/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.log4j.jdbc;

import org.apache.log4j.helpers.PatternConverter;
import org.apache.log4j.helpers.PatternParser;
import org.apache.log4j.spi.LoggingEvent;

import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class JdbcPatternParser {
    private static final String QUESTION_MARK = "?";

    private static final char PERCENT_CHAR = '%';

    private final static Pattern STRING_LITERAL_PATTERN = Pattern.compile("'((?>[^']|'')+)'");
    // NOTE: capturing group work seem to work just as well. 
    // However, the atomic group is needed here to prevent StackOverflowError 
    // See https://bugs.java.com/bugdatabase/view_bug.do?bug_id=6337993
    //private final static Pattern STRING_LITERAL_PATTERN = Pattern.compile("'(([^']|'')+)'");

    private String parameterizedSql;
    final private List<String> patternStringRepresentationList = new ArrayList<String>();
    final private List<PatternConverter> args = new ArrayList<PatternConverter>();

    JdbcPatternParser(String insertString) {
        init(insertString);
    }

    public String getParameterizedSql() {
        return parameterizedSql;
    }

    public List<String> getUnmodifiablePatternStringRepresentationList() {
        return Collections.unmodifiableList(patternStringRepresentationList);
    }

    @Override
    public String toString() {
        return "JdbcPatternParser{sql=" + parameterizedSql + ",args=" + patternStringRepresentationList + "}";
    }

    /**
     * Converts '....' literals into bind variables in JDBC.
     */
    private void init(String insertString) {
        if (insertString == null) {
            throw new IllegalArgumentException("Null pattern");
        }

        Matcher m = STRING_LITERAL_PATTERN.matcher(insertString);
        StringBuffer sb = new StringBuffer();
        while (m.find()) {
            String matchedStr = m.group(1);
            if (matchedStr.indexOf(PERCENT_CHAR) == -1) {
                replaceWithMatchedStr(m, sb);
            } else {
                // Replace with bind
                replaceWithBind(m, sb, matchedStr);
            }
        }
        m.appendTail(sb);
        this.parameterizedSql = sb.toString();
    }

    private void replaceWithMatchedStr(Matcher m, StringBuffer sb) {
        // Just literal, append it as is
        m.appendReplacement(sb, "'$1'");
    }

    private void replaceWithBind(Matcher m, StringBuffer sb, String matchedStr) {
        m.appendReplacement(sb, QUESTION_MARK);
        // We will use prepared statements, so we don't need to escape quotes.
        // And we assume the users had 'That''s a string with quotes' in their configs.
        matchedStr = matchedStr.replaceAll("''", "'");
        patternStringRepresentationList.add(matchedStr);
        args.add(new PatternParser(matchedStr).parse());
    }

    public void setParameters(PreparedStatement ps, LoggingEvent logEvent) throws SQLException {
        for (int i = 0; i < args.size(); i++) {
            final PatternConverter head = args.get(i);
            String value = buildValueStr(logEvent, head);
            ps.setString(i + 1, value);
        }
    }

    private String buildValueStr(LoggingEvent logEvent, final PatternConverter head) {
        StringBuffer buffer = new StringBuffer();
        PatternConverter c = head;
        while (c != null) {
            c.format(buffer, logEvent);
            c = c.next;
        }
        return buffer.toString();
    }
}
