var _ = require('underscore'),
    runner = require('./util/template-runner'),

    eco, dust, Handlebars, Mustache;

try {
  dust = require('dustjs-linkedin');
} catch (err) { /* NOP */ }

try {
  Mustache = require('mustache');
} catch (err) { /* NOP */ }

try {
  eco = require('eco');
} catch (err) { /* NOP */ }

function error() {
  throw new Error('EWOT');
}

function makeSuite(bench, name, template, handlebarsOnly) {
  // Create aliases to minimize any impact from having to walk up the closure tree.
  var templateName = name,

      context = template.context,
      partials = template.partials,

      handlebarsOut,
      compatOut,
      dustOut,
      ecoOut,
      mustacheOut;

  var handlebar = Handlebars.compile(template.handlebars, {data: false}),
      compat = Handlebars.compile(template.handlebars, {data: false, compat: true}),
      options = {helpers: template.helpers};
  _.each(template.partials && template.partials.handlebars, function(partial, partialName) {
    Handlebars.registerPartial(partialName, Handlebars.compile(partial, {data: false}));
  });

  handlebarsOut = handlebar(context, options);
  bench('handlebars', function() {
    handlebar(context, options);
  });

  compatOut = compat(context, options);
  bench('compat', function() {
    compat(context, options);
  });

  if (handlebarsOnly) {
    return;
  }

  if (dust) {
    if (template.dust) {
      dustOut = false;
      dust.loadSource(dust.compile(template.dust, templateName));

      dust.render(templateName, context, function(err, out) { dustOut = out; });

      bench('dust', function() {
        dust.render(templateName, context, function() {});
      });
    } else {
      bench('dust', error);
    }
  }

  if (eco) {
    if (template.eco) {
      var ecoTemplate = eco.compile(template.eco);

      ecoOut = ecoTemplate(context);

      bench('eco', function() {
        ecoTemplate(context);
      });
    } else {
      bench('eco', error);
    }
  }

  if (Mustache) {
    var mustacheSource = template.mustache,
        mustachePartials = partials && partials.mustache;

    if (mustacheSource) {
      mustacheOut = Mustache.to_html(mustacheSource, context, mustachePartials);

      bench('mustache', function() {
        Mustache.to_html(mustacheSource, context, mustachePartials);
      });
    } else {
      bench('mustache', error);
    }
  }

  // Hack around whitespace until we have whitespace control
  handlebarsOut = handlebarsOut.replace(/\s/g, '');
  function compare(b, lang) {
    if (b == null) {
      return;
    }

    b = b.replace(/\s/g, '');

    if (handlebarsOut !== b) {
      throw new Error('Template output mismatch: ' + name
            + '\n\nHandlebars: ' + handlebarsOut
            + '\n\n' + lang + ': ' + b);
    }
  }

  compare(compatOut, 'compat');
  compare(dustOut, 'dust');
  compare(ecoOut, 'eco');
  compare(mustacheOut, 'mustache');
}

module.exports = function(grunt, callback) {
  // Deferring load incase we are being run inline with the grunt build
  Handlebars = require('../lib');

  console.log('Execution Throughput');
  runner(grunt, makeSuite, function(times, scaled) {
    callback(scaled);
  });
};