import React, { useEffect, useRef } from 'react';
import { Article, ReaderSettings } from '../types';
import { FileText, MousePointerClick, Share2, Quote } from 'lucide-react';
import { getDisplayUrl } from '../utils/url';

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,
    readingTone: 'clean',
    pageWidth: 'standard',
    zenMode: false
  };

  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';
    }
  };

  const getToneClasses = () => {
    switch (s.readingTone) {
      case 'sepia':
        return 'bg-amber-50/60 dark:bg-amber-900/30 border border-amber-100 dark:border-amber-800';
      case 'night':
        return 'bg-slate-900 text-slate-100 border border-slate-800';
      default:
        return 'bg-white dark:bg-slate-900 border border-slate-200 dark:border-slate-800';
    }
  };

  const getWidthClass = () => {
    switch (s.pageWidth) {
      case 'cozy':
        return 'max-w-2xl mx-auto';
      case 'wide':
        return 'max-w-6xl mx-auto';
      default:
        return 'max-w-4xl mx-auto';
    }
  };

  const handleShareMoment = (text: string, index: number) => {
    const base = typeof window !== 'undefined' ? `${window.location.origin}${window.location.pathname}` : '';
    const shareUrl = `${base}?segment=${index}`;
    const payload = `"${text.trim()}"\n${shareUrl}`;
    if (navigator?.clipboard?.writeText) {
      navigator.clipboard.writeText(payload).catch(() => console.warn('Unable to copy share link'));
    }
  };

  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>
    );
  }

  const displayUrl = getDisplayUrl(article.url);

  return (
    <div className={`${getToneClasses()} ${getWidthClass()} rounded-2xl shadow-sm overflow-hidden h-[calc(100vh-12rem)] flex flex-col transition-colors duration-300`}>
      {!s.zenMode && (
        <div className="p-6 border-b border-slate-100 dark:border-slate-800 bg-transparent 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={displayUrl.href}
              target="_blank"
              rel="noopener noreferrer"
              className="text-sm text-blue-600 dark:text-blue-400 hover:underline mt-2 inline-block"
              >
              {displayUrl.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-3 custom-scrollbar transition-colors duration-300 ${getFontClass()} ${getSizeClass()} ${getLeadingClass()} ${s.zenMode ? 'pt-10' : ''}`}
      >
        {article.segments.length > 0 ? (
          article.segments.map((segment, idx) => {
            const isActive = article.currentSegmentIndex === idx;
            const isBuffering = isActive && article.status === 'PLAYING' && !segment.audioUrl;

            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
                  ${isActive
                    ? `bg-blue-50 dark:bg-blue-900/20 border-blue-500 shadow-sm ${isBuffering ? 'animate-pulse opacity-70' : 'text-slate-900 dark:text-white'}`
                    : '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'
                  }
                `}
              >
                <div className="flex justify-between items-start gap-3">
                  <p className="flex-1 whitespace-pre-wrap">{segment.text}</p>
                  <div className="flex flex-col gap-2 text-xs text-slate-500 dark:text-slate-400">
                    <button
                      onClick={(e) => { e.stopPropagation(); handleShareMoment(segment.text, idx); }}
                      className="flex items-center gap-1 px-2 py-1 rounded-full bg-slate-100 dark:bg-slate-800 hover:bg-slate-200 dark:hover:bg-slate-700 transition-colors"
                      title="Copy a shareable moment"
                    >
                      <Share2 className="w-3 h-3" /> Share
                    </button>
                    <button
                      onClick={(e) => { e.stopPropagation(); if (navigator?.clipboard?.writeText) navigator.clipboard.writeText(segment.text); }}
                      className="flex items-center gap-1 px-2 py-1 rounded-full bg-blue-50 text-blue-700 dark:bg-blue-900/40 dark:text-blue-200 hover:bg-blue-100 dark:hover:bg-blue-800 transition-colors"
                      title="Copy this quote"
                    >
                      <Quote className="w-3 h-3" /> Clip
                    </button>
                  </div>
                </div>
              </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>
  );
};