/**

 * 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.emul.reflect;

import java.lang.reflect.Method;

import java.util.Enumeration;

import org.apidesign.bck2brwsr.core.JavaScriptBody;

/** Utilities to work on methods.

 *

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

 */

public abstract class MethodImpl {

    public static MethodImpl INSTANCE;

    static {

        try {

            Class.forName(Method.class.getName());

        } catch (ClassNotFoundException ex) {

            throw new IllegalStateException(ex);

        }

    }

    protected abstract Method create(Class<?> declaringClass, String name, Object data, String sig);

    //

    // bck2brwsr implementation

    //

    @JavaScriptBody(args = {"clazz", "prefix"},

        body = ""

        + "var c = clazz.cnstr.prototype;"

        + "var arr = new Array();\n"

        + "for (m in c) {\n"

        + "  if (m.indexOf(prefix) === 0) {\n"

        + "     arr.push(m);\n"

        + "     arr.push(c[m]);\n"

        + "  }"

        + "}\n"

        + "return arr;")

    private static native Object[] findMethodData(

        Class<?> clazz, String prefix);

    public static Method findMethod(

        Class<?> clazz, String name, Class<?>... parameterTypes) {

        Object[] data = findMethodData(clazz, name + "__");

        BIG: for (int i = 0; i < data.length; i += 2) {

            String sig = ((String) data[0]).substring(name.length() + 2);

            Method tmp = INSTANCE.create(clazz, name, data[1], sig);

            Class<?>[] tmpParms = tmp.getParameterTypes();

            if (parameterTypes.length != tmpParms.length) {

                continue;

            }

            for (int j = 0; j < tmpParms.length; j++) {

                if (!parameterTypes[j].equals(tmpParms[j])) {

                    continue BIG;

                }

            }

            return tmp;

        }

        return null;

    }

    public static Method[] findMethods(Class<?> clazz, int mask) {

        Object[] namesAndData = findMethodData(clazz, "");

        int cnt = 0;

        for (int i = 0; i < namesAndData.length; i += 2) {

            String sig = (String) namesAndData[i];

            Object data = namesAndData[i + 1];

            int middle = sig.indexOf("__");

            if (middle == -1) {

                continue;

            }

            String name = sig.substring(0, middle);

            sig = sig.substring(middle + 2);

            final Method m = INSTANCE.create(clazz, name, data, sig);

            if ((m.getModifiers() & mask) == 0) {

                continue;

            }

            namesAndData[cnt++] = m;

        }

        Method[] arr = new Method[cnt];

        for (int i = 0; i < cnt; i++) {

            arr[i] = (Method) namesAndData[i];

        }

        return arr;

    }

    public static int signatureElements(String sig) {

        Enumeration<Class> en = signatureParser(sig);

        int cnt = 0;

        while (en.hasMoreElements()) {

            en.nextElement();

            cnt++;

        }

        return cnt;

    }

    public static Enumeration<Class> signatureParser(final String sig) {

        class E implements Enumeration<Class> {

            int pos;

            public boolean hasMoreElements() {

                return pos < sig.length();

            }

            public Class nextElement() {

                switch (sig.charAt(pos++)) {

                    case 'I':

                        return Integer.TYPE;

                    case 'J':

                        return Long.TYPE;

                    case 'D':

                        return Double.TYPE;

                    case 'F':

                        return Float.TYPE;

                    case 'B':

                        return Byte.TYPE;

                    case 'Z':

                        return Boolean.TYPE;

                    case 'S':

                        return Short.TYPE;

                    case 'V':

                        return Void.TYPE;

                    case 'C':

                        return Character.TYPE;

                    case 'L':

                        try {

                            int up = sig.indexOf("_2");

                            String type = sig.substring(1, up);

                            pos = up + 2;

                            return Class.forName(type);

                        } catch (ClassNotFoundException ex) {

                            // should not happen

                        }

                }

                throw new UnsupportedOperationException(sig + " at " + pos);

            }

        }

        return new E();

    }

}