const track = mw.track;
const MAX_PRINT_TIMEOUT = 3000;
let printSetTimeoutReference = 0;
const mobile = require( 'mobile.startup' );

/**
 * Helper function to detect iOs
 *
 * @ignore
 * @param {string} userAgent User Agent
 * @return {boolean}
 */
function isIos( userAgent ) {
	return /ipad|iphone|ipod/i.test( userAgent );
}

/**
 * Helper function to retrieve the Android version
 *
 * @ignore
 * @param {string} userAgent User Agent
 * @return {number|boolean} Integer version number, or false if not found
 */
function getAndroidVersion( userAgent ) {
	const match = userAgent.toLowerCase().match( /android\s(\d\.]*)/ );
	return match ? parseInt( match[ 1 ] ) : false;
}

/**
 * Helper function to retrieve the Chrome/Chromium version
 *
 * @ignore
 * @param {string} userAgent User Agent
 * @return {number|boolean} Integer version number, or false if not found
 */
function getChromeVersion( userAgent ) {
	const match = userAgent.toLowerCase().match( /chrom(e|ium)\/(\d+)\./ );
	return match ? parseInt( match[ 2 ] ) : false;
}

/**
 * Checks whether DownloadIcon is available for given user agent
 *
 * @memberof DownloadIcon
 * @instance
 * @param {Window} windowObj
 * @param {Page} page to download
 * @param {string} userAgent User agent
 * @param {number[]} supportedNamespaces where printing is possible
 * @return {boolean}
 */
function isAvailable( windowObj, page, userAgent, supportedNamespaces ) {
	const androidVersion = getAndroidVersion( userAgent );
	const chromeVersion = getChromeVersion( userAgent );

	if ( typeof window.print !== 'function' ) {
		// T309591: No window.print support
		return false;
	}

	// Download button is restricted to certain namespaces T181152.
	// Not shown on missing pages
	// Defaults to 0, in case cached JS has been served.
	if ( supportedNamespaces.indexOf( page.getNamespaceId() ) === -1 ||
		page.isMainPage() || page.isMissing ) {
		// namespace is not supported or it's a main page
		return false;
	}

	if ( isIos( userAgent ) || chromeVersion === false ||
		windowObj.chrome === undefined
	) {
		// we support only chrome/chromium on desktop/android
		return false;
	}
	if ( ( androidVersion && androidVersion < 5 ) || chromeVersion < 41 ) {
		return false;
	}
	return true;
}
/**
 * onClick handler for button that invokes print function
 *
 * @private
 * @param {HTMLElement} portletItem
 * @param {Icon} spinner
 * @param {Function} [loadAllImagesInPage]
 */
function onClick( portletItem, spinner, loadAllImagesInPage ) {
	const icon = portletItem.querySelector( '.minerva-icon--download' );
	function doPrint() {
		printSetTimeoutReference = clearTimeout( printSetTimeoutReference );
		track( 'minerva.downloadAsPDF', {
			action: 'callPrint'
		} );
		window.print();
		$( icon ).show();
		spinner.$el.hide();
	}

	function doPrintBeforeTimeout() {
		if ( printSetTimeoutReference ) {
			doPrint();
		}
	}
	// The click handler may be invoked multiple times so if a pending print is occurring
	// do nothing.
	if ( !printSetTimeoutReference ) {
		track( 'minerva.downloadAsPDF', {
			action: 'fetchImages'
		} );
		$( icon ).hide();
		spinner.$el.show();
		// If all image downloads are taking longer to load then the MAX_PRINT_TIMEOUT
		// abort the spinner and print regardless.
		printSetTimeoutReference = setTimeout( doPrint, MAX_PRINT_TIMEOUT );
		( loadAllImagesInPage || mobile.loadAllImagesInPage )()
			.then( doPrintBeforeTimeout, doPrintBeforeTimeout );
	}
}

/**
 * Generate a download icon for triggering print functionality if
 * printing is available.
 * Calling this method has side effects:
 * It calls mw.util.addPortletLink and may inject an element into the page.
 *
 * @ignore
 * @param {Page} page
 * @param {number[]} supportedNamespaces
 * @param {Window} [windowObj] window object
 * @param {boolean} [overflowList] Append to overflow list
 * @return {jQuery|null}
 */
function downloadPageAction( page, supportedNamespaces, windowObj, overflowList ) {
	const spinner = ( overflowList ) ? mobile.spinner( {
		label: '',
		isIconOnly: false
	} ) : mobile.spinner();

	if (
		isAvailable(
			windowObj, page, navigator.userAgent,
			supportedNamespaces
		)
	) {
		// FIXME: Use p-views when cache has cleared.
		const actionID = document.querySelector( '#p-views' ) ? 'p-views' : 'page-actions';
		const portletLink = mw.util.addPortletLink(
			overflowList ? 'page-actions-overflow' : actionID,
			'#',
			mw.msg( 'minerva-download' ),
			// id
			'minerva-download',
			// tooltip
			mw.msg( 'minerva-download' ),
			// access key
			'p',
			overflowList ? null : document.getElementById( 'page-actions-watch' )
		);
		if ( portletLink ) {
			portletLink.addEventListener( 'click', () => {
				onClick( portletLink, spinner, mobile.loadAllImagesInPage );
			} );
			const iconElement = portletLink.querySelector( '.minerva-icon' );
			if ( iconElement ) {
				iconElement.classList.add( 'minerva-icon--download' );
			}
			spinner.$el.hide().insertBefore(
				$( portletLink ).find( '.minerva-icon' )
			);
		}
		return portletLink;
	} else {
		return null;
	}
}

module.exports = {
	downloadPageAction,
	test: {
		isAvailable,
		onClick
	}
};