//! TRACES: FR-DEV-8
//! The spot model: identity, bounds, and which repairs may share a pass.
//!
//! Everything here is arithmetic and bookkeeping, which is exactly why it is
//! tested without a device: the three ways this model can be wrong — an id that
//! is not stable, a bound that drops work silently, a grouping that lets a
//! source read a destination — all produce a *picture* that is subtly wrong and
//! no error anywhere.

use dr_pipeline::spot::{
    Spot, SpotMode, SpotSet, DEFAULT_RADIUS, MAX_SOURCE_DISTANCE, MAX_SPOTS, MIN_RADIUS,
};
use dr_pipeline::EditGraph;

/// A 3:2 frame, which is the shape that catches a unit confusion. On a square
/// one every wrong answer happens to be right.
const ASPECT: f32 = 1.5;

fn spot_at(centre: (f32, f32), offset: (f32, f32)) -> Spot {
    Spot::new(centre, offset, DEFAULT_RADIUS)
}

/// Two devices that remove the same piece of dust must agree on its id, or the
/// sidecar merge treats one repair as two and both survive — a spot drawn
/// twice, which is visible.
#[test]
fn the_same_placement_mints_the_same_id() {
    let a = spot_at((0.25, 0.75), (0.05, 0.0));
    let b = spot_at((0.25, 0.75), (-0.02, 0.03));
    assert_eq!(a.id, b.id, "the id is the position, not the whole spot");

    let elsewhere = spot_at((0.26, 0.75), (0.05, 0.0));
    assert_ne!(a.id, elsewhere.id);
}

/// And the id must not move when the repair does: dragging a spot is an edit to
/// a spot, not the deletion of one and the creation of another. If the id
/// followed the centre, a drag on one device and a radius change on the other
/// would merge as two unrelated spots.
#[test]
fn dragging_a_spot_keeps_its_id() {
    let mut spot = spot_at((0.25, 0.75), (0.05, 0.0));
    let id = spot.id.clone();
    spot.set_centre((0.9, 0.1));
    spot.set_offset((0.1, 0.1));
    spot.set_radius(0.2);
    assert_eq!(spot.id, id);
}

/// Two spots placed on the same point are still two repairs, and a set that
/// held them both under one id would lose one of them at the next save.
#[test]
fn a_second_spot_on_the_same_point_gets_its_own_id() {
    let mut set = SpotSet::new();
    let first = set.place(spot_at((0.5, 0.5), (0.05, 0.0))).unwrap();
    let second = set.place(spot_at((0.5, 0.5), (0.0, 0.05))).unwrap();

    assert_ne!(first, second);
    assert_eq!(set.len(), 2);
    assert!(set.get(&first).is_some() && set.get(&second).is_some());
}

/// The bound refuses rather than dropping. A set that quietly discarded the
/// oldest repair would remove work already on screen, with nothing said.
#[test]
fn the_limit_refuses_and_keeps_what_is_there() {
    let mut set = SpotSet::new();
    for i in 0..MAX_SPOTS {
        let y = i as f32 / MAX_SPOTS as f32;
        assert!(set.place(spot_at((0.5, y), (0.05, 0.0))).is_some());
    }
    let first = set.spots()[0].clone();

    assert!(set.place(spot_at((0.1, 0.1), (0.05, 0.0))).is_none());
    assert_eq!(set.len(), MAX_SPOTS);
    assert_eq!(
        set.spots()[0],
        first,
        "the oldest repair survives the refusal"
    );
}

/// The offset bound is what keeps the detail pass's halo finite, so it has to
/// hold along the diagonal and not merely per axis — and it must keep the
/// direction the photographer dragged in.
#[test]
fn a_source_dragged_too_far_stops_in_the_direction_it_was_going() {
    let spot = spot_at((0.5, 0.5), (3.0, 4.0));
    let distance = spot.distance();
    assert!(
        (distance - MAX_SOURCE_DISTANCE).abs() < 1e-3,
        "clamped to the bound, got {distance}"
    );
    // 3:4 in, 3:4 out.
    assert!((spot.offset.0 / spot.offset.1 - 0.75).abs() < 1e-3);
}

#[test]
fn a_radius_cannot_be_dragged_to_nothing() {
    let mut spot = spot_at((0.5, 0.5), (0.05, 0.0));
    spot.set_radius(0.0);
    assert!(spot.radius >= MIN_RADIUS);
}

/// The offset is in frame units and the source is in normalised ones, and the
/// aspect goes on exactly one of the two axes. Getting this backwards puts the
/// source somewhere the photographer did not drag it, by a third of the frame
/// on a 3:2 — visible, and easy to write.
#[test]
fn the_source_converts_frame_units_to_normalised_ones() {
    let spot = spot_at((0.5, 0.5), (0.15, 0.15));
    let (sx, sy) = spot.source(ASPECT);

    assert!((sx - (0.5 + 0.15 / ASPECT)).abs() < 1e-4);
    assert!((sy - 0.65).abs() < 1e-4);

    // The displacement is equal on both axes in frame units, so it must be
    // *unequal* in normalised ones on a frame that is not square.
    assert!((sx - 0.5) < (sy - 0.5));
}

/// A spot with no source reads the pixel it writes: the identity, at the cost
/// of a dispatch. A freshly placed spot is in that state until a source is
/// found for it, which is why the question is asked per spot.
#[test]
fn a_spot_with_no_offset_draws_nothing() {
    let mut set = SpotSet::new();
    let id = set.place(spot_at((0.5, 0.5), (0.0, 0.0))).unwrap();
    assert!(set.is_neutral());
    assert_eq!(set.rounds(ASPECT).len(), 0);

    set.get_mut(&id).unwrap().set_offset((0.08, 0.0));
    assert!(!set.is_neutral());
    assert_eq!(set.rounds(ASPECT), vec![vec![0]]);
}

#[test]
fn a_disabled_spot_draws_nothing_but_is_kept() {
    let mut set = SpotSet::new();
    let id = set.place(spot_at((0.5, 0.5), (0.08, 0.0))).unwrap();
    set.get_mut(&id).unwrap().enabled = false;

    assert!(set.is_neutral());
    assert_eq!(set.len(), 1, "disabling is not deleting");
}

/// Spots scattered over a sky with their sources beside them are the
/// overwhelming majority, and they must cost one dispatch.
#[test]
fn repairs_that_do_not_interfere_share_one_pass() {
    let mut set = SpotSet::new();
    for i in 0..8 {
        let y = 0.1 + 0.1 * i as f32;
        set.place(spot_at((0.5, y), (0.04, 0.0)));
    }
    assert_eq!(set.rounds(ASPECT), vec![(0..8).collect::<Vec<_>>()]);
}

/// The case the grouping exists for: the second spot reads from where the first
/// one is repairing. In one pass it would copy the mark the first spot is
/// removing, and the mark would reappear somewhere else in the frame.
#[test]
fn a_source_over_an_earlier_repair_opens_a_new_pass() {
    let mut set = SpotSet::new();
    // Repairs (0.30, 0.50) from (0.40, 0.50) — both in frame units on x.
    set.place(spot_at((0.2, 0.5), (0.1, 0.0)));
    // Repairs (0.60, 0.50) by reading (0.30, 0.50): exactly the first
    // destination.
    set.place(spot_at((0.4, 0.5), (-0.3, 0.0)));

    assert_eq!(set.rounds(ASPECT), vec![vec![0], vec![1]]);
}

/// Two repairs landing on top of each other is not a hazard — they write the
/// same output and the later one lands on top, which is the order they were
/// made in. Splitting a pass for it would cost a dispatch for nothing.
#[test]
fn overlapping_destinations_stay_in_one_pass() {
    let mut set = SpotSet::new();
    set.place(spot_at((0.5, 0.5), (0.2, 0.0)));
    set.place(spot_at((0.505, 0.5), (0.2, 0.05)));

    assert_eq!(set.rounds(ASPECT).len(), 1);
}

/// A spot is an edit like any other, so a graph holding one is not clean — and
/// a graph whose only spot draws nothing is.
#[test]
fn a_placed_repair_makes_the_graph_dirty() {
    let mut graph = EditGraph::default_chain();
    assert!(graph.is_neutral());

    graph.spots_mut().place(spot_at((0.5, 0.5), (0.0, 0.0)));
    assert!(graph.is_neutral(), "a spot with no source is not an edit");

    graph.spots_mut().place(spot_at((0.2, 0.2), (0.08, 0.0)));
    assert!(!graph.is_neutral());
}

/// Moving a spot must re-run the neighbourhood passes and nothing before them.
/// If it moved the colour key, dragging a spot would re-run the fused dispatch
/// and every mask on the frame with it (FR-DEV-3d).
#[test]
fn a_repair_moves_the_detail_key_alone() {
    use dr_pipeline::Affects;

    let mut graph = EditGraph::default_chain();
    let before = graph.invalidation();

    let id = graph
        .spots_mut()
        .place(spot_at((0.5, 0.5), (0.08, 0.0)))
        .unwrap();
    let after = graph.invalidation();

    assert_eq!(
        before.through(Affects::Colour),
        after.through(Affects::Colour),
        "a repair is not a colour change"
    );
    assert_ne!(
        before.through(Affects::Detail),
        after.through(Affects::Detail)
    );

    // And a change *to* a spot moves it again.
    let placed = graph.invalidation();
    graph.spots_mut().get_mut(&id).unwrap().set_radius(0.05);
    assert_ne!(
        placed.through(Affects::Detail),
        graph.invalidation().through(Affects::Detail)
    );
}

#[test]
fn modes_survive_their_own_names() {
    for mode in [SpotMode::Heal, SpotMode::Clone] {
        assert_eq!(SpotMode::from_name(mode.name()), Some(mode));
    }
    assert_eq!(SpotMode::from_name("smudge"), None);
}

// ---------------------------------------------------------------------------
// Undo (FR-DEV-5)
// ---------------------------------------------------------------------------

/// The press a photographer reaches for first: place a repair, dislike it,
/// take it back. Before the history carried the spot set this stepped some
/// unrelated slider and left the repair on the photograph, which reads as undo
/// being broken rather than absent.
#[test]
fn undo_takes_a_repair_back() {
    use dr_pipeline::history::{Edit, History};

    let mut graph = EditGraph::default_chain();
    let mut history = History::new(&graph);

    graph.spots_mut().place(spot_at((0.5, 0.5), (0.08, 0.0)));
    assert!(history.record(
        &graph,
        Edit::Action(dr_pipeline::LocalizedKey("history.spot"))
    ));
    assert_eq!(graph.spots().len(), 1);

    assert!(history.undo(&mut graph).moved());
    assert_eq!(graph.spots().len(), 0, "the repair is still on the frame");

    assert!(history.redo(&mut graph).moved());
    assert_eq!(graph.spots().len(), 1, "and redo could not put it back");
}

/// Moving a repair is undoable too, and separately from placing it: the two
/// are different decisions and a photographer who nudges a source expects one
/// press to return it, not to lose the spot entirely.
#[test]
fn undo_steps_back_through_a_moved_source() {
    use dr_pipeline::history::{Edit, History};

    let mut graph = EditGraph::default_chain();
    let id = graph
        .spots_mut()
        .place(spot_at((0.5, 0.5), (0.08, 0.0)))
        .unwrap();
    let mut history = History::new(&graph);

    graph
        .spots_mut()
        .get_mut(&id)
        .unwrap()
        .set_offset((0.2, 0.1));
    history.record(
        &graph,
        Edit::Action(dr_pipeline::LocalizedKey("history.spot")),
    );

    assert!(history.undo(&mut graph).moved());
    assert_eq!(
        graph.spots().get(&id).map(|s| s.offset),
        Some((0.08, 0.0)),
        "the source did not go back where it was"
    );
    assert_eq!(graph.spots().len(), 1, "and the repair itself survived");
}