import { useState, useEffect, useCallback, useRef } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { useNostr } from '@nostrify/react';
import {
  cacheSpot,
  cacheSpots,
  getCachedSpot,
  getAllCachedSpots,
  getRecentlyViewedSpots,
  getCacheStats,
  clearOldCache,
  clearAllCache,
  isOffline,
  onConnectionChange,
  queuePost,
  getPendingPosts,
  getPendingPostsCount,
  prunePendingPosts,
  reconcileStalePendingPosts,
  removePendingPost,
  updatePendingPostStatus,
} from '@/lib/offlineCache';
import { useCurrentUser } from './useCurrentUser';
import { useNostrLogin } from '@nostrify/react/login';
import { isInteractiveSigner } from '@/lib/signerCapabilities';
import { useToast } from './useToast';
import { useTranslation } from '@/contexts/language';
import type { NostrEvent } from '@nostrify/nostrify';
import type { SkateSpot } from '@/lib/types';

// ============ Connection Status Hook ============

/**
 * Hook to track online/offline status
 */
export function useOnlineStatus() {
  const [online, setOnline] = useState(!isOffline());

  useEffect(() => {
    const unsubscribe = onConnectionChange(setOnline);
    return unsubscribe;
  }, []);

  return online;
}

// ============ Spot Caching Hooks ============

/**
 * Hook to cache a spot when viewing
 */
export function useCacheSpotOnView() {
  return useCallback(async (event: NostrEvent, spot: SkateSpot) => {
    try {
      await cacheSpot(event, spot);
    } catch (error) {
      console.warn('[OfflineCache] Failed to cache spot:', error);
    }
  }, []);
}

/**
 * Hook to cache multiple spots (e.g., when loading map)
 */
export function useCacheSpotsOnLoad() {
  return useCallback(async (spotsWithEvents: Array<{ event: NostrEvent; spot: SkateSpot }>) => {
    try {
      await cacheSpots(spotsWithEvents);
    } catch (error) {
      console.warn('[OfflineCache] Failed to cache spots:', error);
    }
  }, []);
}

/**
 * Hook to get a cached spot (for offline fallback)
 */
export function useCachedSpot(pubkey: string | undefined, identifier: string | undefined) {
  return useQuery({
    queryKey: ['cached-spot', pubkey, identifier],
    queryFn: async () => {
      if (!pubkey || !identifier) return null;
      return getCachedSpot(pubkey, identifier);
    },
    enabled: !!pubkey && !!identifier,
    staleTime: Infinity, // Cache never goes stale
  });
}

/**
 * Hook to get all cached spots (for offline browsing)
 */
export function useCachedSpots() {
  return useQuery({
    queryKey: ['cached-spots'],
    queryFn: getAllCachedSpots,
    staleTime: 1000 * 60, // 1 minute
  });
}

/**
 * Hook to get recently viewed spots
 */
export function useRecentlyViewedSpots(limit: number = 50) {
  return useQuery({
    queryKey: ['recently-viewed-spots', limit],
    queryFn: () => getRecentlyViewedSpots(limit),
    staleTime: 1000 * 60,
  });
}

/**
 * Hook to get cache statistics
 */
export function useCacheStats() {
  return useQuery({
    queryKey: ['cache-stats'],
    queryFn: getCacheStats,
    staleTime: 1000 * 60 * 5, // 5 minutes
  });
}

/**
 * Hook to manage cache (clear old/all)
 */
export function useCacheManagement() {
  const { t } = useTranslation();
  const queryClient = useQueryClient();
  const { toast } = useToast();

  const clearOld = useMutation({
    mutationFn: async (maxAgeDays: number = 7) => {
      const maxAgeMs = maxAgeDays * 24 * 60 * 60 * 1000;
      return clearOldCache(maxAgeMs);
    },
    onSuccess: (count) => {
      queryClient.invalidateQueries({ queryKey: ['cached-spots'] });
      queryClient.invalidateQueries({ queryKey: ['cache-stats'] });
      toast({
        title: t('toastsUi.cacheCleaned'),
        description: t('toastsUi.cacheCleanedDesc', { count }),
      });
    },
  });

  const clearAll = useMutation({
    mutationFn: clearAllCache,
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['cached-spots'] });
      queryClient.invalidateQueries({ queryKey: ['cache-stats'] });
      toast({
        title: t('toastsUi.cacheCleared'),
        description: t('toastsUi.cacheClearedDesc'),
      });
    },
  });

  return { clearOld, clearAll };
}

// ============ Pending Posts Hooks ============

/**
 * Module-level lock: the queue must have exactly ONE publisher even though the
 * `OfflineIndicator` (which owns the sync) is mounted twice (mobile + desktop).
 */
let globalSyncing = false;

/**
 * Hook to get pending posts count
 */
export function usePendingPostsCount() {
  const isOnline = useOnlineStatus();

  return useQuery({
    queryKey: ['pending-posts-count'],
    queryFn: getPendingPostsCount,
    refetchInterval: isOnline ? 5000 : false, // Only refresh when online
  });
}

/**
 * Deliver queued actions when we're back online.
 *
 * Publishes the SIGNED event we stored (so an interactive signer is never
 * re-prompted), falls back to signing legacy/unsigned entries, retries failures
 * on an interval, and prunes stale ephemeral actions. Deliberately does NOT go
 * through `useNostrPublish` — that would re-queue on failure and duplicate.
 */
export function useSyncPendingPosts() {
  const { t } = useTranslation();
  const isOnline = useOnlineStatus();
  const queryClient = useQueryClient();
  const { nostr } = useNostr();
  const { user } = useCurrentUser();
  const { logins } = useNostrLogin();
  // Amber must not be popped from a background interval. New queued posts carry
  // an already-signed event; only legacy/unsigned entries need a `signEvent`, and
  // for an interactive signer we leave those queued rather than prompt silently.
  const interactive = isInteractiveSigner(user, logins);
  const { toast } = useToast();
  const [isSyncing, setIsSyncing] = useState(false);
  const syncingRef = useRef(false);

  useEffect(() => {
    if (!isOnline || !user) return;
    let cancelled = false;

    const syncPosts = async () => {
      // The `OfflineIndicator` is mounted twice (mobile + desktop headers), so a
      // module-level lock keeps exactly one publisher at a time.
      if (cancelled || syncingRef.current || globalSyncing) return;

      await prunePendingPosts().catch(() => {});
      await reconcileStalePendingPosts().catch(() => {});
      const pending = await getPendingPosts();
      if (pending.length === 0) return;
      if (cancelled) return;

      syncingRef.current = true;
      globalSyncing = true;
      setIsSyncing(true);
      let successCount = 0;

      for (const post of pending) {
        if (cancelled) break;
        // Interactive signer (Amber): never sign from a background loop.
        // Pre-signed posts still publish; legacy unsigned ones stay queued.
        if (!post.signedEvent && interactive) continue;
        try {
          await updatePendingPostStatus(post.id, 'publishing');
          const event: NostrEvent =
            post.signedEvent ??
            (await user.signer.signEvent({
              kind: post.kind,
              content: post.content,
              tags: post.tags,
              created_at: Math.floor(Date.now() / 1000),
            }));
          await nostr.event(event, { signal: AbortSignal.timeout(15000) });
          await removePendingPost(post.id);
          successCount++;
        } catch {
          // Keep it queued; the interval below will try again.
          await updatePendingPostStatus(post.id, 'failed', post.retries + 1);
        }
      }

      syncingRef.current = false;
      globalSyncing = false;
      setIsSyncing(false);
      queryClient.invalidateQueries({ queryKey: ['pending-posts-count'] });

      if (successCount > 0) {
        toast({
          title: t('toastsUi.backOnline'),
          description: t('toastsUi.backOnlineDesc', { count: successCount }),
        });
      }
    };

    // Small delay so the network settles, then keep retrying while items remain.
    const timeout = setTimeout(syncPosts, 2000);
    const interval = setInterval(syncPosts, 30000);
    return () => {
      cancelled = true;
      clearTimeout(timeout);
      clearInterval(interval);
    };
  }, [isOnline, user, interactive, nostr, queryClient, toast, t]);

  return { isSyncing };
}

/**
 * Hook to queue a post for offline publishing
 */
export function useQueuePost() {
  const { t } = useTranslation();
  const queryClient = useQueryClient();
  const { toast } = useToast();

  return useMutation({
    mutationFn: async ({ kind, content, tags }: { kind: number; content: string; tags: string[][] }) => {
      return queuePost(kind, content, tags);
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['pending-posts-count'] });
      toast({
        title: t('toastsUi.postQueued'),
        description: t('toastsUi.postQueuedDesc'),
      });
    },
  });
}