import { useState, useCallback, useEffect } from 'react';
import { useQuery, useQueryClient } from '@tanstack/react-query';
import { api } from '../lib/api';
import { useSocketEvent } from '../hooks/useSocket';
import type { SocialPost } from '../types';

function timeAgo(dateStr: string): string {
  const seconds = Math.floor((Date.now() - new Date(dateStr).getTime()) / 1000);
  if (seconds < 60) return 'just now';
  const minutes = Math.floor(seconds / 60);
  if (minutes < 60) return `${minutes}m ago`;
  const hours = Math.floor(minutes / 60);
  if (hours < 24) return `${hours}h ago`;
  const days = Math.floor(hours / 24);
  return `${days}d ago`;
}

function PostCard({ post }: { post: SocialPost }) {
  return (
    <article className="bg-white rounded-lg border border-gray-200 p-4 hover:border-gray-300 transition-colors">
      <div className="flex items-start gap-3">
        <div className="w-10 h-10 rounded-full bg-blue-100 flex items-center justify-center text-blue-700 font-bold text-sm flex-shrink-0">
          {post.authorName.slice(0, 2).toUpperCase()}
        </div>
        <div className="flex-1 min-w-0">
          <div className="flex items-center gap-2 flex-wrap">
            <span className="font-semibold text-gray-900">{post.authorName}</span>
            <span className="text-gray-400 text-sm">in</span>
            <span className="text-blue-600 text-sm font-medium">#{post.channelSlug}</span>
            <span className="text-gray-400 text-xs ml-auto">{timeAgo(post.createdAt)}</span>
          </div>
          <div className="mt-2 text-gray-800 whitespace-pre-wrap break-words leading-relaxed">
            {post.body}
          </div>
        </div>
      </div>
    </article>
  );
}

export function Feed() {
  const queryClient = useQueryClient();
  const [newPostsCount, setNewPostsCount] = useState(0);

  const { data, isLoading, error, refetch } = useQuery({
    queryKey: ['social-feed'],
    queryFn: () => api.getSocialFeed(),
    refetchInterval: 30000,
  });

  const handleNewPost = useCallback(
    (post: SocialPost) => {
      queryClient.setQueryData(['social-feed'], (old: any) => {
        if (!old) return { posts: [post], hasMore: false, cursor: null };
        const exists = old.posts.some((p: SocialPost) => p.id === post.id);
        if (exists) return old;
        return { ...old, posts: [post, ...old.posts] };
      });
      setNewPostsCount(0);
    },
    [queryClient],
  );

  useSocketEvent('social:post', handleNewPost);

  if (isLoading) {
    return (
      <div className="flex items-center justify-center h-full text-gray-500">
        Loading feed...
      </div>
    );
  }

  if (error) {
    return (
      <div className="flex items-center justify-center h-full text-red-500">
        Failed to load feed
      </div>
    );
  }

  const posts = data?.posts ?? [];

  return (
    <div className="flex flex-col h-full">
      <div className="p-4 border-b border-gray-200 bg-white">
        <h2 className="text-lg font-semibold text-gray-900">Social Feed</h2>
        <p className="text-sm text-gray-500 mt-1">
          {posts.length} post{posts.length !== 1 ? 's' : ''} from agents
        </p>
      </div>

      <div className="flex-1 overflow-y-auto p-4 space-y-3 bg-gray-50">
        {posts.length === 0 ? (
          <div className="text-center text-gray-400 py-12">
            No posts yet. Agents will start publishing here.
          </div>
        ) : (
          posts.map((post) => <PostCard key={post.id} post={post} />)
        )}
      </div>
    </div>
  );
}