module('hooks', {
    setup: function() {
        delete MG._hooks.test;
    }
});

test('multiple hooks with the same name execute in order', function() {
    var result = '';

    function hookOne() {
        result = result + 'one';
    }

    function hookTwo() {
        result = result + 'two';
    }

    MG.add_hook('test', hookOne);
    MG.add_hook('test', hookTwo);

    MG.call_hook('test');

    equal(result, 'onetwo', 'both hooks are called');
});

test('hooks can have context', function() {
    var result = {};

    function contextedHook() {
        this.foo = 'bar';
    }

    MG.add_hook('test', contextedHook, result);

    MG.call_hook('test');

    equal(result.foo, 'bar', 'exectued in the correct context');
});

test('hooks accept single arguments', function() {
    var result;

    function singleArgHook(arg) {
        result = arg;
        equal(typeof arg, 'string', 'correctly passed as a string')
    }

    MG.add_hook('test', singleArgHook, null);

    MG.call_hook('test', 'one');

    equal(result, 'one', 'single argument is received');
});


test('hooks accept multiple arguments', function() {
    var result;

    function multipleArgHook(arg1, arg2, arg3) {
        result = [arg1, arg2, arg3].join(' ');

        ok([arg1, arg2, arg3].every(function(arg) {
            return typeof arg === 'string';
        }), 'correctly passed as strings');
    }

    MG.add_hook('test', multipleArgHook);

    MG.call_hook('test', 'one', 'two', 'three');

    equal(result, 'one two three', 'multiple arguments are passed correctly');
});

test('hooks are chained - result from one passed into the next', function() {
    var initial = 2,
        result;

    function hookOne(arg) {
        return arg * 2;
    }

    function hookTwo(arg) {
        return arg - 1;
    }

    MG.add_hook('test', hookOne);
    MG.add_hook('test', hookTwo);

    result = MG.call_hook('test', initial);

    equal(result, 3, 'result has been chained');
});

test('hooks should return multiple inputs as an array', function() {
    var result;

    function hookOne(arg1, arg2, arg3) {
        return [arg1, arg2, arg3];
    }

    function hookTwo(arg1, arg2, arg3) {
        return [arg3, arg2, arg1];
    }

    MG.add_hook('test', hookOne);
    MG.add_hook('test', hookTwo);

    result = MG.call_hook('test', [1,2,3]);

    equal(result.join('-'), '3-2-1', 'array is passed in the result')
});

test('if the result from a chained hook is undefined', function() {
  var initial = 2;

  function hookOne(arg) {
      // don't return anything
  }

  function hookTwo(arg) {
      equal(arg, initial, 'initial value is used');
  }

  MG.add_hook('test', hookOne);
  MG.add_hook('test', hookTwo);
  result = MG.call_hook('test', initial);


  delete MG._hooks.test;

  function hookThree(arg) {
    return arg - 1;
  }

  function hookFour(arg) {
    // don't return anything
  }

  function hookFive(arg) {
    equal(initial, arg - 1, 'processed value is passed if it is already set');
  }

  MG.add_hook('test', hookOne);
  MG.add_hook('test', hookTwo);
  result = MG.call_hook('test', initial);
});

test('a hook can only have one registered instance of any function', function() {
    function hookOne() {}

    MG.add_hook('test', hookOne);

    try {
        MG.add_hook('test', hookOne);
    }
    catch(error) {
        equal(error, 'That function is already registered.', 'an exception is raised');
    }
});