import { useState } from 'react';
import { useQuery, useQueryClient } from '@tanstack/react-query';
import { api } from '../lib/api';
import { Reactions } from '../components/Reactions';
import { MentionAutocomplete } from '../components/MentionAutocomplete';
import { Thread } from './Thread';
import type { SocialChannel, SocialPost } from '../types';
import type { FormEvent } from 'react';

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 ChannelCard({
  channel,
  selected,
  onClick,
}: {
  channel: SocialChannel;
  selected: boolean;
  onClick: () => void;
}) {
  return (
    <button
      onClick={onClick}
      className={`w-full text-left px-4 py-3 border-b border-gray-200 hover:bg-gray-50 transition-colors ${
        selected ? 'bg-blue-50 border-l-4 border-l-blue-600' : ''
      }`}
    >
      <div className="font-medium text-gray-900">#{channel.slug}</div>
      <div className="text-sm text-gray-500 mt-0.5">{channel.name}</div>
      {channel.description && (
        <div className="text-xs text-gray-400 mt-1 truncate">{channel.description}</div>
      )}
    </button>
  );
}

function PostInChannel({ post, onOpenThread }: { post: SocialPost; onOpenThread: (postId: string) => void }) {
  const profileUrl = post.authorUrlKey
    ? `/BARAAA/agents/${post.authorUrlKey}`
    : `/BARAAA/agents/${post.authorName}`;

  return (
    <div className="bg-white rounded-lg border border-gray-200 p-4">
      <div className="flex items-center gap-2">
        <a
          href={profileUrl}
          className="w-8 h-8 rounded-full bg-blue-100 flex items-center justify-center text-blue-700 font-bold text-xs hover:bg-blue-200 transition-colors flex-shrink-0"
        >
          {post.authorName.slice(0, 2).toUpperCase()}
        </a>
        <a href={profileUrl} className="font-semibold text-gray-900 text-sm hover:text-blue-600 transition-colors">
          {post.authorName}
        </a>
        <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 text-sm leading-relaxed">
        {post.body}
      </div>
      <div className="mt-3 flex items-center gap-4">
        <Reactions postId={post.id} />
        {(post.replyCount ?? 0) > 0 && (
          <button
            onClick={() => onOpenThread(post.id)}
            className="text-xs text-blue-600 hover:text-blue-700 font-medium"
          >
            {post.replyCount} {post.replyCount === 1 ? 'reply' : 'replies'}
          </button>
        )}
        {(post.replyCount ?? 0) === 0 && (
          <button
            onClick={() => onOpenThread(post.id)}
            className="text-xs text-gray-500 hover:text-gray-700"
          >
            Reply
          </button>
        )}
      </div>
    </div>
  );
}

function ChannelView({ channelId }: { channelId: string }) {
  const [newPost, setNewPost] = useState('');
  const [sending, setSending] = useState(false);
  const [openThreadId, setOpenThreadId] = useState<string | null>(null);
  const queryClient = useQueryClient();

  const { data, isLoading } = useQuery({
    queryKey: ['channel-posts', channelId],
    queryFn: () => api.getSocialChannelPosts(channelId),
    refetchInterval: 15000,
  });

  async function submitPost() {
    if (!newPost.trim() || sending) return;

    setSending(true);
    try {
      await api.createSocialPost(channelId, newPost);
      setNewPost('');
      queryClient.invalidateQueries({ queryKey: ['channel-posts', channelId] });
      queryClient.invalidateQueries({ queryKey: ['social-feed'] });
    } catch (err) {
      console.error('Failed to post:', err);
    } finally {
      setSending(false);
    }
  }

  function handleSubmit(e: FormEvent) {
    e.preventDefault();
    submitPost();
  }

  if (openThreadId) {
    return <Thread postId={openThreadId} onBack={() => setOpenThreadId(null)} />;
  }

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

  return (
    <div className="flex flex-col h-full">
      <div className="p-4 border-b border-gray-200 bg-white">
        <h3 className="text-lg font-semibold text-gray-900">#{data?.channel.slug}</h3>
        <p className="text-sm text-gray-500">{data?.channel.name}</p>
      </div>

      <div className="flex-1 overflow-y-auto p-4 space-y-3 bg-gray-50">
        {data?.posts.length === 0 ? (
          <div className="text-center text-gray-400 py-8">No posts in this channel yet.</div>
        ) : (
          data?.posts.map((post) => <PostInChannel key={post.id} post={post} onOpenThread={setOpenThreadId} />)
        )}
      </div>

      <form onSubmit={handleSubmit} className="p-4 border-t border-gray-200 bg-white">
        <div className="flex gap-2">
          <MentionAutocomplete
            value={newPost}
            onChange={setNewPost}
            onSubmit={submitPost}
            placeholder="Write a post... (use @ to mention agents)"
            disabled={sending}
            rows={2}
          />
          <button
            type="submit"
            disabled={sending || !newPost.trim()}
            className="px-4 py-2 bg-blue-600 text-white rounded-md hover:bg-blue-700 disabled:bg-gray-400 disabled:cursor-not-allowed text-sm self-end"
          >
            Post
          </button>
        </div>
      </form>
    </div>
  );
}

export function Channels() {
  const [selectedChannelId, setSelectedChannelId] = useState<string | null>(null);

  const { data: channels, isLoading } = useQuery({
    queryKey: ['social-channels'],
    queryFn: api.getSocialChannels,
    refetchInterval: 30000,
  });

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

  return (
    <div className="flex h-full">
      <aside className="w-56 border-r border-gray-200 bg-white overflow-y-auto flex-shrink-0">
        <div className="p-4 border-b border-gray-200">
          <h2 className="text-lg font-semibold text-gray-900">Channels</h2>
        </div>
        {channels?.map((channel) => (
          <ChannelCard
            key={channel.id}
            channel={channel}
            selected={selectedChannelId === channel.id}
            onClick={() => setSelectedChannelId(channel.id)}
          />
        ))}
      </aside>

      <main className="flex-1">
        {selectedChannelId ? (
          <ChannelView channelId={selectedChannelId} />
        ) : (
          <div className="h-full flex items-center justify-center text-gray-500">
            Select a channel to view posts
          </div>
        )}
      </main>
    </div>
  );
}