package com.bellsw.simple;

import java.util.concurrent.TimeUnit;
import java.util.Arrays;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Level;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Threads;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.annotations.OperationsPerInvocation;

@Warmup(iterations = 40)
@Measurement(iterations = 5)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Benchmark)
public class StringCompareBench {
    static final int BATCH_DATA_SIZE = 17000000; // a bit more than 16mb(L2)
    @Param({"4", "8", "15", "16", "21", "32", "128", "256", "512", "1024", "1000000"})
    int size;
    int amountOfStrings;

    String[] latinStrings;
    String[] utfStrings;

    @Setup(Level.Trial)
    public void init() {
        amountOfStrings = BATCH_DATA_SIZE / size;
        latinStrings = new String[amountOfStrings];
        utfStrings = new String[amountOfStrings];
        char[] charsL = new char[size];
        char[] charsU = new char[size];
        for (int i = 0; i < size; i++) {
            charsL[i] = 'A';
            charsU[i] = 'A';
        }
        charsU[size - 1] = (char) 0xCAFE;
        for (int i = 0; i < amountOfStrings; i++) {
            latinStrings[i] = new String(charsL);
            utfStrings[i] = new String(charsU);
        }
    }

    @Benchmark
    @Threads(1)
    public int StringCompareLL() {
        int accum = 0;
        for (int i = 0; i < amountOfStrings - 1; i++) {
            accum += latinStrings[i].compareTo(latinStrings[i+1]);
        }
        return accum;
    }

    @Benchmark
    @Threads(1)
    public int StringCompareUU() {
        int accum = 0;
        for (int i = 0; i < amountOfStrings - 1; i++) {
            accum += utfStrings[i].compareTo(utfStrings[i+1]);
        }
        return accum;
    }

    @Benchmark
    @Threads(1)
    public int StringCompareLU() {
        int accum = 0;
        for (int i = 0; i < amountOfStrings - 1; i++) {
            accum += utfStrings[i].compareTo(latinStrings[i+1]);
        }
        return accum;
    }

    @Benchmark
    @Threads(1)
    public int StringCompareUL() {
        int accum = 0;
        for (int i = 0; i < amountOfStrings - 1; i++) {
            accum += latinStrings[i].compareTo(utfStrings[i+1]);
        }
        return accum;
    }
}