In the previous chapter, your first bot just worked. The bot echo message from user.

Receive and send Bitcoin in Mixin Messenger

Add new "Case-condition" in switch block of the App.java

App.java

switch (category) {
...
case SYSTEM_ACCOUNT_SNAPSHOT:
    userId =
      obj.get("data").getAsJsonObject().get("user_id").getAsString();
    byte[] JsData = Base64.decodeBase64(obj.get("data").getAsJsonObject().get("data").getAsString());
    String JsStr = new String(JsData);
    System.out.println("SYSTEM_ACCOUNT_SNAPSHOT json: " + JsStr);
    JsonObject jsObj = new JsonParser().parse(JsStr).getAsJsonObject();
    System.out.println(jsObj.get("amount").getAsString());
    System.out.println(jsObj.get("asset_id").getAsString());
    if (jsObj.get("amount").getAsFloat() > 0) {
      String aesKey = new String (Base64.encodeBase64(Config.PAY_KEY));
      System.out.println(aesKey);
      System.out.println(Config.PAY_KEY.length);
      String encryptPin = MixinUtil.encryptPayKey(Config.PIN,Config.PAY_KEY);
      MixinBot.transfer(
          jsObj.get("asset_id").getAsString(),
          jsObj.get("opponent_id").getAsString(),
          jsObj.get("amount").getAsString(),
          encryptPin,
          Config.RSA_PRIVATE_KEY,
          Config.CLIENT_ID,
          Config.SESSION_ID
      );
    }
    break;
...

Hello Bitcoin!

Execute gradle run in the project directory.

response:Response{protocol=http/1.1, code=101, message=Switching Protocols, url=https://blaze.mixin.one/}
[onMessage !!!]
json: {"id":"712fbde1-1b72-4e8f-b731-b7dc6f689c3e","action":"LIST_PENDING_MESSAGES"}
LIST_PENDING_MESSAGES
<=========----> 75% EXECUTING [13s]
> :run

Developer can send Bitcoin to their bots in chatting page. The bot will send Bitcoin back immediately after receive it. transfer and tokens

User can pay 0.001 Bitcoin to bot by click the button and the 0.001 Bitcoin will be refunded in 1 second. In fact, user can pay any coin. pay-link

Source code summary

if (jsObj.get("amount").getAsFloat() > 0) {
  String encryptPin = MixinUtil.encryptPayKey(Config.PIN,Config.PAY_KEY);
  MixinBot.transfer(
      jsObj.get("asset_id").getAsString(),
      jsObj.get("opponent_id").getAsString(),
      jsObj.get("amount").getAsString(),
      encryptPin,
      Config.RSA_PRIVATE_KEY,
      Config.CLIENT_ID,
      Config.SESSION_ID
  );
}

jsObj.get("amount") is negative if bot sends Bitcoin to user successfully.
jsObj.get("amount") is positive if bot receives Bitcoin from user. Call MixinBot.transfer to refund the coins back to user.

Advanced usage

Mixin Messenger provides many APIs so you can enable user to pay coins to bot.

Send AppCard

Send a link which contains icon, title and description, users click the icon to pay.

if (msgP.toLowerCase().equals("pay")) {
  MixinBot.sendAppCard(webSocket,
                      Config.CLIENT_ID,
                      "6cfe566e-4aad-470b-8c9a-2fd35b49c68d",
                      "0.0001",
                      conversationId);
}

Send Button Group

Create a group of buttons for user, users click one button to pay.

else if (msgP.toLowerCase().equals("appsgroup")) {
  String payLinkEOS = "https://mixin.one/pay?recipient=" +
                 Config.CLIENT_ID  + "&asset=" +
                 "6cfe566e-4aad-470b-8c9a-2fd35b49c68d"   +
                 "&amount=" + "0.1" +
                 "&trace="  + UUID.randomUUID().toString() +
                 "&memo=";
  JsonObject msgJsEOS = new JsonObject();
  msgJsEOS.addProperty("label", "Pay 0.1 EOS");
  msgJsEOS.addProperty("color", "#0080FF");
  msgJsEOS.addProperty("action",payLinkEOS);


  String payLinkBTC = "https://mixin.one/pay?recipient=" +
                 Config.CLIENT_ID  + "&asset=" +
                 "c6d0c728-2624-429b-8e0d-d9d19b6592fa"   +
                 "&amount=" + "0.001" +
                 "&trace="  + UUID.randomUUID().toString() +
                 "&memo=";
  JsonObject msgJsBTC = new JsonObject();
  msgJsBTC.addProperty("label", "Pay 0.001 BTC");
  msgJsBTC.addProperty("color", "#FF8000");
  msgJsBTC.addProperty("action",payLinkBTC);

  JsonArray msgArr = new JsonArray();
  msgArr.add(msgJsEOS);//button for EOS
  msgArr.add(msgJsBTC);//button for Bitcoin

  JsonObject msgParams = new JsonObject();
  msgParams.addProperty("conversation_id",conversationId);
  msgParams.addProperty("category","APP_BUTTON_GROUP");
  msgParams.addProperty("status","SENT");
  msgParams.addProperty("message_id",UUID.randomUUID().toString());
  msgParams.addProperty("data",new String(Base64.encodeBase64(msgArr.toString().getBytes())));

  MixinBot.send(webSocket, MIXIN_Action.CREATE_MESSAGE, msgParams.toString());
}

pay-link