'use strict';

module.exports = function (data, opts) {

if (!opts) opts = {};
if (typeof opts === 'function') opts = { cmp: opts };
var cycles = (typeof opts.cycles === 'boolean') ? opts.cycles : false;

var cmp = opts.cmp && (function (f) {
    return function (node) {
        return function (a, b) {
            var aobj = { key: a, value: node[a] };
            var bobj = { key: b, value: node[b] };
            return f(aobj, bobj);
        };
    };
})(opts.cmp);

var seen = [];
return (function stringify (node) {
    if (node && node.toJSON && typeof node.toJSON === 'function') {
        node = node.toJSON();
    }

    if (node === undefined) return;
    if (typeof node == 'number') return isFinite(node) ? '' + node : 'null';
    if (typeof node !== 'object') return JSON.stringify(node);

    var i, out;
    if (Array.isArray(node)) {
        out = '[';
        for (i = 0; i < node.length; i++) {
            if (i) out += ',';
            out += stringify(node[i]) || 'null';
        }
        return out + ']';
    }

    if (node === null) return 'null';

    if (seen.indexOf(node) !== -1) {
        if (cycles) return JSON.stringify('__cycle__');
        throw new TypeError('Converting circular structure to JSON');
    }

    var seenIndex = seen.push(node) - 1;
    var keys = Object.keys(node).sort(cmp && cmp(node));
    out = '';
    for (i = 0; i < keys.length; i++) {
        var key = keys[i];
        var value = stringify(node[key]);

        if (!value) continue;
        if (out) out += ',';
        out += JSON.stringify(key) + ':' + value;
    }
    seen.splice(seenIndex, 1);
    return '{' + out + '}';
})(data);

};