'use strict';

String.prototype.removeEndNullBytes = function() {
    return this.replace(/\0+$/g, '');
}
String.prototype.removeStartNullBytes = function() {
    return this.replace(/^\0+/g, '');
}

var pluie =
{
    bin : 
    {
        enc             : new TextEncoder("utf-8"),

        dec             : new TextDecoder("utf-8", {fatal: true}),

        intFromBytes    : function(bytes)
        {
            // Big Endian
            for (var i = value = 0, lim = bytes.length; i < lim; i++) {
                value = value * 256 + bytes[i];
            }
            return value;
        },

        bytesFromInt    : function(value, size)
        {
            var bytes = new Uint8Array(size);
            while (value) {
                bytes.set([value & 255], --size);
                value >>= 8;;
            }
            return bytes;
        },

        pack            : function(size, type, value)
        {
            var packed = null 
            if (type == 'n' || type == 'N') {
                // js int max on 32 signed bits
                if (value >= 0 && value <= 2147483647) {
                    packed = this.bytesFromInt(value, type == 'n' ? 2 : 4);
                }
            }
            else if (type == 'a') {
                packed = new Uint8Array(size);
                packed.set(this.enc.encode(value), 0);
            }
            return packed;
        },

        unpack          : function(size, type, bytes)
        {
            var unpacked = null 
            if (type == 'n' || type == 'N') {
                var selByte = bytes.slice(0, size*(type == 'n' ? 2 : 4));
                unpacked = this.intFromBytes(selByte);
            }
            else if (type == 'a') {
                unpacked = this.dec.decode(bytes.slice(0, size)).removeEndNullBytes();
            }
            return unpacked;
        }
    }
}

module.exports = pluie.bin;