1 files changed, 67 insertions, 0 deletions
diff --git a/packages/contracts/src/utils/asset_proxy_utils.ts b/packages/contracts/src/utils/asset_proxy_utils.ts
new file mode 100644
index 000000000..938110a75
--- /dev/null
+++ b/packages/contracts/src/utils/asset_proxy_utils.ts
@@ -0,0 +1,67 @@
+import { BigNumber } from '@0xproject/utils';
+import * as Web3 from 'web3';
+
+import { AssetProxyId } from './types';
+const ethersUtils = require('ethers-utils');
+
+export function zeroPad(value: string, width: number): string {
+    return '0'.repeat(width - value.length) + value;
+}
+
+export function encodeAssetProxyId(assetProxyId: AssetProxyId, encoded_metadata: { value: string }) {
+    encoded_metadata.value += zeroPad(new BigNumber(assetProxyId).toString(16), 2);
+}
+
+export function encodeAddress(address: string, encoded_metadata: { value: string }) {
+    encoded_metadata.value += zeroPad(address.replace('0x', ''), 40);
+}
+
+export function encodeUint256(value: BigNumber, encoded_metadata: { value: string }) {
+    encoded_metadata.value += zeroPad(value.toString(16), 64);
+}
+
+export function encodeERC20ProxyMetadata_V1(tokenAddress: string) {
+    // Encode metadata
+    const encoded_metadata = { value: '0x' };
+    encodeAssetProxyId(AssetProxyId.ERC20_V1, encoded_metadata);
+    encodeAddress(tokenAddress, encoded_metadata);
+
+    // Verify encoding length - '0x' plus 21 bytes of encoded data
+    if (encoded_metadata.value.length != 44) {
+        throw Error('Bad encoding length. Expected 44, got ' + encoded_metadata.value.length);
+    }
+
+    // Return encoded metadata
+    return encoded_metadata.value;
+}
+
+export function encodeERC20ProxyMetadata(tokenAddress: string) {
+    // Encode metadata
+    const encoded_metadata = { value: '0x' };
+    encodeAssetProxyId(AssetProxyId.ERC20, encoded_metadata);
+    encodeAddress(tokenAddress, encoded_metadata);
+
+    // Verify encoding length - '0x' plus 21 bytes of encoded data
+    if (encoded_metadata.value.length != 44) {
+        throw Error('Bad encoding length. Expected 44, got ' + encoded_metadata.value.length);
+    }
+
+    // Return encoded metadata
+    return encoded_metadata.value;
+}
+
+export function encodeERC721ProxyMetadata(tokenAddress: string, tokenId: BigNumber) {
+    // Encode metadata
+    const encoded_metadata = { value: '0x' };
+    encodeAssetProxyId(AssetProxyId.ERC721, encoded_metadata);
+    encodeAddress(tokenAddress, encoded_metadata);
+    encodeUint256(tokenId, encoded_metadata);
+
+    // Verify encoding length - '0x' plus 53 bytes of encoded data
+    if (encoded_metadata.value.length != 108) {
+        throw Error('Bad encoding length. Expected 108, got ' + encoded_metadata.value.length);
+    }
+
+    // Return encoded metadata
+    return encoded_metadata.value;
+}