## Sprint 16 #543: GameState.current_zone_id population tests.
## Verifies that apply_snapshot() correctly extracts zone_id from the player's
## current tile after the O(N) → O(1) refactor. Behavior must be identical
## before and after the change (net-zero behavioral change per ticket spec).
## Spec refs: D-073, #543, #529.
class_name TestSnapshotZoneId
extends GdUnitTestSuite


func before_test() -> void:
	GameState.current_zone_id = ""
	GameState.player_position = Vector2.ZERO
	GameState.visible_tiles = []
	GameState.visible_positions = {}
	GameState.visibility_sectors = {}


# -- Happy path (S16-Z01) ------------------------------------------------------

func test_zone_id_populated_when_player_on_zone_tile() -> void:
	# S16-Z01: Player at (5,5), visible_tiles has zone_id "zone_alpha" at (5,5).
	# D-073: current_zone_id must be set to the server-authoritative zone_id.
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 5.0, "y": 5.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": [
			{"x": 3, "y": 3, "z": 0, "type": "floor", "zone_id": "zone_foyer"},
			{"x": 5, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_alpha"},
			{"x": 7, "y": 7, "z": 0, "type": "floor", "zone_id": "zone_beta"},
		],
	})
	assert_that(GameState.current_zone_id).override_failure_message(
		"current_zone_id must match zone_id at player tile (5,5)"
	).is_equal("zone_alpha")
	assert_that(GameState.current_zone_id.is_empty()).override_failure_message(
		"current_zone_id must be non-empty when player is on a zone-tagged tile"
	).is_false()


# -- Missing zone_id field (S16-Z02) -------------------------------------------

func test_zone_id_empty_when_tile_lacks_zone_field() -> void:
	# S16-Z02: Player's tile exists but has no zone_id key → empty string.
	# Server may send tiles without zone_id when tile is unzoned.
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 5.0, "y": 5.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": [
			{"x": 5, "y": 5, "z": 0, "type": "floor"},
		],
	})
	assert_that(GameState.current_zone_id).override_failure_message(
		"Tile without zone_id field → current_zone_id must default to empty string"
	).is_equal("")


# -- Player off-tile (S16-Z03) -------------------------------------------------

func test_zone_id_empty_when_player_not_on_any_tile() -> void:
	# S16-Z03: Player at (99,99) but no tile at that position → empty string.
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 99.0, "y": 99.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": [
			{"x": 5, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_alpha"},
		],
	})
	assert_that(GameState.current_zone_id).override_failure_message(
		"Player at (99,99) with no matching tile → current_zone_id must be empty"
	).is_equal("")


# -- Empty tiles (S16-Z04) -----------------------------------------------------

func test_zone_id_empty_on_empty_visible_tiles() -> void:
	# S16-Z04: No visible tiles at all → empty string, no crash.
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 5.0, "y": 5.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": [],
	})
	assert_that(GameState.current_zone_id).override_failure_message(
		"Empty visible_tiles → current_zone_id must be empty string (no crash)"
	).is_equal("")


# -- Correct tile selected among many (S16-Z05) --------------------------------

func test_zone_id_selects_correct_tile_among_many() -> void:
	# S16-Z05: 10x10 tile grid, player at (6,4). Only zone_6_4 must be selected.
	# Tests that the lookup doesn't accidentally match a neighboring tile.
	var tiles: Array = []
	for tx in range(10):
		for ty in range(10):
			tiles.append({"x": tx, "y": ty, "z": 0, "type": "floor",
				"zone_id": "zone_%d_%d" % [tx, ty]})
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 6.0, "y": 4.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": tiles,
	})
	assert_that(GameState.current_zone_id).override_failure_message(
		"Player at (6,4) must get zone_6_4, not a neighboring tile"
	).is_equal("zone_6_4")


# -- Zone transition (S16-Z06) -------------------------------------------------

func test_zone_id_updates_on_zone_transition() -> void:
	# S16-Z06: Player moves from zone_alpha (5,5) to zone_beta (6,5).
	# current_zone_id must update on each snapshot.
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 5.0, "y": 5.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": [
			{"x": 5, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_alpha"},
			{"x": 6, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_beta"},
		],
	})
	assert_that(GameState.current_zone_id).is_equal("zone_alpha")

	GameState.apply_snapshot({
		"tick": 2,
		"entities": [
			{"entity_id": 1, "x": 6.0, "y": 5.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": [
			{"x": 5, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_alpha"},
			{"x": 6, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_beta"},
		],
	})
	assert_that(GameState.current_zone_id).override_failure_message(
		"After moving to (6,5), current_zone_id must update to zone_beta"
	).is_equal("zone_beta")


# -- Regression: visible_positions unaffected (S16-Z07) -----------------------

func test_visible_positions_unaffected_by_zone_id_refactor() -> void:
	# S16-Z07: The O(1) refactor must not break visible_positions population.
	# Both zone_id and visible_positions derive from the same visible_tiles loop —
	# verify both are correctly populated after a single apply_snapshot().
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 5.0, "y": 5.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": [
			{"x": 5, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_alpha", "visibility": "Forward"},
			{"x": 6, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_beta", "visibility": "Peripheral"},
		],
	})
	assert_that(GameState.visible_positions.has(Vector2i(5, 5))).override_failure_message(
		"visible_positions must still contain (5,5) after zone_id refactor"
	).is_true()
	assert_that(GameState.visible_positions.has(Vector2i(6, 5))).is_true()
	assert_that(GameState.current_zone_id).override_failure_message(
		"current_zone_id must be zone_alpha after same apply_snapshot call"
	).is_equal("zone_alpha")


# -- Fractional player position (S16-Z08) --------------------------------------

func test_zone_id_uses_int_truncation_of_player_position() -> void:
	# S16-Z08: Player at (5.7, 5.9) → int(5.7)=5, int(5.9)=5 → matches tile (5,5).
	# Server sends player coords as floats; zone lookup must truncate to tile index.
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 5.7, "y": 5.9, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"visible_tiles": [
			{"x": 5, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_alpha"},
		],
	})
	assert_that(GameState.current_zone_id).override_failure_message(
		"Player at (5.7,5.9) must match tile (5,5) — int() truncation applies"
	).is_equal("zone_alpha")


# -- Test-mode tiles key (S16-Z09) --------------------------------------------

func test_zone_id_works_with_test_mode_tiles_key() -> void:
	# S16-Z09: Test mode sends "tiles" key, not "visible_tiles".
	# The O(1) refactor uses member visible_tiles (covers both paths).
	# Regression guard: if _tile_by_coord is moved into the snapshot.visible_tiles
	# block only, this test fails — catching the exact regression Tyre flagged.
	GameState.apply_snapshot({
		"tick": 1,
		"entities": [
			{"entity_id": 1, "x": 5.0, "y": 5.0, "z": 0, "kind": {"variant": "Player", "data": null}},
		],
		"tiles": [
			{"x": 5, "y": 5, "z": 0, "type": "floor", "zone_id": "zone_alpha"},
		],
	})
	assert_that(GameState.current_zone_id).override_failure_message(
		"Test-mode 'tiles' key must populate zone_id via member visible_tiles"
	).is_equal("zone_alpha")