/**
 * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.liferay.ide.project.ui.migration;

import java.io.File;
import java.lang.ref.WeakReference;
import java.util.Map;
import java.util.WeakHashMap;

import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTParser;
import org.eclipse.jdt.core.dom.CompilationUnit;

/**
 * @author Terry Jia
 */
@SuppressWarnings( "deprecation" )
public class CUCache
{

    private static final Map<File, WeakReference<CompilationUnit>> _map = new WeakHashMap<>();

    public static CompilationUnit getCU( File file, char[] javaSource )
    {
        synchronized( _map )
        {
            WeakReference<CompilationUnit> astRef = _map.get( file );

            if( astRef == null || astRef.get() == null )
            {
                final CompilationUnit newAst = createCompilationUnit( file.getName(), javaSource );

                _map.put( file, new WeakReference<CompilationUnit>( newAst ) );

                return newAst;
            }
            else
            {
                return astRef.get();
            }
        }
    }

    public static void unget( File file )
    {
        synchronized( _map )
        {
            _map.remove( file );
        }
    }

    private static CompilationUnit createCompilationUnit( String unitName, char[] javaSource )
    {
        ASTParser parser = ASTParser.newParser( AST.JLS2 );

        Map<String, String> options = JavaCore.getOptions();

        JavaCore.setComplianceOptions( JavaCore.VERSION_1_6, options );

        parser.setCompilerOptions( options );

        // setUnitName for resolve bindings
        parser.setUnitName( unitName );

        String[] sources = { "" };
        String[] classpath = { "" };
        // setEnvironment for resolve bindings even if the args is empty
        parser.setEnvironment( classpath, sources, new String[] { "UTF-8" }, true );

        parser.setResolveBindings( true );
        parser.setStatementsRecovery( true );
        parser.setBindingsRecovery( true );
        parser.setSource( javaSource );
        parser.setIgnoreMethodBodies( false );

        return (CompilationUnit) parser.createAST( null );
    }
}