/*
 * Copyright OpenSearch Contributors
 * SPDX-License-Identifier: Apache-2.0
 */

package org.opensearch.reportsscheduler.metrics;

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.Mock;
import org.mockito.junit.jupiter.MockitoExtension;

import java.time.Clock;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.lessThanOrEqualTo;
import static org.mockito.Mockito.when;

@ExtendWith(MockitoExtension.class)
public class RollingCounterTests {

    @Mock
    Clock clock;

    @Test
    public void increment() {
        RollingCounter counter = new RollingCounter(3, 1, clock);
        for (int i = 0; i < 5; ++i) {
            counter.increment();
        }

        assertThat(counter.getValue(), equalTo(0L));

        when(clock.millis()).thenReturn(1000L); // 1 second passed
        assertThat(counter.getValue(), equalTo(5L));

        counter.increment();
        counter.increment();

        when(clock.millis()).thenReturn(2000L); // 1 second passed
        assertThat(counter.getValue(), lessThanOrEqualTo(3L));

        when(clock.millis()).thenReturn(3000L); // 1 second passed
        assertThat(counter.getValue(), equalTo(0L));

    }

    @Test
    public void add() {
        RollingCounter counter = new RollingCounter(3, 1, clock);

        counter.add(6);
        assertThat(counter.getValue(), equalTo(0L));

        when(clock.millis()).thenReturn(1000L); // 1 second passed
        assertThat(counter.getValue(), equalTo(6L));

        counter.add(4);
        when(clock.millis()).thenReturn(2000L); // 1 second passed
        assertThat(counter.getValue(), equalTo(4L));

        when(clock.millis()).thenReturn(3000L); // 1 second passed
        assertThat(counter.getValue(), equalTo(0L));
    }

    @Test
    public void trim() {
        RollingCounter counter = new RollingCounter(2, 1, clock);

        for (int i = 1; i < 6; ++i) {
            counter.increment();
            assertThat(counter.size(), equalTo(i));
            when(clock.millis()).thenReturn(i * 1000L); // i seconds passed
        }
        counter.increment();
        assertThat(counter.size(), lessThanOrEqualTo(3));
    }
}