import addExtensionsUsed from './addExtensionsUsed.js'
import addToArray from './addToArray.js'
import defined from '../../Core/defined.js'

    /**
     * Adds an extension to gltf.extensionsRequired if it does not already exist.
     * Initializes extensionsRequired if it is not defined.
     *
     * @param {Object} gltf A javascript object containing a glTF asset.
     * @param {String} extension The extension to add.
     *
     * @private
     */
    function addExtensionsRequired(gltf, extension) {
        var extensionsRequired = gltf.extensionsRequired;
        if (!defined(extensionsRequired)) {
            extensionsRequired = [];
            gltf.extensionsRequired = extensionsRequired;
        }
        addToArray(extensionsRequired, extension, true);
        addExtensionsUsed(gltf, extension);
    }

    export default addExtensionsRequired;