package org.drools.template.parser;

/*
 * Copyright 2005 JBoss Inc
 * 
 * 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.
 */
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.drools.core.util.StringUtils;
import org.drools.template.model.Condition;
import org.drools.template.model.Rule;
import org.drools.template.model.SnippetBuilder;

/**
 * 
 * @author <a href="mailto:stevearoonie@gmail.com">Steven Williams</a>
 * 
 * The default column condition for a rule template to be generated. If the
 * conditon starts with "!" then the template will only be generated if the
 * column condition does not exist. If there is no condition string then the
 * template will be generated only if the column contains a value. The condition
 * can be any valid rule condition.
 */
class DefaultTemplateColumn implements TemplateColumn {
	private static final Pattern COLUMN_PATTERN = Pattern
			.compile("^(!?)([a-zA-Z0-9_]*)(\\[([0-9]+)\\])?\\s*(.*)");

	private boolean notCondition;

	private String columnName;

	private String condition;

	private TemplateContainer templateContainer;

	private int index = -1;

	DefaultTemplateColumn(TemplateContainer tc, String columnString) {
		templateContainer = tc;
		Matcher matcher = COLUMN_PATTERN.matcher(columnString);
		if (!matcher.matches())
			throw new IllegalArgumentException("column " + columnString
					+ " is not valid");
		notCondition = !StringUtils.isEmpty(matcher.group(1));
		columnName = matcher.group(2);
		String indexString = matcher.group(4);
		condition = matcher.group(5);
		if (!StringUtils.isEmpty(indexString)) {
			index = Integer.parseInt(indexString);
		}
	}

	private void createCellCondition(final Rule rule) {
		StringBuffer conditionString = new StringBuffer();
		Column column = templateContainer.getColumn(columnName);
		column.getCondition(condition, index);
		
		if (notCondition) {
			conditionString.append("not ");
		}
		conditionString.append("exists ");
		conditionString.append(column.getCondition(condition, index));
		SnippetBuilder snip = new SnippetBuilder(conditionString.toString());
		Condition condition = new Condition();
		condition.setSnippet(snip.build(columnName));
		rule.addCondition(condition);
	}

	private void createColumnCondition(final Rule rule, final String value) {
		SnippetBuilder colSnip = new SnippetBuilder(
				"$param : Column(name == \"$param\")");
		Condition colCondition = new Condition();
		colCondition.setSnippet(colSnip.build(value));
		rule.addCondition(colCondition);
	}

	public void addCondition(Rule rule) {
		createColumnCondition(rule, columnName);
		createCellCondition(rule);
	}

	public String getName() {
		return columnName;
	}

	public boolean isNotCondition() {
		return notCondition;
	}

	public String getCondition() {
		return condition;
	}
}