;(function ($, window) {

    var prices = {"1":25,"2":45,"3":60};

    var calculate_price = function () {
        var price = get_price();
        $('#price').text(price + ' $');
    }

    var get_price = function () {
        var price = 0;
        var challenges = 0;
        var discount = $('#field-size').val() == '' ? 5 : 0;
        $('input[name^=challenges]').each(function () {
            var $this = $(this);
            if ($this.is(':checked')) {
                challenges += 1;
            }
        });
        
        // The keys of 'prices' are strings
        if ('' + challenges in prices) {
            price = parseFloat(prices[challenges]) - discount;
        } else {
            price = 0;
        }

        var donation = $('#field-donation').val();
        if (donation) {
            price += parseFloat(donation.replace(/[\$\s]/, ''));
        }
        if (isNaN(price)) {
            price = 0;
        }

        return price;
    }

    var disable_submit_button = function () {
        $('button[type="submit"]').attr('disabled', 'disabled');
    }

    var check_off_options = function () {
        // if a challenge with options is checked, all non-disabled options are checked too
        // if a challenge is unchecked, all options are unchecked
        // if any of the options are checked, the challenge is also checked
        // if all options are unchecked, the cahllenge is also unchecked

        var $this = $( this ),
            checked = $this.is(':checked'),
            isOption = $this.closest('.field-checkbox').hasClass('option'),
            callback;

        if ( isOption ) {
            if ( checked ) {
                callback = function ( i, el ) {
                    $( el ).prop( 'checked', true );
                }
            } else {
                var hasCheckedSiblings = !! $this.closest('.option').siblings('.option').find('input:checked').length;
                if ( !hasCheckedSiblings ) {
                    callback = function ( i, el ) {
                        $( el ).prop( 'checked', false );
                    }
                }
            }
            if ( callback )  {
                $this.parents('.challenge').find('input[type="checkbox"]:first').each( callback );
            }
        } else {
            if ( checked ) {
                callback = function ( i, el ) {
                    var $el = $( el );
                    if ( !$el.attr( 'disabled' ) ) {
                        $el.prop ( 'checked', true  );
                    }
                };
            } else {
                callback = function ( i, el ) {
                    $( el ).prop( 'checked', false );
                }
            }
            if ( callback ) {
                $this.closest('.challenge').find('.option input').each( callback );
            }
        }
    }

    $(function () {
        $('form')
            .change( calculate_price )
            .submit( disable_submit_button );

        $('form .challenges .field-checkbox input')
            .change( check_off_options )
            .change();

        calculate_price();
    });

})(jQuery, window);