/*
 * Copyright (c) 2022-2023 nosqlbench
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.nosqlbench.engine.api.scripting;

import org.graalvm.polyglot.*;

public class GraalJsEvaluator<T> implements ExprEvaluator<T> {

    private final Class<T> resultType;
    private Context ctx;
    private Source script;

    public GraalJsEvaluator(Class<T> resultType) {
        this.resultType = resultType;
    }

    private Context getCtx() {
        if (ctx == null) {
            Context.Builder contextSettings = Context.newBuilder("js")
                    .allowHostAccess(HostAccess.ALL)
                    .allowNativeAccess(true)
                    .allowCreateThread(true)
                    .allowIO(true)
                    .allowHostClassLookup(s -> true)
                    .allowHostClassLoading(true)
                    .allowCreateProcess(true)
                    .allowAllAccess(true)
                    .allowEnvironmentAccess(EnvironmentAccess.INHERIT)
                    .allowPolyglotAccess(PolyglotAccess.ALL)
                    .option("js.ecmascript-version", "2020")
                    .option("js.nashorn-compat", "true");
            ctx = contextSettings.build();
        }
        return ctx;
    }

    @Override
    public T eval() {
        Value result = getCtx().eval(this.script);
        T asType = result.as(resultType);
        return asType;
    }

    @Override
    public ExprEvaluator<T> script(String scriptText) {
        this.script = Source.create("js", scriptText);
        return this;
    }

    @Override
    public ExprEvaluator<T> put(String varName, Object var) {
        getCtx().getBindings("js").putMember(varName, var);
        return this;
    }
}
