/**
 * @enum{string}
**/
var HttpRequestMethod = {
    GET: "GET",
    POST: "POST",
    PUT: "PUT",
    DELETE: "DELETE"
};


/**
 * @enum{string}
**/
var HttpRequestResponseType = {
    ARRAYBUFFER: "arraybuffer",
    BLOB: "blob",
    DOCUMENT: "document",
    JSON: "json",
    TEXT: "text"
};

/**
 * @constructor
 * @param {HttpRequestMethod|string} urlOrMethod url or method to use (default: GET)
 * @param {string=} url
**/
function HttpRequest(urlOrMethod, url) {
    /** @const @type {XMLHttpRequest} */
    this.xhr = new XMLHttpRequest();

    /** @const @type {string} */
    this.url = url || urlOrMethod;

    /** @const @type {HttpRequestMethod} */
    this.method = url ? /** @type {HttpRequestMethod} */ (urlOrMethod) : HttpRequestMethod.GET;

    /** @type {Array<function(number, string, (string|Object|null))>|undefined} */
    this._callback;

    /** @type {Array<function(number, string, (string|Object|null))>|undefined} */
    this._callbackError;

    /** @type {Array<function(number, string, (string|Object|null))>|undefined} */
    this._callbackSuccess;

    this.xhr.onreadystatechange = (function(e) {
        if (this.xhr.readyState === 4) {
            if (Math.floor(this.xhr.status / 100) === 2) {
                HttpRequest.fireCallbacks(this._callbackSuccess, this.xhr.status, this.xhr.statusText, this.xhr.response);
            } else {
                HttpRequest.fireCallbacks(this._callbackError, this.xhr.status, this.xhr.statusText, this.xhr.response);
            }
            HttpRequest.fireCallbacks(this._callback, this.xhr.status, this.xhr.statusText, this.xhr.response);
        }
    }).bind(this);
}

/**
 * @param {Array<function(number, string, (string|Object|null))>|undefined} callbacks
 * @param {number} statusCode
 * @param {string} statusText
 * @param {string|Object|null} response
**/
HttpRequest.fireCallbacks = function(callbacks, statusCode, statusText, response) {
    if (callbacks)
        callbacks.forEach(function(cb) {
            cb(statusCode, statusText, response);
        });
};


/**
 * @param {function(number, string, (string|Object|null))} cb callback (statusCode statusText responseText)
 * @param {Object=} ctx
 * @return {HttpRequest}
**/
HttpRequest.prototype.callback = function(cb, ctx) {
    if (!this._callback)
        this._callback = [];
    cb.bind(ctx || this);
    this._callback.push(cb);
    return this;
};

/**
 * @param {function(number, string, (string|Object|null))} cb callback (statusCode statusText responseText)
 * @param {Object=} ctx
 * @return {HttpRequest}
**/
HttpRequest.prototype.callbackSuccess = function(cb, ctx) {
    if (!this._callbackSuccess)
        this._callbackSuccess = [];
    cb.bind(ctx || this);
    this._callbackSuccess.push(cb);
    return this;
};

/**
 * @param {function(number, string, (string|Object|null))} cb callback (statusCode statusText responseText)
 * @param {Object=} ctx
 * @return {HttpRequest}
**/
HttpRequest.prototype.callbackError = function(cb, ctx) {
    if (!this._callbackError)
        this._callbackError = [];
    cb.bind(ctx || this);
    this._callbackError.push(cb);
    return this;
};

/**
 * @param {number} timeo
 * @return {HttpRequest}
**/
HttpRequest.prototype.setTimeout = function(timeo) {
    this.xhr.timeout = timeo;
    return this;
};

/**
 * @param {HttpRequestResponseType} respType
 * @return {HttpRequest}
**/
HttpRequest.prototype.setResponseType = function(respType) {
    this.xhr.responseType = respType;
    return this;
};

/**
 * @param {string|FormData=} payload
 * @return {HttpRequest}
**/
HttpRequest.prototype.send = function(payload) {
    this.xhr.open(this.method, this.url, true);
    this.xhr.send(payload);
    return this;
};