import { useCallback, useMemo } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { useNostr } from '@nostrify/react';
import { useNostrLogin } from '@nostrify/react/login';
import { useCurrentUser } from './useCurrentUser';
import { useNostrPublish } from './useNostrPublish';
import { toast } from './useToast';
import { hasNip44 as checkNip44, isInteractiveSigner } from '@/lib/signerCapabilities';
import { cacheStashEvent, getCachedStashEvent } from '@/lib/offlineCache';
import type { NostrEvent } from '@nostrify/nostrify';

// Stash item stored in encrypted NIP-51 list
export interface StashItem {
  id: string;
  title: string;
  category: 'deck' | 'trucks' | 'wheels' | 'bearings' | 'shoes' | 'clothing' | 'protective' | 'complete' | 'other';
  condition: 'new' | 'like_new' | 'good' | 'well_used';
  size?: string;
  brand?: string;
  description?: string;
  minPrice?: number; // Minimum sats willing to accept
  maxPrice?: number; // Maximum sats willing to pay (for WTB)
  images?: string[];
  willingToTrade?: boolean;
  willingToSell?: boolean;
  addedAt: number;
  // Visibility settings
  visibility: 'private' | 'friends' | 'public';
  // Optional geohash for local matching
  geohash?: string;
  // Item type: regular stash item or Want To Buy
  itemType?: 'stash' | 'wtb';
  // Rarity override (for special items)
  rarity?: 'common' | 'uncommon' | 'rare' | 'epic' | 'legendary';
  // Physical storage location
  storageLocation?: 'home' | 'car' | 'skatepark' | 'warehouse' | 'storage_unit' | 'van' | 'friends' | 'parents' | 'wardrobe' | 'backpack' | 'sponsor' | 'other';
  /**
   * Last local modification time (epoch seconds). Used to resolve multi-device
   * merge conflicts — the newest edit of an item wins. Legacy items don't have
   * it; `addedAt` is the fallback (see `itemStamp`).
   */
  updatedAt?: number;
}

export interface Stash {
  items: StashItem[];
  updatedAt: number;
  /**
   * Tombstones for deleted items. The stash is one replaceable blob, so a plain
   * "remove from the array" can be *resurrected* by another device's stale copy
   * during a merge. Recording when an item was deleted lets deletes win instead.
   * Optional — older stashes simply have none.
   */
  deleted?: Array<{ id: string; at: number }>;
}

// Kind 30001 is NIP-51 "Follow sets" - we use a private encrypted list
const STASH_KIND = 30001;
const STASH_D_TAG = 'skatespots-stash';

/** Epoch seconds an item was last touched (legacy items fall back to `addedAt`). */
function itemStamp(i: StashItem): number {
  return i.updatedAt ?? i.addedAt ?? 0;
}

/** Tombstones older than this are dropped — a device offline longer than this
 *  could resurrect a very old delete, which is an acceptable trade. */
const TOMBSTONE_MAX_AGE = 180 * 24 * 60 * 60;
const TOMBSTONE_CAP = 500;

/**
 * Merge two stash snapshots WITHOUT losing data.
 *
 * Why this exists: the stash is a single replaceable event whose content is the
 * WHOLE list, so naive last-write-wins silently drops whatever another device
 * added. This is the multi-device conflict guard. It is deliberately a *blob*
 * merge, not per-item events: per-item events would mean N decrypts per load,
 * and with Amber every decrypt is a popup.
 *
 * Rules:
 *   • union by item id — an item only one side knows about is kept;
 *   • on a collision the newest `updatedAt` (fallback `addedAt`) wins;
 *   • a tombstone (delete) wins when it is at/after the item's last edit;
 *   • tombstones are unioned (newest per id) and pruned.
 *
 * `merged` is true when the remote side contributed something (a new item, a
 * newer edit, or a delete) — the caller can tell the user. For one device this
 * is always a no-op with `merged === false`.
 */
export function mergeStashes(local: Stash, remote: Stash): { stash: Stash; merged: boolean } {
  const localItems = new Map(local.items.map((i) => [i.id, i]));
  const remoteItems = new Map(remote.items.map((i) => [i.id, i]));

  const collectTombs = (s: Stash) => {
    const m = new Map<string, number>();
    for (const t of s.deleted ?? []) {
      if (!t?.id) continue;
      m.set(t.id, Math.max(m.get(t.id) ?? 0, t.at ?? 0));
    }
    return m;
  };
  const localTombs = collectTombs(local);
  const remoteTombs = collectTombs(remote);
  const tombs = new Map(localTombs);
  for (const [id, at] of remoteTombs) tombs.set(id, Math.max(tombs.get(id) ?? 0, at));

  const ids = new Set<string>([...localItems.keys(), ...remoteItems.keys()]);
  const items: StashItem[] = [];
  let merged = false;

  for (const id of ids) {
    const l = localItems.get(id);
    const r = remoteItems.get(id);

    let winner: StashItem;
    if (!l) {
      winner = r!;
      merged = true; // item only the remote knew about
    } else if (!r) {
      winner = l;
    } else if (itemStamp(r) > itemStamp(l)) {
      winner = r;
      merged = true; // the other device edited this item more recently
    } else {
      winner = l;
    }

    const tomb = tombs.get(id);
    if (tomb !== undefined && tomb >= itemStamp(winner)) {
      // Deleted at/after the last edit — keep it deleted.
      if (l && remoteTombs.has(id) && !localTombs.has(id)) merged = true;
      continue;
    }
    items.push(winner);
  }

  const now = Math.floor(Date.now() / 1000);
  const deleted = [...tombs.entries()]
    .filter(([, at]) => at > now - TOMBSTONE_MAX_AGE)
    .sort((a, b) => b[1] - a[1])
    .slice(0, TOMBSTONE_CAP)
    .map(([id, at]) => ({ id, at }));

  return { stash: { items, deleted, updatedAt: now }, merged };
}

/**
 * Hook to manage user's private gear stash
 * Uses NIP-44 encryption to store items privately
 */
/**
 * @param options.enabled  When false, the stash is NOT fetched/decrypted. Used
 *   by callers that mount this hook only for its data-access API (e.g. the
 *   global Sasquatch assistant via usePersonalContext) but must NOT trigger a
 *   decrypt — with Amber every decrypt is a popup, and this hook used to fire on
 *   every page because Sasquatch is mounted in the app-wide Layout. Defaults to
 *   true so the actual Stash page still loads normally. When disabled, `stash`
 *   still resolves from any previously-cached decrypt (React Query cache).
 */
export function useStash(options?: { enabled?: boolean }) {
  const { nostr } = useNostr();
  const { user } = useCurrentUser();
  const { logins } = useNostrLogin();
  const queryClient = useQueryClient();
  const { mutateAsync: createEvent } = useNostrPublish();

  const callerEnabled = options?.enabled ?? true;

  // Determine if nip44 is safely available WITHOUT touching any throwing getter.
  const hasNip44 = useMemo(() => checkNip44(user, logins), [user, logins]);
  // Amber prompts on the stash decrypt — keep it from re-running on window focus
  // (e.g. every time Amber hands focus back) so it decrypts once, not repeatedly.
  const interactive = isInteractiveSigner(user, logins);

  // Fetch and decrypt stash
  const { data: stash, isLoading, error } = useQuery({
    queryKey: ['stash', user?.pubkey],
    queryFn: async ({ signal }): Promise<Stash> => {
      if (!user?.pubkey || !hasNip44) {
        return { items: [], updatedAt: 0 };
      }
      const pubkey = user.pubkey;

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

      // Decrypt handle first — an absent/broken signer means "no stash", not a crash.
      let nip44Dec: typeof user.signer.nip44;
      try { nip44Dec = user.signer?.nip44; } catch { return { items: [], updatedAt: 0 }; }
      if (!nip44Dec) return { items: [], updatedAt: 0 };

      // Prefer the live event; if the relays are unreachable (offline / outage)
      // fall back to the encrypted copy we cached locally — decrypting needs no
      // network, so the stash still works at the skatepark.
      let event: NostrEvent | undefined;
      try {
        const events = await nostr.query([{
          kinds: [STASH_KIND],
          authors: [pubkey],
          '#d': [STASH_D_TAG],
          limit: 1,
        }], { signal: combinedSignal });
        event = events[0];
      } catch {
        // offline — the cache below covers it
      }
      if (!event) event = await getCachedStashEvent(pubkey);
      if (!event) return { items: [], updatedAt: 0 };

      // Keep the ciphertext for next time.
      cacheStashEvent(pubkey, event).catch(() => {});

      try {
        // Decrypt the content (encrypted to self).
        const decrypted = await nip44Dec.decrypt(pubkey, event.content);
        return JSON.parse(decrypted) as Stash;
      } catch (err) {
        console.error('[Stash] Failed to decrypt stash:', err);
        return { items: [], updatedAt: 0 };
      }
    },
    enabled: callerEnabled && !!user?.pubkey && hasNip44,
    staleTime: interactive ? Infinity : 60000,
    // Keep the decrypted stash in memory for the session so navigating away and
    // back doesn't re-open Amber (gcTime would otherwise evict it after 5 min).
    gcTime: interactive ? Infinity : undefined,
    refetchOnMount: !interactive,
    refetchOnWindowFocus: false,
    refetchOnReconnect: !interactive,
  });

  /**
   * Re-fetch + decrypt the freshest stash from relays RIGHT BEFORE a mutation,
   * rather than trusting the `stash` closure value.
   *
   * Why this matters (data-safety): the stash is one replaceable event whose
   * content is the WHOLE list. Every add/update/remove rewrites that entire
   * event. If we based the new list on a stale or not-yet-decrypted `stash`
   * (which is legitimately `undefined` early, and — with Amber — may never have
   * been decrypted because the query is gated / `staleTime: Infinity`), we'd
   * publish a list missing everything the closure didn't know about and
   * silently wipe the user's gear. So we always rebuild from a fresh decrypt.
   *
   * Falls back to the cached query data, then to an empty stash, only if the
   * live fetch genuinely returns nothing.
   */
  const fetchLatestStash = useCallback(async (): Promise<{ stash: Stash; confirmed: boolean }> => {
    const fallback: Stash =
      queryClient.getQueryData<Stash>(['stash', user?.pubkey ?? '']) ??
      stash ?? { items: [], updatedAt: 0 };

    if (!user?.pubkey || !hasNip44) return { stash: fallback, confirmed: false };

    let nip44Dec: typeof user.signer.nip44;
    try { nip44Dec = user.signer?.nip44; } catch { nip44Dec = undefined; }
    if (!nip44Dec) {
      // Can't decrypt now — return what we have, flagged unconfirmed so the
      // caller refuses to write rather than risk a clobber.
      return { stash: fallback, confirmed: false };
    }

    // `confirmed` means a relay actually answered this read. It's the signal the
    // callers use to decide whether a write is safe (see assertConfirmed).
    let confirmed = false;
    let event: NostrEvent | undefined;
    try {
      const events = await nostr.query([{
        kinds: [STASH_KIND],
        authors: [user.pubkey],
        '#d': [STASH_D_TAG],
        limit: 1,
      }], { signal: AbortSignal.timeout(10000) });
      event = events[0];
      confirmed = true; // the relay answered (possibly with "nothing")
    } catch {
      // unreachable — fall through to the cached ciphertext
    }
    if (!event) event = await getCachedStashEvent(user.pubkey);

    if (!event) {
      // No stash anywhere: safe to start fresh, but only "confirmed" if the
      // relay actually answered.
      return { stash: fallback, confirmed };
    }

    cacheStashEvent(user.pubkey, event).catch(() => {});
    const remote = JSON.parse(await nip44Dec.decrypt(user.pubkey, event.content)) as Stash;

    // Multi-device conflict guard. The list we already hold (React Query cache,
    // then the hook's closure) can contain items the relay doesn't have yet —
    // most commonly edits that were made a moment ago. Merge rather than let the
    // remote silently overwrite them; deletes still win via tombstones. On a
    // single device this is always a no-op.
    const known = queryClient.getQueryData<Stash>(['stash', user.pubkey]) ?? stash;
    if (known) {
      const { stash: mergedStash, merged } = mergeStashes(known, remote);
      if (merged) {
        toast({
          title: 'Merged changes from another device',
          description: 'Your stash was edited elsewhere — both sets of changes were kept.',
        });
      }
      return { stash: mergedStash, confirmed };
    }
    return { stash: remote, confirmed };
  }, [user, hasNip44, nostr, queryClient, stash]);

  /**
   * Stash writes rewrite the WHOLE blob, so they must run against a just-read
   * relay copy for the merge above to protect other devices' changes. If the
   * relay couldn't be reached we refuse the write instead of letting
   * `useNostrPublish` queue it: a queued blob is published later as-is, and
   * could silently overwrite an edit another device made meanwhile. (Reads still
   * work offline — only writes need a connection.)
   */
  const assertConfirmed = (confirmed: boolean) => {
    if (!confirmed) {
      throw new Error("Couldn't reach the relays. Reconnect and try again — saving now could overwrite a newer change from another device.");
    }
  };

  // Save stash (encrypt and publish)
  const saveStash = useCallback(async (newStash: Stash) => {
    if (!user?.pubkey || !hasNip44) {
      throw new Error('Encryption not available');
    }

    // Access nip44 inside a try/catch at call time (signer is guaranteed by hasNip44 above)
    let nip44Enc: typeof user.signer.nip44;
    try { nip44Enc = user.signer?.nip44; } catch { throw new Error('Encryption not available'); }
    if (!nip44Enc) throw new Error('Encryption not available');

    // Encrypt to self
    const encrypted = await nip44Enc.encrypt(user.pubkey, JSON.stringify(newStash));

    // Publish as replaceable event
    await createEvent({
      kind: STASH_KIND,
      content: encrypted,
      tags: [
        ['d', STASH_D_TAG],
        ['alt', 'Private gear stash (encrypted)'],
      ],
    });

    // Keep the cache in sync with exactly what we just published, then invalidate.
    queryClient.setQueryData(['stash', user.pubkey], newStash);
    queryClient.invalidateQueries({ queryKey: ['stash', user.pubkey] });
  }, [user, hasNip44, createEvent, queryClient]);

  // Add item mutation
  const addItem = useMutation({
    mutationFn: async (item: Omit<StashItem, 'id' | 'addedAt'>) => {
      const { stash: currentStash, confirmed } = await fetchLatestStash();
      assertConfirmed(confirmed);
      const now = Math.floor(Date.now() / 1000);
      const newItem: StashItem = {
        ...item,
        id: crypto.randomUUID(),
        addedAt: now,
        updatedAt: now,
      };

      const newStash: Stash = {
        items: [...currentStash.items, newItem],
        deleted: currentStash.deleted,
        updatedAt: now,
      };

      await saveStash(newStash);
      return newItem;
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['stash', user?.pubkey] });
    },
  });

  // Update item mutation
  const updateItem = useMutation({
    mutationFn: async (item: StashItem) => {
      const { stash: currentStash, confirmed } = await fetchLatestStash();
      assertConfirmed(confirmed);
      const now = Math.floor(Date.now() / 1000);
      const stamped: StashItem = { ...item, updatedAt: now };
      const newStash: Stash = {
        items: currentStash.items.map(i => i.id === item.id ? stamped : i),
        deleted: currentStash.deleted,
        updatedAt: now,
      };

      await saveStash(newStash);
      return stamped;
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['stash', user?.pubkey] });
    },
  });

  // Remove item mutation
  const removeItem = useMutation({
    mutationFn: async (itemId: string) => {
      const { stash: currentStash, confirmed } = await fetchLatestStash();
      assertConfirmed(confirmed);
      const now = Math.floor(Date.now() / 1000);
      const newStash: Stash = {
        items: currentStash.items.filter(i => i.id !== itemId),
        // Record the delete so a merge with another device's stale copy can't
        // resurrect it.
        deleted: [...(currentStash.deleted ?? []), { id: itemId, at: now }],
        updatedAt: now,
      };

      await saveStash(newStash);
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['stash', user?.pubkey] });
    },
  });

  // Bulk import (Export/Import) — append items, skipping obvious duplicates, in
  // ONE re-encrypt + publish rather than N.
  const importItems = useMutation({
    mutationFn: async (items: Array<Omit<StashItem, 'id' | 'addedAt'>>) => {
      const { stash: currentStash, confirmed } = await fetchLatestStash();
      assertConfirmed(confirmed);
      const keyOf = (i: { title: string; category: string; size?: string }) =>
        `${i.title.trim().toLowerCase()}|${i.category}|${(i.size ?? '').trim().toLowerCase()}`;
      const have = new Set(currentStash.items.map(keyOf));
      const now = Math.floor(Date.now() / 1000);

      const fresh: StashItem[] = [];
      for (const raw of items) {
        if (!raw?.title || !raw?.category) continue;
        const key = keyOf({ title: raw.title, category: raw.category, size: raw.size });
        if (have.has(key)) continue;
        have.add(key);
        fresh.push({ ...raw, id: crypto.randomUUID(), addedAt: now, updatedAt: now });
      }

      if (fresh.length === 0) return { added: 0, skipped: items.length };
      await saveStash({ items: [...currentStash.items, ...fresh], deleted: currentStash.deleted, updatedAt: now });
      return { added: fresh.length, skipped: items.length - fresh.length };
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['stash', user?.pubkey] });
    },
  });

  // Bulk actions — apply to many items in ONE re-encrypt + publish.
  const bulkSetVisibility = useMutation({
    mutationFn: async ({ ids, visibility }: { ids: string[]; visibility: StashItem['visibility'] }) => {
      const { stash: current, confirmed } = await fetchLatestStash();
      assertConfirmed(confirmed);
      const now = Math.floor(Date.now() / 1000);
      const changed: StashItem[] = [];
      const next = current.items.map((i) => {
        if (!ids.includes(i.id)) return i;
        const updated = { ...i, visibility, updatedAt: now };
        changed.push(updated);
        return updated;
      });
      await saveStash({ items: next, deleted: current.deleted, updatedAt: now });
      return { changed };
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['stash', user?.pubkey] });
    },
  });

  const bulkSetForSale = useMutation({
    mutationFn: async ({ ids, forSale }: { ids: string[]; forSale: boolean }) => {
      const { stash: current, confirmed } = await fetchLatestStash();
      assertConfirmed(confirmed);
      const now = Math.floor(Date.now() / 1000);
      const changed: StashItem[] = [];
      const next = current.items.map((i) => {
        if (!ids.includes(i.id)) return i;
        const updated = { ...i, willingToSell: forSale, updatedAt: now };
        changed.push(updated);
        return updated;
      });
      await saveStash({ items: next, deleted: current.deleted, updatedAt: now });
      return { changed };
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['stash', user?.pubkey] });
    },
  });

  const bulkRemove = useMutation({
    mutationFn: async (ids: string[]) => {
      const { stash: current, confirmed } = await fetchLatestStash();
      assertConfirmed(confirmed);
      const now = Math.floor(Date.now() / 1000);
      const removed = current.items.filter((i) => ids.includes(i.id));
      await saveStash({
        items: current.items.filter((i) => !ids.includes(i.id)),
        deleted: [...(current.deleted ?? []), ...removed.map((i) => ({ id: i.id, at: now }))],
        updatedAt: now,
      });
      return { removed };
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['stash', user?.pubkey] });
    },
  });

  // Stats for RPG display
  const stats = useMemo(() => {
    if (!stash) return { total: 0, byCategory: {}, totalValue: 0 };

    const byCategory: Record<string, number> = {};
    let totalValue = 0;

    for (const item of stash.items) {
      byCategory[item.category] = (byCategory[item.category] || 0) + 1;
      if (item.minPrice) totalValue += item.minPrice;
    }

    return {
      total: stash.items.length,
      byCategory,
      totalValue,
    };
  }, [stash]);

  return {
    stash,
    items: stash?.items || [],
    stats,
    isLoading,
    error,
    addItem,
    updateItem,
    removeItem,
    importItems,
    bulkSetVisibility,
    bulkSetForSale,
    bulkRemove,
    isEncryptionAvailable: hasNip44,
  };
}

// Category metadata for RPG display
export const STASH_CATEGORIES = {
  deck: { emoji: '🛹', label: 'Decks', color: '#ff0040', rarity: 'common' },
  trucks: { emoji: '🔧', label: 'Trucks', color: '#ff6600', rarity: 'common' },
  wheels: { emoji: '⚙️', label: 'Wheels', color: '#ccff00', rarity: 'common' },
  bearings: { emoji: '🔩', label: 'Bearings', color: '#00ff88', rarity: 'uncommon' },
  shoes: { emoji: '👟', label: 'Shoes', color: '#00ccff', rarity: 'uncommon' },
  clothing: { emoji: '👕', label: 'Clothing', color: '#9933ff', rarity: 'common' },
  protective: { emoji: '🛡️', label: 'Protective', color: '#ff33cc', rarity: 'rare' },
  complete: { emoji: '🎯', label: 'Completes', color: '#ffd700', rarity: 'epic' },
  other: { emoji: '📦', label: 'Other', color: '#888888', rarity: 'common' },
} as const;

export const CONDITION_LABELS = {
  new: { label: '🆕 New', color: '#00ff00', stars: 5 },
  like_new: { label: '✨ Like New', color: '#ccff00', stars: 4 },
  good: { label: '👍 Good', color: '#ffcc00', stars: 3 },
  well_used: { label: '⚠️ Well Used', color: '#ff6600', stars: 2 },
} as const;

// RPG-style rarity tiers with multipliers for XP
export const RARITY_TIERS = {
  common: { label: 'Common', color: '#9ca3af', xpMultiplier: 1, bgGradient: 'from-gray-500/20 to-gray-600/20' },
  uncommon: { label: 'Uncommon', color: '#22c55e', xpMultiplier: 1.5, bgGradient: 'from-green-500/20 to-emerald-600/20' },
  rare: { label: 'Rare', color: '#3b82f6', xpMultiplier: 2, bgGradient: 'from-blue-500/20 to-indigo-600/20' },
  epic: { label: 'Epic', color: '#a855f7', xpMultiplier: 3, bgGradient: 'from-purple-500/20 to-violet-600/20' },
  legendary: { label: 'Legendary', color: '#fbbf24', xpMultiplier: 5, bgGradient: 'from-yellow-400/20 to-orange-500/20' },
} as const;

// Calculate player level based on total items and value
export function calculateSkaterLevel(stats: { total: number; totalValue: number; byCategory: Record<string, number> }): {
  level: number;
  currentXP: number;
  xpToNextLevel: number;
  title: string;
  progress: number;
} {
  // XP formula: 100 per item + value/100
  const xp = stats.total * 100 + Math.floor(stats.totalValue / 100);
  
  // Level formula: sqrt(xp/100)
  const level = Math.max(1, Math.floor(Math.sqrt(xp / 100)));
  
  const xpForCurrentLevel = level * level * 100;
  const xpForNextLevel = (level + 1) * (level + 1) * 100;
  
  const currentXP = xp - xpForCurrentLevel;
  const xpToNextLevel = xpForNextLevel - xpForCurrentLevel;
  const progress = Math.min(100, (currentXP / xpToNextLevel) * 100);
  
  // Titles based on level
  const titles: Record<number, string> = {
    1: 'Grom',
    2: 'Pusher',
    3: 'Street Rat',
    5: 'Park Local',
    8: 'Session Regular',
    12: 'Spot Hunter',
    15: 'Gear Head',
    20: 'Skate Collector',
    25: 'Board Hoarder',
    30: 'Stash Master',
    50: 'Legendary Collector',
  };
  
  let title = 'Grom';
  for (const [lvl, t] of Object.entries(titles)) {
    if (level >= parseInt(lvl)) title = t;
  }
  
  return { level, currentXP, xpToNextLevel, title, progress };
}