"use strict"

// Parameters we accept
const RE_IDENTIFIER = /^[0-9A-Za-z\\._\\-]+$/; // Identifiers can generally be non-critical SQL characters.
const RE_GUID = /^[0-9a-z\\-]+$/; // GUIDs can only be lower case a-z, numbers and dashes

const exampleGuid: string = "de305d54-75b4-431b-adb2-eb6b9e546014";


export module checks {

    /**
     * Checks if a hash was is empty.
     * http://stackoverflow.com/questions/679915/how-do-i-test-for-an-empty-javascript-object
     * @param  {[type]} obj [description]
     * @return {[type]}     [description]
     */
    export function isEmpty(obj: Object | undefined | null): boolean {
        if (!obj) return true;
        return Object.keys(obj).length === 0;
    }

    /**
     * Checks if the given paramters is compatible with regex and length
     * requriements.
     * @param  {[type]} param  [description]
     * @param  {[type]} regex  [description]
     * @param  {[type]} length [description]
     * @return {[type]}        [description]
     */
    export function isValidParameter(param: string | number, regex?: RegExp, length?: number): boolean {

        // Normal numbers get admitted instantly
        if (typeof param === "number") {
            if (isFinite(param)) return true;
            return false;
        }

        // Here we know what we are.
        const paramstring = <string> param;

        regex = regex || RE_IDENTIFIER;
        length = length || 128;

        if (
            !paramstring
                || paramstring.length > length
                || !regex.test(paramstring)
        ) return false;

        return true;
    }




    /**
     * Checks if a given session ID is actually a valid session ID and properly
     * formed.
     * @param  {interfaces.sessionID} sessionID [description]
     * @return {boolean}                   [description]
     */
    export function isValidGUID(guid: string): boolean {
        if (guid.length != exampleGuid.length) return false;
        if (!(guid.charAt(8) == "-")) return false;
        if (!(guid.charAt(13) == "-")) return false;
        if (!(guid.charAt(18) == "-")) return false;
        if (!(guid.charAt(23) == "-")) return false;
        if (!isValidParameter(guid, RE_GUID, exampleGuid.length)) return false;

        return true;
    }
}