// Exercise data in the form of an array of objects
var data = [{activity:'walking',intensity:'low',calories:176},{activity:'walking',intensity:'medium',calories:232},
            {activity:'walking',intensity:'high',calories:352},{activity:'cycling',intensity:'low',calories:422},
            {activity:'cycling',intensity:'medium',calories:563},{activity:'cycling',intensity:'high',calories:704},
            {activity:'running',intensity:'low',calories:704},{activity:'running',intensity:'medium',calories:880},
            {activity:'running',intensity:'high',calories:1126},{activity:'swimming',intensity:'low',calories:422},
            {activity:'swimming',intensity:'medium',calories:563},{activity:'swimming',intensity:'high',calories:704}];

// A helper function to compute the calories per hour for
// an activity at a certain intensity
function caloriesPerHour(activity,intensity) {
  var n, length;

  length = data.length;
  for(n = 0;n < length;n++) {
    if(data[n].activity==activity && data[n].intensity==intensity)
      return data[n].calories;
  }

  return 0;
}

function computeHandler() {
  var activity,intensity,duration,calories;

  // Gather inputs
  activity = $('#activity').val();
  intensity = $('#intensity').val();
  duration = $('#duration').val();

  // Do the computation
  calories = caloriesPerHour(activity,intensity)*duration/60;
  // Round result to the nearest calorie
  calories = Math.round(calories);

  // Present the result
  $('#result').text('This activity will burn a total of ' + calories + ' calories.');
}

function setup() {
    $('#compute').click(computeHandler);
}

$(document).ready(setup);