/*
 * Copyright 2011 Future Systems
 * 
 * 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.logdb.query;

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

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;
import org.krakenapps.logdb.query.command.Function;

public class FunctionPlaceholder implements Placeholder {
	private Map<String, Class<? extends Function>> func;

	public FunctionPlaceholder() {
	}

	public FunctionPlaceholder(Map<String, Class<? extends Function>> func) {
		this.func = func;
	}

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

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

		StringBuilder sb = new StringBuilder();
		int bracket = 0;
		boolean space = false;
		while (i < text.length()) {
			char c = text.charAt(i++);
			if (c == ',')
				break;
			if (space && bracket == 0 && c != ' ' && c != '(') {
				i--;
				break;
			}

			sb.append(c);

			if (c == ' ')
				space = true;
			else if (c == '(')
				bracket++;
			else if (c == ')') {
				bracket--;
				if (bracket == 0)
					break;
				else if (bracket < 0)
					throw new ParseException("invalid function type", i);
			}
		}
		String funcstr = sb.toString();

		String name = null;
		String target = null;
		int lb = funcstr.indexOf("(");
		int rb = funcstr.lastIndexOf(")");
		if (lb > 0) {
			name = funcstr.substring(0, lb).trim();
			target = funcstr.substring(lb + 1, rb).trim();
		} else {
			name = funcstr.trim();
		}

		i = StringUtil.skipSpaces(text, i);
		if (i < text.length() && text.charAt(i) == ',')
			i++;

		Function f = Function.getFunction(name, target, func);
		if (f == null)
			throw new ParseException("unknown function", i);

		return new Result(new Binding(this, f), i);
	}
}