/*
 * Copyright 2004-2011 H2 Group.
 * Copyright 2011 James Moger.
 *
 * 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 com.iciql.bytecode;

import com.iciql.Query;
import com.iciql.SQLStatement;
import com.iciql.Token;

/**
 * A mathematical or comparison operation.
 */
class Operation implements Token {

	/**
	 * The operation type.
	 */
	enum Type {
		EQUALS("=") {
			Type reverse() {
				return NOT_EQUALS;
			}
		},
		NOT_EQUALS("<>") {
			Type reverse() {
				return EQUALS;
			}
		},
		BIGGER(">") {
			Type reverse() {
				return SMALLER_EQUALS;
			}
		},
		BIGGER_EQUALS(">=") {
			Type reverse() {
				return SMALLER;
			}
		},
		SMALLER_EQUALS("<=") {
			Type reverse() {
				return BIGGER;
			}
		},
		SMALLER("<") {
			Type reverse() {
				return BIGGER_EQUALS;
			}
		},
		ADD("+"), SUBTRACT("-"), MULTIPLY("*"), DIVIDE("/"), MOD("%");

		private String name;

		Type(String name) {
			this.name = name;
		}

		public String toString() {
			return name;
		}

		Type reverse() {
			return null;
		}

	}

	private final Token left, right;
	private final Type op;

	private Operation(Token left, Type op, Token right) {
		this.left = left;
		this.op = op;
		this.right = right;
	}

	static Token get(Token left, Type op, Token right) {
		if (op == Type.NOT_EQUALS && "0".equals(right.toString())) {
			return left;
		}
		return new Operation(left, op, right);
	}

	public String toString() {
		return left + " " + op + " " + right;
	}

	public Token reverse() {
		return get(left, op.reverse(), right);
	}

	public <T> void appendSQL(SQLStatement stat, Query<T> query) {
		left.appendSQL(stat, query);
		stat.appendSQL(op.toString());
		right.appendSQL(stat, query);
	}

}