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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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 *   http://www.apache.org/licenses/LICENSE-2.0
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 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
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 * This software consists of voluntary contributions made by many
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package org.apache.hc.client5.http.impl.classic;


import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.time.Instant;
import java.util.Map;

import org.apache.hc.client5.http.HttpRoute;
import org.apache.hc.core5.http.HttpHost;
import org.apache.hc.core5.util.TimeValue;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

class TestLinearBackoffManager {

    private LinearBackoffManager impl;
    private MockConnPoolControl connPerRoute;
    private HttpRoute route;
    private static final long DEFAULT_COOL_DOWN_MS = 10;

    @BeforeEach
    void setUp() {
        connPerRoute = new MockConnPoolControl();
        route = new HttpRoute(new HttpHost("localhost", 80));
        impl = new LinearBackoffManager(connPerRoute);
        impl.setCoolDown(TimeValue.ofMilliseconds(DEFAULT_COOL_DOWN_MS));
    }

    @Test
    void incrementsConnectionsOnBackoff() {
        final LinearBackoffManager impl = new LinearBackoffManager(connPerRoute);
        impl.setCoolDown(TimeValue.ofMilliseconds(DEFAULT_COOL_DOWN_MS)); // Set the cool-down period
        connPerRoute.setMaxPerRoute(route, 4);
        impl.backOff(route);
        assertEquals(5, connPerRoute.getMaxPerRoute(route));
    }

    @Test
    void decrementsConnectionsOnProbe() {
        connPerRoute.setMaxPerRoute(route, 4);
        impl.probe(route);
        assertEquals(3, connPerRoute.getMaxPerRoute(route));
    }

    @Test
    void backoffDoesNotAdjustDuringCoolDownPeriod() {
        // Arrange
        connPerRoute.setMaxPerRoute(route, 4);
        impl.backOff(route);
        final long max = connPerRoute.getMaxPerRoute(route);

        // Manipulate lastRouteBackoffs to simulate that not enough time has passed for the cooldown period
        final Map<HttpRoute, Instant> lastRouteBackoffs = impl.getLastRouteBackoffs();
        lastRouteBackoffs.put(route, Instant.now().minusMillis(1));

        // Act
        impl.backOff(route);

        // Assert
        assertEquals(max, connPerRoute.getMaxPerRoute(route));
    }
    @Test
    void backoffStillAdjustsAfterCoolDownPeriod() {
        // Arrange
        final LinearBackoffManager impl = new LinearBackoffManager(connPerRoute);
        impl.setCoolDown(TimeValue.ofMilliseconds(DEFAULT_COOL_DOWN_MS)); // Set the cool-down period
        connPerRoute.setMaxPerRoute(route, 4);
        impl.backOff(route);
        final int max1 = connPerRoute.getMaxPerRoute(route);

        // Manipulate lastRouteBackoffs to simulate that enough time has passed for the cooldown period
        final Map<HttpRoute, Instant> lastRouteBackoffs = impl.getLastRouteBackoffs();
        lastRouteBackoffs.put(route, Instant.now().minusMillis(DEFAULT_COOL_DOWN_MS + 1));

        // Act
        impl.backOff(route);
        final int max2 = connPerRoute.getMaxPerRoute(route);

        // Assert
        assertTrue(max2 > max1);
    }

    @Test
    void probeDoesNotAdjustDuringCooldownPeriod() {
        // Arrange
        connPerRoute.setMaxPerRoute(route, 4);
        impl.probe(route);
        final long max = connPerRoute.getMaxPerRoute(route);

        // Manipulate lastRouteProbes to simulate that not enough time has passed for the cooldown period
        final Map<HttpRoute, Instant> lastRouteProbes = impl.getLastRouteProbes();
        lastRouteProbes.put(route, Instant.now());

        // Act
        impl.probe(route);

        // Assert
        assertEquals(max, connPerRoute.getMaxPerRoute(route));
    }

    @Test
    void probeStillAdjustsAfterCoolDownPeriod() {
        // Arrange
        connPerRoute.setMaxPerRoute(route, 4);
        impl.probe(route);

        // Manipulate lastRouteProbes to simulate that enough time has passed for the cooldown period
        final Map<HttpRoute, Instant> lastRouteProbes = impl.getLastRouteProbes();
        lastRouteProbes.put(route, Instant.now().minusMillis(DEFAULT_COOL_DOWN_MS + 1));

        // Act
        impl.probe(route);
        final long newMax = connPerRoute.getMaxPerRoute(route);

        // Assert
        assertEquals(2, newMax); // The cap is set to 2 by default
    }


    @Test
    void testSetPerHostConnectionCap() {
        connPerRoute.setMaxPerRoute(route, 5);
        impl.setPerHostConnectionCap(10); // Set the cap to a higher value
        impl.backOff(route);
        assertEquals(6, connPerRoute.getMaxPerRoute(route));
    }


    public void probeUpdatesRemainingAttemptsIndirectly() {
        // Set initial max per route
        connPerRoute.setMaxPerRoute(route, 4);

        // Apply backOff twice
        impl.backOff(route);

        // Manipulate lastRouteBackoffs to simulate that enough time has passed for the cooldown period
        final Map<HttpRoute, Instant> lastRouteBackoffs = impl.getLastRouteBackoffs();
        lastRouteBackoffs.put(route, Instant.now().minusMillis(DEFAULT_COOL_DOWN_MS + 1));

        impl.backOff(route);

        // Ensure that connection pool size has increased
        assertEquals(6, connPerRoute.getMaxPerRoute(route));

        // Apply probe once
        impl.probe(route);

        // Manipulate lastRouteProbes to simulate that enough time has passed for the cooldown period
        final Map<HttpRoute, Instant> lastRouteProbes = impl.getLastRouteProbes();
        lastRouteProbes.put(route, Instant.now().minusMillis(DEFAULT_COOL_DOWN_MS * 2));

        // Apply probe once more
        impl.probe(route);

        // Check that connection pool size has decreased once, indicating that the remaining attempts were updated
        assertEquals(5, connPerRoute.getMaxPerRoute(route));
    }

    @Test
    void linearIncrementTest() {
        final int initialMax = 4;
        connPerRoute.setMaxPerRoute(route, initialMax);

        // Manipulate lastRouteBackoffs to simulate that enough time has passed for the cooldown period
        final Map<HttpRoute, Instant> lastRouteBackoffs = impl.getLastRouteBackoffs();

        for (int i = 1; i <= 5; i++) {
            // Simulate that enough time has passed for the cooldown period
            lastRouteBackoffs.put(route, Instant.now().minusMillis(DEFAULT_COOL_DOWN_MS + 1));

            // Act
            impl.backOff(route);

            // Assert
            assertEquals(initialMax + i, connPerRoute.getMaxPerRoute(route));
        }
    }

}
