/*
 * Copyright 2010 NCHOVY
 * 
 * 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.krakenapps.sqlparser.syntax;

import java.nio.BufferUnderflowException;
import java.text.ParseException;

import org.krakenapps.bnf.Binding;
import org.krakenapps.bnf.ParserContext;
import org.krakenapps.bnf.Placeholder;
import org.krakenapps.bnf.Result;
import org.krakenapps.bnf.StringUtil;

public class EnclosedStringPlaceholder implements Placeholder {
	private char delimiter;

	public EnclosedStringPlaceholder(char delimiter) {
		this.delimiter = delimiter;
	}

	@Override
	public Result eval(String text, int position, ParserContext ctx) throws ParseException {
		int i = StringUtil.skipSpaces(text, position);

		int begin = i;

		if (text.length() <= begin)
			throw new BufferUnderflowException();

		i = findEnd(text, i);
		String token = text.substring(begin, i);
		token = token.replaceAll("''", "'");

		// remove trailing spaces
		i = StringUtil.skipSpaces(text, i);
		return new Result(new Binding(this, token), i);
	}

	private int findEnd(String text, int position) {
		int i = position;

		while (true) {
			if (i >= text.length())
				break;

			char c = text.charAt(i);
			if (c != delimiter) {
				i++;
				continue;
			}

			if ((i + 1) < text.length() && c == delimiter) {
				c = text.charAt(i + 1);
				if (c == delimiter) {
					i += 2;
					continue;
				}
			}

			break;
		}

		return i;
	}

	@Override
	public String toString() {
		return "id_var";
	}

}