/*
 * Copyright 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package androidx.coordinatorlayout.widget;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;

import androidx.annotation.NonNull;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

import java.util.List;

@RunWith(JUnit4.class)
public class DirectedAcyclicGraphTest {

    private DirectedAcyclicGraph<TestNode> mGraph;

    @Before
    public void setup() {
        mGraph = new DirectedAcyclicGraph<>();
    }

    @Test
    public void test_addNode() {
        final TestNode node = new TestNode("node");
        mGraph.addNode(node);
        assertEquals(1, mGraph.size());
        assertTrue(mGraph.contains(node));
    }

    @Test
    public void test_addNodeAgain() {
        final TestNode node = new TestNode("node");
        mGraph.addNode(node);
        mGraph.addNode(node);

        assertEquals(1, mGraph.size());
        assertTrue(mGraph.contains(node));
    }

    @Test
    public void test_addEdge() {
        final TestNode node = new TestNode("node");
        final TestNode edge = new TestNode("edge");

        mGraph.addNode(node);
        mGraph.addNode(edge);
        mGraph.addEdge(node, edge);
    }

    @Test(expected = IllegalArgumentException.class)
    public void test_addEdgeWithNotAddedEdgeNode() {
        final TestNode node = new TestNode("node");
        final TestNode edge = new TestNode("edge");

        // Add the node, but not the edge node
        mGraph.addNode(node);

        // Now add the link
        mGraph.addEdge(node, edge);
    }

    @Test
    public void test_getIncomingEdges() {
        final TestNode node = new TestNode("node");
        final TestNode edge = new TestNode("edge");
        mGraph.addNode(node);
        mGraph.addNode(edge);
        mGraph.addEdge(node, edge);

        final List<TestNode> incomingEdges = mGraph.getIncomingEdges(node);
        assertNotNull(incomingEdges);
        assertEquals(1, incomingEdges.size());
        assertEquals(edge, incomingEdges.get(0));
    }

    @Test
    public void test_getOutgoingEdges() {
        final TestNode node = new TestNode("node");
        final TestNode edge = new TestNode("edge");
        mGraph.addNode(node);
        mGraph.addNode(edge);
        mGraph.addEdge(node, edge);

        // Now assert the getOutgoingEdges returns a list which has one element (node)
        final List<TestNode> outgoingEdges = mGraph.getOutgoingEdges(edge);
        assertNotNull(outgoingEdges);
        assertEquals(1, outgoingEdges.size());
        assertTrue(outgoingEdges.contains(node));
    }

    @Test
    public void test_getOutgoingEdgesMultiple() {
        final TestNode node1 = new TestNode("1");
        final TestNode node2 = new TestNode("2");
        final TestNode edge = new TestNode("edge");
        mGraph.addNode(node1);
        mGraph.addNode(node2);
        mGraph.addNode(edge);

        mGraph.addEdge(node1, edge);
        mGraph.addEdge(node2, edge);

        // Now assert the getOutgoingEdges returns a list which has 2 elements (node1 & node2)
        final List<TestNode> outgoingEdges = mGraph.getOutgoingEdges(edge);
        assertNotNull(outgoingEdges);
        assertEquals(2, outgoingEdges.size());
        assertTrue(outgoingEdges.contains(node1));
        assertTrue(outgoingEdges.contains(node2));
    }

    @Test
    public void test_hasOutgoingEdges() {
        final TestNode node = new TestNode("node");
        final TestNode edge = new TestNode("edge");
        mGraph.addNode(node);
        mGraph.addNode(edge);

        // There is no edge currently and assert that fact
        assertFalse(mGraph.hasOutgoingEdges(edge));
        // Now add the edge
        mGraph.addEdge(node, edge);
        // and assert that the methods returns true;
        assertTrue(mGraph.hasOutgoingEdges(edge));
    }

    @Test
    public void test_clear() {
        final TestNode node1 = new TestNode("1");
        final TestNode node2 = new TestNode("2");
        final TestNode edge = new TestNode("edge");
        mGraph.addNode(node1);
        mGraph.addNode(node2);
        mGraph.addNode(edge);

        // Now clear the graph
        mGraph.clear();

        // Now assert the graph is empty and that contains returns false
        assertEquals(0, mGraph.size());
        assertFalse(mGraph.contains(node1));
        assertFalse(mGraph.contains(node2));
        assertFalse(mGraph.contains(edge));
    }

    @Test
    public void test_getSortedList() {
        final TestNode node1 = new TestNode("A");
        final TestNode node2 = new TestNode("B");
        final TestNode node3 = new TestNode("C");
        final TestNode node4 = new TestNode("D");

        // Now we'll add the nodes
        mGraph.addNode(node1);
        mGraph.addNode(node2);
        mGraph.addNode(node3);
        mGraph.addNode(node4);

        // Now we'll add edges so that 4 <- 2, 2 <- 3, 3 <- 1  (where <- denotes a dependency)
        mGraph.addEdge(node4, node2);
        mGraph.addEdge(node2, node3);
        mGraph.addEdge(node3, node1);

        final List<TestNode> sorted = mGraph.getSortedList();
        // Assert that it is the correct size
        assertEquals(4, sorted.size());
        // Assert that all of the nodes are present and in their sorted order
        assertEquals(node1, sorted.get(0));
        assertEquals(node3, sorted.get(1));
        assertEquals(node2, sorted.get(2));
        assertEquals(node4, sorted.get(3));
    }

    private static class TestNode {
        private final String mLabel;

        TestNode(@NonNull String label) {
            mLabel = label;
        }

        @Override
        public String toString() {
            return "TestNode: " + mLabel;
        }
    }

}