fix: Correct bag threshold display with CurrencyToVote conversion (#12058)

* fix: bag threshold display with CurrencyToVote conversion

* chore: update comments

Author: rajk93

packages/page-staking/src/Bags/useBagsList.ts

@@ -6,9 +6,9 @@ import type { PalletBagsListListBag } from '@polkadot/types/lookup';
 import type { BN } from '@polkadot/util';
 import type { BagInfo } from './types.js';
 
-import { useEffect, useState } from 'react';
+import { useEffect, useMemo, useState } from 'react';
 
-import { createNamedHook, useCall, useMapKeys } from '@polkadot/react-hooks';
+import { createNamedHook, useApi, useCall, useCurrencyToVote, useMapKeys } from '@polkadot/react-hooks';
 import { BN_ZERO } from '@polkadot/util';
 
 import useQueryModule from './useQueryModule.js';
@@ -54,13 +54,39 @@ function merge (prev: BagInfo[] | undefined, curr: BagInfo[]): BagInfo[] {
 
 function useBagsListImpl (): BagInfo[] | undefined {
   const mod = useQueryModule();
+  const { api } = useApi();
+  const { toCurrency } = useCurrencyToVote();
   const [result, setResult] = useState<BagInfo[] | undefined>();
   const ids = useMapKeys(mod.listBags, [], KEY_OPTS);
   const query = useCall(ids && ids.length !== 0 && mod.listBags.multi, [ids], MULTI_OPTS);
 
+  const converted = useMemo(
+    () => {
+      if (!query || query.length === 0) {
+        return undefined;
+      }
+
+      // Westend Asset Hub uses SaturatingCurrencyToVote (no conversion needed)
+      // See: https://github.com/paritytech/polkadot-sdk/pull/8307
+      const chainName = api.runtimeChain.toString().toLowerCase();
+      const isWestendAssetHub = chainName.includes('westend') && chainName.includes('asset');
+
+      if (isWestendAssetHub) {
+        return query;
+      }
+
+      return query.map((bag) => ({
+        ...bag,
+        bagLower: toCurrency(bag.bagLower),
+        bagUpper: toCurrency(bag.bagUpper)
+      }));
+    },
+    [api.runtimeChain, query, toCurrency]
+  );
+
   useEffect((): void => {
-    query && setResult((prev) => merge(prev, query));
-  }, [query]);
+    converted && setResult((prev) => merge(prev, converted));
+  }, [converted]);
 
   return result;
 }

packages/react-hooks/src/index.ts

@@ -38,6 +38,7 @@ export { useCoreDescriptor } from './useCoreDescriptor.js';
 export { useCoretimeConsts } from './useCoretimeConsts.js';
 export { useCoretimeEndpoint } from './useCoretimeEndpoint.js';
 export { useCoretimeInformation } from './useCoretimeInformation.js';
+export { useCurrencyToVote } from './useCurrencyToVote.js';
 export { useDebounce } from './useDebounce.js';
 export { useDelegations } from './useDelegations.js';
 export { useDeriveAccountFlags } from './useDeriveAccountFlags.js';

packages/react-hooks/src/useCurrencyToVote.ts

@@ -0,0 +1,58 @@
+// Copyright 2017-2025 @polkadot/react-hooks authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import { useMemo } from 'react';
+
+import { BN, BN_ONE } from '@polkadot/util';
+
+import { createNamedHook } from './createNamedHook.js';
+import { useApi } from './useApi.js';
+import { useCall } from './useCall.js';
+
+// u64::MAX = 2^64 - 1 = 18,446,744,073,709,551,615
+const U64_MAX = new BN('18446744073709551615');
+
+interface CurrencyToVote {
+  // The factor to convert from currency to vote
+  factor: BN;
+  // Convert a currency balance to voting power
+  toVote: (balance: BN) => BN;
+  // Convert voting power back to currency balance
+  toCurrency: (vote: BN) => BN;
+}
+
+/**
+ * Calculate the CurrencyToVote factor based on total issuance.
+ *
+ * - If total_issuance < 2^64, then factor = 1 (no conversion needed)
+ * - If total_issuance >= 2^64, then factor = (total_issuance / 2^64).max(1)
+ *
+ * The conversion formulas is:
+ * - vote = balance / factor
+ */
+function calculateFactor (totalIssuance: BN): BN {
+  if (totalIssuance.lte(U64_MAX)) {
+    return BN_ONE;
+  }
+
+  const factor = totalIssuance.div(U64_MAX);
+
+  return factor.isZero() ? BN_ONE : factor;
+}
+
+function useCurrencyToVoteImpl (): CurrencyToVote {
+  const { api } = useApi();
+  const totalIssuance = useCall<BN>(api.query.balances?.totalIssuance);
+
+  return useMemo((): CurrencyToVote => {
+    const factor = totalIssuance ? calculateFactor(totalIssuance) : BN_ONE;
+
+    return {
+      factor,
+      toCurrency: (vote: BN) => vote.mul(factor),
+      toVote: (balance: BN) => balance.div(factor)
+    };
+  }, [totalIssuance]);
+}
+
+export const useCurrencyToVote = createNamedHook('useCurrencyToVote', useCurrencyToVoteImpl);