import { useEffect, useMemo, useState } from 'react';
import { Link } from 'react-router-dom';
import { Bell, Users, Check, Loader2, EyeOff, Globe, CheckCheck, Heart } from 'lucide-react';
import { Button } from '@/components/ui/button';
import { Popover, PopoverContent, PopoverTrigger } from '@/components/ui/popover';
import { ScrollArea } from '@/components/ui/scroll-area';
import { Avatar, AvatarFallback, AvatarImage } from '@/components/ui/avatar';
import { Tabs, TabsList, TabsTrigger, TabsContent } from '@/components/ui/tabs';
import { CrewInviteCard } from '@/components/CrewInviteCard';
import { JoinRequestCard } from '@/components/JoinRequestCard';
import { CollectiveJoinRequestCard } from '@/components/CollectiveJoinRequestCard';
import { ActivityNotificationCard } from '@/components/ActivityNotificationCard';
import { useCrewNotifications, useIsPendingMember } from '@/hooks/useCrewNotifications';
import { useActivityNotifications } from '@/hooks/useActivityNotifications';
import { useNotificationsRead } from '@/hooks/useNotificationsRead';
import { useConfirmMembership } from '@/hooks/useMembershipAttestation';
import { useAuthor } from '@/hooks/useAuthor';
import { useToast } from '@/hooks/useToast';
import { genUserName } from '@/lib/genUserName';
import { SKATE_CREW_KIND, type MemberVisibility, type SkateCrew } from '@/lib/types';
import { cn } from '@/lib/utils';

/**
 * A pending-confirm crew: this user has been LISTED in a crew's member list but
 * hasn't published their own attestation yet. Rendered like an invite so they
 * can confirm (with a visibility choice) right from the bell.
 */
function PendingConfirmCard({ crew, onResolved }: { crew: SkateCrew; onResolved?: () => void }) {
  const isPending = useIsPendingMember(crew);
  const founder = useAuthor(crew.pubkey);
  const founderName = founder.data?.metadata?.name ?? genUserName(crew.pubkey);
  const founderPic = founder.data?.metadata?.picture;
  const { toast } = useToast();
  const { mutateAsync: confirm, isPending: confirming } = useConfirmMembership();
  const [visibility, setVisibility] = useState<MemberVisibility>('public');
  const [done, setDone] = useState(false);

  // Only actionable while the member is genuinely pending confirmation.
  if (!isPending || done) return null;

  const handleConfirm = async () => {
    try {
      await confirm({
        kind: SKATE_CREW_KIND,
        founderPubkey: crew.pubkey,
        identifier: crew.identifier,
        collectiveName: crew.name,
        visibility,
      });
      setDone(true);
      toast({ title: `You're in ${crew.name}! 🛹`, description: 'Membership confirmed.' });
      onResolved?.();
    } catch (err) {
      toast({
        title: 'Could not confirm',
        description: err instanceof Error ? err.message : 'Please try again.',
        variant: 'destructive',
      });
    }
  };

  return (
    <div className="rounded-xl border border-teal-500/25 bg-gradient-to-br from-teal-500/[0.08] to-transparent p-3">
      <div className="flex items-start gap-3">
        <div className="flex h-9 w-9 flex-shrink-0 items-center justify-center rounded-xl bg-teal-500/15">
          <Users className="h-4 w-4 text-teal-400" />
        </div>
        <div className="min-w-0 flex-1">
          <p className="text-sm leading-snug text-gray-200">
            <span className="inline-flex items-center gap-1 font-bold text-white">
              <Avatar className="h-4 w-4">
                <AvatarImage src={founderPic} alt={founderName} />
                <AvatarFallback className="text-[8px]">{founderName.slice(0, 2).toUpperCase()}</AvatarFallback>
              </Avatar>
              {founderName}
            </span>{' '}
            added you to{' '}
            <Link to={`/crew/${crew.pubkey}/${crew.identifier}`} className="font-black text-teal-300 hover:underline">
              {crew.name}
            </Link>
            . Confirm to appear as a member.
          </p>

          {/* Visibility toggle */}
          <div className="mt-2 grid grid-cols-2 gap-1.5">
            {([
              { key: 'public', label: 'Public', icon: Globe },
              { key: 'crew', label: 'Crew only', icon: EyeOff },
            ] as const).map(({ key, label, icon: Icon }) => {
              const active = visibility === key;
              return (
                <button
                  key={key}
                  type="button"
                  onClick={() => setVisibility(key)}
                  className={cn(
                    'flex items-center justify-center gap-1 rounded-lg border px-2 py-1.5 text-xs font-bold transition-all active:scale-95',
                    active
                      ? 'border-transparent bg-teal-500 text-black'
                      : 'border-white/10 bg-white/5 text-gray-400 hover:bg-white/10 hover:text-white',
                  )}
                >
                  <Icon className="h-3 w-3" />
                  {label}
                </button>
              );
            })}
          </div>

          <Button
            size="sm"
            onClick={handleConfirm}
            disabled={confirming}
            className="mt-2.5 h-8 w-full gap-1.5 bg-teal-500 font-bold text-black hover:bg-teal-600"
          >
            {confirming ? <Loader2 className="h-3.5 w-3.5 animate-spin" /> : <Check className="h-3.5 w-3.5" />}
            Confirm membership
          </Button>
        </div>
      </div>
    </div>
  );
}

function EmptyState({ label }: { label: string }) {
  return (
    <div className="flex flex-col items-center gap-2 py-10 text-center">
      <div className="flex h-12 w-12 items-center justify-center rounded-2xl bg-white/5">
        <Bell className="h-5 w-5 text-gray-600" />
      </div>
      <p className="text-sm font-bold text-gray-400">You're all caught up</p>
      <p className="max-w-[220px] text-xs text-gray-600">{label}</p>
    </div>
  );
}

/**
 * Header notification bell — the user's whole activity center, not just crews:
 *
 *  SOCIAL: reactions, reposts, zaps, mentions and replies that reference them.
 *  CREWS:  structured invites, "pending confirmation" crews, and (for crew
 *          leaders) incoming join-requests to approve.
 *
 * Unread state is tracked by a per-account "last read" timestamp; opening the
 * bell (or hitting "mark all read") clears the badge. Only renders when logged in.
 */
export function NotificationBell({ className }: { className?: string }) {
  const [open, setOpen] = useState(false);
  const { user, invites, listedCrews, joinRequests, collectiveRequests, isLoading: crewLoading } =
    useCrewNotifications();
  const { notifications: activity, isLoading: activityLoading } = useActivityNotifications();
  const { lastRead, markAllRead } = useNotificationsRead();

  const crewTotal = useMemo(
    () => invites.length + listedCrews.length + joinRequests.length + collectiveRequests.length,
    [invites, listedCrews, joinRequests, collectiveRequests],
  );

  // Unread social items = activity newer than the last time the bell was opened.
  const unreadActivity = useMemo(
    () => activity.filter((n) => n.createdAt > lastRead).length,
    [activity, lastRead],
  );

  // Crew items are always "actionable" so they always count toward the badge.
  const badgeTotal = crewTotal + unreadActivity;

  // Opening the bell marks everything as read.
  useEffect(() => {
    if (open) markAllRead();
  }, [open, markAllRead]);

  const isLoading = crewLoading || activityLoading;

  if (!user) return null;

  return (
    <Popover open={open} onOpenChange={setOpen}>
      <PopoverTrigger asChild>
        <Button
          variant="ghost"
          size="icon"
          className={cn('relative text-gray-400 hover:text-teal-400 hover:bg-teal-500/10', className)}
          title="Notifications"
          aria-label={`Notifications${badgeTotal > 0 ? ` (${badgeTotal} new)` : ''}`}
        >
          <Bell className="h-5 w-5" />
          {badgeTotal > 0 && (
            <span className="absolute -right-0.5 -top-0.5 flex min-w-[18px] items-center justify-center rounded-full bg-teal-500 px-1 text-[10px] font-black leading-[18px] text-black">
              {badgeTotal > 9 ? '9+' : badgeTotal}
            </span>
          )}
        </Button>
      </PopoverTrigger>
      <PopoverContent align="end" className="w-[380px] max-w-[calc(100vw-1.5rem)] p-0" sideOffset={8}>
        <div className="flex items-center justify-between border-b border-white/10 px-4 py-3">
          <h3 className="flex items-center gap-2 text-sm font-black uppercase tracking-wide text-white">
            <Bell className="h-4 w-4 text-teal-400" /> Notifications
          </h3>
          <button
            type="button"
            onClick={markAllRead}
            className="flex items-center gap-1 text-[10px] font-black uppercase tracking-wide text-gray-500 transition-colors hover:text-teal-400"
          >
            <CheckCheck className="h-3.5 w-3.5" /> Mark read
          </button>
        </div>

        <Tabs defaultValue="all" className="w-full">
          <TabsList className="grid w-full grid-cols-3 rounded-none border-b border-white/10 bg-transparent p-0">
            <TabsTrigger
              value="all"
              className="rounded-none border-b-2 border-transparent py-2.5 text-xs font-bold data-[state=active]:border-teal-400 data-[state=active]:bg-transparent data-[state=active]:text-teal-400"
            >
              All
              {badgeTotal > 0 && <span className="ml-1 text-teal-400">{badgeTotal}</span>}
            </TabsTrigger>
            <TabsTrigger
              value="social"
              className="rounded-none border-b-2 border-transparent py-2.5 text-xs font-bold data-[state=active]:border-teal-400 data-[state=active]:bg-transparent data-[state=active]:text-teal-400"
            >
              <Heart className="mr-1 h-3 w-3" /> Social
            </TabsTrigger>
            <TabsTrigger
              value="crews"
              className="rounded-none border-b-2 border-transparent py-2.5 text-xs font-bold data-[state=active]:border-teal-400 data-[state=active]:bg-transparent data-[state=active]:text-teal-400"
            >
              <Users className="mr-1 h-3 w-3" /> Crews
              {crewTotal > 0 && <span className="ml-1 text-teal-400">{crewTotal}</span>}
            </TabsTrigger>
          </TabsList>

          <ScrollArea className="max-h-[65vh]">
            {/* ─── ALL ─────────────────────────────────────────────────── */}
            <TabsContent value="all" className="m-0 p-3">
              {isLoading && badgeTotal === 0 && (
                <div className="flex items-center justify-center gap-2 py-8 text-sm text-gray-500">
                  <Loader2 className="h-4 w-4 animate-spin" /> Checking for updates…
                </div>
              )}
              {!isLoading && crewTotal === 0 && activity.length === 0 && (
                <EmptyState label="Zaps, reactions, replies and crew activity will show up here." />
              )}
              <div className="space-y-2.5">
                {joinRequests.map(({ request, crew, endorsements }) => (
                  <JoinRequestCard key={request.id} request={request} crew={crew} endorsements={endorsements} compact />
                ))}
                {collectiveRequests.map((request) => (
                  <CollectiveJoinRequestCard key={request.id} request={request} compact />
                ))}
                {invites.map((invite) => (
                  <CrewInviteCard key={invite.id} invite={invite} compact />
                ))}
                {listedCrews.map((crew) => (
                  <PendingConfirmCard key={`${crew.pubkey}:${crew.identifier}`} crew={crew} />
                ))}
                {activity.map((n) => (
                  <ActivityNotificationCard
                    key={n.id}
                    notification={n}
                    unread={n.createdAt > lastRead}
                    onNavigate={() => setOpen(false)}
                  />
                ))}
              </div>
            </TabsContent>

            {/* ─── SOCIAL ──────────────────────────────────────────────── */}
            <TabsContent value="social" className="m-0 p-3">
              {activityLoading && activity.length === 0 && (
                <div className="flex items-center justify-center gap-2 py-8 text-sm text-gray-500">
                  <Loader2 className="h-4 w-4 animate-spin" /> Checking for updates…
                </div>
              )}
              {!activityLoading && activity.length === 0 && (
                <EmptyState label="When people zap, react, repost, mention or reply to you, it lands here." />
              )}
              <div className="space-y-2.5">
                {activity.map((n) => (
                  <ActivityNotificationCard
                    key={n.id}
                    notification={n}
                    unread={n.createdAt > lastRead}
                    onNavigate={() => setOpen(false)}
                  />
                ))}
              </div>
            </TabsContent>

            {/* ─── CREWS ───────────────────────────────────────────────── */}
            <TabsContent value="crews" className="m-0 p-3">
              {crewLoading && crewTotal === 0 && (
                <div className="flex items-center justify-center gap-2 py-8 text-sm text-gray-500">
                  <Loader2 className="h-4 w-4 animate-spin" /> Checking for updates…
                </div>
              )}
              {!crewLoading && crewTotal === 0 && (
                <EmptyState label="Crew invites, collective requests and membership requests will show up here." />
              )}
              <div className="space-y-2.5">
                {joinRequests.map(({ request, crew, endorsements }) => (
                  <JoinRequestCard key={request.id} request={request} crew={crew} endorsements={endorsements} compact />
                ))}
                {collectiveRequests.map((request) => (
                  <CollectiveJoinRequestCard key={request.id} request={request} compact />
                ))}
                {invites.map((invite) => (
                  <CrewInviteCard key={invite.id} invite={invite} compact />
                ))}
                {listedCrews.map((crew) => (
                  <PendingConfirmCard key={`${crew.pubkey}:${crew.identifier}`} crew={crew} />
                ))}
              </div>
            </TabsContent>
          </ScrollArea>
        </Tabs>

        <div className="border-t border-white/10 p-2">
          <Button
            asChild
            variant="ghost"
            size="sm"
            className="w-full text-xs font-bold text-gray-400 hover:text-teal-400"
            onClick={() => setOpen(false)}
          >
            <Link to="/crews">Browse all crews</Link>
          </Button>
        </div>
      </PopoverContent>
    </Popover>
  );
}