/*******************************************************************************
 * Copyright (c) 2005, 2015 BEA Systems, Inc.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *    mkaufman@bea.com - initial API and implementation
 *    
 *******************************************************************************/

package org.eclipse.jdt.apt.core.internal.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Set;

import org.eclipse.core.resources.IFile;
import org.eclipse.jdt.apt.core.internal.AptPlugin;
import org.eclipse.jdt.apt.core.internal.env.BuildEnv;
import org.eclipse.jdt.core.IBuffer;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.ToolFactory;
import org.eclipse.jdt.core.compiler.IScanner;
import org.eclipse.jdt.core.compiler.ITerminalSymbols;
import org.eclipse.jdt.core.compiler.InvalidInputException;

public class ScannerUtil {

	/**
	 * scan the source code to see if there are any annotation tokens
	 */
	public static boolean hasAnnotationInstance( IFile f ) {
		
		InputStreamReader reader = null;
		InputStream input = null;
		try {
			AnnotationScanner scanner;
			// If this is a single byte encoding, we can deal directly 
			// with the bytes, which is *much* faster
			if (SINGLE_BYTE_ENCODINGS.contains(f.getCharset())) {
				input = BuildEnv.getInputStream(f);
				scanner = new InputStreamAnnotationScanner(input);
			}
			else {
				reader = BuildEnv.getFileReader( f );
				scanner = new ReaderAnnotationScanner(reader);
			}
			return scanner.containsAnnotations();
		}
		catch( Exception ioe ) {
			return false;
		}
		finally {
			if (reader != null) { try {reader.close();} catch (IOException ioe) {} }
			if (input != null) { try {input.close();} catch (IOException ioe) {} }
		}
	}
	
	
	public static boolean hasAnnotationInstance( ICompilationUnit cu ) {
		try {
			IBuffer b = cu.getBuffer();
			if ( b == null )
				return false;
			char[] source = b.getCharacters();
			return hasAnnotationInstance( source );
		}
		catch( JavaModelException jme ) {
			return false;
		}
	}

	
	public static boolean hasAnnotationInstance( char[] source ) {
		try {		
			if ( source == null )
				return false;
			IScanner scanner = ToolFactory.createScanner( 
				false, false, false, JavaCore.VERSION_1_5 );
			scanner.setSource( source );
			int token = scanner.getNextToken();
			while ( token != ITerminalSymbols.TokenNameEOF ) {
				token = scanner.getNextToken();
				if ( token == ITerminalSymbols.TokenNameAT )
				{
					//
					// found an @ sign, see if next token is "interface"
					// @interface is an annotation decl and not an annotation
					// instance.  
					//
					token = scanner.getNextToken();
					if ( token != ITerminalSymbols.TokenNameinterface )
						return true;
				}
			}
			return false;
		}
		catch( InvalidInputException iie )
		{
			// lex error, so report false
			return false;
		}
		catch( Exception e )
		{
			AptPlugin.log(e, "Failure scanning source: \n" + new String(source)); //$NON-NLS-1$
			// TODO:  deal with this exception
			return false;
		}
	}
	
	private static final String[] SINGLE_BYTE_ENCODING_ARRAY = {
		"ASCII", //$NON-NLS-1$
		"Cp1250", //$NON-NLS-1$
		"Cp1251", //$NON-NLS-1$
		"Cp1252", //$NON-NLS-1$
		"Cp1253", //$NON-NLS-1$
		"Cp1254", //$NON-NLS-1$
		"Cp1257", //$NON-NLS-1$
		"ISO8859_1", //$NON-NLS-1$
		"ISO8859_2", //$NON-NLS-1$
		"ISO8859_4", //$NON-NLS-1$
		"ISO8859_5", //$NON-NLS-1$
		"ISO8859_7", //$NON-NLS-1$
		"ISO8859_9", //$NON-NLS-1$
		"ISO8859_13", //$NON-NLS-1$
		"ISO8859_15", //$NON-NLS-1$
		"UTF8" //$NON-NLS-1$
	};
	
	private static final Set<String> SINGLE_BYTE_ENCODINGS = 
		new HashSet<>(SINGLE_BYTE_ENCODING_ARRAY.length);
		
	static {
		for (String encoding : SINGLE_BYTE_ENCODING_ARRAY) {
			SINGLE_BYTE_ENCODINGS.add(encoding);
		}
	}
	
}
