// imported for definition purposes only
import * as httpRequestModule from "../../http/http-request";

import * as common from "./image-cache-common";
import { Trace } from "../../trace";
import * as utils from "../../utils/utils";

let httpRequest: typeof httpRequestModule;
function ensureHttpRequest() {
	if (!httpRequest) {
		httpRequest = require("../../http/http-request");
	}
}

class MemmoryWarningHandler extends NSObject {
	static new(): MemmoryWarningHandler {
		return <MemmoryWarningHandler>super.new();
	}

	private _cache: NSCache<any, any>;

	public initWithCache(cache: NSCache<any, any>): MemmoryWarningHandler {
		this._cache = cache;

		NSNotificationCenter.defaultCenter.addObserverSelectorNameObject(
			this,
			"clearCache",
			"UIApplicationDidReceiveMemoryWarningNotification",
			null
		);
		if (Trace.isEnabled()) {
			Trace.write(
				"[MemmoryWarningHandler] Added low memory observer.",
				Trace.categories.Debug
			);
		}

		return this;
	}

	public dealloc(): void {
		NSNotificationCenter.defaultCenter.removeObserverNameObject(
			this,
			"UIApplicationDidReceiveMemoryWarningNotification",
			null
		);
		if (Trace.isEnabled()) {
			Trace.write(
				"[MemmoryWarningHandler] Removed low memory observer.",
				Trace.categories.Debug
			);
		}
		super.dealloc();
	}

	public clearCache(): void {
		if (Trace.isEnabled()) {
			Trace.write(
				"[MemmoryWarningHandler] Clearing Image Cache.",
				Trace.categories.Debug
			);
		}
		this._cache.removeAllObjects();
		utils.GC();
	}

	public static ObjCExposedMethods = {
		clearCache: { returns: interop.types.void, params: [] },
	};
}

export class Cache extends common.Cache {
	private _cache: NSCache<any, any>;

	//@ts-ignore
	private _memoryWarningHandler: MemmoryWarningHandler;

	constructor() {
		super();

		this._cache = new NSCache<any, any>();

		this._memoryWarningHandler = MemmoryWarningHandler.new().initWithCache(
			this._cache
		);
	}

	public _downloadCore(request: common.DownloadRequest) {
		ensureHttpRequest();

		httpRequest.request({ url: request.url, method: "GET" }).then(
			(response) => {
				try {
					const image = UIImage.alloc().initWithData(
						response.content.raw
					);
					if (image) {
						this._onDownloadCompleted(request.key, image);
					} else {
						this._onDownloadError(
							request.key,
							new Error("No result for provided url")
						);
					}
				} catch (err) {
					this._onDownloadError(request.key, err);
				}
			},
			(err) => {
				this._onDownloadError(request.key, err);
			}
		);
	}

	public get(key: string): any {
		return this._cache.objectForKey(key);
	}

	public set(key: string, image: any): void {
		this._cache.setObjectForKey(image, key);
	}

	public remove(key: string): void {
		this._cache.removeObjectForKey(key);
	}

	public clear() {
		this._cache.removeAllObjects();
		utils.GC();
	}
}