/**
 * JavaScript for Special:Preferences
 */
jQuery( document ).ready( function ( $ ) {
	var $preftoc, $preferences, $fieldsets, $legends,
		hash,
		$tzSelect, $tzTextbox, $localtimeHolder, servertime;

	$( '#prefsubmit' ).attr( 'id', 'prefcontrol' );

	$preftoc = $('<ul id="preftoc"></ul>');
	$preferences = $( '#preferences' )
		.addClass( 'jsprefs' )
		.before( $preftoc );
	$fieldsets = $preferences.children( 'fieldset' )
		.hide()
		.addClass( 'prefsection' );
	$legends = $fieldsets
		.children( 'legend' )
		.addClass( 'mainLegend' );

	/**
	 * It uses document.getElementById for security reasons (HTML injections in $()).
	 *
	 * @param String name: the name of a tab without the prefix ("mw-prefsection-")
	 * @param String mode: [optional] A hash will be set according to the current
	 * open section. Set mode 'noHash' to surpress this.
	 */
	function switchPrefTab( name, mode ) {
		var $tab, scrollTop;
		// Handle hash manually to prevent jumping,
		// therefore save and restore scrollTop to prevent jumping.
		scrollTop = $( window ).scrollTop();
		if ( mode !== 'noHash' ) {
			window.location.hash = '#mw-prefsection-' + name;
		}
		$( window ).scrollTop( scrollTop );

		$preftoc.find( 'li' ).removeClass( 'selected' );
		$tab = $( document.getElementById( 'preftab-' + name ) );
		if ( $tab.length ) {
			$tab.parent().addClass( 'selected' );
			$preferences.children( 'fieldset' ).hide();
			$( document.getElementById( 'mw-prefsection-' + name ) ).show();
		}
	}

	// Populate the prefToc
	$legends.each( function ( i, legend ) {
		var $legend = $(legend),
			ident, $li, $a;
		if ( i === 0 ) {
			$legend.parent().show();
		}
		ident = $legend.parent().attr( 'id' );

		$li = $( '<li>' )
			.addClass( i === 0 ? 'selected' : '' );
		$a = $( '<a>' )
			.attr( {
				id: ident.replace( 'mw-prefsection', 'preftab' ),
				href: '#' + ident
			} )
			.text( $legend.text() );
		$li.append( $a );
		$preftoc.append( $li );
	} );

	// If we've reloaded the page or followed an open-in-new-window,
	// make the selected tab visible.
	hash = window.location.hash;
	if ( hash.match( /^#mw-prefsection-[\w\-]+/ ) ) {
		switchPrefTab( hash.replace( '#mw-prefsection-' , '' ) );
	}

	// In browsers that support the onhashchange event we will not bind click
	// handlers and instead let the browser do the default behavior (clicking the
	// <a href="#.."> will naturally set the hash, handled by onhashchange.
	// But other things that change the hash will also be catched (e.g. using
	// the Back and Forward browser navigation).
	// Note the special check for IE "compatibility" mode.
	if ( 'onhashchange' in window &&
		( document.documentMode === undefined || document.documentMode >= 8 )
	) {
		$(window).on( 'hashchange' , function () {
			var hash = window.location.hash;
			if ( hash.match( /^#mw-prefsection-[\w\-]+/ ) ) {
				switchPrefTab( hash.replace( '#mw-prefsection-', '' ) );
			} else if ( hash === '' ) {
				switchPrefTab( 'personal', 'noHash' );
			}
		});
	// In older browsers we'll bind a click handler as fallback.
	// We must not have onhashchange *and* the click handlers, other wise
	// the click handler calls switchPrefTab() which sets the hash value,
	// which triggers onhashcange and calls switchPrefTab() again.
	} else {
		$preftoc.on( 'click', 'li a', function ( e ) {
			switchPrefTab( $( this ).attr( 'href' ).replace( '#mw-prefsection-', '' ) );
			e.preventDefault();
		});
	}

	/**
	* Timezone functions.
	* Guesses Timezone from browser and updates fields onchange
	*/

	$tzSelect = $( '#mw-input-wptimecorrection' );
	$tzTextbox = $( '#mw-input-wptimecorrection-other' );
	$localtimeHolder = $( '#wpLocalTime' );
	servertime = parseInt( $( 'input[name="wpServerTime"]' ).val(), 10 );

	function minutesToHours( min ) {
		var tzHour = Math.floor( Math.abs( min ) / 60 ),
			tzMin = Math.abs( min ) % 60,
			tzString = ( ( min >= 0 ) ? '' : '-' ) + ( ( tzHour < 10 ) ? '0' : '' ) + tzHour +
				':' + ( ( tzMin < 10 ) ? '0' : '' ) + tzMin;
		return tzString;
	}

	function hoursToMinutes( hour ) {
		var minutes,
			arr = hour.split( ':' );

		arr[0] = parseInt( arr[0], 10 );

		if ( arr.length === 1 ) {
			// Specification is of the form [-]XX
			minutes = arr[0] * 60;
		} else {
			// Specification is of the form [-]XX:XX
			minutes = Math.abs( arr[0] ) * 60 + parseInt( arr[1], 10 );
			if ( arr[0] < 0 ) {
				minutes *= -1;
			}
		}
		// Gracefully handle non-numbers.
		if ( isNaN( minutes ) ) {
			return 0;
		} else {
			return minutes;
		}
	}

	function updateTimezoneSelection () {
		var minuteDiff, localTime,
			type = $tzSelect.val();

		if ( type === 'guess' ) {
			// Get browser timezone & fill it in
			minuteDiff = -( new Date().getTimezoneOffset() );
			$tzTextbox.val( minutesToHours( minuteDiff ) );
			$tzSelect.val( 'other' );
			$tzTextbox.prop( 'disabled', false );
		} else if ( type === 'other' ) {
			// Grab data from the textbox, parse it.
			minuteDiff = hoursToMinutes( $tzTextbox.val() );
		} else {
			// Grab data from the $tzSelect value
			minuteDiff = parseInt( type.split( '|' )[1], 10 ) || 0;
			$tzTextbox.val( minutesToHours( minuteDiff ) );
		}

		// Determine local time from server time and minutes difference, for display.
		localTime = servertime + minuteDiff;

		// Bring time within the [0,1440) range.
		while ( localTime < 0 ) {
			localTime += 1440;
		}
		while ( localTime >= 1440 ) {
			localTime -= 1440;
		}
		$localtimeHolder.text( minutesToHours( localTime ) );
	}

	if ( $tzSelect.length && $tzTextbox.length ) {
		$tzSelect.change( updateTimezoneSelection );
		$tzTextbox.blur( updateTimezoneSelection );
		updateTimezoneSelection();
	}

	// Preserve the tab after saving the preferences
	// Not using cookies, because their deletion results are inconsistent.
	// Not using jStorage due to its enormous size (for this feature)
	if ( window.sessionStorage ) {
		if ( sessionStorage.getItem( 'mediawikiPreferencesTab' ) !== null ) {
			switchPrefTab( sessionStorage.getItem( 'mediawikiPreferencesTab' ), 'noHash' );
		}
		// Deleting the key, the tab states should be reset until we press Save
		sessionStorage.removeItem( 'mediawikiPreferencesTab' );

		$( '#mw-prefs-form' ).submit( function () {
			var storageData = $( $preftoc ).find( 'li.selected a' ).attr( 'id' ).replace( 'preftab-', '' );
			sessionStorage.setItem( 'mediawikiPreferencesTab', storageData );
		} );
	}
} );