( function ( mw, $ ) {
	var ProtectionForm,
		reasonCodePointLimit = mw.config.get( 'wgCommentCodePointLimit' ),
		reasonByteLimit = mw.config.get( 'wgCommentByteLimit' );

	ProtectionForm = window.ProtectionForm = {
		/**
		 * Set up the protection chaining interface (i.e. "unlock move permissions" checkbox)
		 * on the protection form
		 *
		 * @return {boolean}
		 */
		init: function () {
			var $cell = $( '<td>' ),
				$row = $( '<tr>' ).append( $cell );

			if ( !$( '#mwProtectSet' ).length ) {
				return false;
			}

			if ( mw.config.get( 'wgCascadeableLevels' ) !== undefined ) {
				$( 'form#mw-Protect-Form' ).submit( this.toggleUnchainedInputs.bind( ProtectionForm, true ) );
			}
			this.getExpirySelectors().each( function () {
				$( this ).change( ProtectionForm.updateExpiryList.bind( ProtectionForm, this ) );
			} );
			this.getExpiryInputs().each( function () {
				$( this ).on( 'keyup change', ProtectionForm.updateExpiry.bind( ProtectionForm, this ) );
			} );
			this.getLevelSelectors().each( function () {
				$( this ).change( ProtectionForm.updateLevels.bind( ProtectionForm, this ) );
			} );

			$( '#mwProtectSet > tbody > tr:first' ).after( $row );

			// If there is only one protection type, there is nothing to chain
			if ( $( '[id ^= mw-protect-table-]' ).length > 1 ) {
				$cell.append(
					$( '<input>' )
						.attr( { id: 'mwProtectUnchained', type: 'checkbox' } )
						.click( this.onChainClick.bind( this ) )
						.prop( 'checked', !this.areAllTypesMatching() ),
					document.createTextNode( ' ' ),
					$( '<label>' )
						.attr( 'for', 'mwProtectUnchained' )
						.text( mw.msg( 'protect-unchain-permissions' ) )
				);

				this.toggleUnchainedInputs( !this.areAllTypesMatching() );
			}

			// Arbitrary 75 to leave some space for the autogenerated null edit's summary
			if ( reasonCodePointLimit ) {
				$( '#mwProtect-reason' ).codePointLimit( reasonCodePointLimit - 75 );
			} else if ( reasonByteLimit ) {
				$( '#mwProtect-reason' ).byteLimit( reasonByteLimit - 75 );
			}

			this.updateCascadeCheckbox();
			return true;
		},

		/**
		 * Sets the disabled attribute on the cascade checkbox depending on the current selected levels
		 */
		updateCascadeCheckbox: function () {
			this.getLevelSelectors().each( function () {
				if ( !ProtectionForm.isCascadeableLevel( $( this ).val() ) ) {
					$( '#mwProtect-cascade' ).prop( { checked: false, disabled: true } );
					return false;
				} else {
					$( '#mwProtect-cascade' ).prop( 'disabled', false );
				}
			} );
		},

		/**
		 * Checks if a certain protection level is cascadeable.
		 *
		 * @param {string} level
		 * @return {boolean}
		 */
		isCascadeableLevel: function ( level ) {
			return $.inArray( level, mw.config.get( 'wgCascadeableLevels' ) ) !== -1;
		},

		/**
		 * When protection levels are locked together, update the rest
		 * when one action's level changes
		 *
		 * @param {Element} source Level selector that changed
		 */
		updateLevels: function ( source ) {
			if ( !this.isUnchained() ) {
				this.setAllSelectors( source.selectedIndex );
			}
			this.updateCascadeCheckbox();
		},

		/**
		 * When protection levels are locked together, update the
		 * expiries when one changes
		 *
		 * @param {Element} source expiry input that changed
		 */

		updateExpiry: function ( source ) {
			if ( !this.isUnchained() ) {
				this.getExpiryInputs().each( function () {
					this.value = source.value;
				} );
			}
			if ( this.isUnchained() ) {
				$( '#' + source.id.replace( /^mwProtect-(\w+)-expires$/, 'mwProtectExpirySelection-$1' ) ).val( 'othertime' );
			} else {
				this.getExpirySelectors().each( function () {
					this.value = 'othertime';
				} );
			}
		},

		/**
		 * When protection levels are locked together, update the
		 * expiry lists when one changes and clear the custom inputs
		 *
		 * @param {Element} source Expiry selector that changed
		 */
		updateExpiryList: function ( source ) {
			if ( !this.isUnchained() ) {
				this.getExpirySelectors().each( function () {
					this.value = source.value;
				} );
				this.getExpiryInputs().each( function () {
					this.value = '';
				} );
			}
		},

		/**
		 * Update chain status and enable/disable various bits of the UI
		 * when the user changes the "unlock move permissions" checkbox
		 */
		onChainClick: function () {
			this.toggleUnchainedInputs( this.isUnchained() );
			if ( !this.isUnchained() ) {
				this.setAllSelectors( this.getMaxLevel() );
			}
			this.updateCascadeCheckbox();
		},

		/**
		 * Returns true if the named attribute in all objects in the given array are matching
		 *
		 * @param {Object[]} objects
		 * @param {string} attrName
		 * @return {boolean}
		 */
		matchAttribute: function ( objects, attrName ) {
			return $.map( objects, function ( object ) {
				return object[ attrName ];
			} ).filter( function ( item, index, a ) {
				return index === a.indexOf( item );
			} ).length === 1;
		},

		/**
		 * Are all actions protected at the same level, with the same expiry time?
		 *
		 * @return {boolean}
		 */
		areAllTypesMatching: function () {
			return this.matchAttribute( this.getLevelSelectors(), 'selectedIndex' ) &&
				this.matchAttribute( this.getExpirySelectors(), 'selectedIndex' ) &&
				this.matchAttribute( this.getExpiryInputs(), 'value' );
		},

		/**
		 * Is protection chaining off?
		 *
		 * @return {boolean}
		 */
		isUnchained: function () {
			var element = document.getElementById( 'mwProtectUnchained' );
			return element ?
				element.checked :
				true; // No control, so we need to let the user set both levels
		},

		/**
		 * Find the highest protection level in any selector
		 *
		 * @return {number}
		 */
		getMaxLevel: function () {
			return Math.max.apply( Math, this.getLevelSelectors().map( function () {
				return this.selectedIndex;
			} ) );
		},

		/**
		 * Protect all actions at the specified level
		 *
		 * @param {number} index Protection level
		 */
		setAllSelectors: function ( index ) {
			this.getLevelSelectors().each( function () {
				this.selectedIndex = index;
			} );
		},

		/**
		 * Get a list of all protection selectors on the page
		 *
		 * @return {jQuery}
		 */
		getLevelSelectors: function () {
			return $( 'select[id ^= mwProtect-level-]' );
		},

		/**
		 * Get a list of all expiry inputs on the page
		 *
		 * @return {jQuery}
		 */
		getExpiryInputs: function () {
			return $( 'input[id ^= mwProtect-][id $= -expires]' );
		},

		/**
		 * Get a list of all expiry selector lists on the page
		 *
		 * @return {jQuery}
		 */
		getExpirySelectors: function () {
			return $( 'select[id ^= mwProtectExpirySelection-]' );
		},

		/**
		 * Enable/disable protection selectors and expiry inputs
		 *
		 * @param {boolean} val Enable?
		 */
		toggleUnchainedInputs: function ( val ) {
			var setDisabled = function () { this.disabled = !val; };
			this.getLevelSelectors().slice( 1 ).each( setDisabled );
			this.getExpiryInputs().slice( 1 ).each( setDisabled );
			this.getExpirySelectors().slice( 1 ).each( setDisabled );
		}
	};

	$( ProtectionForm.init.bind( ProtectionForm ) );

}( mediaWiki, jQuery ) );