/*
 * Copyright 2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * 
 * Licensed under the Amazon Software License (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 * 
 *  http://aws.amazon.com/asl/
 * 
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express
 * or implied. See the License for the specific language governing permissions
 * and limitations under the License.
 */
package com.amazonaws.samples.machinelearning;

/**
 * Utility class to generate random identifiers with prefixes 
 * that indicate which type of entity they are for.
 */
public class Identifiers {
    
    private final static String BASE62_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    
    private static String generateEntityId(String prefix) {
        StringBuilder sb = new StringBuilder();
        sb.append(prefix);
        sb.append("-");
        // 62^11 -> 65 random bits, which is sufficient to avoid collisions
        // until customer has been creating 1 object per second for 200+ years.
        for(int i=0; i<11; i++) {
            int rand = (int) (Math.random() * BASE62_CHARS.length());
            sb.append( BASE62_CHARS.charAt(rand) );
        }
        return sb.toString();
    }
    
    public static String newDataSourceId() {
        return generateEntityId("ds");
    }

    public static String newMLModelId() {
        return generateEntityId("ml");
    }

    public static String newEvaluationId() {
        return generateEntityId("ev");
    }

    public static String newBatchPredictionId() {
        return generateEntityId("bp");
    }
}