'use client';
import React, { useState, useEffect, useRef, useCallback } from 'react';
import Link from 'next/link';
import { useParams } from 'next/navigation';
import Header from '@/components/Header';
import Footer from '@/components/Footer';
import { createClient } from '@/lib/supabase/client';

interface ForumThread {
  id: string;
  title: string;
  body: string;
  author_name: string;
  status: string;
  reply_count: number;
  view_count: number;
  upvotes: number;
  downvotes: number;
  vote_score: number;
  created_at: string;
  forum_categories: { id: string; name: string; slug: string };
}

interface ForumReply {
  id: string;
  body: string;
  author_name: string;
  is_ai_response: boolean;
  upvotes: number;
  downvotes: number;
  vote_score: number;
  created_at: string;
}

function timeAgo(dateStr: string): string {
  const diff = Date.now() - new Date(dateStr).getTime();
  const mins = Math.floor(diff / 60000);
  if (mins < 2) return 'just now';
  if (mins < 60) return `${mins}m ago`;
  const hrs = Math.floor(mins / 60);
  if (hrs < 24) return `${hrs}h ago`;
  const days = Math.floor(hrs / 24);
  if (days < 30) return `${days}d ago`;
  return new Date(dateStr).toLocaleDateString();
}

function Avatar({ name, isAI }: { name: string; isAI: boolean }) {
  if (isAI) {
    return (
      <div className="w-9 h-9 rounded-full bg-[#1e3a5f] border border-[#3b82f6] flex items-center justify-center flex-shrink-0">
        <span className="text-[#3b82f6] text-xs font-bold">AI</span>
      </div>
    );
  }
  const initials = name.split(' ').map(n => n[0]).join('').toUpperCase().slice(0, 2);
  const colors = ['#1e3a5f', '#1a3a2a', '#3a1a1a', '#2a1a3a', '#1a2a3a'];
  const colorIdx = name.charCodeAt(0) % colors.length;
  return (
    <div
      className="w-9 h-9 rounded-full flex items-center justify-center flex-shrink-0 text-white text-xs font-bold"
      style={{ backgroundColor: colors[colorIdx] }}
    >
      {initials || '?'}
    </div>
  );
}

interface VoteButtonsProps {
  targetType: 'thread' | 'reply';
  targetId: string;
  upvotes: number;
  downvotes: number;
  voteScore: number;
  isAI?: boolean;
  isAuthenticated: boolean;
}

function VoteButtons({ targetType, targetId, upvotes, downvotes, voteScore, isAI, isAuthenticated }: VoteButtonsProps) {
  const [currentVote, setCurrentVote] = useState<1 | -1 | null>(null);
  const [counts, setCounts] = useState({ upvotes, downvotes, vote_score: voteScore });
  const [loading, setLoading] = useState(false);
  const [fetched, setFetched] = useState(false);

  useEffect(() => {
    if (!isAuthenticated || fetched) return;
    fetch(`/api/forum/votes?target_type=${targetType}&target_id=${targetId}`)
      .then(r => r.json())
      .then(d => {
        setCurrentVote(d.vote ?? null);
        setFetched(true);
      })
      .catch(() => setFetched(true));
  }, [isAuthenticated, targetType, targetId, fetched]);

  const handleVote = async (value: 1 | -1) => {
    if (!isAuthenticated || loading || isAI) return;
    setLoading(true);
    try {
      const res = await fetch('/api/forum/votes', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ target_type: targetType, target_id: targetId, vote_value: value }),
      });
      const data = await res.json();
      if (!data.error) {
        setCurrentVote(data.vote);
        setCounts({ upvotes: data.upvotes, downvotes: data.downvotes, vote_score: data.vote_score });
      }
    } catch {
      // silent
    } finally {
      setLoading(false);
    }
  };

  const scoreColor = counts.vote_score > 0 ? 'text-[#3b82f6]' : counts.vote_score < 0 ? 'text-red-400' : 'text-[#666]';

  return (
    <div className="flex items-center gap-1 mt-2">
      {/* Upvote */}
      <button
        onClick={() => handleVote(1)}
        disabled={loading || !isAuthenticated || !!isAI}
        title={!isAuthenticated ? 'Sign in to vote' : isAI ? 'Cannot vote on AI responses' : 'Upvote'}
        className={`flex items-center gap-1 px-2 py-1 rounded text-xs font-body font-semibold transition-colors border ${
          currentVote === 1
            ? 'bg-[#3b82f6]/20 border-[#3b82f6] text-[#3b82f6]'
            : 'bg-transparent border-[#2a2a2a] text-[#666] hover:border-[#3b82f6] hover:text-[#3b82f6]'
        } disabled:opacity-40 disabled:cursor-not-allowed`}
        aria-label="Upvote"
      >
        <svg width="12" height="12" viewBox="0 0 24 24" fill={currentVote === 1 ? 'currentColor' : 'none'} stroke="currentColor" strokeWidth="2.5" aria-hidden="true">
          <path d="M12 19V5M5 12l7-7 7 7" />
        </svg>
        <span>{counts.upvotes}</span>
      </button>

      {/* Score */}
      <span className={`text-xs font-body font-bold px-1 min-w-[1.5rem] text-center ${scoreColor}`}>
        {counts.vote_score > 0 ? `+${counts.vote_score}` : counts.vote_score}
      </span>

      {/* Downvote */}
      <button
        onClick={() => handleVote(-1)}
        disabled={loading || !isAuthenticated || !!isAI}
        title={!isAuthenticated ? 'Sign in to vote' : isAI ? 'Cannot vote on AI responses' : 'Downvote'}
        className={`flex items-center gap-1 px-2 py-1 rounded text-xs font-body font-semibold transition-colors border ${
          currentVote === -1
            ? 'bg-red-900/30 border-red-700 text-red-400' :'bg-transparent border-[#2a2a2a] text-[#666] hover:border-red-700 hover:text-red-400'
        } disabled:opacity-40 disabled:cursor-not-allowed`}
        aria-label="Downvote"
      >
        <svg width="12" height="12" viewBox="0 0 24 24" fill={currentVote === -1 ? 'currentColor' : 'none'} stroke="currentColor" strokeWidth="2.5" aria-hidden="true">
          <path d="M12 5v14M5 12l7 7 7-7" />
        </svg>
        <span>{counts.downvotes}</span>
      </button>

      {!isAuthenticated && (
        <Link href="/login" className="text-xs font-body text-[#555] hover:text-[#3b82f6] ml-1 transition-colors">
          Sign in to vote
        </Link>
      )}
    </div>
  );
}

export default function ForumThreadPage() {
  const params = useParams();
  const threadId = params?.id as string;
  const supabase = createClient();

  const [thread, setThread] = useState<ForumThread | null>(null);
  const [replies, setReplies] = useState<ForumReply[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [isAuthenticated, setIsAuthenticated] = useState(false);

  // Reply form
  const [replyBody, setReplyBody] = useState('');
  const [replyAuthor, setReplyAuthor] = useState('');
  const [submitting, setSubmitting] = useState(false);

  // AI assistant
  const [aiQuestion, setAiQuestion] = useState('');
  const [aiLoading, setAiLoading] = useState(false);
  const [aiError, setAiError] = useState<string | null>(null);

  const repliesEndRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    supabase.auth.getUser().then(({ data: { user } }) => {
      setIsAuthenticated(!!user);
    });
  }, []);

  useEffect(() => {
    if (!threadId) return;
    fetch(`/api/forum/threads/${threadId}`)
      .then(r => r.json())
      .then(d => {
        if (d.error) throw new Error(d.error);
        setThread(d.thread);
        setReplies(d.replies || []);
        setLoading(false);
      })
      .catch(e => {
        setError(e.message || 'Failed to load thread.');
        setLoading(false);
      });
  }, [threadId]);

  const handleReply = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!replyBody.trim() || !threadId) return;
    setSubmitting(true);
    try {
      const res = await fetch('/api/forum/replies', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          thread_id: threadId,
          body: replyBody,
          author_name: replyAuthor || 'Anonymous',
        }),
      });
      const data = await res.json();
      if (data.reply) {
        setReplies(prev => [...prev, data.reply]);
        setReplyBody('');
        setReplyAuthor('');
        setTimeout(() => repliesEndRef.current?.scrollIntoView({ behavior: 'smooth' }), 100);
      }
    } catch {
      // silent
    } finally {
      setSubmitting(false);
    }
  };

  const handleAiAssist = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!aiQuestion.trim() || !thread) return;
    setAiLoading(true);
    setAiError(null);
    try {
      const res = await fetch('/api/forum/ai-assist', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          thread_id: threadId,
          question: aiQuestion,
          thread_title: thread.title,
          thread_body: thread.body,
          replies: replies.slice(-5),
        }),
      });
      const data = await res.json();
      if (data.error) throw new Error(data.error);
      if (data.reply) {
        setReplies(prev => [...prev, data.reply]);
        setAiQuestion('');
        setTimeout(() => repliesEndRef.current?.scrollIntoView({ behavior: 'smooth' }), 100);
      }
    } catch (err: any) {
      setAiError(err.message || 'AI assistant unavailable. Please try again.');
    } finally {
      setAiLoading(false);
    }
  };

  if (loading) {
    return (
      <>
        <Header />
        <main className="min-h-screen bg-[#111111]">
          <div className="max-w-container mx-auto px-4 py-10 space-y-4">
            <div className="h-8 bg-[#1a1a1a] rounded animate-pulse w-2/3" />
            <div className="h-32 bg-[#1a1a1a] rounded animate-pulse" />
            <div className="h-20 bg-[#1a1a1a] rounded animate-pulse" />
          </div>
        </main>
        <Footer />
      </>
    );
  }

  if (error || !thread) {
    return (
      <>
        <Header />
        <main className="min-h-screen bg-[#111111]">
          <div className="max-w-container mx-auto px-4 py-10">
            <div className="bg-red-900/20 border border-red-800 rounded-lg p-4 text-red-400 font-body">
              {error || 'Thread not found.'}
            </div>
            <Link href="/forum" className="mt-4 inline-block text-[#3b82f6] hover:underline font-body text-sm">
              ← Back to Forum
            </Link>
          </div>
        </main>
        <Footer />
      </>
    );
  }

  const category = thread.forum_categories;

  return (
    <>
      <Header />
      <main className="min-h-screen bg-[#111111]">
        {/* Breadcrumb */}
        <div className="bg-[#1a2535] border-b border-[#2a3a50]">
          <div className="max-w-container mx-auto px-4 py-4">
            <nav className="text-sm font-body text-[#666]">
              <Link href="/forum" className="hover:text-[#3b82f6] transition-colors">Forum</Link>
              <span className="mx-2">›</span>
              {category && (
                <>
                  <Link href={`/forum/${category.slug}`} className="hover:text-[#3b82f6] transition-colors">{category.name}</Link>
                  <span className="mx-2">›</span>
                </>
              )}
              <span className="text-[#aab4c4] truncate">{thread.title}</span>
            </nav>
          </div>
        </div>

        <div className="max-w-container mx-auto px-4 py-6">
          <div className="max-w-3xl mx-auto">
            {/* Thread Title */}
            <h1 className="text-2xl font-heading font-bold text-white mb-6 leading-snug">{thread.title}</h1>

            {/* Original Post */}
            <div className="bg-[#1a1a1a] border border-[#252525] rounded-lg p-5 mb-4">
              <div className="flex items-start gap-3">
                <Avatar name={thread.author_name} isAI={false} />
                <div className="flex-1 min-w-0">
                  <div className="flex items-center gap-2 mb-2">
                    <span className="text-white font-body font-semibold text-sm">{thread.author_name}</span>
                    <span className="text-[#555] font-body text-xs">·</span>
                    <span className="text-[#555] font-body text-xs">{timeAgo(thread.created_at)}</span>
                    <span className="text-[#555] font-body text-xs">·</span>
                    <span className="text-[#555] font-body text-xs">{thread.view_count} views</span>
                  </div>
                  <p className="text-[#d0d0d0] font-body text-sm leading-relaxed whitespace-pre-wrap">{thread.body}</p>
                  <VoteButtons
                    targetType="thread"
                    targetId={thread.id}
                    upvotes={thread.upvotes ?? 0}
                    downvotes={thread.downvotes ?? 0}
                    voteScore={thread.vote_score ?? 0}
                    isAuthenticated={isAuthenticated}
                  />
                </div>
              </div>
            </div>

            {/* Replies */}
            {replies.length > 0 && (
              <div className="space-y-3 mb-6">
                {replies.map((reply, idx) => (
                  <div
                    key={reply.id}
                    className={`border rounded-lg p-5 ${
                      reply.is_ai_response
                        ? 'bg-[#0d1f35] border-[#1e3a5f]'
                        : 'bg-[#1a1a1a] border-[#252525]'
                    }`}
                  >
                    <div className="flex items-start gap-3">
                      <Avatar name={reply.author_name} isAI={reply.is_ai_response} />
                      <div className="flex-1 min-w-0">
                        <div className="flex items-center gap-2 mb-2 flex-wrap">
                          <span className="text-white font-body font-semibold text-sm">{reply.author_name}</span>
                          {reply.is_ai_response && (
                            <span className="text-xs bg-[#3b82f6]/20 text-[#3b82f6] border border-[#3b82f6]/30 px-2 py-0.5 rounded font-body font-semibold">
                              AI Assistant
                            </span>
                          )}
                          <span className="text-[#555] font-body text-xs">·</span>
                          <span className="text-[#555] font-body text-xs">#{idx + 1}</span>
                          <span className="text-[#555] font-body text-xs">·</span>
                          <span className="text-[#555] font-body text-xs">{timeAgo(reply.created_at)}</span>
                        </div>
                        <p className="text-[#d0d0d0] font-body text-sm leading-relaxed whitespace-pre-wrap">{reply.body}</p>
                        <VoteButtons
                          targetType="reply"
                          targetId={reply.id}
                          upvotes={reply.upvotes ?? 0}
                          downvotes={reply.downvotes ?? 0}
                          voteScore={reply.vote_score ?? 0}
                          isAI={reply.is_ai_response}
                          isAuthenticated={isAuthenticated}
                        />
                      </div>
                    </div>
                  </div>
                ))}
                <div ref={repliesEndRef} />
              </div>
            )}

            {/* AI Assistant Panel */}
            <div className="bg-[#0d1f35] border border-[#1e3a5f] rounded-lg p-5 mb-6">
              <div className="flex items-center gap-2 mb-3">
                <div className="w-7 h-7 rounded-full bg-[#1e3a5f] border border-[#3b82f6] flex items-center justify-center">
                  <span className="text-[#3b82f6] text-xs font-bold">AI</span>
                </div>
                <div>
                  <span className="text-white font-body font-semibold text-sm">Broadcast Beat AI Assistant</span>
                  <span className="ml-2 text-xs bg-[#3b82f6]/20 text-[#3b82f6] border border-[#3b82f6]/30 px-2 py-0.5 rounded font-body">AI — Not a human</span>
                </div>
              </div>
              <p className="text-[#7a9ab8] font-body text-xs mb-3">
                Ask the AI assistant a question related to this thread. Responses are generated by AI and should be verified for critical decisions.
              </p>
              <form onSubmit={handleAiAssist} className="flex gap-2">
                <input
                  type="text"
                  placeholder="Ask a question about this topic..."
                  value={aiQuestion}
                  onChange={e => setAiQuestion(e.target.value)}
                  disabled={aiLoading}
                  className="flex-1 bg-[#111] border border-[#2a3a50] rounded-lg px-3 py-2 text-white font-body text-sm placeholder-[#3a5a7a] focus:outline-none focus:border-[#3b82f6] disabled:opacity-50"
                />
                <button
                  type="submit"
                  disabled={aiLoading || !aiQuestion.trim()}
                  className="bg-[#3b82f6] hover:bg-[#2563eb] disabled:opacity-50 text-white font-body font-semibold text-sm px-4 py-2 rounded-lg transition-colors flex-shrink-0"
                >
                  {aiLoading ? (
                    <span className="flex items-center gap-1">
                      <svg className="animate-spin w-3 h-3" fill="none" viewBox="0 0 24 24">
                        <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4" />
                        <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z" />
                      </svg>
                      Thinking...
                    </span>
                  ) : 'Ask AI'}
                </button>
              </form>
              {aiError && (
                <p className="text-red-400 font-body text-xs mt-2">{aiError}</p>
              )}
            </div>

            {/* Reply Form */}
            {thread.status !== 'closed' && (
              <div className="bg-[#1a1a1a] border border-[#252525] rounded-lg p-5">
                <h3 className="text-white font-heading font-semibold mb-4">Post a Reply</h3>
                <form onSubmit={handleReply} className="space-y-3">
                  <input
                    type="text"
                    placeholder="Your name (optional)"
                    value={replyAuthor}
                    onChange={e => setReplyAuthor(e.target.value)}
                    className="w-full bg-[#111] border border-[#333] rounded-lg px-3 py-2 text-white font-body text-sm placeholder-[#555] focus:outline-none focus:border-[#3b82f6]"
                  />
                  <textarea
                    placeholder="Share your thoughts, experience, or answer..."
                    value={replyBody}
                    onChange={e => setReplyBody(e.target.value)}
                    required
                    rows={5}
                    className="w-full bg-[#111] border border-[#333] rounded-lg px-3 py-2 text-white font-body text-sm placeholder-[#555] focus:outline-none focus:border-[#3b82f6] resize-none"
                  />
                  <button
                    type="submit"
                    disabled={submitting || !replyBody.trim()}
                    className="bg-[#3b82f6] hover:bg-[#2563eb] disabled:opacity-50 text-white font-body font-semibold text-sm px-5 py-2 rounded-lg transition-colors"
                  >
                    {submitting ? 'Posting...' : 'Post Reply'}
                  </button>
                </form>
              </div>
            )}

            {thread.status === 'closed' && (
              <div className="bg-[#1a1a1a] border border-[#333] rounded-lg p-4 text-center text-[#666] font-body text-sm">
                This thread is closed to new replies.
              </div>
            )}
          </div>
        </div>
      </main>
      <Footer />
    </>
  );
}
