package ${package};

import java.io.Closeable;

import java.io.Reader;

import java.net.URL;

import java.util.ArrayList;

import java.util.List;

import javax.script.Invocable;

import javax.script.ScriptEngine;

import javax.script.ScriptEngineManager;

import javax.script.ScriptException;

import org.apidesign.html.boot.spi.Fn;

import static org.testng.Assert.assertEquals;

import org.testng.annotations.AfterMethod;

import org.testng.annotations.BeforeMethod;

import org.testng.annotations.Test;

/** Tests for behavior of @JavaScriptBody methods. Set your JavaScript 

 * environment up (for example define <code>alert</code> or use some

 * emulation library like <em>env.js</em>), register script presenter 

 * and then you can call methods that deal with JavaScript in your tests.

 */

public class JsInteractionTest {

    private Closeable jsEngine;

    @BeforeMethod public void initializeJSEngine() throws Exception {

        jsEngine = Fn.activate(new ScriptPresenter());

    }

    @AfterMethod public void shutdownJSEngine() throws Exception {

        jsEngine.close();

    }

    @Test public void testCallbackFromJavaScript() throws Exception {

        class R implements Runnable {

            int called;

            @Override

            public void run() {

                called++;

            }

        }

        R callback = new R();

        DataModel.confirmByUser("Hello", callback);

        assertEquals(callback.called, 1, "One immediate callback");

    }

    private static class ScriptPresenter implements Fn.Presenter {

        private final ScriptEngine eng;

        public ScriptPresenter() throws ScriptException {

            eng = new ScriptEngineManager().getEngineByName("javascript");

            eng.eval("function alert(msg) { Packages.java.lang.System.out.println(msg); };");

        }

        @Override

        public Fn defineFn(String code, String... names) {

            StringBuilder sb = new StringBuilder();

            sb.append("(function() {");

            sb.append("  return function(");

            String sep = "";

            for (String n : names) {

                sb.append(sep).append(n);

                sep = ",";

            }

            sb.append(") {\n");

            sb.append(code);

            sb.append("};");

            sb.append("})()");

            final Object fn;

            try {

                fn = eng.eval(sb.toString());

            } catch (ScriptException ex) {

                throw new IllegalStateException(ex);

            }

            return new Fn(this) {

                @Override

                public Object invoke(Object thiz, Object... args) throws Exception {

                    List<Object> all = new ArrayList<Object>(args.length + 1);

                    all.add(thiz == null ? fn : thiz);

                    for (int i = 0; i < args.length; i++) {

                        all.add(args[i]);

                    }

                    Object ret = ((Invocable)eng).invokeMethod(fn, "call", all.toArray()); // NOI18N

                    return fn.equals(ret) ? null : thiz;

                }

            };

        }

        @Override

        public void displayPage(URL page, Runnable onPageLoad) {

            // not really displaying anything

            onPageLoad.run();

        }

        @Override

        public void loadScript(Reader code) throws Exception {

            eng.eval(code);

        }

    }

}