/**
* Heartbeat API
*
* Heartbeat is a simple server polling API that sends XHR requests to
* the server every 15 - 60 seconds and triggers events (or callbacks) upon
* receiving data. Currently these 'ticks' handle transports for post locking,
* login-expiration warnings, autosave, and related tasks while a user is logged in.
*
* Available PHP filters (in ajax-actions.php):
* - heartbeat_received
* - heartbeat_send
* - heartbeat_tick
* - heartbeat_nopriv_received
* - heartbeat_nopriv_send
* - heartbeat_nopriv_tick
* @see wp_ajax_nopriv_heartbeat(), wp_ajax_heartbeat()
*
* Custom jQuery events:
* - heartbeat-send
* - heartbeat-tick
* - heartbeat-error
* - heartbeat-connection-lost
* - heartbeat-connection-restored
* - heartbeat-nonces-expired
*
* @since 3.6.0
* @output wp-includes/js/heartbeat.js
*/

( function( $, window, undefined ) {

/**
* Constructs the Heartbeat API.
*
* @since 3.6.0
*
* @return {Object} An instance of the Heartbeat class.
* @constructor
*/
var Heartbeat = function() {
var $document = $(document),
settings = {
// Suspend/resume.
suspend: false,

// Whether suspending is enabled.
suspendEnabled: true,

// Current screen id, defaults to the JS global 'pagenow' when present
// (in the admin) or 'front'.
screenId: '',

// XHR request URL, defaults to the JS global 'ajaxurl' when present.
url: '',

// Timestamp, start of the last connection request.
lastTick: 0,

// Container for the enqueued items.
queue: {},

// Connect interval (in seconds).
mainInterval: 60,

// Used when the interval is set to 5 seconds temporarily.
tempInterval: 0,

// Used when the interval is reset.
originalInterval: 0,

// Used to limit the number of Ajax requests.
minimalInterval: 0,

// Used together with tempInterval.
countdown: 0,

// Whether a connection is currently in progress.
connecting: false,

// Whether a connection error occurred.
connectionError: false,

// Used to track non-critical errors.
errorcount: 0,

// Whether at least one connection has been completed successfully.
hasConnected: false,

// Whether the current browser window is in focus and the user is active.
hasFocus: true,

// Timestamp, last time the user was active. Checked every 30 seconds.
userActivity: 0,

// Flag whether events tracking user activity were set.
userActivityEvents: false,

// Timer that keeps track of how long a user has focus.
checkFocusTimer: 0,

// Timer that keeps track of how long needs to be waited before connecting to
// the server again.
beatTimer: 0
};

/**
* Sets local variables and events, then starts the heartbeat.
*
* @since 3.8.0
* @access private
*
* @return {void}
*/
function initialize() {
var options, hidden, visibilityState, visibilitychange;

if ( typeof window.pagenow === 'string' ) {
settings.screenId = window.pagenow;
}

if ( typeof window.ajaxurl === 'string' ) {
settings.url = window.ajaxurl;
}

// Pull in options passed from PHP.
if ( typeof window.heartbeatSettings === 'object' ) {
options = window.heartbeatSettings;

// The XHR URL can be passed as option when window.ajaxurl is not set.
if ( ! settings.url && options.ajaxurl ) {
settings.url = options.ajaxurl;
}

/*
* Logic check: the interval can be from 1 to 3600 seconds and can be set temporarily
* to 5 seconds. It can be set in the initial options or changed later from JS
* or from PHP through the AJAX responses.
*/
if ( options.interval ) {
settings.mainInterval = options.interval;

if ( settings.mainInterval < 1 ) {
settings.mainInterval = 1;
} else if ( settings.mainInterval > 3600 ) {
settings.mainInterval = 3600;
}
}

/*
* Used to limit the number of Ajax requests. Overrides all other intervals
* if they are shorter. Needed for some hosts that cannot handle frequent requests
* and the user may exceed the allocated server CPU time, etc. The minimal interval
* can be up to 600 seconds, however setting it to longer than 120 seconds
* will limit or disable some of the functionality (like post locks).
* Once set at initialization, minimalInterval cannot be changed/overridden.
*/
if ( options.minimalInterval ) {
options.minimalInterval = parseInt( options.minimalInterval, 10 );
settings.minimalInterval = options.minimalInterval > 0 && options.minimalInterval <= 600 ? options.minimalInterval : 0;
}

if ( settings.minimalInterval && settings.mainInterval < settings.minimalInterval ) {
settings.mainInterval = settings.minimalInterval;
}

// 'screenId' can be added from settings on the front end where the JS global
// 'pagenow' is not set.
if ( ! settings.screenId ) {
settings.screenId = options.screenId || 'front';
}

if ( options.suspension === 'disable' ) {
settings.suspendEnabled = false;
}
}

// Convert to milliseconds.
settings.mainInterval = settings.mainInterval * 1000;
settings.originalInterval = settings.mainInterval;
if ( settings.minimalInterval ) {
settings.minimalInterval = settings.minimalInterval * 1000;
}

/*
* Switch the interval to 120 seconds by using the Page Visibility API.
* If the browser doesn't support it (Safari < 7, Android < 4.4, IE < 10), the
* interval will be increased to 120 seconds after 5 minutes of mouse and keyboard
* inactivity.
*/
if ( typeof document.hidden !== 'undefined' ) {
hidden = 'hidden';
visibilitychange = 'visibilitychange';
visibilityState = 'visibilityState';
} else if ( typeof document.msHidden !== 'undefined' ) { // IE10.
hidden = 'msHidden';
visibilitychange = 'msvisibilitychange';
visibilityState = 'msVisibilityState';
} else if ( typeof document.webkitHidden !== 'undefined' ) { // Android.
hidden = 'webkitHidden';
visibilitychange = 'webkitvisibilitychange';
visibilityState = 'webkitVisibilityState';
}

if ( hidden ) {
if ( document[hidden] ) {
settings.hasFocus = false;
}

$document.on( visibilitychange + '.wp-heartbeat', function() {
if ( document[visibilityState] === 'hidden' ) {
blurred();
window.clearInterval( settings.checkFocusTimer );
} else {
focused();
if ( document.hasFocus ) {
settings.checkFocusTimer = window.setInterval( checkFocus, 10000 );
}
}
});
}

// Use document.hasFocus() if available.
if ( document.hasFocus ) {
settings.checkFocusTimer = window.setInterval( checkFocus, 10000 );
}

$(window).on( 'pagehide.wp-heartbeat', function() {
// Don't connect anymore.
suspend();

// Abort the last request if not completed.
if ( settings.xhr && settings.xhr.readyState !== 4 ) {
settings.xhr.abort();
}
});

$(window).on(
'pageshow.wp-heartbeat',
/**
* Handles pageshow event, specifically when page navigation is restored from back/forward cache.
*
* @param {jQuery.Event} event
* @param {PageTransitionEvent} event.originalEvent
*/
function ( event ) {
if ( event.originalEvent.persisted ) {
/*
* When page navigation is stored via bfcache (Back/Forward Cache), consider this the same as
* if the user had just switched to the tab since the behavior is similar.
*/
focused();
}
}
);

// Check for user activity every 30 seconds.
window.setInterval( checkUserActivity, 30000 );

// Start one tick after DOM ready.
$( function() {
settings.lastTick = time();
scheduleNextTick();
});
}

/**
* Returns the current time according to the browser.
*
* @since 3.6.0
* @access private
*
* @return {number} Returns the current time.
*/
function time() {
return (new Date()).getTime();
}

/**
* Checks if the iframe is from the same origin.
*
* @since 3.6.0
* @access private
*
* @return {boolean} Returns whether or not the iframe is from the same origin.
*/
function isLocalFrame( frame ) {
var origin, src = frame.src;

/*
* Need to compare strings as WebKit doesn't throw JS errors when iframes have
* different origin. It throws uncatchable exceptions.
*/
if ( src && /^https?:\/\//.test( src ) ) {
origin = window.location.origin ? window.location.origin : window.location.protocol + '//' + window.location.host;

if ( src.indexOf( origin ) !== 0 ) {
return false;
}
}

try {
if ( frame.contentWindow.document ) {
return true;
}
} catch(e) {}

return false;
}

/**
* Checks if the document's focus has changed.
*
* @since 4.1.0
* @access private
*
* @return {void}
*/
function checkFocus() {
if ( settings.hasFocus && ! document.hasFocus() ) {
blurred();
} else if ( ! settings.hasFocus && document.hasFocus() ) {
focused();
}
}

/**
* Sets error state and fires an event on XHR errors or timeout.
*
* @since 3.8.0
* @access private
*
* @param {string} error The error type passed from the XHR.
* @param {number} status The HTTP status code passed from jqXHR
* (200, 404, 500, etc.).
*
* @return {void}
*/
function setErrorState( error, status ) {
var trigger;

if ( error ) {
switch ( error ) {
case 'abort':
// Do nothing.
break;
case 'timeout':
// No response for 30 seconds.
trigger = true;
break;
case 'error':
if ( 503 === status && settings.hasConnected ) {
trigger = true;
break;
}
/* falls through */
case 'parsererror':
case 'empty':
case 'unknown':
settings.errorcount++;

if ( settings.errorcount > 2 && settings.hasConnected ) {
trigger = true;
}

break;
}

if ( trigger && ! hasConnectionError() ) {
settings.connectionError = true;
$document.trigger( 'heartbeat-connection-lost', [error, status] );
wp.hooks.doAction( 'heartbeat.connection-lost', error, status );
}
}
}

/**
* Clears the error state and fires an event if there is a connection error.
*
* @since 3.8.0
* @access private
*
* @return {void}
*/
function clearErrorState() {
// Has connected successfully.
settings.hasConnected = true;

if ( hasConnectionError() ) {
settings.errorcount = 0;
settings.connectionError = false;
$document.trigger( 'heartbeat-connection-restored' );
wp.hooks.doAction( 'heartbeat.connection-restored' );
}
}

/**
* Gathers the data and connects to the server.
*
* @since 3.6.0
* @access private
*
* @return {void}
*/
function connect() {
var ajaxData, heartbeatData;

// If the connection to the server is slower than the interval,
// heartbeat connects as soon as the previous connection's response is received.
if ( settings.connecting || settings.suspend ) {
return;
}

settings.lastTick = time();

heartbeatData = $.extend( {}, settings.queue );
// Clear the data queue. Anything added after this point will be sent on the next tick.
settings.queue = {};

$document.trigger( 'heartbeat-send', [ heartbeatData ] );
wp.hooks.doAction( 'heartbeat.send', heartbeatData );

ajaxData = {
data: heartbeatData,
interval: settings.tempInterval ? settings.tempInterval / 1000 : settings.mainInterval / 1000,
_nonce: typeof window.heartbeatSettings === 'object' ? window.heartbeatSettings.nonce : '',
action: 'heartbeat',
screen_id: settings.screenId,
has_focus: settings.hasFocus
};

if ( 'customize' === settings.screenId ) {
ajaxData.wp_customize = 'on';
}

settings.connecting = true;
settings.xhr = $.ajax({
url: settings.url,
type: 'post',
timeout: 30000, // Throw an error if not completed after 30 seconds.
data: ajaxData,
dataType: 'json'
}).always( function() {
settings.connecting = false;
scheduleNextTick();
}).done( function( response, textStatus, jqXHR ) {
var newInterval;

if ( ! response ) {
setErrorState( 'empty' );
return;
}

clearErrorState();

if ( response.nonces_expired ) {
$document.trigger( 'heartbeat-nonces-expired' );
wp.hooks.doAction( 'heartbeat.nonces-expired' );
}

// Change the interval from PHP.
if ( response.heartbeat_interval ) {
newInterval = response.heartbeat_interval;
delete response.heartbeat_interval;
}

// Update the heartbeat nonce if set.
if ( response.heartbeat_nonce && typeof window.heartbeatSettings === 'object' ) {
window.heartbeatSettings.nonce = response.heartbeat_nonce;
delete response.heartbeat_nonce;
}

// Update the Rest API nonce if set and wp-api loaded.
if ( response.rest_nonce && typeof window.wpApiSettings === 'object' ) {
window.wpApiSettings.nonce = response.rest_nonce;
// This nonce is required for api-fetch through heartbeat.tick.
// delete response.rest_nonce;
}

$document.trigger( 'heartbeat-tick', [response, textStatus, jqXHR] );
wp.hooks.doAction( 'heartbeat.tick', response, textStatus, jqXHR );

// Do this last. Can trigger the next XHR if connection time > 5 seconds and newInterval == 'fast'.
if ( newInterval ) {
interval( newInterval );
}
}).fail( function( jqXHR, textStatus, error ) {
setErrorState( textStatus || 'unknown', jqXHR.status );
$document.trigger( 'heartbeat-error', [jqXHR, textStatus, error] );
wp.hooks.doAction( 'heartbeat.error', jqXHR, textStatus, error );
});
}

/**
* Schedules the next connection.
*
* Fires immediately if the connection time is longer than the interval.
*
* @since 3.8.0
* @access private
*
* @return {void}
*/
function scheduleNextTick() {
var delta = time() - settings.lastTick,
interval = settings.mainInterval;

if ( settings.suspend ) {
return;
}

if ( ! settings.hasFocus ) {
interval = 120000; // 120 seconds. Post locks expire after 150 seconds.
} else if ( settings.countdown > 0 && settings.tempInterval ) {
interval = settings.tempInterval;
settings.countdown--;

if ( settings.countdown < 1 ) {
settings.tempInterval = 0;
}
}

if ( settings.minimalInterval && interval < settings.minimalInterval ) {
interval = settings.minimalInterval;
}

window.clearTimeout( settings.beatTimer );

if ( delta < interval ) {
settings.beatTimer = window.setTimeout(
function() {
connect();
},
interval - delta
);
} else {
connect();
}
}

/**
* Sets the internal state when the browser window becomes hidden or loses focus.
*
* @since 3.6.0
* @access private
*
* @return {void}
*/
function blurred() {
settings.hasFocus = false;
}

/**
* Sets the internal state when the browser window becomes visible or is in focus.
*
* @since 3.6.0
* @access private
*
* @return {void}
*/
function focused() {
settings.userActivity = time();

// Resume if suspended.
resume();

if ( ! settings.hasFocus ) {
settings.hasFocus = true;
scheduleNextTick();
}
}

/**
* Suspends connecting.
*/
function suspend() {
settings.suspend = true;
}

/**
* Resumes connecting.
*/
function resume() {
settings.suspend = false;
}

/**
* Runs when the user becomes active after a period of inactivity.
*
* @since 3.6.0
* @access private
*
* @return {void}
*/
function userIsActive() {
settings.userActivityEvents = false;
$document.off( '.wp-heartbeat-active' );

$('iframe').each( function( i, frame ) {
if ( isLocalFrame( frame ) ) {
$( frame.contentWindow ).off( '.wp-heartbeat-active' );
}
});

focused();
}

/**
* Checks for user activity.
*
* Runs every 30 seconds. Sets 'hasFocus = true' if user is active and the window
* is in the background. Sets 'hasFocus = false' if the user has been inactive
* (no mouse or keyboard activity) for 5 minutes even when the window has focus.
*
* @since 3.8.0
* @access private
*
* @return {void}
*/
function checkUserActivity() {
var lastActive = settings.userActivity ? time() - settings.userActivity : 0;

// Throttle down when no mouse or keyboard activity for 5 minutes.
if ( lastActive > 300000 && settings.hasFocus ) {
blurred();
}

// Suspend after 10 minutes of inactivity when suspending is enabled.
// Always suspend after 60 minutes of inactivity. This will release the post lock, etc.
if ( ( settings.suspendEnabled && lastActive > 600000 ) || lastActive > 3600000 ) {
suspend();
}

if ( ! settings.userActivityEvents ) {
$document.on( 'mouseover.wp-heartbeat-active keyup.wp-heartbeat-active touchend.wp-heartbeat-active', function() {
userIsActive();
});

$('iframe').each( function( i, frame ) {
if ( isLocalFrame( frame ) ) {
$( frame.contentWindow ).on( 'mouseover.wp-heartbeat-active keyup.wp-heartbeat-active touchend.wp-heartbeat-active', function() {
userIsActive();
});
}
});

settings.userActivityEvents = true;
}
}

// Public methods.

/**
* Checks whether the window (or any local iframe in it) has focus, or the user
* is active.
*
* @since 3.6.0
* @memberOf wp.heartbeat.prototype
*
* @return {boolean} True if the window or the user is active.
*/
function hasFocus() {
return settings.hasFocus;
}

/**
* Checks whether there is a connection error.
*
* @since 3.6.0
*
* @memberOf wp.heartbeat.prototype
*
* @return {boolean} True if a connection error was found.
*/
function hasConnectionError() {
return settings.connectionError;
}

/**
* Connects as soon as possible regardless of 'hasFocus' state.
*
* Will not open two concurrent connections. If a connection is in progress,
* will connect again immediately after the current connection completes.
*
* @since 3.8.0
*
* @memberOf wp.heartbeat.prototype
*
* @return {void}
*/
function connectNow() {
settings.lastTick = 0;
scheduleNextTick();
}

/**
* Disables suspending.
*
* Should be used only when Heartbeat is performing critical tasks like
* autosave, post-locking, etc. Using this on many screens may overload
* the user's hosting account if several browser windows/tabs are left open
* for a long time.
*
* @since 3.8.0
*
* @memberOf wp.heartbeat.prototype
*
* @return {void}
*/
function disableSuspend() {
settings.suspendEnabled = false;
}

/**
* Gets/Sets the interval.
*
* When setting to 'fast' or 5, the interval is 5 seconds for the next 30 ticks
* (for 2 minutes and 30 seconds) by default. In this case the number of 'ticks'
* can be passed as second argument. If the window doesn't have focus,
* the interval slows down to 2 minutes.
*
* @since 3.6.0
*
* @memberOf wp.heartbeat.prototype
*
* @param {string|number} speed Interval: 'fast' or integer between 1 and 3600 (seconds).
* Fast equals 5.
* @param {number} ticks Tells how many ticks before the interval reverts back.
* Value must be between 1 and 30. Used with speed = 'fast' or 5.
*
* @return {number} Current interval in seconds.
*/
function interval( speed, ticks ) {
var newInterval,
oldInterval = settings.tempInterval ? settings.tempInterval : settings.mainInterval;

if ( speed ) {
if ( 'fast' === speed ) {
// Special case, see below.
newInterval = 5000;
} else if ( 'long-polling' === speed ) {
// Allow long polling (experimental).
settings.mainInterval = 0;
return 0;
} else {
speed = parseInt( speed, 10 );

if ( speed >= 1 && speed <= 3600 ) {
newInterval = speed * 1000;
} else {
newInterval = settings.originalInterval;
}
}

if ( settings.minimalInterval && newInterval < settings.minimalInterval ) {
newInterval = settings.minimalInterval;
}

// Special case, runs for a number of ticks then reverts to the previous interval.
if ( 5000 === newInterval ) {
ticks = parseInt( ticks, 10 ) || 30;
ticks = ticks < 1 || ticks > 30 ? 30 : ticks;

settings.countdown = ticks;
settings.tempInterval = newInterval;
} else {
settings.countdown = 0;
settings.tempInterval = 0;
settings.mainInterval = newInterval;
}

/*
* Change the next connection time if new interval has been set.
* Will connect immediately if the time since the last connection
* is greater than the new interval.
*/
if ( newInterval !== oldInterval ) {
scheduleNextTick();
}
}

return settings.tempInterval ? settings.tempInterval / 1000 : settings.mainInterval / 1000;
}

/**
* Enqueues data to send with the next XHR.
*
* As the data is send asynchronously, this function doesn't return the XHR
* response. To see the response, use the custom jQuery event 'heartbeat-tick'
* on the document, example:
* $(document).on( 'heartbeat-tick.myname', function( event, data, textStatus, jqXHR ) {
* // code
* });
* If the same 'handle' is used more than once, the data is not overwritten when
* the third argument is 'true'. Use `wp.heartbeat.isQueued('handle')` to see if
* any data is already queued for that handle.
*
* @since 3.6.0
*
* @memberOf wp.heartbeat.prototype
*
* @param {string} handle Unique handle for the data, used in PHP to
* receive the data.
* @param {*} data The data to send.
* @param {boolean} noOverwrite Whether to overwrite existing data in the queue.
*
* @return {boolean} True if the data was queued.
*/
function enqueue( handle, data, noOverwrite ) {
if ( handle ) {
if ( noOverwrite && this.isQueued( handle ) ) {
return false;
}

settings.queue[handle] = data;
return true;
}
return false;
}

/**
* Checks if data with a particular handle is queued.
*
* @since 3.6.0
*
* @param {string} handle The handle for the data.
*
* @return {boolean} True if the data is queued with this handle.
*/
function isQueued( handle ) {
if ( handle ) {
return settings.queue.hasOwnProperty( handle );
}
}

/**
* Removes data with a particular handle from the queue.
*
* @since 3.7.0
*
* @memberOf wp.heartbeat.prototype
*
* @param {string} handle The handle for the data.
*
* @return {void}
*/
function dequeue( handle ) {
if ( handle ) {
delete settings.queue[handle];
}
}

/**
* Gets data that was enqueued with a particular handle.
*
* @since 3.7.0
*
* @memberOf wp.heartbeat.prototype
*
* @param {string} handle The handle for the data.
*
* @return {*} The data or undefined.
*/
function getQueuedItem( handle ) {
if ( handle ) {
return this.isQueued( handle ) ? settings.queue[handle] : undefined;
}
}

initialize();

// Expose public methods.
return {
hasFocus: hasFocus,
connectNow: connectNow,
disableSuspend: disableSuspend,
interval: interval,
hasConnectionError: hasConnectionError,
enqueue: enqueue,
dequeue: dequeue,
isQueued: isQueued,
getQueuedItem: getQueuedItem
};
};

/**
* Ensure the global `wp` object exists.
*
* @namespace wp
*/
window.wp = window.wp || {};

/**
* Contains the Heartbeat API.
*
* @namespace wp.heartbeat
* @type {Heartbeat}
*/
window.wp.heartbeat = new Heartbeat();

}( jQuery, window ));