export class Utils {
    static createKey(keyLength: number){
        let keyspace: String = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
        let text = '';
        let index;
        for (let i = 0; i < keyLength; i++)
        {
            index = Math.floor(Math.random() * keyspace.length);
            text += keyspace.charAt(index);
        }
        return text;
    }

    static toUTF8Array(str) {
        let utf8 = [];
        for (var i=0; i < str.length; i++) {
            let charcode = str.charCodeAt(i);
            if (charcode < 0x80) utf8.push(charcode);
            else if (charcode < 0x800) {
                utf8.push(0xc0 | (charcode >> 6), 
                          0x80 | (charcode & 0x3f));
            }
            else if (charcode < 0xd800 || charcode >= 0xe000) {
                utf8.push(0xe0 | (charcode >> 12), 
                          0x80 | ((charcode>>6) & 0x3f), 
                          0x80 | (charcode & 0x3f));
            }
            // surrogate pair
            else {
                i++;
                charcode = ((charcode&0x3ff)<<10)|(str.charCodeAt(i)&0x3ff)
                utf8.push(0xf0 | (charcode >>18), 
                          0x80 | ((charcode>>12) & 0x3f), 
                          0x80 | ((charcode>>6) & 0x3f), 
                          0x80 | (charcode & 0x3f));
            }
        }
        return utf8;
    }
}