/**
	 * Render a banner in a containing element.
	 * if in group B, a learn more link will be append to any amboxes inside $container
	 * if in group A or control, any amboxes in container will be removed and a link "page issues"
	 * will be rendered above the heading.
	 * This function comes with side effects. It will populate a global "allIssues" object which
	 * will link section numbers to issues.
	 * @param {Page} page to search for page issues inside
	 * @param {string} labelText what the label of the page issues banner should say
	 * @param {string} section that the banner and its issues belong to.
	 *  If string KEYWORD_ALL_SECTIONS banner should apply to entire page.
	 * @param {boolean} inline - if true the first ambox in the section will become the entry point
	 *                           for the issues overlay
	 *  and if false, a link will be rendered under the heading.
	 * @param {OverlayManager} overlayManager
	 * @ignore
	 *
	 * @return {JQuery.Object}
	 */
	function createBanner( page, labelText, section, inline, overlayManager ) {
		var
			$metadata,
			issueUrl = section === KEYWORD_ALL_SECTIONS ? '#/issues/' + KEYWORD_ALL_SECTIONS : '#/issues/' + section,
			selector = 'table.ambox, table.tmbox, table.cmbox, table.fmbox',
			issueSummaries = [];

		if ( section === KEYWORD_ALL_SECTIONS ) {
			$metadata = page.$( selector );
		} else {
			// find heading associated with the section
			$metadata = page.findChildInSectionLead( parseInt( section, 10 ), selector );
		}
		// clean it up a little
		$metadata.find( '.NavFrame' ).remove();
		$metadata.each( function () {
			var issueSummary,
				$this = $( this );

			if ( $this.find( selector ).length === 0 ) {
				issueSummary = pageIssuesParser.extract( $this );
				// Some issues after "extract" has been run will have no text.
				// For example in Template:Talk header the table will be removed and no issue found.
				// These should not be rendered.
				if ( issueSummary.text ) {
					issueSummaries.push( issueSummary );
				}
			}
		} );
		// store it for later
		allIssues[section] = issueSummaries;

		if ( inline ) {
			issueSummaries.forEach( function ( issueSummary, i ) {
				var isGrouped = issueSummary.issue.grouped,
					lastIssueIsGrouped = issueSummaries[ i - 1] &&
						issueSummaries[ i - 1].issue.grouped;
				// only render the first grouped issue of each group
				if ( isGrouped && !lastIssueIsGrouped ) {
					createPageIssueBannerMultiple( issueSummary, mw.msg( 'skin-minerva-issue-learn-more' ), issueUrl, overlayManager );
				} else {
					createPageIssueBanner( issueSummary, mw.msg( 'skin-minerva-issue-learn-more' ), issueUrl, overlayManager );
				}
			} );
		} else if ( issueSummaries.length ) {
			createPageIssueNotice( labelText, section );
		}

		return $metadata;
	}

	/**
	 * Obtains the list of issues for the current page and provided section
	 * @param {number|string} section either KEYWORD_ALL_SECTIONS or a number relating to the
	 *                                section the issues belong to
	 * @return {jQuery.Object[]} array of all issues.
	 */
	function getIssues( section ) {
		if ( section !== KEYWORD_ALL_SECTIONS ) {
			return allIssues[section] || [];
		}
		// Note section.all may not exist, depending on the structure of the HTML page.
		// It will only exist when Minerva has been run in desktop mode.
		// If it's absent, we'll reduce all the other lists into one.
		return allIssues.all || Object.keys( allIssues ).reduce(
			function ( all, key ) {
				return all.concat( allIssues[key] );
			},
			[]
		);
	}

	/**
	 * Returns an array containing the section of each page issue.
	 * In the case that several page issues are grouped in a 'multiple issues' template,
	 * returns the section of those issues as one item.
	 * @param {Object} allIssues mapping section {Number} to {IssueSummary}
	 * @return {array}
	 */
	function getAllIssuesSections( allIssues ) {
		return Object.keys( allIssues ).reduce( function ( acc, section ) {
			if ( allIssues[ section ].length ) {
				allIssues[ section ].forEach( function ( issue, i ) {
					var lastIssue = allIssues[ section ][i - 1];
					// If the last issue belongs to a "Multiple issues" template,
					// and so does the current one, don't add the current one.
					if ( lastIssue && lastIssue.grouped && issue.grouped ) {
						acc[ acc.length - 1 ] = section;
					} else {
						acc.push( section );
					}
				} );
			}
			return acc;
		}, [] );
	}