use std::fmt::Debug;

use grapherity::algorithms;
use grapherity::testing::fixtures;
use grapherity::testing::fixtures::MakeTestGraph;

macro_rules! bfs_tests {
    ($T:ty) => {
        bfs_tests!(@wrap $T,
            bfs_single_vertex,
            bfs_disconnected,
            bfs,
            bfs_distances_single_vertex,
            bfs_distances_disconnected,
            bfs_distances,
            bfs_find_source,
            bfs_find_disconnected,
            bfs_find,
            bfs_find_where_source_matches,
            bfs_find_where_disconnected,
            bfs_find_where_no_match,
            bfs_find_where_nearest,
            bfs_find_path_source_equals_target,
            bfs_find_path_disconnected,
            bfs_find_path_adjacent,
            bfs_find_path,
            bfs_find_path_where_source_matches,
            bfs_find_path_where_disconnected,
            bfs_find_path_where_no_match,
            bfs_find_path_where,
        );
    };

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

mod frozen_graph {
    use grapherity::models::FrozenGraph;

    bfs_tests!(FrozenGraph);
}

mod append_graph {
    use grapherity::models::AppendGraph;

    bfs_tests!(AppendGraph);
}

mod graph {
    use grapherity::models::Graph;

    bfs_tests!(Graph);
}

fn bfs_single_vertex<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, v) = G::single_vertex();
    let result = algorithms::bfs(&graph, v);
    assert_eq!(
        result.distances[v],
        Some(0),
        "unexpected distance of source vertex"
    );
    assert_eq!(
        result.predecessors[v], None,
        "unexpected predecessor of source vertex"
    );
}

fn bfs_disconnected<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, vertices) = G::disconnected();
    let result = algorithms::bfs(&graph, vertices[0]);
    assert_eq!(
        result.distances[vertices[0]],
        Some(0),
        "unexpected distance of source vertex"
    );
    assert_eq!(
        result.predecessors[vertices[0]], None,
        "unexpected predecessor of source vertex"
    );
    for &v in &vertices[1..3] {
        assert_eq!(
            result.distances[v], None,
            "disconnected vertex {v:?} should have no distance"
        );
        assert_eq!(
            result.predecessors[v], None,
            "disconnected vertex {v:?} should have no predecessor"
        );
    }
}

fn bfs<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, vertices, _, _) = G::standard();
    let result = algorithms::bfs(&graph, vertices[0]);
    fixtures::assert_standard_unweighted_distances_v0(|v| result.distances[v], &vertices);
    fixtures::assert_standard_unweighted_predecessors_v0(&result.predecessors, &vertices);
}

fn bfs_distances_single_vertex<G: MakeTestGraph>() {
    let (graph, v) = G::single_vertex();
    let distances = algorithms::bfs_distances(&graph, v);
    assert_eq!(
        distances[v],
        Some(0),
        "unexpected distance of source vertex"
    );
}

fn bfs_distances_disconnected<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, vertices) = G::disconnected();
    let distances = algorithms::bfs_distances(&graph, vertices[0]);
    assert_eq!(
        distances[vertices[0]],
        Some(0),
        "unexpected distance of source vertex"
    );
    for &v in &vertices[1..3] {
        assert_eq!(
            distances[v], None,
            "disconnected vertex {v:?} should have no distance"
        );
    }
}

fn bfs_distances<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, vertices, _, _) = G::standard();
    let distances = algorithms::bfs_distances(&graph, vertices[0]);
    fixtures::assert_standard_unweighted_distances_v0(|v| distances[v], &vertices);
}

fn bfs_find_source<G: MakeTestGraph>() {
    let (graph, v) = G::single_vertex();
    assert_eq!(
        algorithms::bfs_find(&graph, v, v),
        Some(0),
        "source should be found at distance 0"
    );
}

fn bfs_find_disconnected<G: MakeTestGraph>() {
    let (graph, vertices) = G::disconnected();
    assert_eq!(
        algorithms::bfs_find(&graph, vertices[0], vertices[1]),
        None,
        "disconnected target should not be found"
    );
}

fn bfs_find<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, vertices, _, _) = G::standard();
    fixtures::assert_standard_unweighted_distances_v0(
        |v| algorithms::bfs_find(&graph, vertices[0], v),
        &vertices,
    );
}

fn bfs_find_where_source_matches<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, v) = G::single_vertex();
    assert_eq!(
        algorithms::bfs_find_where(&graph, v, |u| u == v),
        Some((v, 0)),
        "source should match with distance 0"
    );
}

fn bfs_find_where_disconnected<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, vertices) = G::disconnected();
    assert_eq!(
        algorithms::bfs_find_where(&graph, vertices[0], |v| v == vertices[1]),
        None,
        "disconnected vertex {:?} should not be found",
        vertices[1]
    );
}

fn bfs_find_where_no_match<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, vertices, _, _) = G::standard();
    assert_eq!(
        algorithms::bfs_find_where(&graph, vertices[0], |_| false),
        None,
        "no vertex should match an always-false predicate"
    );
}

fn bfs_find_where_nearest<G: MakeTestGraph>()
where
    G::Vertex: Debug,
{
    let (graph, vertices, _, _) = G::standard();
    // vertices[5], vertices[6], vertices[7], vertices[8] are all at distance 3 from vertices[0].
    // vertices[9] is at distance 4. Predicate matches vertices[7], vertices[8], vertices[9].
    // BFS must return one of the distance-3 ones, not vertices[9].
    let result = algorithms::bfs_find_where(&graph, vertices[0], |v| {
        v == vertices[7] || v == vertices[8] || v == vertices[9]
    });
    assert!(result.is_some(), "expected a match");
    let (found, distance) = result.unwrap();
    assert_eq!(
        distance, 3,
        "unexpected distance to nearest matching vertex {found:?}",
    );
    assert!(
        found == vertices[7] || found == vertices[8],
        "unexpected nearest match vertex {found:?}, should be {:?} or {:?}",
        vertices[7],
        vertices[8]
    );
}

fn bfs_find_path_source_equals_target<G: MakeTestGraph>()
where
    G::Edge: Debug,
{
    let (graph, v) = G::single_vertex();
    assert_eq!(
        algorithms::bfs_find_path(&graph, v, v),
        Some(vec![]),
        "path from source to itself should be empty"
    );
}

fn bfs_find_path_disconnected<G: MakeTestGraph>()
where
    G::Edge: Debug,
{
    let (graph, vertices) = G::disconnected();
    assert_eq!(
        algorithms::bfs_find_path(&graph, vertices[0], vertices[1]),
        None,
        "no path should exist to disconnected vertex"
    );
}

fn bfs_find_path_adjacent<G: MakeTestGraph>()
where
    G::Edge: Debug,
{
    let (graph, vertices, e) = G::single_edge();
    let path = algorithms::bfs_find_path(&graph, vertices[0], vertices[1])
        .expect("path should exist between adjacent vertices");
    assert_eq!(path, [e], "path should contain only the connecting edge");
}

fn bfs_find_path<G: MakeTestGraph>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (graph, vertices, _, _) = G::standard();
    fixtures::assert_standard_unweighted_distances_v0(
        |v| {
            let result = algorithms::bfs_find_path(&graph, vertices[0], v);
            let path = fixtures::assert_valid_path(&graph, result, vertices[0], &[v]);
            Some(u32::try_from(path.len()).unwrap())
        },
        &vertices,
    );
}

fn bfs_find_path_where_source_matches<G: MakeTestGraph>()
where
    G::Edge: Debug,
{
    let (graph, v) = G::single_vertex();
    assert_eq!(
        algorithms::bfs_find_path_where(&graph, v, |u| u == v),
        Some(vec![]),
        "path from source to itself should be empty"
    );
}

fn bfs_find_path_where_disconnected<G: MakeTestGraph>()
where
    G::Edge: Debug,
{
    let (graph, vertices) = G::disconnected();
    assert_eq!(
        algorithms::bfs_find_path_where(&graph, vertices[0], |v| v == vertices[1]),
        None,
        "no path should exist to disconnected vertex"
    );
}

fn bfs_find_path_where_no_match<G: MakeTestGraph>()
where
    G::Edge: Debug,
{
    let (graph, vertices, _, _) = G::standard();
    assert_eq!(
        algorithms::bfs_find_path_where(&graph, vertices[0], |_| false),
        None,
        "no path should exist when predicate never matches"
    );
}

fn bfs_find_path_where<G: MakeTestGraph>()
where
    G::Vertex: Debug,
    G::Edge: Debug,
{
    let (graph, vertices, _, _) = G::standard();
    // vertices[7] and vertices[8] are at distance 3 from vertices[0]; vertices[9] is at distance 4.
    // BFS must return one shortest path, so it must lead to one of the distance-3 matches.
    let result = algorithms::bfs_find_path_where(&graph, vertices[0], |v| {
        v == vertices[7] || v == vertices[8] || v == vertices[9]
    });
    let path =
        fixtures::assert_valid_path(&graph, result, vertices[0], &[vertices[7], vertices[8]]);
    assert_eq!(
        path.len(),
        3,
        "BFS should return shortest path to a matching vertex"
    );
}