/**
 * 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.activemq.apollo.selector;

import org.apache.activemq.apollo.filter.BooleanExpression;
import org.apache.activemq.apollo.filter.ComparisonExpression;
import org.apache.activemq.apollo.filter.FilterException;
import org.apache.activemq.apollo.selector.hyphenated.HyphenatedParser;
import org.apache.activemq.apollo.selector.strict.StrictParser;

import java.io.StringReader;

/**
 */
public class SelectorParser {

    private static final LRUCache cache = new LRUCache(100);
    private static final String CONVERT_STRING_EXPRESSIONS_PREFIX = "convert_string_expressions:";
    private static final String HYPHENATED_PROPS_PREFIX = "hyphenated_props:";
    private static final String NO_CONVERT_STRING_EXPRESSIONS_PREFIX = "no_convert_string_expressions:";
    private static final String NO_HYPHENATED_PROPS_PREFIX = "no_hyphenated_props:";

    public static BooleanExpression parse(String sql) throws FilterException {
        Object result = cache.get(sql);
        if (result instanceof FilterException) {
            throw (FilterException) result;
        } else if (result instanceof BooleanExpression) {
            return (BooleanExpression) result;
        } else {
            String actual = sql;
            boolean convertStringExpressions = false;
            boolean hyphenatedProps=false;
            while(true) {
              if( actual.startsWith(CONVERT_STRING_EXPRESSIONS_PREFIX)) {
                  convertStringExpressions = true;
                  actual = actual.substring(CONVERT_STRING_EXPRESSIONS_PREFIX.length());
                  continue;
              }
              if( actual.startsWith(HYPHENATED_PROPS_PREFIX)) {
                  hyphenatedProps = true;
                  actual = actual.substring(HYPHENATED_PROPS_PREFIX.length());
                  continue;
              }
              if( actual.startsWith(NO_CONVERT_STRING_EXPRESSIONS_PREFIX)) {
                  convertStringExpressions = false;
                  actual = actual.substring(NO_CONVERT_STRING_EXPRESSIONS_PREFIX.length());
                  continue;
              }
              if( actual.startsWith(NO_HYPHENATED_PROPS_PREFIX)) {
                  hyphenatedProps = false;
                  actual = actual.substring(NO_HYPHENATED_PROPS_PREFIX.length());
                  continue;
              }
              break;
            }

            if( convertStringExpressions ) {
                ComparisonExpression.CONVERT_STRING_EXPRESSIONS.set(true);
            }
            try {
                BooleanExpression e = null;
                if( hyphenatedProps ) {
                    HyphenatedParser parser = new HyphenatedParser(new StringReader(actual));
                    e = parser.JmsSelector();
                } else {
                    StrictParser parser = new StrictParser(new StringReader(actual));
                    e = parser.JmsSelector();
                }
                cache.put(sql, e);
                return e;
            } catch (Throwable e) {
                FilterException fe = new FilterException(actual, e);
                cache.put(sql, fe);
                throw fe;
            } finally {
                if( convertStringExpressions ) {
                    ComparisonExpression.CONVERT_STRING_EXPRESSIONS.remove();
                }
            }
        }
    }

    public static void clearCache() {
        cache.clear();
    }
}
