index.js

/*global exports*/
var blockies = require("ethereum-blockies");
var web3Utils = require("web3-utils");
var Canvas = require("canvas");

const querystring = require("querystring");

const small = 4;
const medium = 8;
const large = 16;

exports.handler = function blockies_generator(event, context, callback) {
  const request = event.Records[0].cf.request;
  const options = querystring.parse(request.querystring);

  const sizes = { small: small, medium: medium, large: large };

  var size;

  var error_response = {
    status: "400",
    statusDescription: "Error"
  };

  if (!request.uri.includes(".png") || request.uri.includes("img/")) {
    // Assume request is for a landing page asset
    callback(null, request);
    return;
  }

  // This strips out the appending slash and the .png part of the request URI
  const wallet = request.uri
    .substr(1)
    .split(".")[0]
    .toLowerCase();

  if (!web3Utils.isAddress(wallet)) {
    error_response.statusDescription = "Error: Invalid wallet address.";
    callback(null, error_response);
    return;
  }

  if (options.size) {
    if (!sizes.hasOwnProperty(options.size)) {
      error_response.statusDescription = "Error: Invalid size given.";
      callback(null, error_response);
      return;
    }
    size = sizes[options.size];
  } else {
    size = medium;
  }

  const canvas = Canvas.createCanvas(size * 8, size * 8);

  var icon = blockies.render(
    {
      seed: wallet,
      scale: size
    },
    canvas
  );

  var stringIcon = icon
    .toDataURL()
    .replace(/^data:image\/(png|jpg);base64,/, "");

  const response = {
    bodyEncoding: "base64",
    body: stringIcon,
    status: "200",
    statusDescription: "OK",
    headers: {
      "content-type": [{ key: "Content-Type", value: "image/png" }]
    }
  };

  callback(null, response);
};