export class UploadFile<T> {

    // tslint:disable-next-line:max-line-length
    constructor(public file: File, public parameters: {}, public url,
        private onCompleted?: (data: T) => void,
        private onProgress?: (evt: Event) => void,
        private onError?: (error: any) => void) { }

    startUpload(): UploadFile<T> {
        this.uploadFile(this.file);
        return this;
    }
    private uploadFile(file: File) {
        const xhr: XMLHttpRequest = new XMLHttpRequest();
        const formData: FormData = new FormData();
        xhr.open('POST', this.url, true);
        xhr.upload.onprogress = this.onProgressHandler;
        xhr.upload.onload = this.onProgressCompleted;
        xhr.onload = this.onLoadCompleted;

        for (const key in this.parameters) {
            if (this.parameters.hasOwnProperty(key)) {
                formData.append(key, this.parameters[key]);
            }
        }
        formData.append('file', file);
        xhr.send(formData);
    }
    private onProgressHandler = (evt: Event) => {
        if (this.onProgress != null) {
            this.onProgress(evt);
        }
    }
    private onProgressCompleted = (evt: Event) => {
        if (this.onProgress != null) {
            this.onProgress(evt);
        }
    }
    private onLoadCompleted = (evt: Event) => {
        const xhr: any = evt.srcElement;

        try {
            const result: T = JSON.parse(xhr.responseText);
            if (this.onCompleted != null) {
                this.onCompleted(result);
            }
        } catch (e) {
            if (this.onError != null) {
                this.onError(e);
            }
        }
    }
}