/*
    GNU LESSER GENERAL PUBLIC LICENSE
    Copyright (C) 2006 The Lobo Project

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Contact info: lobochief@users.sourceforge.net
*/
package org.lobobrowser.js;

import org.mozilla.javascript.*;
import java.lang.reflect.*;
import java.util.logging.*;
import java.util.*;
import org.lobobrowser.util.*;
import org.lobobrowser.util.Objects;

public class JavaFunctionObject extends ScriptableObject implements Function {
	private static final Logger logger = Logger.getLogger(JavaFunctionObject.class.getName());
	private static final boolean loggableInfo = logger.isLoggable(Level.INFO);
	private final String className;
	private final ArrayList methods = new ArrayList();
		
	public JavaFunctionObject(String name) {
		super();
		this.className = name;		
	}

	public void addMethod(Method m) {
		this.methods.add(m);
	}
	
	public String getClassName() {
		return this.className;
	}
	
	private String getTypeName(Object object) {
		return object == null ? "[null]" : object.getClass().getName();
	}

	private Method getBestMethod(Object[] args) {
		ArrayList methods = this.methods;
		int size = methods.size();
		int matchingNumParams = 0;
		Method matchingMethod = null;
		for(int i = 0; i < size; i++) {
			Method m = (Method) methods.get(i);
			Class[] parameterTypes = m.getParameterTypes();
			if(args == null) {
				if(parameterTypes == null || parameterTypes.length == 0) {
					return m;
				}
			}
			else if(parameterTypes != null && args.length >= parameterTypes.length) {
				if(Objects.areAssignableTo(args, parameterTypes)) {
					return m;
				}
				if(matchingMethod == null || parameterTypes.length > matchingNumParams) {
					matchingNumParams = parameterTypes.length;
					matchingMethod = m;
				}
			}
		}
		if(size == 0) {
			throw new IllegalStateException("zero methods");
		}
		return matchingMethod;
	}
	
	public Object call(Context cx, Scriptable scope, Scriptable thisObj,
			Object[] args)  {
		JavaObjectWrapper jcw = (JavaObjectWrapper) thisObj;
		Method method = this.getBestMethod(args);
		if(method == null) {
			throw new EvaluatorException("No method matching " + this.className + " with " + (args == null ? 0 : args.length) + " arguments.");
		}
		Class[] actualArgTypes = method.getParameterTypes();
		int numParams = actualArgTypes.length;
		Object[] actualArgs = args == null ? new Object[0] : new Object[numParams];
		boolean linfo = loggableInfo;
		if(linfo) {
			Object javaObject = jcw.getJavaObject();
			logger.info("call(): Calling method " + method.getName() + " on object " + javaObject + " of type " + this.getTypeName(javaObject));
		}
		JavaScript manager = JavaScript.getInstance();
		for(int i = 0; i < numParams; i++) {
			Object arg = args[i];
			Object actualArg = manager.getJavaObject(arg, actualArgTypes[i]);
			if(linfo) {
				logger.info("call(): For method=" + method.getName() + ": Converted arg=" + arg + " (type=" + this.getTypeName(arg) + ") into actualArg=" + actualArg + ". Type expected by method is " + actualArgTypes[i].getName() + ".");
			}
			actualArgs[i] = actualArg;
		}
		try {
			Object raw = method.invoke(jcw.getJavaObject(), actualArgs);
			return manager.getJavascriptObject(raw, scope);
		} catch(IllegalAccessException iae) {
			throw new IllegalStateException("Unable to call " + this.className + ".", iae); 
		} catch(InvocationTargetException ite) {
			throw new WrappedException(new InvocationTargetException(ite.getCause(), "Unable to call " + this.className + " on " + jcw.getJavaObject() + ".")); 
		} catch(IllegalArgumentException iae) {
			StringBuffer argTypes = new StringBuffer();
			for(int i = 0; i < actualArgs.length; i++) {
				if(i > 0) {
					argTypes.append(", ");
				}
				argTypes.append(actualArgs[i] == null ? "<null>" : actualArgs[i].getClass().getName());
			}
			throw new WrappedException(new IllegalArgumentException("Unable to call " + this.className + ". Argument types: " + argTypes + ".", iae)); 
		}
	}
	
	public java.lang.Object getDefaultValue(java.lang.Class hint) {
		if(loggableInfo) {
			logger.info("getDefaultValue(): hint=" + hint + ",this=" + this);
		}
		if(hint == null || String.class.equals(hint)) {
			return "function " + this.className;
		}
		else {
			return super.getDefaultValue(hint);
		}
	}
	
	public Scriptable construct(Context cx, Scriptable scope, Object[] args) {
		throw new UnsupportedOperationException();
	}	
}