/**

  * 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);

         } 

     }

 }