/*
This file is part of Ext JS 4.2

Copyright (c) 2011-2013 Sencha Inc

Contact:  http://www.sencha.com/contact

GNU General Public License Usage
This file may be used under the terms of the GNU General Public License version 3.0 as
published by the Free Software Foundation and appearing in the file LICENSE included in the
packaging of this file.

Please review the following information to ensure the GNU General Public License version 3.0
requirements will be met: http://www.gnu.org/copyleft/gpl.html.

If you are unsure which license is appropriate for your use, please contact the sales department
at http://www.sencha.com/contact.

Build date: 2013-05-16 14:36:50 (f9be68accb407158ba2b1be2c226a6ce1f649314)
*/
// @tag extras,core
// @require Format.js

/**
 * Provides the ability to execute one or more arbitrary tasks in a asynchronous manner.
 * Generally, you can use the singleton {@link Ext.TaskManager} 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 runner = new Ext.util.TaskRunner();
 *      var task = runner.start({
 *          run: updateClock,
 *          interval: 1000
 *      }
 *
 * The equivalent using TaskManager:
 *
 *      var task = Ext.TaskManager.start({
 *          run: updateClock,
 *          interval: 1000
 *      });
 *
 * To end a running task:
 * 
 *      task.destroy();
 *
 * If a task needs to be started and stopped repeated over time, you can create a
 * {@link Ext.util.TaskRunner.Task Task} instance.
 *
 *      var task = runner.newTask({
 *          run: function () {
 *              // useful code
 *          },
 *          interval: 1000
 *      });
 *      
 *      task.start();
 *      
 *      // ...
 *      
 *      task.stop();
 *      
 *      // ...
 *      
 *      task.start();
 *
 * A re-usable, one-shot task can be managed similar to the above:
 *
 *      var task = runner.newTask({
 *          run: function () {
 *              // useful code to run once
 *          },
 *          repeat: 1
 *      });
 *      
 *      task.start();
 *      
 *      // ...
 *      
 *      task.start();
 *
 * See the {@link #start} method for details about how to configure a task object.
 *
 * Also see {@link Ext.util.DelayedTask}. 
 * 
 * @constructor
 * @param {Number/Object} [interval=10] The minimum precision in milliseconds supported by this
 * TaskRunner instance. Alternatively, a config object to apply to the new instance.
 */
Ext.define('Ext.util.TaskRunner', {
    /**
     * @cfg {Boolean} [fireIdleEvent=true]
     * This may be configured `false` to inhibit firing of the {@link Ext.EventManager#idleEvent idle event} after task invocation.
     */

    /**
     * @cfg interval
     * The timer resolution.
     */
    interval: 10,

    /**
     * @property timerId
     * The id of the current timer.
     * @private
     */
    timerId: null,

    constructor: function (interval) {
        var me = this;

        if (typeof interval == 'number') {
            me.interval = interval;
        } else if (interval) {
            Ext.apply(me, interval);
        }

        me.tasks = [];
        me.timerFn = Ext.Function.bind(me.onTick, me);
    },

    /**
     * Creates a new {@link Ext.util.TaskRunner.Task Task} instance. These instances can
     * be easily started and stopped.
     * @param {Object} config The config object. For details on the supported properties,
     * see {@link #start}.
     */
    newTask: function (config) {
        var task = new Ext.util.TaskRunner.Task(config);
        task.manager = this;
        return task;
    },

    /**
     * Starts a new task.
     *
     * Before each invocation, Ext injects the property `taskRunCount` into the task object
     * so that calculations based on the repeat count can be performed.
     * 
     * The returned task will contain a `destroy` method that can be used to destroy the
     * task and cancel further calls. This is equivalent to the {@link #stop} method.
     *
     * @param {Object} task A config object that supports the following properties:
     * @param {Function} task.run The function to execute each time the task is invoked. The
     * function will be called at each interval and passed the `args` argument if specified,
     * and the current invocation count if not.
     * 
     * If a particular scope (`this` reference) is required, be sure to specify it using
     * the `scope` argument.
     * 
     * @param {Function} task.onError The function to execute in case of unhandled
     * error on task.run.
     *
     * @param {Boolean} task.run.return `false` from this function to terminate the task.
     *
     * @param {Number} task.interval The frequency in milliseconds with which the task
     * should be invoked.
     *
     * @param {Object[]} task.args An array of arguments to be passed to the function
     * specified by `run`. If not specified, the current invocation count is passed.
     *
     * @param {Object} task.scope The scope (`this` reference) in which to execute the
     * `run` function. Defaults to the task config object.
     *
     * @param {Number} task.duration The length of time in milliseconds to invoke the task
     * before stopping automatically (defaults to indefinite).
     *
     * @param {Number} task.repeat The number of times to invoke the task before stopping
     * automatically (defaults to indefinite).
     * @return {Object} The task
     */
    start: function(task) {
        var me = this,
            now = Ext.Date.now();

        if (!task.pending) {
            me.tasks.push(task);
            task.pending = true; // don't allow the task to be added to me.tasks again
        }

        task.stopped = false; // might have been previously stopped...
        task.taskStartTime = now;
        task.taskRunTime = task.fireOnStart !== false ? 0 : task.taskStartTime;
        task.taskRunCount = 0;

        if (!me.firing) {
            if (task.fireOnStart !== false) {
                me.startTimer(0, now);
            } else {
                me.startTimer(task.interval, now);
            }
        }

        return task;
    },

    /**
     * Stops an existing running task.
     * @param {Object} task The task to stop
     * @return {Object} The task
     */
    stop: function(task) {
        // NOTE: we don't attempt to remove the task from me.tasks at this point because
        // this could be called from inside a task which would then corrupt the state of
        // the loop in onTick
        if (!task.stopped) {
            task.stopped = true;

            if (task.onStop) {
                task.onStop.call(task.scope || task, task);
            }
        }

        return task;
    },

    /**
     * Stops all tasks that are currently running.
     */
    stopAll: function() {
        // onTick will take care of cleaning up the mess after this point...
        Ext.each(this.tasks, this.stop, this);
    },

    //-------------------------------------------------------------------------

    firing: false,

    nextExpires: 1e99,

    // private
    onTick: function () {
        var me = this,
            tasks = me.tasks,
            now = Ext.Date.now(),
            nextExpires = 1e99,
            len = tasks.length,
            expires, newTasks, i, task, rt, remove;

        me.timerId = null;
        me.firing = true; // ensure we don't startTimer during this loop...

        // tasks.length can be > len if start is called during a task.run call... so we
        // first check len to avoid tasks.length reference but eventually we need to also
        // check tasks.length. we avoid repeating use of tasks.length by setting len at
        // that time (to help the next loop)
        for (i = 0; i < len || i < (len = tasks.length); ++i) {
            task = tasks[i];

            if (!(remove = task.stopped)) {
                expires = task.taskRunTime + task.interval;

                if (expires <= now) {
                    rt = 1; // otherwise we have a stale "rt"
                    try {
                        rt = task.run.apply(task.scope || task, task.args || [++task.taskRunCount]);
                    } catch (taskError) {
                        try {
                            // <debug>
                            Ext.log({
                                msg: taskError,
                                level: 'error'
                            });
                            // </debug>
                            if (task.onError) {
                                rt = task.onError.call(task.scope || task, task, taskError);
                            }
                        } catch (ignore) { }
                        }
                    task.taskRunTime = now;
                    if (rt === false || task.taskRunCount === task.repeat) {
                        me.stop(task);
                        remove = true;
                    } else {
                        remove = task.stopped; // in case stop was called by run
                        expires = now + task.interval;
                    }
                }

                if (!remove && task.duration && task.duration <= (now - task.taskStartTime)) {
                    me.stop(task);
                    remove = true;
                }
            }

            if (remove) {
                task.pending = false; // allow the task to be added to me.tasks again

                // once we detect that a task needs to be removed, we copy the tasks that
                // will carry forward into newTasks... this way we avoid O(N*N) to remove
                // each task from the tasks array (and ripple the array down) and also the
                // potentially wasted effort of making a new tasks[] even if all tasks are
                // going into the next wave.
                if (!newTasks) {
                    newTasks = tasks.slice(0, i);
                    // we don't set me.tasks here because callbacks can also start tasks,
                    // which get added to me.tasks... so we will visit them in this loop
                    // and account for their expirations in nextExpires...
                }
            } else {
                if (newTasks) {
                    newTasks.push(task); // we've cloned the tasks[], so keep this one...
                }

                if (nextExpires > expires) {
                    nextExpires = expires; // track the nearest expiration time
                }
            }
        }

        if (newTasks) {
            // only now can we copy the newTasks to me.tasks since no user callbacks can
            // take place
            me.tasks = newTasks;
        }

        me.firing = false; // we're done, so allow startTimer afterwards

        if (me.tasks.length) {
            // we create a new Date here because all the callbacks could have taken a long
            // time... we want to base the next timeout on the current time (after the
            // callback storm):
            me.startTimer(nextExpires - now, Ext.Date.now());
        }
        
        // After a tick
        if (me.fireIdleEvent !== false) {
            Ext.EventManager.idleEvent.fire();
        }
   },

    // private
    startTimer: function (timeout, now) {
        var me = this,
            expires = now + timeout,
            timerId = me.timerId;

        // Check to see if this request is enough in advance of the current timer. If so,
        // we reschedule the timer based on this new expiration.
        if (timerId && me.nextExpires - expires > me.interval) {
            clearTimeout(timerId);
            timerId = null;
        }

        if (!timerId) {
            if (timeout < me.interval) {
                timeout = me.interval;
            }

            me.timerId = setTimeout(me.timerFn, timeout);
            me.nextExpires = expires;
        }
    }
},
function () {
    var me = this,
        proto = me.prototype;

    /**
     * Destroys this instance, stopping all tasks that are currently running.
     * @method destroy
     */
    proto.destroy = proto.stopAll;

    // Documented in TaskManager.js
    Ext.util.TaskManager = Ext.TaskManager = new me();

    /**
     * Instances of this class are created by {@link Ext.util.TaskRunner#newTask} method.
     * 
     * For details on config properties, see {@link Ext.util.TaskRunner#start}.
     * @class Ext.util.TaskRunner.Task
     */
    me.Task = new Ext.Class({
        isTask: true,

        /**
         * This flag is set to `true` by {@link #stop}.
         * @private
         */
        stopped: true, // this avoids the odd combination of !stopped && !pending

        /**
         * Override default behavior
         */
        fireOnStart: false,

        constructor: function (config) {
            Ext.apply(this, config);
        },

        /**
         * Restarts this task, clearing it duration, expiration and run count.
         * @param {Number} [interval] Optionally reset this task's interval.
         */
        restart: function (interval) {
            if (interval !== undefined) {
                this.interval = interval;
            }

            this.manager.start(this);
        },

        /**
         * Starts this task if it is not already started.
         * @param {Number} [interval] Optionally reset this task's interval.
         */
        start: function (interval) {
            if (this.stopped) {
                this.restart(interval);
            }
        },

        /**
         * Stops this task.
         */
        stop: function () {
            this.manager.stop(this);
        }
    });

    proto = me.Task.prototype;

    /**
     * Destroys this instance, stopping this task's execution.
     * @method destroy
     */
    proto.destroy = proto.stop;
});









