/*
 * Copyright 1999-2017 Alibaba Group Holding Ltd.
 *
 * 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.alibaba.druid.sql.visitor.functions;

import com.alibaba.druid.sql.ast.SQLExpr;
import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
import com.alibaba.druid.sql.visitor.SQLEvalVisitor;

import java.util.List;

import static com.alibaba.druid.sql.visitor.SQLEvalVisitor.EVAL_VALUE;

public class Locate implements Function {
    public static final Locate instance = new Locate();

    public Object eval(SQLEvalVisitor visitor, SQLMethodInvokeExpr x) {
        List<SQLExpr> params = x.getArguments();
        int paramSize = params.size();
        if (paramSize != 2 && paramSize != 3) {
            return SQLEvalVisitor.EVAL_ERROR;
        }

        SQLExpr param0 = params.get(0);
        SQLExpr param1 = params.get(1);
        SQLExpr param2 = null;

        param0.accept(visitor);
        param1.accept(visitor);
        if (paramSize == 3) {
            param2 = params.get(2);
            param2.accept(visitor);
        }

        Object param0Value = param0.getAttributes().get(EVAL_VALUE);
        Object param1Value = param1.getAttributes().get(EVAL_VALUE);
        if (param0Value == null || param1Value == null) {
            return SQLEvalVisitor.EVAL_ERROR;
        }

        String strValue0 = param0Value.toString();
        String strValue1 = param1Value.toString();

        if (paramSize == 2) {
            int result = strValue1.indexOf(strValue0) + 1;
            return result;
        }

        Object param2Value = param2.getAttributes().get(EVAL_VALUE);
        int start = ((Number) param2Value).intValue();

        int result = strValue1.indexOf(strValue0, start + 1) + 1;
        return result;
    }
}
