use std::fmt::Debug;

use crate::testing::fixtures::MakeTestGraph;
use crate::traits::{
    GraphTopology, GraphTopologyAddition, GraphTopologyDeletion, Incidence, IncidenceCursor,
};

#[doc(hidden)]
#[macro_export]
macro_rules! graph_topology_deletion_tests {
    ($T:ty) => {
        $crate::graph_topology_deletion_tests!(@wrap $T,
            delete_vertex,
            delete_vertex_loop,
            delete_vertex_invalid_index,
            delete_vertex_connected,
            delete_edge,
            delete_edge_loop,
            delete_edge_multiple,
            delete_edge_invalid_index,
            vertices_after_delete,
            incident_vertices_after_delete_edge,
            edges_after_delete,
            incident_edges_after_delete_edge,
            incident_edges_after_delete_vertex,
            incidences_after_delete_vertex,
            incidences_after_delete_edge,
            incidence_cursor_after_delete_vertex,
            incidence_cursor_after_delete_edge,
        );
    };

    (@wrap $T:ty, $($name:ident),* $(,)?) => {
        $(
            #[test]
            fn $name() {
                $crate::testing::graph_topology_deletion_testing::$name::<$T>();
            }
        )*
    };
}

pub fn delete_vertex<G: GraphTopologyDeletion + GraphTopologyAddition>() {
    let (mut graph, v) = G::single_vertex();
    assert_eq!(
        graph.vertex_count(),
        1,
        "unexpected vertex count before delete"
    );
    graph.delete_vertex(v);
    assert_eq!(
        graph.vertex_count(),
        0,
        "unexpected vertex count after delete"
    );
}

pub fn delete_vertex_loop<G: GraphTopologyDeletion + GraphTopologyAddition>() {
    let (mut graph, v, _) = G::loop_edge();
    assert_eq!(
        graph.vertex_count(),
        1,
        "unexpected vertex count before delete"
    );
    assert_eq!(graph.edge_count(), 1, "unexpected edge count before delete");
    assert!(
        graph.are_adjacent(v, v),
        "expected vertex to be self-adjacent before delete"
    );
    assert_eq!(graph.degree(v), 2, "unexpected vertex degree before delete");
    graph.delete_vertex(v);
    assert_eq!(
        graph.vertex_count(),
        0,
        "unexpected vertex count after delete"
    );
    assert_eq!(graph.edge_count(), 0, "unexpected edge count after delete");
}

pub fn delete_vertex_invalid_index<G: GraphTopologyDeletion + GraphTopologyAddition>() {
    let (mut graph, v) = G::single_vertex();
    graph.delete_vertex(v);
    let result =
        std::panic::catch_unwind(std::panic::AssertUnwindSafe(move || graph.delete_vertex(v)));
    assert!(result.is_err(), "second deletion should panic");
}

pub fn delete_vertex_connected<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
{
    let (mut graph, vertices, _, _) = G::standard();
    assert_eq!(
        graph.vertex_count(),
        10,
        "unexpected vertex count before delete"
    );
    assert_eq!(
        graph.edge_count(),
        18,
        "unexpected edge count before delete"
    );
    graph.delete_vertex(vertices[2]);
    assert_eq!(
        graph.vertex_count(),
        9,
        "unexpected vertex count after delete"
    );
    assert_eq!(graph.edge_count(), 12, "unexpected edge count after delete");
    let expected_edges = [
        (vertices[0], vertices[1]),
        (vertices[1], vertices[3]),
        (vertices[1], vertices[4]),
        (vertices[3], vertices[6]),
        (vertices[4], vertices[4]),
        (vertices[4], vertices[7]),
        (vertices[4], vertices[8]),
        (vertices[5], vertices[9]),
        (vertices[6], vertices[9]),
        (vertices[7], vertices[8]),
        (vertices[7], vertices[9]),
    ];
    for (v, u) in expected_edges {
        assert!(
            graph.are_adjacent(v, u),
            "expected {v:?} and {u:?} to be adjacent after delete"
        );
    }
    for v in [vertices[1], vertices[4], vertices[5], vertices[6]] {
        assert!(
            !graph.adjacent_vertices(v).any(|u| u == vertices[2]),
            "unexpected adjacency of {v:?} to deleted vertex {:?}",
            vertices[2]
        );
    }
}

pub fn delete_edge<G: GraphTopologyDeletion + GraphTopologyAddition>() {
    let (mut graph, [v0, v1], e) = G::single_edge();
    assert_eq!(
        graph.vertex_count(),
        2,
        "unexpected vertex count before delete"
    );
    assert_eq!(graph.edge_count(), 1, "unexpected edge count before delete");
    assert!(
        graph.are_adjacent(v0, v1),
        "expected vertices to be adjacent before delete"
    );
    assert_eq!(
        graph.degree(v0),
        1,
        "unexpected vertex degree before delete"
    );
    assert_eq!(
        graph.degree(v1),
        1,
        "unexpected vertex degree before delete"
    );
    graph.delete_edge(e);
    assert_eq!(
        graph.vertex_count(),
        2,
        "unexpected vertex count after delete"
    );
    assert_eq!(graph.edge_count(), 0, "unexpected edge count after delete");
    assert!(
        !graph.are_adjacent(v0, v1),
        "unexpected adjacency after delete"
    );
    assert_eq!(graph.degree(v0), 0, "unexpected vertex degree after delete");
    assert_eq!(graph.degree(v1), 0, "unexpected vertex degree after delete");
}

pub fn delete_edge_loop<G: GraphTopologyDeletion + GraphTopologyAddition>() {
    let (mut graph, v, e) = G::loop_edge();
    assert_eq!(
        graph.vertex_count(),
        1,
        "unexpected vertex count before delete"
    );
    assert_eq!(graph.edge_count(), 1, "unexpected edge count before delete");
    assert!(
        graph.are_adjacent(v, v),
        "expected vertex to be self-adjacent before delete"
    );
    assert_eq!(graph.degree(v), 2, "unexpected vertex degree before delete");
    graph.delete_edge(e);
    assert_eq!(
        graph.vertex_count(),
        1,
        "unexpected vertex count after delete"
    );
    assert_eq!(graph.edge_count(), 0, "unexpected edge count after delete");
    assert!(
        !graph.are_adjacent(v, v),
        "unexpected adjacency after delete"
    );
    assert_eq!(graph.degree(v), 0, "unexpected vertex degree after delete");
}

pub fn delete_edge_multiple<G: GraphTopologyDeletion + GraphTopologyAddition>() {
    const K: usize = 2;
    let (mut graph, [v0, v1], edges) = G::multiple_edges::<K>();
    assert_eq!(
        graph.vertex_count(),
        2,
        "unexpected vertex count before delete"
    );
    assert_eq!(graph.edge_count(), K, "unexpected edge count before delete");
    assert!(
        graph.are_adjacent(v0, v1),
        "expected vertices to be adjacent before delete"
    );
    assert_eq!(
        graph.degree(v0),
        K,
        "unexpected vertex degree before delete"
    );
    assert_eq!(
        graph.degree(v1),
        K,
        "unexpected vertex degree before delete"
    );
    graph.delete_edge(edges[0]);
    assert_eq!(
        graph.vertex_count(),
        2,
        "unexpected vertex count after delete"
    );
    assert_eq!(
        graph.edge_count(),
        K - 1,
        "unexpected edge count after delete"
    );
    assert!(
        graph.are_adjacent(v0, v1),
        "expected vertices to be adjacent after delete"
    );
    assert_eq!(
        graph.degree(v0),
        K - 1,
        "unexpected vertex degree after delete"
    );
    assert_eq!(
        graph.degree(v1),
        K - 1,
        "unexpected vertex degree after delete"
    );
}

pub fn delete_edge_invalid_index<G: GraphTopologyDeletion + GraphTopologyAddition>() {
    let (mut graph, _, e) = G::single_edge();
    graph.delete_edge(e);
    let result =
        std::panic::catch_unwind(std::panic::AssertUnwindSafe(move || graph.delete_edge(e)));
    assert!(result.is_err(), "second deletion should panic");
}

pub fn vertices_after_delete<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
{
    let (mut graph, vertices, _, _) = G::standard();
    let del = vertices[2];
    graph.delete_vertex(del);
    assert_eq!(
        graph.vertex_count(),
        9,
        "unexpected vertex count after delete"
    );
    assert_eq!(
        graph.vertices().count(),
        9,
        "unexpected vertex iterator count after delete"
    );
    for v in graph.vertices() {
        assert_ne!(v, del, "deleted vertex {del:?} appeared in iterator");
    }
    for &v in vertices.iter().filter(|&&u| u != del) {
        assert!(
            graph.vertices().any(|u| u == v),
            "expected vertex {v:?} missing from iterator after delete"
        );
    }
}

pub fn incident_vertices_after_delete_edge<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (mut graph, _, edges, _) = G::standard();
    let del = edges[2].0;
    graph.delete_edge(del);
    for &(f, v0, v1) in edges.iter().filter(|&&(f, _, _)| f != del) {
        let (u0, u1) = graph.incident_vertices(f);
        assert!(
            (u0 == v0 && u1 == v1) || (u0 == v1 && u1 == v0),
            "unexpected incident vertices {u0:?} and {u1:?} for edge {f:?} after delete"
        );
    }
}

pub fn edges_after_delete<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Edge: Debug,
{
    let (mut graph, vertices, edges, _) = G::standard();
    graph.delete_vertex(vertices[2]);
    assert_eq!(graph.edge_count(), 12, "unexpected edge count after delete");
    assert_eq!(
        graph.edges().count(),
        12,
        "unexpected edge iterator count after delete"
    );
    for i in [2, 5, 6, 7, 8, 9] {
        assert!(
            !graph.edges().any(|e| e == edges[i].0),
            "deleted edge {:?} appeared in iterator",
            edges[i].0
        );
    }
    for i in [0, 1, 3, 4, 10, 11, 12, 13, 14, 15, 16, 17] {
        assert!(
            graph.edges().any(|e| e == edges[i].0),
            "expected edge {:?} missing from iterator after delete",
            edges[i].0
        );
    }
}

pub fn incident_edges_after_delete_edge<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (mut graph, vertices, edges, incidences) = G::standard();
    let del = edges[2].0;
    graph.delete_edge(del);
    assert_eq!(vertices.len(), incidences.len());
    for (&v, incs) in vertices.iter().zip(&incidences) {
        let mut expected = incs
            .iter()
            .filter_map(|x| (x.edge != del).then_some(x.edge))
            .collect();
        assert_incident_edges_after_delete(&graph, v, &mut expected);
    }
}

pub fn incident_edges_after_delete_vertex<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (mut graph, vertices, _, incidences) = G::standard();
    let del = vertices[2];
    graph.delete_vertex(del);
    for (&v, incs) in vertices.iter().zip(&incidences).filter(|&(&u, _)| u != del) {
        let mut expected = incs
            .iter()
            .filter_map(|x| (x.vertex != del).then_some(x.edge))
            .collect();
        assert_incident_edges_after_delete(&graph, v, &mut expected);
    }
}

pub fn incidences_after_delete_vertex<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (mut graph, vertices, _, incidences) = G::standard();
    let del = vertices[2];
    graph.delete_vertex(del);
    for (&v, incs) in vertices.iter().zip(&incidences).filter(|&(&u, _)| u != del) {
        let remaining = incs.iter().filter(|x| x.vertex != del).cloned().collect();
        assert_vertex_incidences(&graph, v, remaining);
    }
}

pub fn incidences_after_delete_edge<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (mut graph, vertices, edges, incidences) = G::standard();
    let del = edges[2].0;
    graph.delete_edge(del);
    assert_eq!(vertices.len(), incidences.len());
    for (&v, incs) in vertices.iter().zip(&incidences) {
        let remaining = incs.iter().filter(|x| x.edge != del).cloned().collect();
        assert_vertex_incidences(&graph, v, remaining);
    }
}

pub fn incidence_cursor_after_delete_vertex<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (mut graph, vertices, _, incidences) = G::standard();
    let del = vertices[2];
    graph.delete_vertex(del);
    for (&v, incs) in vertices.iter().zip(&incidences).filter(|&(&u, _)| u != del) {
        let remaining = incs.iter().filter(|x| x.vertex != del).cloned().collect();
        assert_vertex_incidence_cursor(&graph, v, remaining);
    }
}

pub fn incidence_cursor_after_delete_edge<G: GraphTopologyDeletion + GraphTopologyAddition>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (mut graph, vertices, edges, incidences) = G::standard();
    let del = edges[2].0;
    graph.delete_edge(del);
    assert_eq!(vertices.len(), incidences.len());
    for (&v, incs) in vertices.iter().zip(&incidences) {
        let remaining = incs.iter().filter(|x| x.edge != del).cloned().collect();
        assert_vertex_incidence_cursor(&graph, v, remaining);
    }
}

fn assert_vertex_incidences<G: GraphTopology>(
    graph: &G,
    v: G::Vertex,
    mut expected: Vec<Incidence<G::Vertex, G::Edge>>,
) where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    assert_eq!(
        graph.incidences(v).count(),
        expected.len(),
        "unexpected incidence count for vertex {v:?} after delete"
    );
    for incidence in graph.incidences(v) {
        let pos = expected
            .iter()
            .position(|&x| x == incidence)
            .unwrap_or_else(|| {
                panic!(
                    "unexpected incidence {incidence:?} of vertex {v:?} from iterator after delete"
                )
            });
        expected.swap_remove(pos);
    }
    assert!(
        expected.is_empty(),
        "expected incidences {expected:?} of vertex {v:?} not matched by iterator after delete"
    );
}

fn assert_vertex_incidence_cursor<G: GraphTopology>(
    graph: &G,
    v: G::Vertex,
    mut expected: Vec<Incidence<G::Vertex, G::Edge>>,
) where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let mut cursor = graph.incidence_cursor(v);
    while let Some(incidence) = cursor.next(graph) {
        let pos = expected
            .iter()
            .position(|&x| x == incidence)
            .unwrap_or_else(|| {
                panic!(
                    "unexpected incidence {incidence:?} of vertex {v:?} from cursor after delete"
                )
            });
        expected.swap_remove(pos);
    }
    assert!(
        expected.is_empty(),
        "expected incidences {expected:?} of vertex {v:?} not matched by cursor after delete"
    );
}

fn assert_incident_edges_after_delete<G: GraphTopology>(
    graph: &G,
    v: G::Vertex,
    expected: &mut Vec<G::Edge>,
) where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    assert_eq!(
        graph.incident_edges(v).count(),
        expected.len(),
        "unexpected incident edge count for vertex {v:?} after delete"
    );
    for e in graph.incident_edges(v) {
        let pos = expected.iter().position(|&f| f == e).unwrap_or_else(|| {
            panic!("unexpected incident edge {e:?} of vertex {v:?} after delete")
        });
        expected.swap_remove(pos);
    }
    assert!(
        expected.is_empty(),
        "expected incident edges {expected:?} of vertex {v:?} not matched after delete"
    );
}