'use strict';

var convert = require('./convert');
var utf8 = require('./utf8');
var keccak256 = require('./keccak256');

var Zeros = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
var Partition = new RegExp("^((.*)\\.)?([^.]+)$");
var UseSTD3ASCIIRules = new RegExp("^[a-z0-9.-]*$");

function namehash(name, depth) {
    name = name.toLowerCase();

    // Supporting the full UTF-8 space requires additional (and large)
    // libraries, so for now we simply do not support them.
    // It should be fairly easy in the future to support systems with
    // String.normalize, but that is future work.
    if (!name.match(UseSTD3ASCIIRules)) {
        throw new Error('contains invalid UseSTD3ASCIIRules characters');
    }

    var result = Zeros;
    var processed = 0;
    while (name.length && (!depth || processed < depth)) {
        var partition = name.match(Partition);
        var label = utf8.toUtf8Bytes(partition[3]);
        result = keccak256(convert.concat([result, keccak256(label)]));

        name = partition[2] || '';

        processed++;
    }

    return convert.hexlify(result);
}

module.exports = namehash;