package ch.usi.inf.sp.graph;

import ch.usi.inf.sp.graph.DiGraph;
import ch.usi.inf.sp.graph.Edge;
import ch.usi.inf.sp.graph.Node;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.*;

class DiGraphTest {

    @Test
    void newDiGraph() {
        DiGraph g = new DiGraph();
        assertEquals(0, g.getNodes().size());
        assertEquals(0, g.getEdges().size());
    }

    @Test
    void toStringEmpty() {
        DiGraph g = new DiGraph();
        assertEquals("digraph G {\n}\n", g.toString());
    }

    @Test
    void toStringOneEdge() {
        DiGraph g = new DiGraph();
        Node n1 = new Node();
        Node n2 = new Node();
        Edge e = new Edge();
        g.addNode(n1);
        g.addNode(n2);
        g.addEdge(e);
        g.connect(n1, e, n2);
        assertEquals("digraph G {\n"+
                "  "+n1.toString()+"\n"+
                "  "+n2.toString()+"\n"+
                "  "+e.toString()+"\n"+
                "}\n", g.toString());
    }

    @Test
    void addNode() {
        DiGraph g = new DiGraph();
        Node n = new Node();
        g.addNode(n);
        assertEquals(1, g.getNodes().size());
        assertSame(n, g.getNodes().get(0));
        assertEquals(0, g.getEdges().size());
    }

    @Test
    void addEdge() {
        DiGraph g = new DiGraph();
        Edge e = new Edge();
        g.addEdge(e);
        assertEquals(0, g.getNodes().size());
        assertEquals(1, g.getEdges().size());
        assertSame(e, g.getEdges().get(0));
    }

    @Test
    void connect() {
        DiGraph g = new DiGraph();
        Edge e = new Edge();
        Node n1 = new Node();
        Node n2 = new Node();
        g.addNode(n1);
        g.addNode(n2);
        g.addEdge(e);
        g.connect(n1, e, n2);
        assertEquals(2, g.getNodes().size());
        assertTrue(g.getNodes().contains(n1));
        assertTrue(g.getNodes().contains(n2));
        assertEquals(1, g.getEdges().size());
        assertSame(e, g.getEdges().get(0));
        assertSame(e, n1.getOutEdges().get(0));
        assertSame(e, n2.getInEdges().get(0));
        assertSame(n1, e.getFrom());
        assertSame(n2, e.getTo());
    }

    @Test
    void connectEdgeNotContained() {
        DiGraph g = new DiGraph();
        Edge e = new Edge();
        Node n1 = new Node();
        Node n2 = new Node();
        g.addNode(n1);
        g.addNode(n2);
        assertThrows(IllegalStateException.class, () -> g.connect(n1, e, n2));
    }

    @Test
    void connectFromNodeNotContained() {
        DiGraph g = new DiGraph();
        Edge e = new Edge();
        Node n1 = new Node();
        Node n2 = new Node();
        g.addNode(n2);
        g.addEdge(e);
        assertThrows(IllegalStateException.class, () -> g.connect(n1, e, n2));
    }

    @Test
    void connectToNodeNotContained() {
        DiGraph g = new DiGraph();
        Edge e = new Edge();
        Node n1 = new Node();
        Node n2 = new Node();
        g.addNode(n1);
        g.addEdge(e);
        assertThrows(IllegalStateException.class, () -> g.connect(n1, e, n2));
    }

    @Test
    void connectSelfLoop() {
        DiGraph g = new DiGraph();
        Edge e = new Edge();
        Node n = new Node();
        g.addNode(n);
        g.addEdge(e);
        g.connect(n, e, n);
        assertEquals(1, g.getNodes().size());
        assertTrue(g.getNodes().contains(n));
        assertEquals(1, g.getEdges().size());
        assertSame(e, g.getEdges().get(0));
        assertSame(e, n.getOutEdges().get(0));
        assertSame(e, n.getInEdges().get(0));
        assertSame(n, e.getFrom());
        assertSame(n, e.getTo());
    }

    @Test
    void connectSameEdgeTwice() {
        DiGraph g = new DiGraph();
        Edge e = new Edge();
        Node n1 = new Node();
        Node n2 = new Node();
        g.addNode(n1);
        g.addNode(n2);
        g.addEdge(e);
        g.connect(n1, e, n2);
        assertThrows(IllegalStateException.class, () -> g.connect(n1, e, n2));
    }

}