thumbnail.js

var exports = module.exports = {};
var child = require('child_process');
var fs = require('fs');

exports.save = function save(gistId, imageData, token, cb) {
  // imageData is base64 encoded. TODO: more efficient transport?
  var data = {
    id: gistId,
    image: imageData,
    token: token
  };

  // 4 steps to add thumbnail:
  // 1) clone gist
  // 2) write image to same folder
  // 3) commit
  // 4) push

  cleanGist(data, function(err) {
    if (err) return cb(err);
    gitClone(data, function(err) {
      if (err) return cb(err);
      writeImage(data, function(err) {
        if (err) return cb(err);
        gitCommit(data, function(err) {
          if (err) return cb(err);
          gitPush(data, function(err) {
            if (err) return cb(err);
            cleanGist(data, cb);
          });
        });
      });
    });
  });
};

// Big ups to gistup! https://github.com/mbostock/gistup/blob/master/bin/gistup
function gitClone(data, cb) {
  // we need to use our token to avoid rate limiting
  // https://github.com/blog/1270-easier-builds-and-deployments-using-git-over-https-and-oauth
  // TODO: switch to using git init and putting token in pull url (to avoid token being written to disk)
  // var url = "https://" + data.token + "@gist.github.com/" + data.id + ".git"
  var url = "https://gist.github.com/" + data.id + ".git";
  console.log("cloning", url);
  child.exec("cd /tmp; git clone " + url, function(error, stdout, stderr) {
    if (!error && stderr && stderr.toLowerCase().indexOf("error") >= 0) {
      process.stderr.write(stderr);
      error = new Error("git clone failed: ", data.id);
    } else if (stderr) { process.stdout.write(stderr); }
    if (!error && stdout) process.stdout.write(stdout);
    cb(error);
  });
}
function gitCommit(data, cb) {
  console.log("adding and commiting thumbnail", data.id);
  var author = '"Building blocks <enjalot+buildingblocks@gmail.com>"';
  child.exec("cd /tmp/" + data.id + "; git add thumbnail.png; git commit --author " + author + " -m 'update thumbnail.png'", function(error, stdout, stderr) {
    if (!error && stderr && stderr.toLowerCase().indexOf("error") >= 0) {
      process.stderr.write(stderr);
      error = new Error("git commit failed.", data.id);
    } else if (stderr) { process.stdout.write(stderr); }
    if (!error && stdout) process.stdout.write(stdout);
    cb(error);
  });
}

function gitPush(data, cb) {
  // figured this out from here: http://stackoverflow.com/questions/14092636/why-doesnt-my-git-auto-update-expect-script-work
  console.log("pushing to master", data.id);
  // TODO: switch to using token in push url
  var filePath = __dirname + "/scripts/gitpush.expect";
  child.execFile(filePath, [ "enjalot", data.token ],
    {
      cwd: "/tmp/" + data.id
    }, function(error, stdout, stderr) {
      if (!error && stderr && stderr.toLowerCase().indexOf("error") >= 0) {
        process.stderr.write(stderr);
        error = new Error("git push failed.", data.id);
      } else if (stderr) { process.stdout.write(stderr); }
      if (!error && stdout) process.stdout.write(stdout);
      cb(error);
    });
}

function writeImage(data, cb) {
  console.log("writing image", data.id);
  // http://stackoverflow.com/questions/6926016/nodejs-saving-a-base64-encoded-image-to-disk
  // http://stackoverflow.com/questions/5669541/node-js-how-to-save-base64-encoded-images-on-server-as-png-jpg
  console.log("DATA IMAGE", data.image.slice(0, 25));
  var base64Data = data.image.replace(/^data:image\/png;base64,/, "");
  var binaryData = new Buffer(base64Data, 'base64');
  fs.writeFile("/tmp/" + data.id + "/thumbnail.png", binaryData, 'binary', function(err) { // ...
    if (err) console.log("IMAGE WRITE ERROR", err);
    cb(err);
  });
}

function cleanGist(data, cb) {
  child.exec("cd /tmp; rm -rf " + data.id, function(error, stdout, stderr) {
    if (!error && stderr && stderr.toLowerCase().indexOf("error") >= 0) {
      process.stderr.write(stderr);
      error = new Error("rm -rf failed.", data.id);
    } else if (stderr) { process.stdout.write(stderr); }
    if (!error && stdout) process.stdout.write(stdout);
    cb(error);
  });
}