import React, { useEffect, useRef } from 'react';
import { Article, ReaderSettings } from '../types';
import { FileText, MousePointerClick } from 'lucide-react';

interface ReaderViewProps {
  article?: Article | null;
  settings?: ReaderSettings;
  onToggleAutoScroll?: () => void;
  onSegmentSelect?: (index: number) => void;
}

export const ReaderView: React.FC<ReaderViewProps> = ({ article, settings, onToggleAutoScroll, onSegmentSelect }) => {
  const scrollRef = useRef<HTMLDivElement>(null);

  // Auto-scroll to active segment
  useEffect(() => {
    if (!article || article.status !== 'PLAYING' || settings?.autoScroll === false) return;
    
    const activeEl = document.getElementById(`segment-${article.currentSegmentIndex}`);
    if (activeEl && scrollRef.current) {
      activeEl.scrollIntoView({ behavior: 'smooth', block: 'center' });
    }
  }, [article?.currentSegmentIndex, article?.status, settings?.autoScroll]);

  // Default settings fallback
  const s = settings || {
    isDarkMode: false,
    fontSize: 'lg',
    lineHeight: 'relaxed',
    fontFamily: 'serif',
    autoScroll: true
  };

  const getFontClass = () => {
    switch(s.fontFamily) {
      case 'sans': return 'font-sans';
      case 'mono': return 'font-mono';
      default: return 'font-serif';
    }
  };

  const getSizeClass = () => {
    switch(s.fontSize) {
      case 'sm': return 'text-sm';
      case 'base': return 'text-base';
      case 'xl': return 'text-xl';
      case '2xl': return 'text-2xl';
      default: return 'text-lg';
    }
  };

  const getLeadingClass = () => {
    switch(s.lineHeight) {
      case 'normal': return 'leading-normal';
      case 'loose': return 'leading-loose';
      default: return 'leading-relaxed';
    }
  };

  if (!article) {
    return (
      <div className="h-full flex flex-col items-center justify-center text-slate-400 dark:text-slate-600 p-12 border-2 border-dashed border-slate-200 dark:border-slate-800 rounded-2xl bg-slate-50/50 dark:bg-slate-900/50 transition-colors duration-300">
        <FileText className="w-12 h-12 mb-4 opacity-50" />
        <p className="text-lg font-medium">Select an article to read along</p>
        <p className="text-sm">The text will appear here while you listen.</p>
      </div>
    );
  }

  return (
    <div className="bg-white dark:bg-slate-900 rounded-2xl border border-slate-200 dark:border-slate-800 shadow-sm overflow-hidden h-[calc(100vh-12rem)] flex flex-col transition-colors duration-300">
      <div className="p-6 border-b border-slate-100 dark:border-slate-800 bg-white dark:bg-slate-900 sticky top-0 z-10 flex justify-between items-start">
        <div className="flex-1 pr-4">
            <h2 className="text-2xl font-bold text-slate-900 dark:text-slate-100 leading-tight">
            {article.title}
            </h2>
            <a 
            href={article.url} 
            target="_blank" 
            rel="noopener noreferrer"
            className="text-sm text-blue-600 dark:text-blue-400 hover:underline mt-2 inline-block"
            >
            {new URL(article.url).hostname}
            </a>
        </div>
        
        {/* Auto Scroll Toggle */}
        <button 
           onClick={onToggleAutoScroll}
           title={s.autoScroll ? "Disable auto-scroll" : "Enable auto-scroll"}
           className={`p-2 rounded-lg transition-all ${
             s.autoScroll 
             ? 'text-blue-600 bg-blue-50 dark:bg-blue-900/30 dark:text-blue-400' 
             : 'text-slate-400 hover:bg-slate-100 dark:hover:bg-slate-800'
           }`}
        >
            <MousePointerClick className="w-5 h-5" />
        </button>
      </div>
      
      <div 
        ref={scrollRef} 
        className={`flex-grow overflow-y-auto p-6 sm:p-8 space-y-1 custom-scrollbar bg-white dark:bg-slate-900 transition-colors duration-300 ${getFontClass()} ${getSizeClass()}`}
      >
        {article.segments.length > 0 ? (
          article.segments.map((segment, idx) => {
            const isActive = article.currentSegmentIndex === idx;
            return (
              <div 
                key={segment.id} 
                id={`segment-${idx}`}
                onClick={() => onSegmentSelect?.(idx)}
                title="Click to play from here"
                className={`
                  transition-all duration-200 whitespace-pre-wrap rounded-xl p-3 sm:p-4 -mx-2 sm:-mx-4 border-l-4 mb-2
                  ${getLeadingClass()}
                  ${isActive 
                    ? 'text-slate-900 dark:text-white bg-blue-50 dark:bg-blue-900/20 border-blue-500 shadow-sm' 
                    : 'text-slate-700 dark:text-slate-300 border-transparent hover:bg-slate-100 dark:hover:bg-slate-800/50 cursor-pointer hover:border-slate-300 dark:hover:border-slate-600'
                  }
                `}
              >
                {segment.text}
              </div>
            );
          })
        ) : (
          // Loading State skeleton
          <div className="space-y-4 animate-pulse">
             {[1,2,3,4].map(i => (
                 <div key={i} className="space-y-2">
                    <div className="h-4 bg-slate-100 dark:bg-slate-800 rounded w-full"></div>
                    <div className="h-4 bg-slate-100 dark:bg-slate-800 rounded w-full"></div>
                    <div className="h-4 bg-slate-100 dark:bg-slate-800 rounded w-3/4"></div>
                 </div>
             ))}
            <p className="text-slate-400 dark:text-slate-600 italic mt-4">Extracting article content...</p>
          </div>
        )}
      </div>
    </div>
  );
};