import { useNostr } from '@nostrify/react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { useCurrentUser } from './useCurrentUser';
import { useToast } from './useToast';
import { nip19 } from 'nostr-tools';

/**
 * Hook to fetch the list of pubkeys that a user follows
 */
export function useFollowing(pubkey?: string) {
  const { nostr } = useNostr();
  const { user } = useCurrentUser();
  const targetPubkey = pubkey || user?.pubkey;

  return useQuery({
    queryKey: ['following', targetPubkey],
    queryFn: async (c) => {
      if (!targetPubkey) return [];

      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(5000)]);

      const events = await nostr.query(
        [{ kinds: [3], authors: [targetPubkey], limit: 1 }],
        { signal }
      );

      if (!events[0]) return [];

      // Extract followed pubkeys from p tags
      const following = events[0].tags
        .filter(([tag]) => tag === 'p')
        .map(([, pubkey]) => pubkey);

      return following;
    },
    enabled: !!targetPubkey,
    staleTime: 60000, // 1 minute
  });
}

/**
 * Hook to fetch the list of pubkeys that follow a user
 */
export function useFollowers(pubkey?: string) {
  const { nostr } = useNostr();
  const { user } = useCurrentUser();
  const targetPubkey = pubkey || user?.pubkey;

  return useQuery({
    queryKey: ['followers', targetPubkey],
    queryFn: async (c) => {
      if (!targetPubkey) return [];

      const signal = AbortSignal.any([c.signal, AbortSignal.timeout(10000)]);

      // Query all kind 3 events that have a p tag with our pubkey
      const events = await nostr.query(
        [{ kinds: [3], '#p': [targetPubkey], limit: 100 }],
        { signal }
      );

      // Extract the authors (people who follow us)
      const followers = events.map((event) => event.pubkey);

      // Deduplicate (same person might have multiple follow lists)
      return Array.from(new Set(followers));
    },
    enabled: !!targetPubkey,
    staleTime: 60000, // 1 minute
  });
}

/**
 * Hook to follow/unfollow users
 */
export function useFollowActions() {
  const { nostr } = useNostr();
  const { user } = useCurrentUser();
  const { toast } = useToast();
  const queryClient = useQueryClient();

  const followMutation = useMutation({
    mutationFn: async (targetPubkey: string) => {
      if (!user) throw new Error('Must be logged in to follow users');

      // Get current follow list
      const events = await nostr.query(
        [{ kinds: [3], authors: [user.pubkey], limit: 1 }],
        { signal: AbortSignal.timeout(5000) }
      );

      const currentFollowList = events[0];
      const currentTags = currentFollowList?.tags || [];

      // Check if already following
      const alreadyFollowing = currentTags.some(
        ([tag, pubkey]) => tag === 'p' && pubkey === targetPubkey
      );

      if (alreadyFollowing) {
        throw new Error('Already following this user');
      }

      // Add new p tag
      const newTags = [...currentTags, ['p', targetPubkey]];

      // Publish new follow list
      await user.signer.signEvent({
        kind: 3,
        content: currentFollowList?.content || '',
        tags: newTags,
        created_at: Math.floor(Date.now() / 1000),
      }).then((signedEvent) => nostr.event(signedEvent));

      return targetPubkey;
    },
    onSuccess: (targetPubkey) => {
      // Invalidate queries to refetch
      queryClient.invalidateQueries({ queryKey: ['following', user?.pubkey] });
      queryClient.invalidateQueries({ queryKey: ['trust-score'] });

      toast({
        title: 'Followed successfully',
        description: 'This user is now in your network',
      });
    },
    onError: (error) => {
      toast({
        title: 'Failed to follow',
        description: error instanceof Error ? error.message : 'Unknown error',
        variant: 'destructive',
      });
    },
  });

  const unfollowMutation = useMutation({
    mutationFn: async (targetPubkey: string) => {
      if (!user) throw new Error('Must be logged in to unfollow users');

      // Get current follow list
      const events = await nostr.query(
        [{ kinds: [3], authors: [user.pubkey], limit: 1 }],
        { signal: AbortSignal.timeout(5000) }
      );

      const currentFollowList = events[0];
      if (!currentFollowList) {
        throw new Error('No follow list found');
      }

      // Remove the p tag for this pubkey
      const newTags = currentFollowList.tags.filter(
        ([tag, pubkey]) => !(tag === 'p' && pubkey === targetPubkey)
      );

      // Publish updated follow list
      await user.signer.signEvent({
        kind: 3,
        content: currentFollowList.content || '',
        tags: newTags,
        created_at: Math.floor(Date.now() / 1000),
      }).then((signedEvent) => nostr.event(signedEvent));

      return targetPubkey;
    },
    onSuccess: () => {
      // Invalidate queries
      queryClient.invalidateQueries({ queryKey: ['following', user?.pubkey] });
      queryClient.invalidateQueries({ queryKey: ['trust-score'] });

      toast({
        title: 'Unfollowed successfully',
        description: 'Removed from your network',
      });
    },
    onError: (error) => {
      toast({
        title: 'Failed to unfollow',
        description: error instanceof Error ? error.message : 'Unknown error',
        variant: 'destructive',
      });
    },
  });

  /**
   * Parse npub/nip05 and follow the user
   */
  const followByIdentifier = async (identifier: string) => {
    try {
      // Try to decode as npub first
      if (identifier.startsWith('npub1')) {
        const decoded = nip19.decode(identifier);
        if (decoded.type === 'npub') {
          await followMutation.mutateAsync(decoded.data);
          return;
        }
      }

      // Try to resolve as NIP-05
      if (identifier.includes('@')) {
        const [name, domain] = identifier.split('@');
        const response = await fetch(
          `https://${domain}/.well-known/nostr.json?name=${name}`
        );
        const data = await response.json();
        const pubkey = data.names?.[name];
        
        if (pubkey) {
          await followMutation.mutateAsync(pubkey);
          return;
        }
      }

      // Try as raw hex pubkey
      if (identifier.length === 64 && /^[0-9a-f]+$/.test(identifier)) {
        await followMutation.mutateAsync(identifier);
        return;
      }

      throw new Error('Invalid identifier. Use npub1..., user@domain.com, or hex pubkey');
    } catch (error) {
      toast({
        title: 'Failed to follow',
        description: error instanceof Error ? error.message : 'Invalid identifier',
        variant: 'destructive',
      });
    }
  };

  return {
    follow: followMutation.mutateAsync,
    unfollow: unfollowMutation.mutateAsync,
    followByIdentifier,
    isFollowing: followMutation.isPending,
    isUnfollowing: unfollowMutation.isPending,
  };
}

/**
 * Check if current user is following a specific pubkey
 */
export function useIsFollowing(targetPubkey: string | undefined) {
  const { data: following = [] } = useFollowing();

  if (!targetPubkey) return false;
  return following.includes(targetPubkey);
}