## SnapshotEventRouter unit tests (#559).
## Verifies callable-based dispatch: keyed handlers receive correct field values,
## always handlers run on every dispatch, absent fields don't trigger handlers.
##
## D-030: fixture-based, server-free, no subprocess required.
class_name TestSnapshotEventRouter
extends GdUnitTestSuite


# -- Keyed handlers -----------------------------------------------------------

func test_keyed_handler_called_when_field_present() -> void:
	var router := SnapshotEventRouter.new()
	var received: Array = []
	router.register("current_monologue", func(): received.append("monologue"))
	router.dispatch({"current_monologue": {"text": "Test."}})
	assert_that(received.size()).is_equal(1)
	assert_that(received[0]).is_equal("monologue")


func test_keyed_handler_not_called_when_field_absent() -> void:
	var router := SnapshotEventRouter.new()
	var received: Array = []
	router.register("current_monologue", func(): received.append("monologue"))
	router.dispatch({"tick": 1})
	assert_that(received.size()).is_equal(0)


func test_multiple_keyed_handlers_same_field() -> void:
	## Multiple handlers on the same key run in registration order.
	var router := SnapshotEventRouter.new()
	var order: Array = []
	router.register("save_result", func(): order.append("first"))
	router.register("save_result", func(): order.append("second"))
	router.dispatch({"save_result": {"success": true}})
	assert_that(order).is_equal(["first", "second"])


func test_keyed_handlers_multiple_fields() -> void:
	## Each keyed handler fires only for its registered field.
	var router := SnapshotEventRouter.new()
	var received: Array = []
	router.register("current_monologue", func(): received.append("mono"))
	router.register("current_dialogue", func(): received.append("dlg"))
	router.dispatch({"current_monologue": {"text": "Hi."}})
	assert_that(received).is_equal(["mono"])
	received.clear()
	router.dispatch({"current_dialogue": {"speech": "Hello."}, "current_monologue": {"text": "Hmm."}})
	assert_bool(received.has("mono")).is_true()
	assert_bool(received.has("dlg")).is_true()


# -- Always handlers ----------------------------------------------------------

func test_always_handler_called_on_every_dispatch() -> void:
	var router := SnapshotEventRouter.new()
	var count: Array[int] = [0]
	router.register_always(func(): count[0] += 1)
	router.dispatch({"tick": 1})
	router.dispatch({"tick": 2})
	router.dispatch({})
	assert_int(count[0]).is_equal(3)


func test_always_handler_runs_before_keyed() -> void:
	## Always handlers run before keyed handlers (dispatch order guarantee).
	var router := SnapshotEventRouter.new()
	var order: Array = []
	router.register("current_monologue", func(): order.append("keyed"))
	router.register_always(func(): order.append("always"))
	router.dispatch({"current_monologue": {"text": "Hi."}})
	assert_that(order[0]).is_equal("always")
	assert_that(order[1]).is_equal("keyed")


# -- Empty dispatch ------------------------------------------------------------

func test_empty_snapshot_no_crash() -> void:
	var router := SnapshotEventRouter.new()
	router.register("foo", func(): pass)
	router.register_always(func(): pass)
	# Must not crash
	router.dispatch({})


func test_no_handlers_no_crash() -> void:
	var router := SnapshotEventRouter.new()
	# Must not crash
	router.dispatch({"tick": 1, "entities": []})