/*
 * Copyright 2009-2010 by The Regents of the University of California
 * 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 from
 * 
 *     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 edu.uci.ics.hyracks.storage.am.common;

import edu.uci.ics.hyracks.storage.am.common.datagen.ProbabilityHelper;


public class TestOperationSelector {

    public static enum TestOperation {
        INSERT,
        DELETE,
        UPDATE,
        UPSERT,
        POINT_SEARCH,
        RANGE_SEARCH,
        SCAN,
        DISKORDER_SCAN,
        MERGE        
    }
    
    private final TestOperation[] ops;
    private final int[] cumulIntRanges;    
    
    public TestOperationSelector(TestOperation[] ops, double[] opProbs) {
        sanityCheck(ops, opProbs);
        this.ops = ops;
        this.cumulIntRanges = ProbabilityHelper.getCumulIntRanges(opProbs);
    }
    
    private void sanityCheck(TestOperation[] ops, double[] opProbs) {
        if (ops.length == 0) {
            throw new RuntimeException("Empty op array.");
        }
        if (opProbs.length == 0) {
            throw new RuntimeException("Empty op probabilities.");
        }
        if (ops.length != opProbs.length) {
            throw new RuntimeException("Ops and op probabilities have unequal length.");
        }
        float sum = 0.0f;
        for (int i = 0; i < opProbs.length; i++) {
            sum += opProbs[i];
        }
        if (sum != 1.0f) {
            throw new RuntimeException("Op probabilities don't add up to 1.");
        }
    }
    
    public TestOperation getOp(int randomInt) {
        int ix = ProbabilityHelper.choose(cumulIntRanges, randomInt);
        return ops[ix];
    }
}