import { Locator, Page, Frame } from 'playwright';
import envVariables from './env-variables';

const coreNavTabParent = 'div.components-tab-panel__tabs';
const calypsoNavTabParent = 'div.section-nav';

const selectors = {
	// clickNavTab
	navTabItem: ( {
		name = '',
		selected = false,
		isCoreTabs = false,
	}: { name?: string; selected?: boolean; isCoreTabs?: boolean } = {} ) =>
		! isCoreTabs || envVariables.VIEWPORT_NAME === 'mobile'
			? `${ calypsoNavTabParent } a[aria-current="${ selected }"]:has(span:has-text("${ name }"))`
			: `${ coreNavTabParent } button[aria-selected="${ selected }"]:has-text("${ name }")`,
	navTabMobileToggleButton: `${ calypsoNavTabParent } button.section-nav__mobile-header`,
};

/**
 * Waits for the element specified by the selector to become enabled.
 *
 * There are two definitions of disabled on wp-calypso:
 * 		- traditional: set the `disabled` property on element.
 * 		- aria: using the `aria-disabled` attribute.
 *
 * Playwright's `isEnabled` method does not look into `aria-disabled = "true"` when determining
 * actionability. This means test steps may fail if it depends on the built-in `isEnabled` to
 * assert actionability.
 *
 * This function will check for both the`disabled` property and `aria-disabled="false"` attributes
 * to determine whether the element is enabled.
 *
 * @param {Page} page Page object.
 * @param {string} selector Selector of the target element.
 * @param {{[key: string]: number}} options Object parameter.
 * @param {number} options.timeout Timeout to override the default value.
 */
export async function waitForElementEnabled(
	page: Page,
	selector: string,
	options?: { timeout?: number }
) {
	const elementHandle = await page.waitForSelector( selector, options );
	await Promise.all( [
		elementHandle.waitForElementState( 'enabled', options ),
		page.waitForFunction(
			( element: SVGElement | HTMLElement ) => element.ariaDisabled !== 'true',
			elementHandle
		),
	] );

	return elementHandle;
}

/**
 * Locates and clicks on a specified tab on the NavTab.
 *
 * NavTabs are used throughout calypso to contain sub-pages within the parent page.
 * For instance, on the Media gallery page a NavTab is used to filter the gallery to
 * show a specific category of gallery items.
 *
 * @param {Page} page Underlying page on which interactions take place.
 * @param {string} name Name of the tab to be clicked.
 * @throws {Error} If the tab name is not the active tab.
 */
export async function clickNavTab(
	page: Page,
	name: string,
	{ force, isCoreTabs = false }: { force?: boolean; isCoreTabs?: boolean } = {}
): Promise< void > {
	// Short circuit operation if the active tab and target tabs are the same.
	// Strip numerals from the extracted tab name to account for the slightly
	// different implementation in PostsPage.
	const selectedTabLocator = page.locator( selectors.navTabItem( { selected: true, isCoreTabs } ) );
	const selectedTabName = await selectedTabLocator.innerText();
	if ( selectedTabName.replace( /[0-9]|,/g, '' ) === name ) {
		return;
	}

	// If force option is specified, force click using a `dispatchEvent`.
	if ( force ) {
		return await page.dispatchEvent( selectors.navTabItem( { name: name, isCoreTabs } ), 'click' );
	}

	// Mobile view - navtabs become a dropdown and thus it must be opened first.
	if ( envVariables.VIEWPORT_NAME === 'mobile' ) {
		// Open the Navtabs which now act as a pseudo-dropdown menu.
		const navTabsButtonLocator = page.locator( selectors.navTabMobileToggleButton );
		await navTabsButtonLocator.click( { noWaitAfter: true } );

		const navTabIsOpenLocator = page.locator( `${ calypsoNavTabParent }.is-open` );
		await navTabIsOpenLocator.waitFor();
	}

	// Click on the intended item and wait for navigation to finish.
	const navTabItem = page.locator(
		selectors.navTabItem( { name: name, selected: false, isCoreTabs } )
	);

	const regex = new RegExp( `.*/${ name.toLowerCase() }/.*` );
	await Promise.all( [ page.waitForURL( regex ), navTabItem.click() ] );

	// Final verification, check that we are now on the expected navtab.
	const newSelectedTabLocator = page.locator(
		selectors.navTabItem( { name: name, selected: true, isCoreTabs } )
	);
	const newSelectedTabName = await newSelectedTabLocator.innerText();

	if ( newSelectedTabName.replace( /[0-9]|,/g, '' ) !== name ) {
		throw new Error(
			`Failed to confirm NavTab is active: expected ${ name }, got ${ newSelectedTabName }`
		);
	}
}

/**
 * Retry any function up to three times or action passes without throwing an exception,
 * whichever comes first.
 *
 * The function being passed in must throw an exception for this retry to work.
 *
 * This is useful for situations where the backend must process the results of a
 * previous action then inform the front end of the result of the process.
 * An example of this is the user invitation system where the backend must receive,
 * verify and send the invitation issued by a user. If the resulting checks were
 * successful, the resulting invitation is shown as 'pending'.
 *
 * @param {Page} page Page object.
 */
export async function reloadAndRetry(
	page: Page,
	func: ( page: Page ) => Promise< void >
): Promise< void > {
	for ( let retries = 3; retries > 0; retries -= 1 ) {
		try {
			return await func( page );
		} catch ( err ) {
			// Throw the error if final retry failed.
			if ( retries === 1 ) {
				throw err;
			} else {
				await page.reload();
			}
		}
	}
	return;
}

/**
 * Gets and validates the block ID from a Locator to a parent Block element in the editor.
 *
 * @param {Locator} block A frame-safe Loccator to the top of a block.
 * @returns A block ID that can be used to identify the block in the DOM later.
 */
export async function getIdFromBlock( block: Locator ): Promise< string > {
	const blockId = await block.getAttribute( 'id' );
	const blockIdRegex = /^block-[0-9a-fA-F]{8}-([0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}$/;
	if ( ! blockId || ! blockIdRegex.test( blockId ) ) {
		throw new Error( `Unable to find valid block ID from Locator. ID was "${ blockId }"` );
	}

	return blockId;
}

/**
 * Waits until DOM mutations for given target element become idle. Can be used
 * in situations where Playwright auto-waiting is not working for some reason.
 *
 * @example
 * await Promise.all( [
 *   waitForMutations( page, '.foobars-wrapper' ),
 *   page.click( 'button.load-foobars' ),
 * ] );
 * const foobarsText = await page.innerText( '.foobars' );
 * @param {Page} page Page object.
 * @param {string} selector Observer target selector.
 * @param {Object} options
 * @param {number} options.timeout Maximum time in milliseconds, defaults to 10
 * seconds, pass 0 to disable timeout.
 * @param {number} options.debounce Maximum time to wait between consecutive
 * mutations, defaults to 1 second.
 * @param {Object} options.observe Mutation observation options.
 */
export async function waitForMutations(
	page: Page | Frame,
	selector: string,
	options?: {
		timeout?: number;
		debounce?: number;
		observe?: MutationObserverInit;
	}
): Promise< void > {
	const timeout = options?.timeout || 10000;
	const debounce = options?.debounce || 1000;
	const observe = options?.observe || { attributes: true, subtree: true, childList: true };
	const target = await page.waitForSelector( selector );

	await Promise.race( [
		new Promise( ( resolve, reject ) => {
			if ( timeout > 0 ) {
				setTimeout( () => {
					reject( `Waiting for ${ selector } mutations timed out.` );
				}, timeout );
			}
		} ),
		page.evaluate(
			async ( args ) => {
				await new Promise( ( resolve ) => {
					const debounceResolve = () => {
						let timer: NodeJS.Timeout;
						return () => {
							clearTimeout( timer );
							timer = setTimeout( resolve, args.debounce );
						};
					};

					const observer = new MutationObserver( debounceResolve() );
					observer.observe( args.target, args.observe );
				} );
			},
			{ target, debounce, observe }
		),
	] );
}

/**
 * Resolves once widgets.wp.com `message` events become idle or when no
 * `message` events are dispatched within the first 3 seconds. Once resolved,
 * all the widgets should be ready to be interacted with. This helper can be
 * used on Atomic sites where the iframed widgets have, e.g., custom resize
 * handlers (like the like button), causing layout shifting and, consequently,
 * Playwright's stability checks to fail.
 *
 * @param {Page} page The parent page object.
 */
export async function waitForWPWidgetsIfNecessary( page: Page ): Promise< void > {
	await page.evaluate( async () => {
		await new Promise( ( resolve ) => {
			let timer: NodeJS.Timeout;
			const setResolveTimer = ( delay: number ) => {
				clearTimeout( timer );
				timer = setTimeout( resolve, delay );
			};

			setResolveTimer( 3000 );

			window.addEventListener( 'message', ( event ) => {
				if ( event.origin === 'https://widgets.wp.com' ) {
					setResolveTimer( 1000 );
				}
			} );
		} );
	} );
}