import {IStringMap} from "./Interfaces";
class XhrRequest {
    // Method that performs the ajax request
    public static ajax(
        method: XhrRequest.Method,
        url: string,
        args: IStringMap = null,
        headers: IStringMap = null,
        options: IStringMap = {}
    ): Promise<any> {

        // Creating a promise
        return new Promise((resolve, reject) => {

            // Instantiates the XMLHttpRequest
            const client: XMLHttpRequest = XhrRequest.createXMLHTTPObject();
            let uri: string = url;
            let payload = null;

            // Add given payload to get request
            if (args && (method === XhrRequest.Method.GET)) {
                uri += "?";
                let argcount = 0;
                for (const key in args) {
                    if (args.hasOwnProperty(key)) {
                        if (argcount++) {
                            uri += "&";
                        }
                        uri += encodeURIComponent(key) + "=" + encodeURIComponent(args[key]);
                    }
                }
            } else if (args) {
                if (!headers) {
                    headers = {};
                }
                headers["Content-Type"] = "application/json; charset=utf-8";
                payload = JSON.stringify(args);
            }

            for (const key in options) {
                if (key in client) {
                    client[key] = options[key];
                }
            }

            // hack: method[method] is somewhat like .toString for enum Method
            // should be made in normal way
            client.open(XhrRequest.Method[method], uri, true);
            // Add given headers

            if (headers) {
                for (const key in headers) {
                    if (headers.hasOwnProperty(key)) {
                        client.setRequestHeader(key, headers[key]);
                    }
                }
            }

            payload ? client.send(payload) : client.send();

            client.onload = () => {
                if (client.status >= 200 && client.status < 300) {
                    // Performs the function "resolve" when this.status is equal to 2xx
                    resolve(client);
                } else {
                    // Performs the function "reject" when this.status is different than 2xx
                    reject(client);
                }
            };
            client.onerror = () => {
                reject(client);
            };
        });

    }

    public static get(url, payload: IStringMap = null, headers: IStringMap = null, options = {}): Promise<any> {
        return XhrRequest.ajax(XhrRequest.Method.GET, url, payload, headers, options);
    }

    public static post(url: string, payload: IStringMap = null, headers: IStringMap = null,
                       options = {}): Promise<any> {
        return XhrRequest.ajax(XhrRequest.Method.POST, url, payload, headers, options);
    }

    public static put(url: string, payload: IStringMap = null, headers: IStringMap = null,
                      options = {}): Promise<any>  {
        return XhrRequest.ajax(XhrRequest.Method.PUT, url, payload, headers, options);
    }

    public static delete(url: string, payload: IStringMap = null, headers: IStringMap = null,
                         options = {}): Promise<any>  {
        return XhrRequest.ajax(XhrRequest.Method.DELETE, url, payload, headers, options);
    }

    private static XMLHttpFactories: Function[] = [
        () => new XMLHttpRequest(),
        () => new window["ActiveXObject"]("Msxml2.XMLHTTP"),
        () => new window["ActiveXObject"]("Msxml3.XMLHTTP"),
        () => new window["ActiveXObject"]("Microsoft.XMLHTTP")
    ];

    private static createXMLHTTPObject(): XMLHttpRequest {
        let xmlhttp: XMLHttpRequest = null;
        for (const i of XhrRequest.XMLHttpFactories) {
            try {
                xmlhttp = i();
            } catch (e) {
                continue;
            }
            break;
        }

        return xmlhttp;
    }
}

namespace XhrRequest {
    export enum Method {
        GET = "GET" as any,
        POST = "POST" as any,
        PUT = "PUT" as any,
        DELETE = "DELETE" as any
    }
}

export default XhrRequest;