import { useMutation, useQueryClient } from '@tanstack/react-query';
import { useNostrPublish } from '@/hooks/useNostrPublish';
import { useCurrentUser } from '@/hooks/useCurrentUser';
import { isAdminPubkey } from '@/lib/admins';
import {
  MODERATION_LABEL_NAMESPACE,
  MODERATION_LABEL_HIDDEN,
} from '@/lib/types';
import { addLocalHidden } from '@/lib/localModeration';
import type { NostrEvent } from '@nostrify/nostrify';

/**
 * Hard ceiling on how long the whole delete can run before we give up and
 * surface an error. Guarantees the UI spinner can NEVER hang indefinitely,
 * whatever the signer/relay does underneath.
 */
const DELETE_TIMEOUT_MS = 40_000;

function withHardTimeout<T>(promise: Promise<T>, ms: number): Promise<T> {
  return new Promise<T>((resolve, reject) => {
    const timer = setTimeout(() => {
      reject(
        new Error(
          'This is taking longer than expected. If you approved the request in ' +
            'your signer, the takedown may still go through — check back in a moment.',
        ),
      );
    }, ms);
    promise.then(
      (v) => {
        clearTimeout(timer);
        resolve(v);
      },
      (e) => {
        clearTimeout(timer);
        reject(e);
      },
    );
  });
}

/**
 * Deletion / takedown for an ADDRESSABLE event (kinds 30000–39999) such as a
 * skate crew, a Lab profile, a spot, a tour, an event, etc.
 *
 * Two callers, two mechanisms:
 *
 *   1. The ORIGINAL AUTHOR deleting their own listing → NIP-09 kind:5 deletion
 *      request. Relays that honor NIP-09 stop serving the event. A deletion
 *      request is only valid when signed by the pubkey that created the target,
 *      so an author's request is respected network-wide.
 *
 *   2. A SkateSpots ADMIN (see src/lib/admins.ts) taking down someone else's
 *      content → we ALSO publish a kind:5 (honored by the community relay for
 *      its own stored events) AND a NIP-32 kind:1985 `hidden` label referencing
 *      the target coordinate. The label is authored by the admin, so the app's
 *      client-side moderation layer (useAdminModeration) can hide the content
 *      everywhere regardless of whether a given relay honors a cross-author
 *      NIP-09 request. This makes admin takedowns reliable inside the app.
 *
 * In all cases deletion on a decentralized network is best-effort: a relay that
 * ignores NIP-09 may keep a cached copy, and other users' relays may retain it.
 */
export function useDeleteEntity() {
  const { mutateAsync: publishEvent } = useNostrPublish();
  const { user } = useCurrentUser();
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({
      event,
      reason,
    }: {
      /** The full addressable event to delete. */
      event: NostrEvent;
      /** Optional human-readable reason, stored in the deletion request content. */
      reason?: string;
    }) => withHardTimeout(runDelete(event, reason), DELETE_TIMEOUT_MS),
    onSuccess: () => {
      // Nudge every list/detail query to refetch so the deleted entity drops out.
      queryClient.invalidateQueries();
    },
  });

  async function runDelete(event: NostrEvent, reason?: string): Promise<void> {
      if (!user) throw new Error('You must be logged in to delete.');

      const isOwner = user.pubkey === event.pubkey;
      const isAdmin = isAdminPubkey(user.pubkey);
      if (!isOwner && !isAdmin) {
        throw new Error('You can only delete your own listing.');
      }

      const dTag = event.tags.find(([name]) => name === 'd')?.[1] ?? '';
      const coord = `${event.kind}:${event.pubkey}:${dTag}`;

      // NIP-09: reference by both the addressable coordinate (`a`) and the
      // concrete event id (`e`), plus the kind (`k`), for maximum relay support.
      const deletionTags: string[][] = [
        ['a', coord],
        ['e', event.id],
        ['k', String(event.kind)],
      ];

      // STEP 1 (required): publish the NIP-09 kind:5 deletion request. This is
      // the ONE signature the UI waits on. useNostrPublish has its own internal
      // sign + relay timeouts, and we wrap the whole thing in a hard ceiling
      // (below) so the spinner can never hang forever.
      await publishEvent({
        kind: 5,
        content: reason?.trim() || '',
        tags: deletionTags,
      });

      // STEP 2 (admin takedown only): record the target locally RIGHT NOW so the
      // app hides it on this device immediately — no waiting on a second signer
      // round-trip. Then fire the cross-device kind:1985 moderation label in the
      // BACKGROUND (not awaited): a second Amber approval, if needed, happens
      // after the dialog has already closed and never blocks the UI. This is the
      // fix for "stuck on Deleting…": the mutation resolves as soon as kind:5 is
      // published, regardless of the label.
      if (isAdmin && !isOwner) {
        addLocalHidden({ coord, id: event.id });

        const labelTags: string[][] = [
          ['L', MODERATION_LABEL_NAMESPACE],
          ['l', MODERATION_LABEL_HIDDEN, MODERATION_LABEL_NAMESPACE],
          ['a', coord],
          ['e', event.id],
          ['k', String(event.kind)],
          ['p', event.pubkey],
          ['alt', `SkateSpots admin takedown${reason?.trim() ? `: ${reason.trim()}` : ''}`],
        ];
        // Intentionally NOT awaited — background best-effort.
        void publishEvent({
          kind: 1985,
          content: reason?.trim() || 'Removed by SkateSpots admin',
          tags: labelTags,
        }).catch((labelError) => {
          console.warn(
            '[useDeleteEntity] background moderation label failed (content is ' +
              'already hidden locally; kind:5 was published):',
            labelError,
          );
        });
      }
  }
}