// an example channel service that lets consumers
// subscribe and publish for nuclear reactor meltdowns

var CoreReactorChannel = function($rootScope) {

    // local constants for the message ids.
    // these are private implementation detail
    var ELEVATED_CORE_TEMPERATURE_MESSAGE = "elevatedCoreMessage";

    // publish elevatedCoreTemperature
    // note that the parameters are particular to the problem domain
    var elevatedCoreTemperature = function(core_id, temperature) {
        $rootScope.$broadcast(ELEVATED_CORE_TEMPERATURE_MESSAGE,
            {
                core_id: core_id,
                temperature: temperature
            });
    };

    // subscribe to elevatedCoreTemperature event.
    // note that you should require $scope first
    // so that when the subscriber is destroyed you
    // don't create a closure over it, and te scope can clean up.
    var onElevatedCoreTemperature = function($scope, handler) {
        $scope.$on(ELEVATED_CORE_TEMPERATURE_MESSAGE, function(event, message){
            // note that the handler is passed the problem domain parameters
            handler(message.core_id, message.temperature);
        });
    };

    // other CoreReactorChannel events would go here.

    return {
        elevatedCoreTemperature: elevatedCoreTemperature,
        onElevatedCoreTemperature: onElevatedCoreTemperature
    };
};


//Usage elsewhere in the application
var MyController = function($scope, CoreReactorChannel){
    // Handle core temperature changes
    var onCoreTemperatureChange = function(core_id, temperature){
        console.log(core_id, temperature);
    }

    // Let the CoreReactorChannel know the temperature has changed
    $scope.changeTemperature = function(core_id, temperature){
        CoreReactorChannel.elevatedCoreTemperature(core_id, temperature);
    }

    // Listen for temperature changes and call a handler
    // Note: The handler can be an inline function
    CoreReactorChannel.onElevatedCoreTemperature($scope, onCoreTemperatureChange);
};