdrop overlay (no blur) */}
          <motion.div
            initial={{ opacity: 0 }}
            animate={{ opacity: 1 }}
            exit={{ opacity: 0 }}
            onClick={() => !aiLoading && setIsAIActive(false)}
            className="fixed inset-0 bg-primary/20 z-40 cursor-pointer"
          />

          {/* Sketchbook Parchment Drawer */}
          <motion.div
            initial={{ x: '100%', opacity: 0.9 }}
            animate={{ x: 0, opacity: 1 }}
            exit={{ x: '100%', opacity: 0.9 }}
            transition={{ type: 'spring', damping: 25, stiffness: 150 }}
            className="fixed top-0 right-0 h-full w-[460px] max-w-full bg-[#fdfbf7] border-l-4 border-primary z-50 shadow-2xl flex flex-col overflow-hidden"
          >
            {/* Spiral binding rings style visualization on the left edge */}
            <div className="absolute left-0 top-0 bottom-0 w-3 flex flex-col justify-around py-8 pointer-events-none z-10">
              {[...Array(12)].map((_, i) => (
                <div key={i} className="w-6 h-3 bg-gradient-to-r from-stone-400 to-stone-600 rounded-full border border-stone-800 -ml-3 shadow-md" />
              ))}
            </div>

            {/* Notebook Margin Line */}
            <div className="absolute left-10 top-0 bottom-0 w-[2px] bg-red-400/40 pointer-events-none" />

            {/* Notebook Paper Lines Pattern */}
            <div 
              className="absolute inset-0 opacity-[0.03] pointer-events-none" 
              style={{
                backgroundImage: 'linear-gradient(#000 1px, transparent 1px)',
                backgroundSize: '100% 28px'
              }}
            />

            {/* Content Container */}
            <div className="flex-grow flex flex-col pl-14 pr-6 py-6 overflow-hidden relative z-0">
              
              {/* Header */}
              <div className="flex items-start justify-between mb-4 border-b-2 border-primary/10 pb-4">
                <div>
                  <div className="flex items-center gap-2 mb-1">
                    <Sparkles className="text-amber-500 animate-pulse" size={20} />
                    <span className="font-accent-note text-amber-600 font-bold uppercase tracking-wider text-xs">TaskFlow AI</span>
                  </div>
                  <h2 className="font-display text-2xl text-primary leading-none">
                    {t('canvas.ai_roadmap_strategist', 'Roadmap Strategist')}
                  </h2>
                </div>
                
                <button
                  onClick={() => !aiLoading && setIsAIActive(false)}
                  disabled={aiLoading}
                  className="p-1.5 border-2 border-primary/20 hover:border-primary rounded-xl transition-all hover:scale-105 cursor-pointer disabled:opacity-50"
                >
                  <X size={18} className="text-primary/70" />
                </button>
              </div>

              {/* Thread Selector Section */}
              <div className="flex items-center justify-between gap-2 mb-3 bg-[#f5efe0]/30 border-2 border-primary/10 p-2 rounded-xl relative">
                <div className="flex-1 flex items-center gap-2 overflow-hidden">
                  {isEditingThreadTitle ? (
                    <input
                      type="text"
                      value={editTitleVal}
                      onChange={(e) => setEditTitleVal(e.target.value)}
                      onBlur={handleFinishRename}
                      onKeyDown={(e) => {
                        if (e.key === 'Enter') handleFinishRename();
                        if (e.key === 'Escape') setIsEditingThreadTitle(false);
                      }}
                      autoFocus
                      className="flex-grow bg-transparent text-sm font-bold text-primary border-b-2 border-primary outline-none py-0.5 px-1 font-display"
                    />
                  ) : (
                    <div className="flex-grow relative flex items-center overflow-hidden">
                      <select
                        value={activeThreadId}
                        onChange={(e) => setActiveThreadId(e.target.value)}
                        className="w-full bg-[#faf7f2] border-2 border-primary/30 rounded-lg py-1 pl-2 pr-6 text-xs font-bold text-primary focus:border-primary outline-none cursor-pointer appearance-none font-display"
                      >
                        {chatThreads.map(thread => (
                          <option key={thread.id} value={thread.id}>
                            {thread.title}
                          </option>
                        ))}
                      </select>
                      <span className="absolute right-2 pointer-events-none text-primary/60 text-[10px]">▼</span>
                    </div>
                  )}
                </div>

                <div className="flex items-center gap-1.5">
                  {!isEditingThreadTitle && (
                    <button
                      onClick={handleStartRename}
                      title={t('canvas.ai_rename_title', 'Перейменувати чат')}
                      className="p-1.5 border-2 border-primary/10 hover:border-primary/40 rounded-lg hover:bg-[#faf7f2] transition-all cursor-pointer flex items-center justify-center"
                    >
                      <Pencil size={12} className="text-primary/70" />
                    </button>
                  )}
                  
                  <button
                    onClick={() => {
                      const newId = createNewThread();
                      // Start renaming the new thread immediately
                      setActiveThreadId(newId);
                      setEditTitleVal(`Чат ${chatThreads.length + 1}`);
                      setIsEditingThreadTitle(true);
                    }}
                    title={t('canvas.ai_new_chat', 'Новий')}
                    className="h-[28px] border-2 border-primary/30 hover:border-primary rounded-lg bg-[#faf7f2] hover:bg-primary/5 px-2 text-[11px] font-bold text-primary transition-all cursor-pointer flex items-center gap-1 shadow-[1px_1px_0px_0px_rgba(0,0,0,0.1)] active:translate-y-[1px]"
                  >
                    <span>+ {t('canvas.ai_new_chat', 'Новий')}</span>
                  </button>

                  <button
                    onClick={() => {
                      if (window.confirm(t('canvas.ai_delete_confirm', "Ви впевнені, що хочете видалити цей чат?"))) {
                        deleteThread(activeThreadId);
                      }
                    }}
                    title={t('canvas.ai_delete_title', 'Видалити чат')}
                    disabled={chatThreads.length <= 1}
                    className="p-1.5 border-2 border-red-200 hover:border-red-400 rounded-lg hover:bg-red-50 transition-all cursor-pointer disabled:opacity-30 disabled:cursor-not-allowed flex items-center justify-center"
                  >
                    <X size={12} className="text-red-600" />
                  </button>
                </div>
              </div>

              {/* Chat Message Area */}
              <div className="flex-1 overflow-y-auto pr-2 mb-4 space-y-4 scrollbar-hide">
                {chatMessages.map((msg) => (
                  <div 
                    key={msg.id} 
                    className={`flex flex-col ${msg.sender === 'user' ? 'items-end' : 'items-start'}`}
                  >
                    <div 
                      className={`max-w-[90%] p-3.5 rounded-2xl shadow-[2px_2px_0px_0px_rgba(0,0,0,0.15)] border-2 ${
                        msg.sender === 'user'
                          ? 'bg-[#eef5fc] border-blue-500/30 text-primary rounded-tr-none rotate-[0.5deg]'
                          : msg.isError
                          ? 'bg-red-50 border-red-500/30 text-red-700 rounded-tl-none rotate-[-0.5deg]'
                          : 'bg-[#faf7f2] border-primary/20 text-primary rounded-tl-none rotate-[-0.5deg]'
                      }`}
                    >
                      {msg.sender === 'user' ? (
                        <p className="text-sm font-body leading-relaxed whitespace-pre-wrap">{msg.text}</p>
                      ) : (
                        <div className="space-y-1">
                          {renderMarkdown(msg.text)}
                        </div>
                      )}
                    </div>
                    
                    {/* Timestamp */}
                    <span className="text-[9px] font-extrabold text-primary/40 uppercase tracking-widest mt-1.5 px-2">
                      {msg.sender === 'user' ? 'Ви' : 'Стратег'}
                    </span>
                  </div>
                ))}

                {/* Loading state showing pencil sketching & steps */}
                {aiLoading && (
                  <div className="flex flex-col items-start animate-pulse">
                    <div className="max-w-[90%] p-4 bg-[#faf7f2] border-2 border-primary/20 rounded-2xl rounded-tl-none shadow-[2px_2px_0px_0px_rgba(0,0,0,0.15)] flex flex-col gap-3">
                      <div className="flex items-center gap-3">
                        {/* Pencil writing micro-animation */}
                        <motion.div
                          animate={{
                            x: [0, 8, -8, 6, 0],
                            y: [0, -5, 8, -4, 0],
                            rotate: [0, 15, -15, 10, 0]
                          }}
                          transition={{
                            duration: 2,
                            repeat: Infinity,
                            ease: "easeInOut"
                          }}
                          className="w-8 h-8 rounded-lg bg-[#faf7f2] border border-primary flex items-center justify-center shadow-sm"
                        >
                          <Pencil className="text-amber-500" size={16} />
                        </motion.div>
                        
                        <div className="flex flex-col">
                          <span className="text-xs font-bold text-primary">Стратег планує...</span>
                          <span className="text-[10px] font-extrabold text-primary/40 uppercase tracking-wider">Генерація графів</span>
                        </div>
                      </div>

                      <div className="flex items-center gap-2 bg-[#f4ebd0]/30 border border-primary/10 px-3 py-2 rounded-xl">
                        <Loader2 className="animate-spin text-amber-600" size={14} />
                        <span className="text-xs font-body italic text-primary/75">{loadingSteps[loadingStepIndex]}</span>
                      </div>
                    </div>
                  </div>
                )}
                <div ref={messagesEndRef} />
              </div>

              {/* Suggestions chips (only visible if not loading) */}
              {!aiLoading && chatMessages.length === 1 && (
                <div className="flex flex-col gap-2 mb-4 bg-primary/5 p-3 rounded-2xl border-2 border-dashed border-primary/10">
                  <span className="text-[10px] font-extrabold uppercase text-primary/60 tracking-wider flex items-center gap-1.5">
                    <Sparkles size={12} className="text-amber-500" />
                    <span>Підказки для старту</span>
                  </span>
                  <div className="flex flex-wrap gap-2">
                    {suggestions.map((sug, idx) => (
                      <button
                        key={idx}
                        onClick={() => setPrompt(sug.text)}
                        className="flex items-center gap-1.5 px-3 py-1.5 bg-[#faf7f2] hover:bg-[#faf7f2]/80 border border-primary/20 hover:border-primary rounded-xl text-xs font-bold text-primary transition-all cursor-pointer shadow-[1px_1px_0px_0px_rgba(0,0,0,0.1)] hover:scale-[1.02]"
                      >
                        {sug.icon}
                        <span>{sug.tag}</span>
                      </button>
                    ))}
                  </div>
                </div>
              )}

              {/* Chat Input Form */}
              <form onSubmit={handleSubmit} className="mt-auto">
                <div className="relative border-2 border-primary rounded-2xl bg-[#faf7f2] shadow-[3px_3px_0px_0px_var(--color-primary)] flex items-center p-1 group focus-within:shadow-[4px_4px_0px_0px_var(--color-primary)] transition-all">
                  <textarea
                    rows={1}
                    value={prompt}
                    onChange={(e) => setPrompt(e.target.value)}
                    onKeyDown={handleKeyDown}
                    disabled={aiLoading}
                    placeholder={t('canvas.ask_ai_placeholder', 'Спроси стратега...')}
                    className="flex-grow pl-3 pr-12 py-2 bg-transparent text-sm text-primary font-body outline-none resize-none max-h-24 scrollbar-hide placeholder:text-primary/40 placeholder:font-bold disabled:opacity-50"
                  />
                  
                  <button
                    type="submit"
                    disabled={!prompt.trim() || aiLoading}
                    className="absolute right-2 top-1/2 -translate-y-1/2 p-2 bg-primary text-white rounded-xl hover:scale-105 active:scale-95 disabled:scale-100 disabled:opacity-35 disabled:cursor-not-allowed transition-all cursor-pointer flex items-center justify-center"
                  >
                    <Send size={14} />
                  </button>
                </div>
              </form>

            </div>
          </motion.div>
        </>
      )}
    </AnimatePresence>
  );
};

export default AIHintOverlay;