import { useMemo, useState } from 'react';
import { useSeoMeta } from '@unhead/react';
import { Link } from 'react-router-dom';
import { nip19 } from 'nostr-tools';
import { PageHeader } from '@/components/PageHeader';
import { Card, CardContent } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import { Skeleton } from '@/components/ui/skeleton';
import { Avatar, AvatarFallback, AvatarImage } from '@/components/ui/avatar';
import { Tabs, TabsList, TabsTrigger, TabsContent } from '@/components/ui/tabs';
import { LoginArea } from '@/components/auth/LoginArea';
import { ZapButton } from '@/components/ZapButton';
import { useCurrentUser } from '@/hooks/useCurrentUser';
import { useNostrLogin } from '@nostrify/react/login';
import { hasNip44 as checkNip44 } from '@/lib/signerCapabilities';
import { useAuthor } from '@/hooks/useAuthor';
import { useFollowing } from '@/hooks/useFollowing';
import { useConversations } from '@/hooks/useDirectMessages';
import { useCrewmates, type Crewmate } from '@/hooks/useCrewmates';
import { useTranslation } from '@/contexts/language';
import { usePrivateContacts, usePrivateContactActions } from '@/hooks/usePrivateContacts';
import { useToast } from '@/hooks/useToast';
import { genUserName } from '@/lib/genUserName';
import {
  Users,
  MessageCircle,
  UserCheck,
  Lock,
  Star,
  StarOff,
  Search,
  X,
  Loader2,
} from 'lucide-react';
import { cn } from '@/lib/utils';

function ContactRow({
  pubkey,
  subtitle,
  isSaved,
  onToggleSave,
  saving,
}: {
  pubkey: string;
  subtitle?: React.ReactNode;
  isSaved: boolean;
  onToggleSave: () => void;
  saving: boolean;
}) {
  const { t } = useTranslation();
  const author = useAuthor(pubkey);
  const meta = author.data?.metadata;
  const name = meta?.name ?? genUserName(pubkey);
  const npub = nip19.npubEncode(pubkey);
  // Build a minimal event-like object for ZapButton (needs pubkey).
  const zapTarget = author.data?.event;

  return (
    <div className="flex items-center gap-3 rounded-xl border border-white/5 bg-black/40 p-3">
      <Link to={`/${npub}`} className="shrink-0">
        <Avatar className="h-11 w-11">
          <AvatarImage src={meta?.picture} alt={name} />
          <AvatarFallback className="bg-teal-900/40 text-teal-300 font-bold">
            {name.slice(0, 2).toUpperCase()}
          </AvatarFallback>
        </Avatar>
      </Link>
      <div className="min-w-0 flex-1">
        <Link to={`/${npub}`} className="block truncate font-bold text-white hover:text-teal-300">
          {name}
        </Link>
        {subtitle && <div className="truncate text-xs text-gray-500">{subtitle}</div>}
      </div>

      <div className="flex shrink-0 items-center gap-1">
        {zapTarget && <ZapButton target={zapTarget} className="text-xs" showCount={false} />}
        <Link to={`/messages/${npub}`} title={t('socialUi.contacts.message')}>
          <Button variant="ghost" size="icon" className="h-8 w-8 text-gray-400 hover:text-teal-400">
            <MessageCircle className="h-4 w-4" />
          </Button>
        </Link>
        <Button
          variant="ghost"
          size="icon"
          onClick={onToggleSave}
          disabled={saving}
          title={isSaved ? t('socialUi.contacts.removePrivate') : t('socialUi.contacts.savePrivate')}
          className={cn(
            'h-8 w-8',
            isSaved ? 'text-amber-400 hover:text-amber-300' : 'text-gray-500 hover:text-amber-400',
          )}
        >
          {saving ? (
            <Loader2 className="h-4 w-4 animate-spin" />
          ) : isSaved ? (
            <Star className="h-4 w-4 fill-current" />
          ) : (
            <StarOff className="h-4 w-4" />
          )}
        </Button>
      </div>
    </div>
  );
}

function EmptyTab({ icon: Icon, text }: { icon: typeof Users; text: string }) {
  return (
    <Card className="border-dashed border-white/10 bg-transparent">
      <CardContent className="flex flex-col items-center gap-3 py-12 text-center">
        <div className="flex h-14 w-14 items-center justify-center rounded-2xl bg-white/5">
          <Icon className="h-7 w-7 text-gray-600" />
        </div>
        <p className="max-w-xs text-sm text-gray-500">{text}</p>
      </CardContent>
    </Card>
  );
}

export default function ContactsPage() {
  const { t } = useTranslation();
  useSeoMeta({
    title: t('socialUi.contacts.seoTitle'),
    description: t('socialUi.contacts.seoDescription'),
  });

  const { user } = useCurrentUser();
  const { logins } = useNostrLogin();
  const { toast } = useToast();
  const [query, setQuery] = useState('');

  const { data: following, isLoading: followingLoading } = useFollowing();
  const { crewmates, isLoading: crewmatesLoading } = useCrewmates();
  const { data: inbox, isLoading: convosLoading } = useConversations();
  const { data: savedContacts } = usePrivateContacts();
  const { addContact, removeContact, isAdding, isRemoving } = usePrivateContactActions();

  const savedSet = useMemo(() => new Set(savedContacts ?? []), [savedContacts]);
  const [pendingPubkey, setPendingPubkey] = useState<string | null>(null);

  const toggleSave = async (pubkey: string) => {
    if (!checkNip44(user, logins)) {
      toast({
        title: t('socialUi.chat.encryptionUnavailable'),
        description: t('socialUi.contacts.encryptionUnavailableDesc'),
        variant: 'destructive',
      });
      return;
    }
    setPendingPubkey(pubkey);
    try {
      if (savedSet.has(pubkey)) {
        await removeContact(pubkey);
        toast({ title: t('socialUi.contacts.removed') });
      } else {
        await addContact(pubkey);
        toast({ title: t('socialUi.contacts.saved'), description: t('socialUi.contacts.savedDesc') });
      }
    } catch (err) {
      toast({
        title: t('socialUi.contacts.updateFailed'),
        description: err instanceof Error ? err.message : t('common.tryAgain'),
        variant: 'destructive',
      });
    } finally {
      setPendingPubkey(null);
    }
  };

  const q = query.trim().toLowerCase();
  const matchNpub = (pk: string) => !q || nip19.npubEncode(pk).toLowerCase().includes(q);

  if (!user) {
    return (
      <>
        <div className="container max-w-2xl px-4 py-12">
          <Card className="border-dashed">
            <CardContent className="flex flex-col items-center gap-4 py-12 text-center">
              <Users className="h-12 w-12 text-teal-400/50" />
              <div>
                <h2 className="mb-1 text-xl font-black">{t('socialUi.contacts.loginTitle')}</h2>
                <p className="max-w-sm text-sm text-muted-foreground">
                  {t('socialUi.contacts.loginDesc')}
                </p>
              </div>
              <LoginArea className="justify-center" />
            </CardContent>
          </Card>
        </div>
      </>
    );
  }

  const crewmatesFiltered = crewmates.filter((c) => matchNpub(c.pubkey));
  const followingFiltered = (following ?? []).filter(matchNpub);
  const convoPubkeys = (inbox?.conversations ?? []).map((c) => c.pubkey).filter(matchNpub);
  const savedFiltered = (savedContacts ?? []).filter(matchNpub);

  const renderList = (pubkeys: string[], subtitleFor?: (pk: string) => React.ReactNode) => (
    <div className="space-y-2">
      {pubkeys.map((pk) => (
        <ContactRow
          key={pk}
          pubkey={pk}
          subtitle={subtitleFor?.(pk)}
          isSaved={savedSet.has(pk)}
          onToggleSave={() => toggleSave(pk)}
          saving={(isAdding || isRemoving) && pendingPubkey === pk}
        />
      ))}
    </div>
  );

  const crewmateSubtitle = (c: Crewmate) =>
    c.sharedCrews.length > 0 ? (
      <span className="flex items-center gap-1">
        <Users className="h-3 w-3 text-teal-500" />
        {c.sharedCrews.slice(0, 2).join(', ')}
        {c.sharedCrews.length > 2 && ` +${c.sharedCrews.length - 2}`}
      </span>
    ) : undefined;

  return (
    <>
      <div className="container max-w-2xl px-4 py-6">
        {/* Header */}
        <PageHeader
          title={t('socialUi.contacts.title')}
          icon={Users}
          accent="#2dd4bf"
          subtitle={t('socialUi.contacts.subtitle')}
        />

        {/* Search */}
        <div className="relative mb-4">
          <Search className="pointer-events-none absolute left-3 top-1/2 h-4 w-4 -translate-y-1/2 text-gray-500" />
          <input
            type="text"
            value={query}
            onChange={(e) => setQuery(e.target.value)}
            placeholder={t('socialUi.contacts.filterPlaceholder')}
            className="h-10 w-full rounded-xl border border-white/10 bg-white/5 pl-9 pr-9 text-sm text-white placeholder:text-gray-600 focus:border-teal-500/50 focus:outline-none"
          />
          {query && (
            <button
              onClick={() => setQuery('')}
              className="absolute right-3 top-1/2 -translate-y-1/2 text-gray-500 hover:text-white"
            >
              <X className="h-4 w-4" />
            </button>
          )}
        </div>

        <Tabs defaultValue="crewmates">
          <TabsList className="grid w-full grid-cols-4">
            <TabsTrigger value="crewmates" className="gap-1 text-xs">
              <Users className="h-3.5 w-3.5" /> {t('socialUi.contacts.tabCrew')}
            </TabsTrigger>
            <TabsTrigger value="following" className="gap-1 text-xs">
              <UserCheck className="h-3.5 w-3.5" /> {t('socialUi.contacts.tabFollows')}
            </TabsTrigger>
            <TabsTrigger value="dms" className="gap-1 text-xs">
              <MessageCircle className="h-3.5 w-3.5" /> {t('socialUi.contacts.tabDms')}
            </TabsTrigger>
            <TabsTrigger value="saved" className="gap-1 text-xs">
              <Lock className="h-3.5 w-3.5" /> {t('socialUi.contacts.tabSaved')}
            </TabsTrigger>
          </TabsList>

          {/* Crew-mates */}
          <TabsContent value="crewmates" className="mt-4">
            {crewmatesLoading ? (
              <ListSkeleton />
            ) : crewmatesFiltered.length === 0 ? (
              <EmptyTab
                icon={Users}
                text={t('socialUi.contacts.emptyCrewmates')}
              />
            ) : (
              renderList(
                crewmatesFiltered.map((c) => c.pubkey),
                (pk) => {
                  const cm = crewmatesFiltered.find((c) => c.pubkey === pk);
                  return cm ? crewmateSubtitle(cm) : undefined;
                },
              )
            )}
          </TabsContent>

          {/* Following */}
          <TabsContent value="following" className="mt-4">
            {followingLoading ? (
              <ListSkeleton />
            ) : followingFiltered.length === 0 ? (
              <EmptyTab icon={UserCheck} text={t('socialUi.contacts.emptyFollowing')} />
            ) : (
              renderList(followingFiltered)
            )}
          </TabsContent>

          {/* Recent DMs */}
          <TabsContent value="dms" className="mt-4">
            {convosLoading ? (
              <ListSkeleton />
            ) : convoPubkeys.length === 0 ? (
              <EmptyTab
                icon={MessageCircle}
                text={t('socialUi.contacts.emptyDms')}
              />
            ) : (
              renderList(convoPubkeys)
            )}
          </TabsContent>

          {/* Saved private contacts */}
          <TabsContent value="saved" className="mt-4">
            <p className="mb-3 flex items-center gap-1.5 rounded-lg border border-amber-500/20 bg-amber-500/5 px-3 py-2 text-[11px] text-amber-300/80">
              <Lock className="h-3 w-3 shrink-0" />
              {t('socialUi.contacts.savedHint')}
            </p>
            {savedFiltered.length === 0 ? (
              <EmptyTab
                icon={Star}
                text={t('socialUi.contacts.emptySaved')}
              />
            ) : (
              renderList(savedFiltered)
            )}
          </TabsContent>
        </Tabs>
      </div>
    </>
  );
}

function ListSkeleton() {
  return (
    <div className="space-y-2">
      {Array.from({ length: 5 }).map((_, i) => (
        <div key={i} className="flex items-center gap-3 rounded-xl border border-white/5 p-3">
          <Skeleton className="h-11 w-11 rounded-full" />
          <div className="flex-1 space-y-1.5">
            <Skeleton className="h-4 w-32" />
            <Skeleton className="h-3 w-20" />
          </div>
        </div>
      ))}
    </div>
  );
}