var assert = require('assert');
var fs = require('fs');

module.exports = function (gm, dir, finish, GM) {
  // Same image
  GM.compare(dir + '/original.jpg', dir + '/original.png', function(err, same) {
    if (err) return finish(err);
    if (!same) return finish(new Error('Compare should be the same!'));

    // Compare almost similar images for which ImageMagick
    // returns a exponent-style floating point number
    gm.compare(__dirname + '/fixtures/compare_1.png', __dirname + '/fixtures/compare_2.png', function(err, same, diff) {
      if (err) return finish(err);

      // Create a new noisy image
      gm.noise(0.3).write(dir + '/noise3.png', function (err) {
        if (err) return finish(err);
        if (!same) return finish(new Error('Compare should be the same!'));

        var options = {
          highlightColor: '#fff',
          highlightStyle: 'XOR',
          file: dir + '/diff.png',
          tolerance: 0.001
        };

        // Compare these images and write to a file.
        GM.compare(dir + '/original.jpg', dir + '/noise3.png', options, function(err) {
          if (err) return finish(err);

          fs.exists(options.file, function(exists) {
            if (exists) {
		fs.unlink(options.file, finish);
		}
            else finish(new Error('Diff file does not exist.'));
          });
        });
      });
    });
  });
};