export default class XHRRetry {
    private url: any;
    private headers: any;
    private maxAttempts: number;
    private retryPeriod: number;
    private responseChecker: Function;
    constructor(url: any, headers: any, params: any) {
        this.url = url;
        this.headers = headers;
        this.maxAttempts = params.maxAttempts || 5;
        this.retryPeriod = params.retryPeriod || 5000;
        this.responseChecker = params.responseChecker;
    }

    retrieve() {
        let maxAttempts = this.maxAttempts;
        let retryPeriod = this.retryPeriod;

        return new Promise((resolve, reject) => {
            this.retrieveInternal()
                .then((responseText) => {
                    resolve(responseText);
                })
                .catch(() => {
                    let interval = setInterval(() => {
                        this.retrieveInternal()
                            .then((responseText) => {
                                clearInterval(interval);
                                resolve(responseText);
                                return;
                            })
                            .catch((err) => {
                                maxAttempts--;
                                if (maxAttempts <= 0) {
                                    clearInterval(interval);
                                    reject(err);
                                }
                            });
                    }, retryPeriod);
                });
        });
    }

    checkXHRResponse(response: any) {
        if (this.responseChecker) {
            return this.responseChecker(response);
        }

        return true;
    }

    retrieveInternal() {
        return new Promise((resolve, reject) => {
            let xhr = new XMLHttpRequest();

            xhr.onreadystatechange = () => {
                if (xhr.readyState === XMLHttpRequest.DONE) {
                    if (xhr.status >= 200 && xhr.status < 300 && this.checkXHRResponse(xhr.responseText)) {
                        resolve(xhr.responseText);
                    } else {
                        reject(xhr.status);
                    }
                }
            };

            xhr.open('GET', this.url, true);
            this.setHeaders(xhr);
            xhr.send();
        });
    }

    setHeaders(xhr: any) {
        if (Array.isArray(this.headers)) {
            this.headers.forEach((x) => xhr.setRequestHeader(x.key, x.value));
        } else {
            xhr.setRequestHeader(this.headers.key, this.headers.value);
        }
    }
}