/**

 * Back 2 Browser Bytecode Translator

 * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, version 2 of the License.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. Look for COPYING file in the top folder.

 * If not, see http://opensource.org/licenses/GPL-2.0.

 */

package org.apidesign.bck2brwsr.launcher;

import java.io.IOException;

import java.io.InputStream;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.net.URL;

import java.util.Enumeration;

import org.apidesign.bck2brwsr.core.JavaScriptBody;

/**

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 */

public class Console {

    static {

        turnAssetionStatusOn();

    }

    public static String welcome() {

        return "HellofromBck2Brwsr";

    }

    public static String multiply() {

        return String.valueOf(Integer.MAX_VALUE / 2 + Integer.MAX_VALUE);

    }

    @JavaScriptBody(args = {"id", "attr"}, body = 

        "return window.document.getElementById(id)[attr].toString();")

    private static native Object getAttr(String id, String attr);

    @JavaScriptBody(args = {"id", "attr", "value"}, body = 

        "window.document.getElementById(id)[attr] = value;")

    private static native void setAttr(String id, String attr, Object value);

    @JavaScriptBody(args = {}, body = "return; window.close();")

    private static native void closeWindow();

    private static void log(String newText) {

        String id = "bck2brwsr.result";

        String attr = "value";

        setAttr(id, attr, getAttr(id, attr) + "\n" + newText);

        setAttr(id, "scrollTop", getAttr(id, "scrollHeight"));

    }

    public static void execute() throws Exception {

        String clazz = (String) getAttr("clazz", "value");

        String method = (String) getAttr("method", "value");

        Object res = invokeMethod(clazz, method);

        setAttr("bck2brwsr.result", "value", res);

    }

    @JavaScriptBody(args = { "url", "callback", "arr" }, body = ""

        + "var request = new XMLHttpRequest();\n"

        + "request.open('GET', url, true);\n"

        + "request.onreadystatechange = function() {\n"

        + "  if (this.readyState!==4) return;\n"

        + "  arr[0] = this.responseText;\n"

        + "  callback.run__V();\n"

        + "};"

        + "request.send();"

    )

    private static native void loadText(String url, Runnable callback, String[] arr) throws IOException;

    public static void harness(String url) throws IOException {

        log("Connecting to " + url);

        Request r = new Request(url);

    }

    private static class Request implements Runnable {

        private final String[] arr = { null };

        private final String url;

        private Request(String url) throws IOException {

            this.url = url;

            loadText(url, this, arr);

        }

        @Override

        public void run() {

            try {

                String data = arr[0];

                log("\nGot \"" + data + "\"");

                if (data == null) {

                    log("Some error exiting");

                    closeWindow();

                    return;

                }

                if (data.isEmpty()) {

                    log("No data, exiting");

                    closeWindow();

                    return;

                }

                Case c = Case.parseData(data);

                if (c.getHtmlFragment() != null) {

                    setAttr("bck2brwsr.fragment", "innerHTML", c.getHtmlFragment());

                }

                log("Invoking " + c.getClassName() + '.' + c.getMethodName() + " as request: " + c.getRequestId());

                Object result = invokeMethod(c.getClassName(), c.getMethodName());

                setAttr("bck2brwsr.fragment", "innerHTML", "");

                log("Result: " + result);

                result = encodeURL("" + result);

                log("Sending back: " + url + "?request=" + c.getRequestId() + "&result=" + result);

                String u = url + "?request=" + c.getRequestId() + "&result=" + result;

                loadText(u, this, arr);

            } catch (Exception ex) {

                log(ex.getMessage());

            }

        }

    }

    private static String encodeURL(String r) {

        StringBuilder sb = new StringBuilder();

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

            int ch = r.charAt(i);

            if (ch < 32 || ch == '%' || ch == '+') {

                sb.append("%").append(("0" + Integer.toHexString(ch)).substring(0, 2));

            } else {

                if (ch == 32) {

                    sb.append("+");

                } else {

                    sb.append((char)ch);

                }

            }

        }

        return sb.toString();

    }

    static String invoke(String clazz, String method) throws ClassNotFoundException, InvocationTargetException, IllegalAccessException, InstantiationException {

        final Object r = invokeMethod(clazz, method);

        return r == null ? "null" : r.toString().toString();

    }

    /** Helper method that inspects the classpath and loads given resource

     * (usually a class file). Used while running tests in Rhino.

     * 

     * @param name resource name to find

     * @return the array of bytes in the given resource

     * @throws IOException I/O in case something goes wrong

     */

    public static byte[] read(String name) throws IOException {

        URL u = null;

        Enumeration<URL> en = Console.class.getClassLoader().getResources(name);

        while (en.hasMoreElements()) {

            u = en.nextElement();

        }

        if (u == null) {

            throw new IOException("Can't find " + name);

        }

        try (InputStream is = u.openStream()) {

            byte[] arr;

            arr = new byte[is.available()];

            int offset = 0;

            while (offset < arr.length) {

                int len = is.read(arr, offset, arr.length - offset);

                if (len == -1) {

                    throw new IOException("Can't read " + name);

                }

                offset += len;

            }

            return arr;

        }

    }

    private static Object invokeMethod(String clazz, String method) 

    throws ClassNotFoundException, InvocationTargetException, 

    SecurityException, IllegalAccessException, IllegalArgumentException,

    InstantiationException {

        Method found = null;

        Class<?> c = Class.forName(clazz);

        for (Method m : c.getMethods()) {

            if (m.getName().equals(method)) {

                found = m;

            }

        }

        Object res;

        if (found != null) {

            try {

                if ((found.getModifiers() & Modifier.STATIC) != 0) {

                    res = found.invoke(null);

                } else {

                    res = found.invoke(c.newInstance());

                }

            } catch (Exception | Error ex) {

                res = ex.getClass().getName() + ":" + ex.getMessage();

            }

        } else {

            res = "Can't find method " + method + " in " + clazz;

        }

        return res;

    }

    @JavaScriptBody(args = {}, body = "vm.desiredAssertionStatus = true;")

    private static void turnAssetionStatusOn() {

    }

    private static final class Case {

        private final Object data;

        private Case(Object data) {

            this.data = data;

        }

        public static Case parseData(String s) {

            return new Case(toJSON(s));

        }

        public String getMethodName() {

            return value("methodName", data);

        }

        public String getClassName() {

            return value("className", data);

        }

        public String getRequestId() {

            return value("request", data);

        }

        public String getHtmlFragment() {

            return value("html", data);

        }

        @JavaScriptBody(args = "s", body = "return eval('(' + s + ')');")

        private static native Object toJSON(String s);

        @JavaScriptBody(args = {"p", "d"}, body = 

              "var v = d[p];\n"

            + "if (typeof v === 'undefined') return null;\n"

            + "return v.toString();"

        )

        private static native String value(String p, Object d);

    }

}