CosmicClash/Game/tests/cases/test_replay_log.gd

extends "res://tests/test_case.gd"

# Task 5.10. The log's whole value is that a recorded match can be replayed
# faithfully enough to reproduce a reported snap, so what matters is that the
# bytes come back BYTE-IDENTICAL and correctly framed — not merely that
# something was written.

const ReplayLogScript = preload("res://scripts/replay_log.gd")


func _temp_path(suffix: String) -> String:
	return "user://test_replay_%s_%d.ccrp" % [suffix, Time.get_ticks_usec()]


func test_records_round_trip_byte_for_byte() -> void:
	var path := _temp_path("roundtrip")
	var log_writer = ReplayLogScript.new()
	assert_eq(log_writer.open_for_write(path), OK, "opens for write")

	var input_payload := PackedByteArray([0x01, 0xFF, 0x00, 0x7F, 0x80])
	var snapshot_payload := PackedByteArray([0xDE, 0xAD, 0xBE, 0xEF])
	log_writer.record_input(120, 4242, input_payload)
	log_writer.record_snapshot(121, snapshot_payload)
	log_writer.close()

	var read := ReplayLogScript.read_all(path)
	assert_eq(read.get("version", -1), ReplayLogScript.FORMAT_VERSION, "version round-trips")
	assert_eq(read.get("tick_hz", -1), SimConstants.TICK_HZ, "tick rate is recorded so a reader need not guess")
	var records: Array = read.get("records", [])
	assert_eq(records.size(), 2, "both records read back")

	assert_eq(records[0]["kind"], ReplayLogScript.RecordKind.INPUT, "first is an input")
	assert_eq(records[0]["tick"], 120, "input tick")
	assert_eq(records[0]["peer_id"], 4242, "input peer")
	assert_eq(records[0]["payload"], input_payload, "input payload is byte-identical")

	assert_eq(records[1]["kind"], ReplayLogScript.RecordKind.SNAPSHOT, "second is a snapshot")
	assert_eq(records[1]["tick"], 121, "snapshot tick")
	assert_eq(records[1]["payload"], snapshot_payload, "snapshot payload is byte-identical")
	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))


func test_a_real_packet_survives_the_round_trip() -> void:
	# The payloads above are hand-made. Use a genuine NetCodec input packet so
	# a framing bug that only shows up at real packet sizes cannot hide.
	var path := _temp_path("realpacket")
	var action := ShipAction.new()
	action.thrust = Vector3(0.5, -0.25, 1.0)
	action.turbo = true
	var packet := NetCodec.pack_input(77, 55, 1234, [action, action, action])

	var log_writer = ReplayLogScript.new()
	log_writer.open_for_write(path)
	log_writer.record_input(500, 7, packet)
	log_writer.close()

	var records: Array = ReplayLogScript.read_all(path).get("records", [])
	assert_eq(records.size(), 1, "one record")
	assert_eq(records[0]["payload"], packet, "a real input packet round-trips unchanged")
	# And it must still decode as the packet it was.
	var decoded := NetCodec.unpack_input(records[0]["payload"])
	assert_eq(decoded["seq"], 77, "the replayed packet still decodes to its own sequence")
	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))


func test_empty_log_reads_back_as_no_records() -> void:
	var path := _temp_path("empty")
	var log_writer = ReplayLogScript.new()
	log_writer.open_for_write(path)
	log_writer.close()
	var read := ReplayLogScript.read_all(path)
	assert_eq(read.get("records", [-1]).size(), 0, "a header-only log has no records")
	assert_eq(read.get("tick_hz", -1), SimConstants.TICK_HZ, "but still reports its header")
	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))


func test_a_non_replay_file_is_rejected_rather_than_misread() -> void:
	# FileAccess zero-fills past EOF exactly as StreamPeerBuffer does, so
	# without a magic check an arbitrary file decodes as an endless run of
	# zero-length records instead of failing.
	var path := _temp_path("garbage")
	var f := FileAccess.open(path, FileAccess.WRITE)
	f.store_string("this is definitely not a replay log")
	f.close()
	assert_true(ReplayLogScript.read_all(path).is_empty(), "a foreign file is refused")
	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))


func test_a_truncated_log_yields_its_intact_records() -> void:
	# A server killed mid-write is the NORMAL way one of these ends, so a
	# partial final record must not discard the whole session.
	var path := _temp_path("truncated")
	var log_writer = ReplayLogScript.new()
	log_writer.open_for_write(path)
	log_writer.record_input(1, 1, PackedByteArray([1, 2, 3, 4]))
	log_writer.record_input(2, 1, PackedByteArray([5, 6, 7, 8]))
	log_writer.close()

	var whole := FileAccess.get_file_as_bytes(path)
	var cut := whole.slice(0, whole.size() - 3)   # lop off part of the last payload
	var f := FileAccess.open(path, FileAccess.WRITE)
	f.store_buffer(cut)
	f.close()

	var records: Array = ReplayLogScript.read_all(path).get("records", [])
	assert_eq(records.size(), 1, "the intact record survives a truncated tail")
	assert_eq(records[0]["payload"], PackedByteArray([1, 2, 3, 4]), "and is still correct")
	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))


func test_rejected_packets_are_recorded_and_distinguishable_by_reason() -> void:
	# The log exists to answer "my input did nothing", and the packets that
	# explain that are exactly the ones the server threw away. Recording them
	# is only useful if the reason survives too, so a reader can tell a
	# malformed packet from one the rate limiter dropped.
	var path := _temp_path("rejects")
	var log_writer = ReplayLogScript.new()
	log_writer.open_for_write(path)
	var malformed := PackedByteArray([0x01, 0x02])
	var flooded := PackedByteArray([0x09, 0x08, 0x07])
	var far_future := PackedByteArray([0x11, 0x22, 0x33, 0x44])
	log_writer.record_rejected_input(ReplayLogScript.RecordKind.REJECTED_MALFORMED, 10, 5, malformed)
	log_writer.record_rejected_input(ReplayLogScript.RecordKind.REJECTED_RATE_LIMIT, 11, 5, flooded)
	log_writer.record_rejected_input(ReplayLogScript.RecordKind.REJECTED_SEQ_GUARD, 12, 6, far_future)
	log_writer.record_input(13, 5, PackedByteArray([0xAA]))
	log_writer.close()

	var records: Array = ReplayLogScript.read_all(path).get("records", [])
	assert_eq(records.size(), 4, "rejects and accepted input share one ordered stream")
	assert_eq(records[0]["kind"], ReplayLogScript.RecordKind.REJECTED_MALFORMED, "malformed reason survives")
	assert_eq(records[0]["payload"], malformed, "and so do the bytes that caused it")
	assert_eq(records[1]["kind"], ReplayLogScript.RecordKind.REJECTED_RATE_LIMIT, "rate-limit reason survives")
	assert_eq(records[1]["payload"], flooded, "with its own payload")
	assert_eq(records[2]["kind"], ReplayLogScript.RecordKind.REJECTED_SEQ_GUARD, "seq-guard reason survives")
	assert_eq(records[2]["peer_id"], 6, "attributed to the peer that sent it")
	assert_eq(records[3]["kind"], ReplayLogScript.RecordKind.INPUT, "an accepted packet is still its own kind")
	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))


func test_a_failed_write_stops_the_log_instead_of_corrupting_it() -> void:
	# A half-written record desyncs the framing of everything after it, turning
	# "the disk filled up" into "the file is garbage". Forcing a real ENOSPC is
	# out of scope for a unit test, so the failure is injected directly — this
	# covers the guard and the accounting, not the detection, which is a
	# get_error() check on the real FileAccess.
	var path := _temp_path("writefail")
	var log_writer = ReplayLogScript.new()
	log_writer.open_for_write(path)
	log_writer.record_input(1, 1, PackedByteArray([1, 2, 3, 4]))
	log_writer.write_failed = true
	log_writer.record_input(2, 1, PackedByteArray([5, 6, 7, 8]))
	log_writer.record_snapshot(3, PackedByteArray([9]))
	assert_eq(log_writer.records_written, 1, "nothing is written after a failure")
	log_writer.close()

	var records: Array = ReplayLogScript.read_all(path).get("records", [])
	assert_eq(records.size(), 1, "what was written before the failure is still readable")
	assert_eq(records[0]["payload"], PackedByteArray([1, 2, 3, 4]), "and intact")
	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))


func test_an_oversized_payload_is_dropped_without_breaking_later_records() -> void:
	# `length` is a u16. Truncating an over-64KB payload to fit would leave the
	# reader parsing the payload's own tail as the next record header.
	var path := _temp_path("oversized")
	var log_writer = ReplayLogScript.new()
	log_writer.open_for_write(path)
	var oversized := PackedByteArray()
	oversized.resize(0x10000)
	log_writer.record_input(1, 1, oversized)
	assert_eq(log_writer.records_dropped, 1, "the oversized record is counted as dropped")
	log_writer.record_input(2, 1, PackedByteArray([7, 7]))
	log_writer.close()

	var records: Array = ReplayLogScript.read_all(path).get("records", [])
	assert_eq(records.size(), 1, "only the well-sized record is present")
	assert_eq(records[0]["tick"], 2, "and it is the one that came after the drop, correctly framed")
	DirAccess.remove_absolute(ProjectSettings.globalize_path(path))


func test_writing_to_an_unopened_log_is_a_no_op() -> void:
	# --replay-log is optional, so every record_* call happens behind a null
	# check in production — but the class must not corrupt or crash if that
	# check is ever missed.
	var log_writer = ReplayLogScript.new()
	assert_true(not log_writer.is_open(), "starts closed")
	log_writer.record_input(1, 1, PackedByteArray([1]))
	log_writer.record_snapshot(1, PackedByteArray([1]))
	assert_eq(log_writer.records_written, 0, "nothing was recorded")
	log_writer.close()