(function (root, factory){
    if (typeof define === 'function' && define.amd){ // AMD
        define(factory);
    } else if (typeof module !== 'undefined' && module.exports) { // Node.js
        module.exports = factory();
    } else { // Browser
        root.VectorTileLayer = factory();
    }
})(this, function () {
    function VectorTileLayer(pbf, end) {
        // Public
        this.version = 1;
        this.name = null;
        this.extent = 4096;
        this.length = 0;

        // Private
        this._pbf = pbf;
        this._keys = [];
        this._values = [];
        this._features = [];

        pbf.readFields(readLayer, this, end);

        this.length = this._features.length;
    }

    function readLayer(tag, layer, pbf) {
        if (tag === 15) layer.version = pbf.readVarint();
        else if (tag === 1) layer.name = pbf.readString();
        else if (tag === 5) layer.extent = pbf.readVarint();
        else if (tag === 2) layer._features.push(pbf.pos);
        else if (tag === 3) layer._keys.push(pbf.readString());
        else if (tag === 4) layer._values.push(readValueMessage(pbf));
    }

    function readValueMessage(pbf) {
        var value = null,
            end = pbf.readVarint() + pbf.pos;

        while (pbf.pos < end) {
            var tag = pbf.readVarint() >> 3;

            value = tag === 1 ? pbf.readString() :
                tag === 2 ? pbf.readFloat() :
                tag === 3 ? pbf.readDouble() :
                tag === 4 ? pbf.readVarint64() :
                tag === 5 ? pbf.readVarint() :
                tag === 6 ? pbf.readSVarint() :
                tag === 7 ? pbf.readBoolean() : null;
        }

        return value;
    }

    // return feature `i` from this layer as a `VectorTileFeature`
    VectorTileLayer.prototype.feature = function(i) {
        if (i < 0 || i >= this._features.length) throw new Error('feature index out of bounds');

        this._pbf.pos = this._features[i];

        var end = this._pbf.readVarint() + this._pbf.pos;
        return new VectorTileFeature(this._pbf, end, this.extent, this._keys, this._values);
    };

    return VectorTileLayer;

});