/*
 * Copyright  2001-2004 The Apache Software Foundation
 *
 *  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 org.apache.tools.ant.util.regexp;

import java.util.Vector;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
import org.apache.tools.ant.BuildException;

/**
 * Implementation of RegexpMatcher for the built-in regexp matcher of
 * JDK 1.4. UNIX_LINES option is enabled as a default.
 *
 */
public class Jdk14RegexpMatcher implements RegexpMatcher {

    private String pattern;

    public Jdk14RegexpMatcher() {
    }

    /**
     * Set the regexp pattern from the String description.
     */
    public void setPattern(String pattern) {
        this.pattern = pattern;
    }

    /**
     * Get a String representation of the regexp pattern
     */
    public String getPattern() {
        return pattern;
    }

    protected Pattern getCompiledPattern(int options)
        throws BuildException {
        int cOptions = getCompilerOptions(options);
        try {
            Pattern p = Pattern.compile(this.pattern, cOptions);
            return p;
        } catch (PatternSyntaxException e) {
            throw new BuildException(e);
        }
    }

    /**
     * Does the given argument match the pattern?
     */
    public boolean matches(String argument) throws BuildException {
        return matches(argument, MATCH_DEFAULT);
    }

    /**
     * Does the given argument match the pattern?
     */
    public boolean matches(String input, int options)
        throws BuildException {
        try {
            Pattern p = getCompiledPattern(options);
            return p.matcher(input).find();
        } catch (Exception e) {
            throw new BuildException(e);
        }
    }

    /**
     * Returns a Vector of matched groups found in the argument.
     *
     * <p>Group 0 will be the full match, the rest are the
     * parenthesized subexpressions</p>.
     */
    public Vector getGroups(String argument) throws BuildException {
        return getGroups(argument, MATCH_DEFAULT);
    }

    /**
     * Returns a Vector of matched groups found in the argument.
     *
     * <p>Group 0 will be the full match, the rest are the
     * parenthesized subexpressions</p>.
     */
    public Vector getGroups(String input, int options)
        throws BuildException {
        Pattern p = getCompiledPattern(options);
        Matcher matcher = p.matcher(input);
        if (!matcher.find()) {
            return null;
        }
        Vector v = new Vector();
        int cnt = matcher.groupCount();
        for (int i = 0; i <= cnt; i++) {
            String match = matcher.group(i);
            // treat non-matching groups as empty matches
            if (match == null) {
                match = "";
            }
            v.addElement(match);
        }
        return v;
    }

    protected int getCompilerOptions(int options) {
        // be strict about line separator
        int cOptions = Pattern.UNIX_LINES;

        if (RegexpUtil.hasFlag(options, MATCH_CASE_INSENSITIVE)) {
            cOptions |= Pattern.CASE_INSENSITIVE;
        }
        if (RegexpUtil.hasFlag(options, MATCH_MULTILINE)) {
            cOptions |= Pattern.MULTILINE;
        }
        if (RegexpUtil.hasFlag(options, MATCH_SINGLELINE)) {
            cOptions |= Pattern.DOTALL;
        }

        return cOptions;
    }

}