## T-1138 (D-226 T-1124 amendment §4): tests for the client-side
## DistrictWindowLayer LRU cache — keyed on (body_id, center, n), LRU-evict
## only (D-227 determinism means no freshness check is ever needed).
class_name TestAtlasWindowCache
extends GdUnitTestSuite

const AtlasWindowCache := preload("res://ui/implant/apps/atlas/atlas_window_cache.gd")


func test_make_key_distinguishes_body_center_and_n() -> void:
	var k1 := AtlasWindowCache.make_key("GJ1c", Vector2i(10, 20), 32)
	var k2 := AtlasWindowCache.make_key("GJ1d", Vector2i(10, 20), 32)  # different body
	var k3 := AtlasWindowCache.make_key("GJ1c", Vector2i(11, 20), 32)  # different center
	var k4 := AtlasWindowCache.make_key("GJ1c", Vector2i(10, 20), 64)  # different n
	assert_str(k1).is_not_equal(k2)
	assert_str(k1).is_not_equal(k3)
	assert_str(k1).is_not_equal(k4)


func test_miss_returns_null_and_has_reports_false() -> void:
	var cache := AtlasWindowCache.new()
	assert_that(cache.get_window("GJ1c", Vector2i(0, 0), 32)).is_null()
	assert_bool(cache.has("GJ1c", Vector2i(0, 0), 32)).is_false()


func test_put_then_get_round_trips_exact_window() -> void:
	var cache := AtlasWindowCache.new()
	var window := {"center": [10, 20], "n": 32, "morphology": PackedByteArray([1, 2, 3])}
	cache.put("GJ1c", Vector2i(10, 20), 32, window)
	assert_bool(cache.has("GJ1c", Vector2i(10, 20), 32)).is_true()
	assert_that(cache.get_window("GJ1c", Vector2i(10, 20), 32)).is_equal(window)


## D-227: a window fetched once is valid FOREVER for that (body, center, n) —
## no expiry, no invalidation path. Repeated get_window() calls across a
## simulated time gap (just repeated calls here — there is no clock in this
## cache at all) must keep returning the same stored value.
func test_cached_window_never_expires() -> void:
	var cache := AtlasWindowCache.new()
	var window := {"center": [0, 0], "n": 32}
	cache.put("GJ1c", Vector2i(0, 0), 32, window)
	for _i in range(50):
		assert_that(cache.get_window("GJ1c", Vector2i(0, 0), 32)).is_equal(window)


## Different (body_id, center, n) tuples never collide — this is the whole
## point of the composite key (§4: "cacheable client-side keyed on
## (body_id, center, n)").
func test_different_bodies_same_center_do_not_collide() -> void:
	var cache := AtlasWindowCache.new()
	var window_a := {"body": "GJ1c"}
	var window_b := {"body": "GJ1d"}
	cache.put("GJ1c", Vector2i(10, 20), 32, window_a)
	cache.put("GJ1d", Vector2i(10, 20), 32, window_b)
	assert_that(cache.get_window("GJ1c", Vector2i(10, 20), 32)).is_equal(window_a)
	assert_that(cache.get_window("GJ1d", Vector2i(10, 20), 32)).is_equal(window_b)


## Overwriting the same key replaces the value (e.g. a re-fetch of an
## already-cached window from a server that somehow returns a different
## payload — should never happen under D-227, but the cache itself must not
## silently keep the stale one on an explicit put()).
func test_put_overwrites_existing_key() -> void:
	var cache := AtlasWindowCache.new()
	cache.put("GJ1c", Vector2i(0, 0), 32, {"v": 1})
	cache.put("GJ1c", Vector2i(0, 0), 32, {"v": 2})
	assert_int(cache.size()).is_equal(1)
	assert_that(cache.get_window("GJ1c", Vector2i(0, 0), 32)).is_equal({"v": 2})


# =============================================================================
# LRU eviction
# =============================================================================


func test_eviction_drops_least_recently_used_on_overflow() -> void:
	var cache := AtlasWindowCache.new(2)  # max 2 entries
	cache.put("GJ1c", Vector2i(0, 0), 32, {"id": "a"})
	cache.put("GJ1c", Vector2i(1, 0), 32, {"id": "b"})
	cache.put("GJ1c", Vector2i(2, 0), 32, {"id": "c"})  # evicts (0,0) — oldest, untouched

	assert_int(cache.size()).is_equal(2)
	assert_bool(cache.has("GJ1c", Vector2i(0, 0), 32)).override_failure_message(
		"oldest entry should have been evicted"
	).is_false()
	assert_bool(cache.has("GJ1c", Vector2i(1, 0), 32)).is_true()
	assert_bool(cache.has("GJ1c", Vector2i(2, 0), 32)).is_true()


## get_window() touches an entry (moves it to most-recently-used) — reading an
## entry must protect it from the NEXT eviction, otherwise "LRU" degrades to
## FIFO the moment anything reads from the cache (the common case: Esc-then-
## re-enter and pan-back are exactly "read a recently-cached window", §4).
func test_get_touches_entry_and_protects_it_from_eviction() -> void:
	var cache := AtlasWindowCache.new(2)
	cache.put("GJ1c", Vector2i(0, 0), 32, {"id": "a"})
	cache.put("GJ1c", Vector2i(1, 0), 32, {"id": "b"})
	cache.get_window("GJ1c", Vector2i(0, 0), 32)  # touch (0,0) — now most-recently-used
	cache.put("GJ1c", Vector2i(2, 0), 32, {"id": "c"})  # should evict (1,0), not (0,0)

	assert_bool(cache.has("GJ1c", Vector2i(0, 0), 32)).override_failure_message(
		"touched entry should survive eviction"
	).is_true()
	assert_bool(cache.has("GJ1c", Vector2i(1, 0), 32)).override_failure_message(
		"untouched entry should be the one evicted"
	).is_false()


func test_max_entries_clamped_to_at_least_one() -> void:
	var cache := AtlasWindowCache.new(0)
	cache.put("GJ1c", Vector2i(0, 0), 32, {"id": "a"})
	cache.put("GJ1c", Vector2i(1, 0), 32, {"id": "b"})
	assert_int(cache.size()).is_equal(1)


func test_clear_empties_the_cache() -> void:
	var cache := AtlasWindowCache.new()
	cache.put("GJ1c", Vector2i(0, 0), 32, {"id": "a"})
	cache.clear()
	assert_int(cache.size()).is_equal(0)
	assert_bool(cache.has("GJ1c", Vector2i(0, 0), 32)).is_false()