import { useEffect, useMemo, useRef, useState } from 'react';
import { formatDistanceToNowStrict } from 'date-fns';
import { Link } from 'react-router-dom';
import { nip19 } from 'nostr-tools';
import { MessageCircle, Send, Radio, Info, Globe } from 'lucide-react';

import { Avatar, AvatarFallback, AvatarImage } from '@/components/ui/avatar';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Badge } from '@/components/ui/badge';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import {
  ToggleGroup,
  ToggleGroupItem,
} from '@/components/ui/toggle-group';
import { LoginArea } from '@/components/auth/LoginArea';
import { NoteContent } from '@/components/NoteContent';

import { useCurrentUser } from '@/hooks/useCurrentUser';
import { useAuthor } from '@/hooks/useAuthor';
import { useToast } from '@/hooks/useToast';
import { useBatchTrustScores } from '@/hooks/useBatchTrustScores';
import { genUserName } from '@/lib/genUserName';
import {
  TrustFilter,
  filterByTrustLevel,
  type TrustFilterLevel,
} from '@/components/TrustFilter';
import {
  useSpotChat,
  useSendSpotChat,
  channelGeohash,
  CHAT_PRECISION_LABEL,
  type ChatPrecision,
  type SpotChatMessage,
} from '@/hooks/useSpotChat';
import { cn } from '@/lib/utils';

interface SpotChatProps {
  /** The geohash to anchor this chat to (from a spot or the map center). */
  geohash: string;
  /** Whether to show the Block/Neighborhood/City precision selector. */
  showPrecisionToggle?: boolean;
  /** Initial precision. */
  defaultPrecision?: ChatPrecision;
  className?: string;
}

/** A single chat message row, resolving the author's profile. */
function ChatMessageRow({
  message,
  isOwn,
}: {
  message: SpotChatMessage;
  isOwn: boolean;
}) {
  const author = useAuthor(message.pubkey);
  const metadata = author.data?.metadata;
  const name = metadata?.name ?? genUserName(message.pubkey);
  const npub = useMemo(() => nip19.npubEncode(message.pubkey), [message.pubkey]);

  if (message.isAction) {
    return (
      <div className="px-1 py-1 text-sm text-muted-foreground italic">
        <span aria-hidden>✳ </span>
        <Link to={`/${npub}`} className="font-medium text-foreground hover:underline not-italic">
          {name}
        </Link>{' '}
        {message.content}
      </div>
    );
  }

  return (
    <div className={cn('flex gap-2.5 py-1.5', isOwn && 'flex-row-reverse')}>
      <Link to={`/${npub}`} className="shrink-0">
        <Avatar className="h-8 w-8">
          <AvatarImage src={metadata?.picture} alt={name} />
          <AvatarFallback className="text-xs">
            {name.slice(0, 2).toUpperCase()}
          </AvatarFallback>
        </Avatar>
      </Link>
      <div className={cn('flex max-w-[78%] flex-col gap-0.5', isOwn && 'items-end')}>
        <div className={cn('flex items-baseline gap-2', isOwn && 'flex-row-reverse')}>
          <Link
            to={`/${npub}`}
            className="text-xs font-semibold hover:underline truncate max-w-[10rem]"
          >
            {name}
          </Link>
          <span className="text-[10px] text-muted-foreground shrink-0">
            {formatDistanceToNowStrict(message.createdAt * 1000, { addSuffix: true })}
          </span>
        </div>
        <div
          className={cn(
            'rounded-2xl px-3 py-2 text-sm break-words',
            isOwn
              ? 'bg-orange-500 text-white rounded-tr-sm'
              : 'bg-muted rounded-tl-sm',
          )}
        >
          <NoteContent
            event={{
              id: message.id,
              pubkey: message.pubkey,
              content: message.content,
              created_at: message.createdAt,
              kind: 24899,
              tags: [],
              sig: '',
            }}
            className="text-sm [&_a]:underline"
          />
        </div>
      </div>
    </div>
  );
}

export function SpotChat({
  geohash,
  showPrecisionToggle = false,
  defaultPrecision = 'block',
  className,
}: SpotChatProps) {
  const { user } = useCurrentUser();
  const { toast } = useToast();
  const [precision, setPrecision] = useState<ChatPrecision>(defaultPrecision);
  const [trustLevel, setTrustLevel] = useState<TrustFilterLevel>('all');
  const [draft, setDraft] = useState('');
  const scrollRef = useRef<HTMLDivElement>(null);

  const { data: rawMessages, isLoading } = useSpotChat(geohash, precision);
  const { mutateAsync: sendMessage, isPending } = useSendSpotChat();

  const channel = channelGeohash(geohash, precision);

  // Trust scores for everyone who posted in this channel.
  const authorPubkeys = useMemo(
    () => Array.from(new Set((rawMessages ?? []).map((m) => m.pubkey))),
    [rawMessages],
  );
  const { data: trustScores } = useBatchTrustScores(
    trustLevel === 'all' ? [] : authorPubkeys,
  );

  // Apply the trust filter. The user's own messages are always kept so their
  // sent messages never vanish behind the filter.
  const messages = useMemo(() => {
    if (!rawMessages) return rawMessages;
    if (trustLevel === 'all') return rawMessages;
    const filtered = filterByTrustLevel(
      rawMessages,
      trustLevel,
      (pk) => trustScores?.get(pk),
    );
    const kept = new Set(filtered.map((m) => m.id));
    return rawMessages.filter((m) => kept.has(m.id) || m.pubkey === user?.pubkey);
  }, [rawMessages, trustLevel, trustScores, user?.pubkey]);

  const hiddenCount = (rawMessages?.length ?? 0) - (messages?.length ?? 0);

  // Auto-scroll to newest message when the list grows.
  const lastCount = useRef(0);
  useEffect(() => {
    const count = messages?.length ?? 0;
    if (count !== lastCount.current) {
      lastCount.current = count;
      scrollRef.current?.scrollTo({ top: scrollRef.current.scrollHeight, behavior: 'smooth' });
    }
  }, [messages]);

  const handleSend = async (e: React.FormEvent) => {
    e.preventDefault();
    const text = draft.trim();
    if (!text) return;

    // IRC-style /who — list recent participants (easter-egg power-user command).
    if (text === '/who' || text.startsWith('/who ')) {
      const recent = new Set((rawMessages ?? []).map((m) => m.pubkey));
      toast({
        title: `${recent.size} skater${recent.size === 1 ? '' : 's'} active here`,
        description:
          recent.size > 0
            ? 'People who posted in this channel in the last 24h.'
            : 'Be the first to say something.',
      });
      setDraft('');
      return;
    }

    try {
      await sendMessage({ geohash, precision, content: text });
      setDraft('');
    } catch (err) {
      toast({
        title: 'Message failed',
        description: err instanceof Error ? err.message : 'Could not send message.',
        variant: 'destructive',
      });
    }
  };

  return (
    <Card className={cn('flex flex-col overflow-hidden', className)}>
      <CardHeader className="pb-3 border-b">
        <div className="flex items-center justify-between gap-3">
          <CardTitle className="text-lg flex items-center gap-2">
            <MessageCircle className="h-5 w-5 text-orange-500" />
            Spot Chat
            <Badge
              variant="outline"
              className="gap-1 border-amber-500/40 bg-amber-500/10 text-amber-600 dark:text-amber-400 text-[10px] font-bold uppercase tracking-wide"
              title="Anyone can read messages in this channel — it is public and unencrypted."
            >
              <Globe className="h-3 w-3" />
              Public
            </Badge>
          </CardTitle>
          <div className="flex items-center gap-2">
            <TrustFilter value={trustLevel} onChange={setTrustLevel} compact />
            <Badge variant="secondary" className="font-mono text-[10px] gap-1">
              <Radio className="h-3 w-3" />#{channel}
            </Badge>
          </div>
        </div>
        {showPrecisionToggle && (
          <div className="pt-1">
            <ToggleGroup
              type="single"
              value={precision}
              onValueChange={(v) => v && setPrecision(v as ChatPrecision)}
              className="justify-start"
              size="sm"
              variant="outline"
            >
              {(Object.keys(CHAT_PRECISION_LABEL) as ChatPrecision[]).map((p) => (
                <ToggleGroupItem key={p} value={p} className="text-xs px-3">
                  {CHAT_PRECISION_LABEL[p]}
                </ToggleGroupItem>
              ))}
            </ToggleGroup>
          </div>
        )}
      </CardHeader>

      <CardContent className="p-0 flex flex-col flex-1 min-h-0">
        <div
          ref={scrollRef}
          className="flex-1 overflow-y-auto px-4 py-3 space-y-0.5 min-h-[280px] max-h-[440px]"
        >
          {isLoading && (
            <div className="flex h-full items-center justify-center text-sm text-muted-foreground">
              Loading chat…
            </div>
          )}
          {!isLoading && (!messages || messages.length === 0) && (
            <div className="flex h-full flex-col items-center justify-center text-center gap-2 py-8">
              <MessageCircle className="h-8 w-8 text-muted-foreground/40" />
              {hiddenCount > 0 ? (
                <p className="text-sm text-muted-foreground max-w-[16rem]">
                  {hiddenCount} message{hiddenCount === 1 ? '' : 's'} hidden by your trust filter.
                  Lower the filter to see more.
                </p>
              ) : (
                <p className="text-sm text-muted-foreground max-w-[16rem]">
                  No messages yet in this local channel. Say hi — "anyone skating tonight?"
                </p>
              )}
            </div>
          )}
          {messages?.map((m) => (
            <ChatMessageRow key={m.id} message={m} isOwn={m.pubkey === user?.pubkey} />
          ))}
          {!isLoading && messages && messages.length > 0 && hiddenCount > 0 && (
            <div className="pt-2 text-center text-[11px] text-muted-foreground">
              {hiddenCount} message{hiddenCount === 1 ? '' : 's'} hidden by your trust filter
            </div>
          )}
        </div>

        <div className="border-t p-3">
          {user ? (
            <>
              <form onSubmit={handleSend} className="flex items-center gap-2">
                <Input
                  value={draft}
                  onChange={(e) => setDraft(e.target.value)}
                  placeholder="Message this spot…  (try /me or /who)"
                  maxLength={500}
                  className="flex-1"
                />
                <Button
                  type="submit"
                  size="icon"
                  disabled={isPending || !draft.trim()}
                  className="bg-orange-500 hover:bg-orange-600 shrink-0"
                >
                  <Send className="h-4 w-4" />
                </Button>
              </form>
              <p className="mt-1.5 flex items-center gap-1 text-[10px] text-muted-foreground">
                <Info className="h-3 w-3 shrink-0" />
                Anyone can read this — messages are public &amp; ephemeral. For private
                chats, use Direct Messages.
              </p>
            </>
          ) : (
            <div className="flex flex-col items-center gap-2 py-1 text-center">
              <p className="text-sm text-muted-foreground">Log in to join the local chat.</p>
              <LoginArea className="max-w-60" />
            </div>
          )}
        </div>
      </CardContent>
    </Card>
  );
}