## T-1182 tests: StepCanvasAnnotationLayer — the unscaled screen-space
## sibling's world->screen placement math (course polylines, settlement
## markers) and course visibility/terminus handling. Draw-call correctness
## itself needs a live render pass (this cluster's existing "state-level is
## fine" allowance, per test_atlas_descend_entry.gd's own precedent) — these
## tests pin the FRAME state (_world_to_local, _cell_center_world_m) a draw
## call would read from, without requiring a SubViewport.
class_name TestStepCanvasAnnotationLayer
extends GdUnitTestSuite

const StepCanvasTransport := preload("res://ui/implant/apps/atlas/step_canvas/step_canvas_transport.gd")


func test_set_frame_stores_the_frame_and_triggers_no_crash_on_draw() -> void:
	var layer: StepCanvasAnnotationLayer = auto_free(StepCanvasAnnotationLayer.new())
	add_child(layer)
	var canvas := {
		"width": 4,
		"height": 4,
		"courses": [],
		"settlement_id": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
	}
	layer.set_frame(canvas, Vector2(1000.0, 2000.0), "District", Vector2i(4, 4))
	# No assertion beyond "did not crash" — set_frame()/queue_redraw() with a
	# well-formed empty-feature canvas is the baseline no-op path every
	# richer test below builds on.
	assert_object(layer).is_not_null()


func test_clear_frame_drops_the_held_canvas() -> void:
	var layer: StepCanvasAnnotationLayer = auto_free(StepCanvasAnnotationLayer.new())
	add_child(layer)
	layer.set_frame({"width": 1, "height": 1, "courses": []}, Vector2.ZERO, "Chunk", Vector2i(1, 1))
	layer.clear_frame()
	assert_that(layer._canvas).is_null()


## _cell_center_world_m() is the inverse of step_canvas.rs's own per-cell
## placement (center_world_m + (col - half_w) * step_m) — a settlement id
## read from cell (col, row) must map back to the world point that cell was
## actually derived at.
func test_cell_center_world_m_matches_the_servers_own_per_cell_placement() -> void:
	var layer: StepCanvasAnnotationLayer = auto_free(StepCanvasAnnotationLayer.new())
	add_child(layer)
	layer.set_frame({"width": 4, "height": 4, "courses": []}, Vector2(0.0, 0.0), "District", Vector2i(4, 4))

	# half_w = half_h = 2; spacing = 2048. Cell (0,0) -> (0-2)*2048 = -4096 on
	# both axes; cell (2,2) (the center-ish cell) -> (2-2)*2048 = 0.
	assert_that(layer._cell_center_world_m(0, 0)).is_equal(Vector2(-4096.0, -4096.0))
	assert_that(layer._cell_center_world_m(2, 2)).is_equal(Vector2.ZERO)


func test_cell_center_world_m_offsets_by_the_frames_world_center() -> void:
	var layer: StepCanvasAnnotationLayer = auto_free(StepCanvasAnnotationLayer.new())
	add_child(layer)
	layer.set_frame(
		{"width": 2, "height": 2, "courses": []}, Vector2(10_000.0, 20_000.0), "Chunk", Vector2i(2, 2)
	)
	# half_w = half_h = 1; spacing = 64. Cell (1,1) -> center + (1-1)*64 = center.
	assert_that(layer._cell_center_world_m(1, 1)).is_equal(Vector2(10_000.0, 20_000.0))


## _world_to_local() delegates to StepCanvasTransport.world_m_to_canvas_local
## with the layer's OWN held frame — this pins that the layer actually reads
## its stored _world_center/_rung/_extent_cells, not stale defaults.
func test_world_to_local_uses_the_held_frame() -> void:
	var layer: StepCanvasAnnotationLayer = auto_free(StepCanvasAnnotationLayer.new())
	add_child(layer)
	var world_center := Vector2(5_000.0, -3_000.0)
	var extent := Vector2i(32, 32)
	layer.set_frame({"width": 32, "height": 32, "courses": []}, world_center, "Quarter", extent)

	var expected: Vector2 = StepCanvasTransport.world_m_to_canvas_local(
		world_center, world_center, "Quarter", extent
	)
	assert_that(layer._world_to_local(world_center)).is_equal_approx(expected, Vector2(0.01, 0.01))