/*******************************************************************************
 * Copyright (c) 2007 Oracle Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Cameron Bateman/Oracle - initial API and implementation
 *    
 ********************************************************************************/
package org.eclipse.jst.jsf.common.util;

import java.beans.Introspector;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.jdt.core.Flags;
import org.eclipse.jdt.core.IMethod;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.ITypeHierarchy;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.Signature;
import org.eclipse.jst.jsf.common.JSFCommonPlugin;

/**
 * A class that does bean introspection on a JDT IType
 * 
 * This functionality is not meant to replace runtime bean 
 * introspection.  Rather, it is meant to provide a 
 * more "lightweight" (in terms of class loading as well as
 * error handling of bean instantiation out of context) way
 * to determine a bean's properties at design time.
 * 
 * This class may not be sub-classed by clients.
 * 
 * @author cbateman
 *
 */
public class JDTBeanIntrospector 
{
	private final static String GET_PREFIX = "get"; //$NON-NLS-1$
	private final static String SET_PREFIX = "set"; //$NON-NLS-1$
	private final static String IS_PREFIX = "is"; //$NON-NLS-1$
	
	private final IType 	_type;

	/**
	 * @param type
	 */
	public JDTBeanIntrospector(IType type)
	{
		_type = type;
	}
	
	/**
	 * @return an map of all properties with the property names
     * as keys and the values being JDTBeanProperty objects representing
     * the properties.
	 */
	public Map<String, JDTBeanProperty> getProperties()
	{
		final Map<String, JDTBeanProperty>   propertiesWorkingCopy = 
		    new HashMap<String, JDTBeanProperty>();
		final IMethod[] methods = getAllMethods();
		
		for (int i = 0; i < methods.length; i++)
		{
			final IMethod  method = methods[i];

			try
			{
				processPropertyMethod(method, propertiesWorkingCopy);
			}
			catch (JavaModelException jme)
			{
				// log and then proceed to next method
				JSFCommonPlugin.log(jme, "Error processing IMethod for bean property info"); //$NON-NLS-1$
			}
		}

        final Map properties = new HashMap();
        
        for (Entry<String, JDTBeanProperty> entry : propertiesWorkingCopy.entrySet())
        {
            final String key = entry.getKey();
            JDTBeanPropertyWorkingCopy  wcopy = (JDTBeanPropertyWorkingCopy) entry.getValue();
            properties.put(key, wcopy.toValueObject());
        }

		return properties;
	}

	private void processPropertyMethod(IMethod method, Map<String, JDTBeanProperty> properties) throws JavaModelException
	{
		// to be a bean method, it must not a constructor, must be public
		// and must not be static
		if (!method.isConstructor()
				&& ( Flags.isPublic(method.getFlags())
				        || _type.isInterface())
				&& !Flags.isStatic(method.getFlags()))
		{
			final String methodName = method.getElementName();
			final String returnType = method.getReturnType();
			
			// either starts with get or is boolean and starts with is
			
			// is access must start with 'is', have a boolean return type and no parameters
			final boolean  startsWithIs = methodName.startsWith(IS_PREFIX) 
					&& Signature.SIG_BOOLEAN.equals(returnType)
					&& method.getNumberOfParameters() == 0
                    && methodName.length() > IS_PREFIX.length();
			
			// get accessor must start with 'get', have no parameters and return non-void
			final boolean  startsWithGet = (methodName.startsWith(GET_PREFIX)
											&& method.getNumberOfParameters() == 0)
											&& !Signature.SIG_VOID.equals(returnType)                    
                                            && methodName.length() > GET_PREFIX.length();
			
			// mutator must start with 'set' and have one parameter and a void return type
			final boolean  startsWithSet = methodName.startsWith(SET_PREFIX)
											&& method.getNumberOfParameters() == 1
											&& Signature.SIG_VOID.equals(returnType)
                                            && methodName.length() > SET_PREFIX.length();

			if (startsWithGet || startsWithSet || startsWithIs)
			{
				final String propertyName = 
					Introspector.decapitalize(methodName.substring(startsWithIs ? 2 : 3));

				JDTBeanPropertyWorkingCopy workingCopy = 
					(JDTBeanPropertyWorkingCopy) properties.get(propertyName);

				if (workingCopy == null)
				{
					workingCopy = new JDTBeanPropertyWorkingCopy(_type);
					properties.put(propertyName, workingCopy);
				}

				if  (startsWithIs)
				{
					workingCopy.setIsGetter(method);
				}
				else if (startsWithGet)
				{
					workingCopy.setGetter(method);
				}
				else if (startsWithSet)
				{
					workingCopy.addSetter(method);
				}
			}
		}
	}

	/**
	 * @return all methods for the type including inherited ones
	 */
	public IMethod[] getAllMethods()
	{
		IMethod[] methods = new IMethod[0];
		
		try
		{
            // type not resolved so don't proceed
            if (_type != null)
            {
	            // TODO: type hierarchy is potentially expensive, should
	            // cache once and listen for changes
	            ITypeHierarchy  hierarchy = _type.newSupertypeHierarchy(new NullProgressMonitor());
	            
				methods = getAllMethods(hierarchy, _type);
            }
		}
		catch(JavaModelException jme)
		{
            JSFCommonPlugin.log(jme, "Error getting type information for bean"); //$NON-NLS-1$
		}

		return methods;
	}

    /**
     * @param typeHierarchy
     * @param type
     * @return all methods of the type and it's super types
     */
    private static IMethod[] getAllMethods(final ITypeHierarchy typeHierarchy, final IType type)
    {
        final List<IMethod>   methods = new ArrayList<IMethod>();
        final IType[] superTypes = typeHierarchy.getAllSuperclasses(type);
        final IType[] closure = new IType[superTypes.length+1];
        closure[0] = type;
        System.arraycopy(superTypes, 0, closure, 1, superTypes.length);
        
        for (int i = 0; i < closure.length; i++)
        {
            try {
                final IType superType = closure[i];
                methods.addAll(Arrays.asList(superType.getMethods()));
            } catch (JavaModelException e) {
                JSFCommonPlugin.log(e, "Error getting super type information for bean"); //$NON-NLS-1$
            }
        }
            
        return methods.toArray(new IMethod[methods.size()]);
    }
}