package build.demo;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.Random;
import java.util.concurrent.TimeUnit;

@State(Scope.Thread)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@Fork(1)
@Warmup(iterations = 2, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
public class TimeDemo {

    // JMH will run the benchmark for arrays of size 100 and 1000
    @Param({"100", "1000"})
    private int testsize;

    private int[] originalArray;
    private int[] arrayToSort;

    // Generated once per benchmark trial run
    @Setup(Level.Trial)
    public void setupData() {
        originalArray = new int[testsize];
        Random random = new Random(42); // Fixed seed makes tests reproducible
        for (int i = 0; i < testsize; i++) {
            originalArray[i] = random.nextInt(10000);
        }
    }

    // Generated right before every single iteration execution
    @Setup(Level.Invocation)
    public void copyArray() {
        // Crucial for sorting algorithms so we never benchmark an already-sorted array
        arrayToSort = originalArray.clone();
    }

    @Benchmark
    public int[] benchmarkInsertionSort() {
        insertionSort(arrayToSort);
        return arrayToSort; // Returning prevents Dead Code Elimination optimization
    }

    // Classic Insertion Sort implementation
    private void insertionSort(int[] array) {
        for (int i = 1; i < array.length; i++) {
            int key = array[i];
            int j = i - 1;
            while (j >= 0 && array[j] > key) {
                array[j + 1] = array[j];
                j = j - 1;
            }
            array[j + 1] = key;
        }
    }

    // Built-in main method so you can kick it off easily from your command line execution
    public static void main(String[] args) throws Exception {
        Options opt = new OptionsBuilder()
                .include(TimeDemo.class.getSimpleName())
                .build();

        new Runner(opt).run();
    }
}