1 files changed, 149 insertions, 0 deletions
diff --git a/packages/order-utils/src/asset_proxy_utils.ts b/packages/order-utils/src/asset_proxy_utils.ts
new file mode 100644
index 000000000..11f81c656
--- /dev/null
+++ b/packages/order-utils/src/asset_proxy_utils.ts
@@ -0,0 +1,149 @@
+import { AssetProxyId, ERC20ProxyData, ERC721ProxyData, ProxyData } from '@0xproject/types';
+import { BigNumber } from '@0xproject/utils';
+import BN = require('bn.js');
+import ethUtil = require('ethereumjs-util');
+
+const ERC20_PROXY_METADATA_BYTE_LENGTH = 21;
+const ERC721_PROXY_METADATA_BYTE_LENGTH = 53;
+
+export const assetProxyUtils = {
+    encodeAssetProxyId(assetProxyId: AssetProxyId): Buffer {
+        return ethUtil.toBuffer(assetProxyId);
+    },
+    decodeAssetProxyId(encodedAssetProxyId: Buffer): AssetProxyId {
+        return ethUtil.bufferToInt(encodedAssetProxyId);
+    },
+    encodeAddress(address: string): Buffer {
+        if (!ethUtil.isValidAddress(address)) {
+            throw new Error(`Invalid Address: ${address}`);
+        }
+        const encodedAddress = ethUtil.toBuffer(address);
+        return encodedAddress;
+    },
+    decodeAddress(encodedAddress: Buffer): string {
+        const address = ethUtil.bufferToHex(encodedAddress);
+        if (!ethUtil.isValidAddress(address)) {
+            throw new Error(`Invalid Address: ${address}`);
+        }
+        return address;
+    },
+    encodeUint256(value: BigNumber): Buffer {
+        const base = 10;
+        const formattedValue = new BN(value.toString(base));
+        const encodedValue = ethUtil.toBuffer(formattedValue);
+        // tslint:disable-next-line:custom-no-magic-numbers
+        const paddedValue = ethUtil.setLengthLeft(encodedValue, 32);
+        return paddedValue;
+    },
+    decodeUint256(encodedValue: Buffer): BigNumber {
+        const formattedValue = ethUtil.bufferToHex(encodedValue);
+        const value = new BigNumber(formattedValue, 16);
+        return value;
+    },
+    encodeERC20ProxyData(tokenAddress: string): string {
+        const encodedAssetProxyId = assetProxyUtils.encodeAssetProxyId(AssetProxyId.ERC20);
+        const encodedAddress = assetProxyUtils.encodeAddress(tokenAddress);
+        const encodedMetadata = Buffer.concat([encodedAssetProxyId, encodedAddress]);
+        const encodedMetadataHex = ethUtil.bufferToHex(encodedMetadata);
+        return encodedMetadataHex;
+    },
+    decodeERC20ProxyData(proxyData: string): ERC20ProxyData {
+        const encodedProxyMetadata = ethUtil.toBuffer(proxyData);
+        if (encodedProxyMetadata.byteLength !== ERC20_PROXY_METADATA_BYTE_LENGTH) {
+            throw new Error(
+                `Could not decode ERC20 Proxy Data. Expected length of encoded data to be 21. Got ${
+                    encodedProxyMetadata.byteLength
+                }`,
+            );
+        }
+        const encodedAssetProxyId = encodedProxyMetadata.slice(0, 1);
+        const assetProxyId = assetProxyUtils.decodeAssetProxyId(encodedAssetProxyId);
+        if (assetProxyId !== AssetProxyId.ERC20) {
+            throw new Error(
+                `Could not decode ERC20 Proxy Data. Expected Asset Proxy Id to be ERC20 (${
+                    AssetProxyId.ERC20
+                }), but got ${assetProxyId}`,
+            );
+        }
+        const encodedTokenAddress = encodedProxyMetadata.slice(1, ERC20_PROXY_METADATA_BYTE_LENGTH);
+        const tokenAddress = assetProxyUtils.decodeAddress(encodedTokenAddress);
+        const erc20ProxyData = {
+            assetProxyId,
+            tokenAddress,
+        };
+        return erc20ProxyData;
+    },
+    encodeERC721ProxyData(tokenAddress: string, tokenId: BigNumber): string {
+        const encodedAssetProxyId = assetProxyUtils.encodeAssetProxyId(AssetProxyId.ERC721);
+        const encodedAddress = assetProxyUtils.encodeAddress(tokenAddress);
+        const encodedTokenId = assetProxyUtils.encodeUint256(tokenId);
+        const encodedMetadata = Buffer.concat([encodedAssetProxyId, encodedAddress, encodedTokenId]);
+        const encodedMetadataHex = ethUtil.bufferToHex(encodedMetadata);
+        return encodedMetadataHex;
+    },
+    decodeERC721ProxyData(proxyData: string): ERC721ProxyData {
+        const encodedProxyMetadata = ethUtil.toBuffer(proxyData);
+        if (encodedProxyMetadata.byteLength !== ERC721_PROXY_METADATA_BYTE_LENGTH) {
+            throw new Error(
+                `Could not decode ERC20 Proxy Data. Expected length of encoded data to be 53. Got ${
+                    encodedProxyMetadata.byteLength
+                }`,
+            );
+        }
+        const encodedAssetProxyId = encodedProxyMetadata.slice(0, 1);
+        const assetProxyId = assetProxyUtils.decodeAssetProxyId(encodedAssetProxyId);
+        if (assetProxyId !== AssetProxyId.ERC721) {
+            throw new Error(
+                `Could not decode ERC721 Proxy Data. Expected Asset Proxy Id to be ERC721 (${
+                    AssetProxyId.ERC721
+                }), but got ${assetProxyId}`,
+            );
+        }
+        const addressOffset = 21;
+        const encodedTokenAddress = encodedProxyMetadata.slice(1, addressOffset);
+        const tokenAddress = assetProxyUtils.decodeAddress(encodedTokenAddress);
+        const encodedTokenId = encodedProxyMetadata.slice(addressOffset, ERC721_PROXY_METADATA_BYTE_LENGTH);
+        const tokenId = assetProxyUtils.decodeUint256(encodedTokenId);
+        const erc721ProxyData = {
+            assetProxyId,
+            tokenAddress,
+            tokenId,
+        };
+        return erc721ProxyData;
+    },
+    decodeProxyDataId(proxyData: string): AssetProxyId {
+        const encodedProxyMetadata = ethUtil.toBuffer(proxyData);
+        if (encodedProxyMetadata.byteLength < 1) {
+            throw new Error(
+                `Could not decode Proxy Data. Expected length of encoded data to be at least 1. Got ${
+                    encodedProxyMetadata.byteLength
+                }`,
+            );
+        }
+        const encodedAssetProxyId = encodedProxyMetadata.slice(0, 1);
+        const assetProxyId = assetProxyUtils.decodeAssetProxyId(encodedAssetProxyId);
+        return assetProxyId;
+    },
+    decodeProxyData(proxyData: string): ProxyData {
+        const assetProxyId = assetProxyUtils.decodeProxyDataId(proxyData);
+        switch (assetProxyId) {
+            case AssetProxyId.ERC20:
+                const erc20ProxyData = assetProxyUtils.decodeERC20ProxyData(proxyData);
+                const generalizedERC20ProxyData = {
+                    assetProxyId,
+                    tokenAddress: erc20ProxyData.tokenAddress,
+                };
+                return generalizedERC20ProxyData;
+            case AssetProxyId.ERC721:
+                const erc721ProxyData = assetProxyUtils.decodeERC721ProxyData(proxyData);
+                const generaliedERC721ProxyData = {
+                    assetProxyId,
+                    tokenAddress: erc721ProxyData.tokenAddress,
+                    data: erc721ProxyData.tokenId,
+                };
+                return generaliedERC721ProxyData;
+            default:
+                throw new Error(`Unrecognized asset proxy id: ${assetProxyId}`);
+        }
+    },
+};