import * as Application from '../application';
import type { View } from '../ui/core/view';
import { notifyAccessibilityFocusState } from './accessibility-common';
import { AccessibilityLiveRegion, AccessibilityRole, AccessibilityState, AccessibilityTrait } from './accessibility-types';

export * from './accessibility-common';
export * from './accessibility-types';
export * from './font-scale';

function enforceArray(val: string | string[]): string[] {
	if (Array.isArray(val)) {
		return val;
	}

	if (typeof val === 'string') {
		return val.split(/[, ]/g).filter((v: string) => !!v);
	}

	return [];
}

/**
 * Convert array of values into a bitmask.
 *
 * @param values string values
 * @param map    map lower-case name to integer value.
 */
function inputArrayToBitMask(values: string | string[], map: Map<string, number>): number {
	return (
		enforceArray(values)
			.filter((value) => !!value)
			.map((value) => `${value}`.toLocaleLowerCase())
			.filter((value) => map.has(value))
			.reduce((res, value) => res | map.get(value), 0) || 0
	);
}

let AccessibilityTraitsMap: Map<string, number>;
let RoleTypeMap: Map<AccessibilityRole, number>;

let nativeFocusedNotificationObserver;
let lastFocusedView: WeakRef<View>;
function ensureNativeClasses() {
	if (AccessibilityTraitsMap && nativeFocusedNotificationObserver) {
		return;
	}

	AccessibilityTraitsMap = new Map<AccessibilityTrait, number>([
		[AccessibilityTrait.None, UIAccessibilityTraitNone],
		[AccessibilityTrait.Button, UIAccessibilityTraitButton],
		[AccessibilityTrait.Link, UIAccessibilityTraitLink],
		[AccessibilityTrait.SearchField, UIAccessibilityTraitSearchField],
		[AccessibilityTrait.Image, UIAccessibilityTraitImage],
		[AccessibilityTrait.Selected, UIAccessibilityTraitSelected],
		[AccessibilityTrait.PlaysSound, UIAccessibilityTraitPlaysSound],
		[AccessibilityTrait.StaticText, UIAccessibilityTraitStaticText],
		[AccessibilityTrait.SummaryElement, UIAccessibilityTraitSummaryElement],
		[AccessibilityTrait.NotEnabled, UIAccessibilityTraitNotEnabled],
		[AccessibilityTrait.UpdatesFrequently, UIAccessibilityTraitUpdatesFrequently],
		[AccessibilityTrait.StartsMediaSession, UIAccessibilityTraitStartsMediaSession],
		[AccessibilityTrait.Adjustable, UIAccessibilityTraitAdjustable],
		[AccessibilityTrait.AllowsDirectInteraction, UIAccessibilityTraitAllowsDirectInteraction],
		[AccessibilityTrait.CausesPageTurn, UIAccessibilityTraitCausesPageTurn],
		[AccessibilityTrait.Header, UIAccessibilityTraitHeader],
	]);

	RoleTypeMap = new Map<AccessibilityRole, number>([
		[AccessibilityRole.Button, UIAccessibilityTraitButton],
		[AccessibilityRole.Header, UIAccessibilityTraitHeader],
		[AccessibilityRole.Link, UIAccessibilityTraitLink],
		[AccessibilityRole.Search, UIAccessibilityTraitSearchField],
		[AccessibilityRole.Image, UIAccessibilityTraitImage],
		[AccessibilityRole.ImageButton, UIAccessibilityTraitImage | UIAccessibilityTraitButton],
		[AccessibilityRole.KeyboardKey, UIAccessibilityTraitKeyboardKey],
		[AccessibilityRole.StaticText, UIAccessibilityTraitStaticText],
		[AccessibilityRole.Summary, UIAccessibilityTraitSummaryElement],
		[AccessibilityRole.Adjustable, UIAccessibilityTraitAdjustable],
		[AccessibilityRole.Checkbox, UIAccessibilityTraitButton],
		[AccessibilityRole.Switch, UIAccessibilityTraitButton],
		[AccessibilityRole.RadioButton, UIAccessibilityTraitButton],
	]);

	nativeFocusedNotificationObserver = Application.ios.addNotificationObserver(UIAccessibilityElementFocusedNotification, (args: NSNotification) => {
		const uiView = args.userInfo.objectForKey(UIAccessibilityFocusedElementKey) as UIView;
		if (!uiView.tag) {
			return;
		}

		const rootView = Application.getRootView();

		// We use the UIView's tag to find the NativeScript View by its domId.
		let view = rootView.getViewByDomId<View>(uiView.tag);
		if (!view) {
			for (const modalView of <Array<View>>rootView._getRootModalViews()) {
				view = modalView.getViewByDomId(uiView.tag);
				if (view) {
					break;
				}
			}
		}

		if (!view) {
			return;
		}

		const lastView = lastFocusedView?.get();
		if (lastView && view !== lastView) {
			const lastFocusedUIView = lastView.nativeViewProtected as UIView;
			if (lastFocusedUIView) {
				lastFocusedView = null;

				notifyAccessibilityFocusState(lastView, false, true);
			}
		}

		lastFocusedView = new WeakRef(view);

		notifyAccessibilityFocusState(view, true, false);
	});

	Application.on(Application.exitEvent, () => {
		if (nativeFocusedNotificationObserver) {
			Application.ios.removeNotificationObserver(nativeFocusedNotificationObserver, UIAccessibilityElementFocusedNotification);
		}

		nativeFocusedNotificationObserver = null;
		lastFocusedView = null;
	});
}

export function setupAccessibleView(view: View): void {
	const uiView = view.nativeViewProtected as UIView;
	if (!uiView) {
		return;
	}

	/**
	 * We need to map back from the UIView to the NativeScript View.
	 *
	 * We do that by setting the uiView's tag to the View's domId.
	 * This way we can do reverse lookup.
	 */
	uiView.tag = view._domId;
}

export function updateAccessibilityProperties(view: View): void {
	const uiView = view.nativeViewProtected as UIView;
	if (!uiView) {
		return;
	}

	ensureNativeClasses();

	const accessibilityRole = view.accessibilityRole;
	const accessibilityState = view.accessibilityState;

	if (!view.accessible || view.accessibilityHidden) {
		uiView.accessibilityTraits = UIAccessibilityTraitNone;

		return;
	}

	let a11yTraits = UIAccessibilityTraitNone;
	if (RoleTypeMap.has(accessibilityRole)) {
		a11yTraits |= RoleTypeMap.get(accessibilityRole);
	}

	switch (accessibilityRole) {
		case AccessibilityRole.Checkbox:
		case AccessibilityRole.RadioButton:
		case AccessibilityRole.Switch: {
			if (accessibilityState === AccessibilityState.Checked) {
				a11yTraits |= AccessibilityTraitsMap.get(AccessibilityTrait.Selected);
			}
			break;
		}
		default: {
			if (accessibilityState === AccessibilityState.Selected) {
				a11yTraits |= AccessibilityTraitsMap.get(AccessibilityTrait.Selected);
			}
			if (accessibilityState === AccessibilityState.Disabled) {
				a11yTraits |= AccessibilityTraitsMap.get(AccessibilityTrait.NotEnabled);
			}
			break;
		}
	}

	const UpdatesFrequentlyTrait = AccessibilityTraitsMap.get(AccessibilityTrait.UpdatesFrequently);

	switch (view.accessibilityLiveRegion) {
		case AccessibilityLiveRegion.Polite:
		case AccessibilityLiveRegion.Assertive: {
			a11yTraits |= UpdatesFrequentlyTrait;
			break;
		}
		default: {
			a11yTraits &= ~UpdatesFrequentlyTrait;
			break;
		}
	}

	if (view.accessibilityMediaSession) {
		a11yTraits |= AccessibilityTraitsMap.get(AccessibilityTrait.StartsMediaSession);
	}

	if (view.accessibilityTraits) {
		a11yTraits |= inputArrayToBitMask(view.accessibilityTraits, AccessibilityTraitsMap);
	}

	uiView.accessibilityTraits = a11yTraits;
}

// eslint-disable-next-line @typescript-eslint/no-empty-function
export const sendAccessibilityEvent = (): void => {};
export const updateContentDescription = (): string | null => null;

let accessibilityServiceEnabled: boolean;
let nativeObserver;
export function isAccessibilityServiceEnabled(): boolean {
	if (typeof accessibilityServiceEnabled === 'boolean') {
		return accessibilityServiceEnabled;
	}

	let isVoiceOverRunning: () => boolean;
	if (typeof UIAccessibilityIsVoiceOverRunning === 'function') {
		isVoiceOverRunning = UIAccessibilityIsVoiceOverRunning;
	} else {
		// iOS is too old to tell us if voice over is enabled
		if (typeof UIAccessibilityIsVoiceOverRunning !== 'function') {
			accessibilityServiceEnabled = false;
			return accessibilityServiceEnabled;
		}
	}

	accessibilityServiceEnabled = isVoiceOverRunning();

	let voiceOverStatusChangedNotificationName: string | null = null;
	if (typeof UIAccessibilityVoiceOverStatusDidChangeNotification !== 'undefined') {
		voiceOverStatusChangedNotificationName = UIAccessibilityVoiceOverStatusDidChangeNotification;
	} else if (typeof UIAccessibilityVoiceOverStatusChanged !== 'undefined') {
		voiceOverStatusChangedNotificationName = UIAccessibilityVoiceOverStatusChanged;
	}

	if (voiceOverStatusChangedNotificationName) {
		nativeObserver = Application.ios.addNotificationObserver(voiceOverStatusChangedNotificationName, () => {
			accessibilityServiceEnabled = isVoiceOverRunning();
		});

		Application.on(Application.exitEvent, () => {
			if (nativeObserver) {
				Application.ios.removeNotificationObserver(nativeObserver, voiceOverStatusChangedNotificationName);
			}

			accessibilityServiceEnabled = undefined;
			nativeObserver = null;
		});
	}

	Application.on(Application.resumeEvent, () => {
		accessibilityServiceEnabled = isVoiceOverRunning();
	});

	return accessibilityServiceEnabled;
}