server.js

/**
 * Module dependencies.
 */
var express = require('express')
  , fs = require('fs')
  , Img = require('./lib/image.js')
  , gm = require('gm')
  , morgan = require('morgan')
  , Montage = require('./lib/montage')
  ,  util = require('util')
  ,  async = require('async')
  ;

/**
 * Options.
 */
var img_path = __dirname + '/img/';
if (!fs.existsSync(img_path)) {
  fs.mkdirSync(img_path);
}
var resize_message = 'Specify an url \'u\', width \'w\' and height \'h\'';
var crop_message = 'Specify an url \'u\', width \'w\', height \'h\', x-offset \'x\' and y-offset \'y\'';
/**
 * Express server.
 */
var app = express()
  .use(morgan('dev'))
  .set('static_server', process.env.NODE_STATIC_SERVER || "https://zooniversestatic.z13.web.core.windows.net/")
  .set('port', process.env.NODE_PORT || 80)
  .set('env', process.env.NODE_ENV || "development")
  .set('debug', process.env.NODE_DEBUG || false);

// server to find the images on
var static_host = app.settings.static_server;

// function cropImage(u, w, h, x, y, res, next){
function cropImage(paramSource, res, next){
  var u = paramSource.u
    , w = paramSource.w
    , h = paramSource.h
    , x = paramSource.x
    , y = paramSource.y
    ;
  if (!u || !w || !h || !x || !y) res.send(400, {error: crop_message});

  var url = computeURL(static_host, u);
  var img = new Img(url,img_path).load(function(err,im) {
    if (err) res.status(500).send({ error: err })
    else {
      if (app.get("debug")) {
        console.log("\nCrop image:");
        console.log(im);
      }
      var outFile = im.cropHashFilename(w,h,x,y);
      fs.stat(outFile, function(err, stat) {
        if (!err) {
          res.sendFile(outFile);
        }else {
          gm(im.destHashed)
          .crop(w, h, x, y)
          .write(outFile, function (err) {
            if (err) {
              next(new Error(err));
            } else {
              res.sendFile(outFile);
            };
          });
        }
      });
    }
  });
};

function escapeRegExp(string){
  return string.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1");
};

function validUrl(arr, url) {
  return arr.some(function(arrVal) {
    var host_regex = new RegExp(escapeRegExp(arrVal), 'g');
    return url.match(host_regex);
  });
}

function computeURL(static_host, u){
  var whitelists = [
    's3.amazonaws.com/astronomy-rewind',
    'panoptes-uploads.zooniverse.org'
  ];
  if (validUrl(whitelists, u)) {
    return 'https://' + u;
  } else {
    return static_host + u;
  }
};

/**
 * Express routes.
 */
app.get('/resize', function(req, res, next){
  var u = req.query.u // URL
    , w = req.query.w // width
    , h = req.query.h // height
    , o = req.query.o // opts, support http://www.graphicsmagick.org/GraphicsMagick.html#details-resize
    ;
  if (!u || !w || !h) res.send(400, {error: resize_message});

  var img = new Img(computeURL(static_host, u),img_path).load(function(err,im) {
    if (err) res.status(500).send({ error: err })
    else {
      gm(im.destHashed)
        .resize(w, h, o)
        .stream(function streamOut (err, stdout, stderr) {
          if (err) res.status(500).send({ error: err })
          stdout.pipe(res); //pipe to response
          stdout.on('error', next);
        });
    }
  });
});

app.get('/resize_crop', function(req, res, next){
  var u = req.query.u // URL
    , w = req.query.w // width
    , h = req.query.h // height
    ;
  if (!u || !w || !h) res.send(400, {error: resize_message});

  var img = new Img(computeURL(static_host, u),img_path).load(function(err,im) {
    if (err) res.status(500).send({ error: err })
    else {
      im.resize(w,h,function(err,im) {
        if (err) res.status(500).send({ error: err })
        else {
          res.writeHead(200, {"Content-Type": "image/" + im.extension});
          res.end(im.resized, "binary");
        }
      })
    }
  });
});

app.get('/crop/:w/:h/:x/:y/:u', function(req, res, next){
  cropImage(req.params, res, next);
});

app.get('/crop', function(req, res, next){
  cropImage(req.query, res, next);
});

/**
 * Montage route. Takes multiple images and combines them into a pleasing grid/tile layout
 */
app.get('/montage', function(req, res, next){
  // Get url(s)
  var u = req.query.u;
  if (!Array.isArray(u)) {
    return next(new Error('Please specify at least two images'));
  }

  // Load all source images
  async.map(req.query.u, function (u, done) {
    new Img(computeURL(static_host, u),img_path).load(done);
  }, function (err, images) {
    if (err) next(new Error(err));
    var montage = new Montage(images, req.query.w, req.query.mw);
    montage.construct(function (err, outfile) {
      if (err) next(new Error(err));
      res.sendFile(outfile);
    });
  });
});

/**
 * Start server.
 */
app.listen(app.get("port"), function() {
  console.log("Express server listening on port %d in %s mode", app.settings.port || 3000, app.settings.env);
});