## T-1145 item 3 (interim presentation, pending the T-1143 design pass):
## tests for AtlasWindowOverlay's smoothed-composite texture rebuild cache —
## the "rebuild ONLY when window/overlay/tint inputs change, not per frame"
## requirement. Does not test the actual PIXEL CONTENT of the built texture
## (that content is exactly _cell_color()/_apply_glaciation(), already
## covered by test_atlas_window_colors.gd's colorizer tests — this file is
## about WHEN a rebuild happens, not what color a given cell produces).
class_name TestAtlasWindowOverlay
extends GdUnitTestSuite


static func _mock_window(n: int = 2) -> Dictionary:
	return {
		"center": [0, 0],
		"n": n,
		"morphology": PackedByteArray([8, 14, 0, 1]),
		"elev_q": PackedByteArray([40, 90, 5, 60]),
		"temp_dc": [120, 95, -32768, 60],
		"moisture_q": PackedByteArray([50, 30, 90, 20]),
		"vegetation": PackedByteArray([2, 1, 6, 3]),
		"glaciation": PackedByteArray([0, 0, 1, 2]),
	}


## Minimal viewer stub — AtlasWindowOverlay only reaches the viewer through
## get_district_window()/is_overlay_visible()/get_cell_pixel_size(), so a
## bare stub with just those three methods is a legitimate "viewer" for
## these tests, matching the duck-typed-viewer precedent this whole overlay
## cluster already relies on (atlas_overlay_bar.gd/atlas_legend_panel.gd).
class _ViewerStub:
	var window: Variant = null
	var active_overlay: String = ""

	func get_district_window() -> Variant:
		return window

	func is_overlay_visible(overlay_id: String) -> bool:
		return overlay_id == active_overlay

	func get_cell_pixel_size() -> float:
		return 16.0


func test_composite_smooth_defaults_true() -> void:
	assert_bool(AtlasWindowOverlay.COMPOSITE_SMOOTH).override_failure_message(
		"T-1145 item 3 ships the smoothed composite as the DEFAULT presentation"
	).is_true()


## A fresh overlay with no draw yet has never built a texture — the cache
## starts empty.
func test_no_texture_before_first_draw() -> void:
	var o: AtlasWindowOverlay = auto_free(AtlasWindowOverlay.new())
	assert_that(o._cached_texture).is_null()


## First _rebuild_texture_if_needed() call for a real window builds a texture.
func test_rebuild_builds_a_texture_on_first_call() -> void:
	var o: AtlasWindowOverlay = auto_free(AtlasWindowOverlay.new())
	var window: Dictionary = _mock_window()
	o._rebuild_texture_if_needed(window, 2, "")
	assert_that(o._cached_texture).override_failure_message(
		"the first rebuild call for a real window must produce a texture"
	).is_not_null()


## Calling _rebuild_texture_if_needed() AGAIN with the SAME window object
## (same reference) and the same active toggle must NOT rebuild — the exact
## same ImageTexture instance survives (reference equality, not just
## "another texture that happens to look the same").
func test_rebuild_is_a_noop_when_window_and_toggle_are_unchanged() -> void:
	var o: AtlasWindowOverlay = auto_free(AtlasWindowOverlay.new())
	var window: Dictionary = _mock_window()
	o._rebuild_texture_if_needed(window, 2, "")
	var first_texture: ImageTexture = o._cached_texture

	o._rebuild_texture_if_needed(window, 2, "")

	assert_bool(is_same(o._cached_texture, first_texture)).override_failure_message(
		"an unchanged (window, active_toggle) pair must reuse the SAME texture"
		+ " object, not rebuild an equivalent-but-new one"
	).is_true()


## A DIFFERENT window object (even with identical field VALUES) — matching
## what a fresh server response always is, a new Dictionary — MUST trigger a
## rebuild. This is the reference-vs-value distinction the class doc calls
## out explicitly (is_same(), not a deep compare).
func test_rebuild_fires_for_a_different_window_object_with_same_values() -> void:
	var o: AtlasWindowOverlay = auto_free(AtlasWindowOverlay.new())
	var window_a: Dictionary = _mock_window()
	o._rebuild_texture_if_needed(window_a, 2, "")
	var first_texture: ImageTexture = o._cached_texture

	# A structurally-IDENTICAL but DISTINCT Dictionary object — the exact
	# shape a second server response for the same window content would be.
	var window_b: Dictionary = _mock_window()
	o._rebuild_texture_if_needed(window_b, 2, "")

	assert_bool(is_same(o._cached_texture, first_texture)).override_failure_message(
		"a new window object (even with identical field values) must trigger a"
		+ " fresh rebuild — the cache key is REFERENCE identity, not value equality"
	).is_false()


## Changing the active toggle overlay (same window object) must ALSO trigger
## a rebuild — temp/moisture/veg/base each read different colors per cell.
func test_rebuild_fires_when_active_toggle_changes() -> void:
	var o: AtlasWindowOverlay = auto_free(AtlasWindowOverlay.new())
	var window: Dictionary = _mock_window()
	o._rebuild_texture_if_needed(window, 2, "")
	var first_texture: ImageTexture = o._cached_texture

	o._rebuild_texture_if_needed(window, 2, "gen_dw_temp")

	assert_bool(is_same(o._cached_texture, first_texture)).override_failure_message(
		"switching the active toggle overlay must trigger a rebuild — the SAME"
		+ " window's cells read different colors under a different toggle"
	).is_false()


## Panning/zooming (which redraw this node constantly via _apply_transform())
## never touches window/overlay state — repeated rebuild CALLS with identical
## inputs (simulating many redraws while nothing about the DATA changed) must
## all be no-ops after the first, confirming the "not per frame" requirement
## end to end, not just for a single repeat.
func test_repeated_rebuild_calls_with_unchanged_inputs_all_reuse_the_same_texture() -> void:
	var o: AtlasWindowOverlay = auto_free(AtlasWindowOverlay.new())
	var window: Dictionary = _mock_window()
	o._rebuild_texture_if_needed(window, 2, "")
	var first_texture: ImageTexture = o._cached_texture

	for _i in range(20):  # 20 simulated redraws (pan/zoom frames)
		o._rebuild_texture_if_needed(window, 2, "")

	assert_bool(is_same(o._cached_texture, first_texture)).override_failure_message(
		"20 repeated rebuild calls with unchanged inputs must never touch the cache"
	).is_true()


## The overlay's real _draw() entry point (via the smoothed path) produces a
## texture through the SAME _ViewerStub duck-typed interface every other
## caller in this cluster uses — an end-to-end sanity check that _draw()
## actually reaches _rebuild_texture_if_needed() for a real window, not just
## that the helper works in isolation.
func test_draw_builds_a_texture_through_the_viewer_stub() -> void:
	var o: AtlasWindowOverlay = auto_free(AtlasWindowOverlay.new())
	var stub := _ViewerStub.new()
	stub.window = _mock_window()
	o.viewer = stub
	o._draw()
	assert_that(o._cached_texture).is_not_null()