/**

 * HTML via Java(tm) Language Bindings

 * Copyright (C) 2013 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. apidesign.org

 * designates this particular file as subject to the

 * "Classpath" exception as provided by apidesign.org

 * in the License file that accompanied this code.

 *

 * 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://wiki.apidesign.org/wiki/GPLwithClassPathException

 */

package org.apidesign.html.boot.impl;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.Reader;

import java.lang.reflect.Method;

import java.net.URL;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Enumeration;

import java.util.List;

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

import org.objectweb.asm.Type;

/**

 *

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

 */

public final class FnUtils {

    private FnUtils() {

    }

    public static Fn define(Class<?> caller, String code, String... names) {

        JsClassLoader cl = (JsClassLoader)caller.getClassLoader();

        return cl.defineFn(code, names);

    }

    public static ClassLoader newLoader(final FindResources f, final Fn.Presenter d, ClassLoader parent) {

        return new JsClassLoader(parent) {

            @Override

            protected URL findResource(String name) {

                List<URL> l = res(name, true);

                return l.isEmpty() ? null : l.get(0);

            }

            @Override

            protected Enumeration<URL> findResources(String name) {

                return Collections.enumeration(res(name, false));

            }

            private List<URL> res(String name, boolean oneIsEnough) {

                List<URL> l = new ArrayList<URL>();

                f.findResources(name, l, oneIsEnough);

                return l;

            }

            @Override

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

                return d.defineFn(code, names);

            }

            @Override

            protected void loadScript(Reader code) throws Exception {

                d.loadScript(code);

            }

        };

    }

    static String callback(String body, ClassLoader loader) {

        try {

            return callbackImpl(body, loader);

        } catch (ClassNotFoundException ex) {

            throw new IllegalStateException("Can't parse " + body, ex);

        } catch (NoSuchMethodException ex) {

            throw new IllegalStateException("Can't parse " + body, ex);

        }

    }

    private static String callbackImpl(String body, ClassLoader loader)

    throws ClassNotFoundException, NoSuchMethodException {

        StringBuilder sb = new StringBuilder();

        int pos = 0;

        for (;;) {

            int next = body.indexOf(".@", pos);

            if (next == -1) {

                sb.append(body.substring(pos));

                return sb.toString();

            }

            sb.append(body.substring(pos, next));

            int sigBeg = body.indexOf('(', next);

            int sigEnd = body.indexOf(')', sigBeg);

            int colon4 = body.indexOf("::", next);

            if (sigBeg == -1 || sigEnd == -1 || colon4 == -1) {

                throw new IllegalStateException("Malformed body " + body);

            }

            String fqn = body.substring(next + 2, colon4);

            String method = body.substring(colon4 + 2, sigBeg);

            String params = body.substring(sigBeg, sigEnd + 1);

            Class<?> clazz = Class.forName(fqn, false, loader);

            final Type[] argTps = Type.getArgumentTypes(params);

            Class<?>[] argCls = new Class<?>[argTps.length];

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

                argCls[i] = toClass(argTps[i], loader);

            }

            Method m = clazz.getMethod(method, argCls);

            sb.append("['").append(m.getName()).append("(");

            String sep = "";

            for (Class<?> pt : m.getParameterTypes()) {

                sb.append(sep).append(pt.getName());

                sep = ",";

            }

            sb.append(")']");

            pos = sigEnd + 1;

        }

    }

    private static Class<?> toClass(final Type t, ClassLoader loader) throws ClassNotFoundException {

        if (t == Type.INT_TYPE) {

            return Integer.TYPE;

        } else if (t == Type.VOID_TYPE) {

            return Void.TYPE;

        } else if (t == Type.BOOLEAN_TYPE) {

            return Boolean.TYPE;

        } else if (t == Type.BYTE_TYPE) {

            return Byte.TYPE;

        } else if (t == Type.CHAR_TYPE) {

            return Character.TYPE;

        } else if (t == Type.SHORT_TYPE) {

            return Short.TYPE;

        } else if (t == Type.DOUBLE_TYPE) {

            return Double.TYPE;

        } else if (t == Type.FLOAT_TYPE) {

            return Float.TYPE;

        } else if (t == Type.LONG_TYPE) {

            return Long.TYPE;

        }

        return Class.forName(t.getClassName(), false, loader);

    }

    static void loadScript(JsClassLoader jcl, String resource) {

        final InputStream script = jcl.getResourceAsStream(resource);

        if (script == null) {

            throw new NullPointerException("Can't find " + resource);

        }

        try {

            Reader isr = null;

            try {

                isr = new InputStreamReader(script, "UTF-8");

                jcl.loadScript(isr);

            } finally {

                if (isr != null) {

                    isr.close();

                }

            }

        } catch (Exception ex) {

            throw new IllegalStateException("Can't execute " + resource, ex);

        } 

    }

}