/**
 * @class Ext.util.TaskRunner
 * Provides the ability to execute one or more arbitrary tasks in a multithreaded
 * manner.  Generally, you can use the singleton {@link Ext.TaskMgr} instead, but
 * if needed, you can create separate instances of TaskRunner.  Any number of
 * separate tasks can be started at any time and will run independently of each
 * other. Example usage:
 * 

// Start a simple clock task that updates a div once per second
var updateClock = function(){
    Ext.fly('clock').update(new Date().format('g:i:s A'));
} 
var task = {
    run: updateClock,
    interval: 1000 //1 second
}
var runner = new Ext.util.TaskRunner();
runner.start(task);

// equivalent using TaskMgr
Ext.TaskMgr.start({
    run: updateClock,
    interval: 1000
});

 * 
 * Also see {@link Ext.util.DelayedTask}. 
 * 
 * @constructor
 * @param {Number} interval (optional) The minimum precision in milliseconds supported by this TaskRunner instance
 * (defaults to 10)
 */
Ext.util.TaskRunner = function(interval){
    interval = interval || 10;
    var tasks = [], 
    	removeQueue = [],
    	id = 0,
    	running = false,

    	// private
    	stopThread = function(){
	        running = false;
	        clearInterval(id);
	        id = 0;
	    },

    	// private
    	startThread = function(){
	        if(!running){
	            running = true;
	            id = setInterval(runTasks, interval);
	        }
	    },

    	// private
    	removeTask = function(t){
	        removeQueue.push(t);
	        if(t.onStop){
	            t.onStop.apply(t.scope || t);
	        }
	    },
	    
    	// private
    	runTasks = function(){
	    	var rqLen = removeQueue.length,
	    		now = new Date().getTime();	    			    		
	    
	        if(rqLen > 0){
	            for(var i = 0; i < rqLen; i++){
	                tasks.remove(removeQueue[i]);
	            }
	            removeQueue = [];
	            if(tasks.length < 1){
	                stopThread();
	                return;
	            }
	        }	        
	        for(var i = 0, t, itime, rt, len = tasks.length; i < len; ++i){
	            t = tasks[i];
	            itime = now - t.taskRunTime;
	            if(t.interval <= itime){
	                rt = t.run.apply(t.scope || t, t.args || [++t.taskRunCount]);
	                t.taskRunTime = now;
	                if(rt === false || t.taskRunCount === t.repeat){
	                    removeTask(t);
	                    return;
	                }
	            }
	            if(t.duration && t.duration <= (now - t.taskStartTime)){
	                removeTask(t);
	            }
	        }
	    };

    
/**
     * Starts a new task.
     * @method start
     * @param {Object} task A config object that supports the following properties:

     * 
run : Function
The function to execute each time the task is run. The
     * function will be called at each interval and passed the args argument if specified.  If a
     * particular scope is required, be sure to specify it using the scope argument.
     * 
interval : Number
The frequency in milliseconds with which the task
     * should be executed.
     * 
args : Array
(optional) An array of arguments to be passed to the function
     * specified by run.
     * 
scope : Object
(optional) The scope (this reference) in which to execute the
     * run function. Defaults to the task config object.
     * 
duration : Number
(optional) The length of time in milliseconds to execute
     * the task before stopping automatically (defaults to indefinite).
     * 
repeat : Number
(optional) The number of times to execute the task before
     * stopping automatically (defaults to indefinite).
     * 
     * @return {Object} The task
     */
    this.start = function(task){
        tasks.push(task);
        task.taskStartTime = new Date().getTime();
        task.taskRunTime = 0;
        task.taskRunCount = 0;
        startThread();
        return task;
    };

    
/**
     * Stops an existing running task.
     * @method stop
     * @param {Object} task The task to stop
     * @return {Object} The task
     */
    this.stop = function(task){
        removeTask(task);
        return task;
    };

    
/**
     * Stops all tasks that are currently running.
     * @method stopAll
     */
    this.stopAll = function(){
        stopThread();
        for(var i = 0, len = tasks.length; i < len; i++){
            if(tasks[i].onStop){
                tasks[i].onStop();
            }
        }
        tasks = [];
        removeQueue = [];
    };
};

/**
 * @class Ext.TaskMgr
 * @extends Ext.util.TaskRunner
 * A static {@link Ext.util.TaskRunner} instance that can be used to start and stop arbitrary tasks.  See
 * {@link Ext.util.TaskRunner} for supported methods and task config properties.
 * 

// Start a simple clock task that updates a div once per second
var task = {
    run: function(){
        Ext.fly('clock').update(new Date().format('g:i:s A'));
    },
    interval: 1000 //1 second
}
Ext.TaskMgr.start(task);

 * @singleton
 */
Ext.TaskMgr = new Ext.util.TaskRunner();