From 4a7a39de85a30cb17b262038945dd78af214d918 Mon Sep 17 00:00:00 2001
From: James Sangalli <j.l.sangalli@gmail.com>
Date: Mon, 12 Feb 2018 21:38:47 +0800
Subject: [PATCH] Create TradeImplementationExample.java

---
 TradeImplementationExample.java | 127 ++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 TradeImplementationExample.java

diff --git a/TradeImplementationExample.java b/TradeImplementationExample.java
new file mode 100644
index 0000000..63f09eb
--- /dev/null
+++ b/TradeImplementationExample.java
@@ -0,0 +1,127 @@
+package tapi.utils;
+
+import org.web3j.crypto.ECKeyPair;
+import org.web3j.crypto.Sign;
+import java.math.BigInteger;
+import java.nio.ByteBuffer;
+import java.nio.ShortBuffer;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by sangalli on 12/2/18.
+ */
+
+class TransactionDetails
+{
+    BigInteger value;
+    List<BigInteger> ticketIndices;
+    Sign.SignatureData signatureData;
+}
+
+public class TradeImplementationExample 
+{
+
+    private static final String contractAddress = "fFAB5Ce7C012bc942F5CA0cd42c3C2e1AE5F0005";
+
+    public static void main(String[] args)
+    {
+        short[] ticketPlaces = new short[]{3, 4};
+        //zero timestamp means unlimited
+        byte[] msg = encodeMessageForTrade(BigInteger.ONE, BigInteger.ZERO, ticketPlaces);
+        List<BigInteger> indices = new ArrayList<>();
+        for(int i = 0; i < ticketPlaces.length; i++)
+        {
+            indices.add(BigInteger.valueOf(ticketPlaces[i]));
+        }
+        TransactionDetails td = createTrade(msg, indices, BigInteger.ONE);
+
+        System.out.println("Price: 1 ");
+        System.out.println("expiry: 0 (does not expiry)");
+        System.out.println("Signature v value: " + td.signatureData.getV());
+        System.out.println("Signature r value: 0x" + bytesToHex(td.signatureData.getR()));
+        System.out.println("Signature s value: 0x" + bytesToHex(td.signatureData.getS()));
+        System.out.println("Ticket indices: 3, 4");
+    }
+
+    public static byte[] encodeMessageForTrade(BigInteger price, BigInteger expiryTimestamp, short[] tickets)
+    {
+        byte[] priceInWei = price.toByteArray();
+        byte[] expiry = expiryTimestamp.toByteArray();
+        ByteBuffer message = ByteBuffer.allocate(96 + tickets.length * 2);
+        byte[] leadingZeros = new byte[32 - priceInWei.length];
+        message.put(leadingZeros);
+        message.put(priceInWei);
+        byte[] leadingZerosExpiry = new byte[32 - expiry.length];
+        message.put(leadingZerosExpiry);
+        message.put(expiry);
+        byte[] prefix = "ERC800-CNID1".getBytes();
+        byte[] contract = hexStringToBytes(contractAddress);
+        message.put(prefix);
+        message.put(contract);
+        ShortBuffer shortBuffer = message.slice().asShortBuffer();
+        shortBuffer.put(tickets);
+
+        return message.array();
+    }
+
+    private static String bytesToHex(byte[] bytes)
+    {
+        final char[] hexArray = "0123456789ABCDEF".toCharArray();
+        char[] hexChars = new char[bytes.length * 2];
+        for ( int j = 0; j < bytes.length; j++ )
+        {
+            int v = bytes[j] & 0xFF;
+            hexChars[j * 2] = hexArray[v >>> 4];
+            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
+        }
+        String finalHex = new String(hexChars);
+        return finalHex;
+    }
+
+    private static byte[] hexStringToBytes(String s)
+    {
+        int len = s.length();
+        byte[] data = new byte[len / 2];
+        for (int i = 0; i < len; i += 2)
+        {
+            data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+                    + Character.digit(s.charAt(i + 1), 16));
+        }
+        return data;
+    }
+
+    public static TransactionDetails createTrade(byte[] message, List<BigInteger> indices, BigInteger price)
+    {
+        try
+        {
+            //Note: you can replace with your own key instead of using same key generated from BigInteger.ONE
+            Sign.SignatureData sigData = Sign.signMessage(message,
+                    ECKeyPair.create(BigInteger.ONE));
+            TransactionDetails TransactionDetails = new TransactionDetails();
+            TransactionDetails.ticketIndices = indices;
+            TransactionDetails.value = price;
+
+            byte v = sigData.getV();
+
+            String hexR = bytesToHex(sigData.getR());
+            String hexS = bytesToHex(sigData.getS());
+
+            byte[] rBytes = hexStringToBytes(hexR);
+            byte[] sBytes = hexStringToBytes(hexS);
+
+            BigInteger r = new BigInteger(rBytes);
+            BigInteger s = new BigInteger(sBytes);
+
+            TransactionDetails.signatureData = new Sign.SignatureData(v, r.toByteArray(), s.toByteArray());
+
+            return TransactionDetails;
+        }
+        catch(Exception e)
+        {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+}