settled-reach/client/tests/test_step_canvas_protocol.gd

## T-1182 tests: StepCanvasRequest/StepCanvasResponse wire codec
## (step_canvas_protocol.gd, delegated via protocol.gd) — the D-255(c)
## tagged-envelope carrier. Mirrors test_atlas_data_delivery.gd's own
## encode/decode round-trip + decode_inbound classification conventions.
class_name TestStepCanvasProtocol
extends GdUnitTestSuite


# =============================================================================
# Encode
# =============================================================================


func test_encode_step_canvas_request_carries_discriminator_and_fields() -> void:
	var bytes := Protocol.encode_step_canvas_request(
		"GJ380c", "District", Vector2i(10, 20), Vector2i(64, 64), 512
	)
	assert_int(bytes.size()).is_greater(0)
	var decoded = Messagepack.decode(bytes)
	assert_that(decoded.status == null).is_true()
	var raw: Dictionary = decoded.value
	assert_bool(raw.get("step_canvas")).is_true()
	assert_str(raw.get("body_id")).is_equal("GJ380c")
	assert_str(raw.get("rung")).is_equal("District")
	assert_that(raw.get("center")).is_equal([10, 20])
	assert_that(raw.get("extent")).is_equal([64, 64])
	assert_int(raw.get("min_wl_m")).is_equal(512)


## The rung is sent as a bare string (rmp_serde's unit-variant convention),
## never a raw integer — a Global request must carry the literal tag
## "Global", matching step_canvas.rs's own StepCanvasRung enum encoding.
func test_encode_step_canvas_request_global_rung_is_bare_string() -> void:
	var bytes := Protocol.encode_step_canvas_request(
		"GJ380c", "Global", Vector2i.ZERO, Vector2i.ZERO, 0
	)
	var decoded = Messagepack.decode(bytes)
	assert_str(decoded.value.get("rung")).is_equal("Global")


# =============================================================================
# Decode — status variants
# =============================================================================


func test_step_canvas_response_from_raw_decodes_ready_status() -> void:
	var raw := {
		"body_id": "GJ380c",
		"rung": "District",
		"center": [10, 20],
		"extent": [64, 64],
		"min_wl_m": 0,
		"status": "Ready",
		"canvas": null,
	}
	var decoded = Protocol.step_canvas_response_from_raw(raw)
	assert_str(decoded["status"]).is_equal("Ready")
	assert_str(decoded["error"]).is_equal("")
	assert_str(decoded["rung"]).is_equal("District")
	assert_that(decoded["center"]).is_equal(Vector2i(10, 20))
	assert_that(decoded["extent"]).is_equal(Vector2i(64, 64))


func test_step_canvas_response_from_raw_decodes_pending_status() -> void:
	var raw := {"body_id": "GJ380c", "rung": "Chunk", "status": "Pending"}
	var decoded = Protocol.step_canvas_response_from_raw(raw)
	assert_str(decoded["status"]).is_equal("Pending")
	assert_that(decoded["canvas"]).is_null()


func test_step_canvas_response_from_raw_decodes_error_status() -> void:
	var raw := {
		"body_id": "GJ380c", "rung": "Region", "status": {"Error": "no heightmap"}
	}
	var decoded = Protocol.step_canvas_response_from_raw(raw)
	assert_str(decoded["status"]).is_equal("Error")
	assert_str(decoded["error"]).is_equal("no heightmap")


## Not a step-canvas response (no "rung" key) -> null, so decode_inbound's
## dispatch doesn't misroute a plain AtlasLayerResponse here.
func test_step_canvas_response_from_raw_returns_null_without_rung_key() -> void:
	var raw := {"body_id": "GJ380c", "status": "Ready"}
	assert_that(Protocol.step_canvas_response_from_raw(raw)).is_null()


# =============================================================================
# decode_inbound classification — the "rung" discriminator must win BEFORE
# the generic "status"-only AtlasLayerResponse fallback (a step-canvas
# response also carries "status").
# =============================================================================


func test_decode_inbound_classifies_step_canvas() -> void:
	var raw := {"body_id": "GJ380c", "rung": "District", "status": "Pending"}
	var encoded = Messagepack.encode(raw)
	var inbound: Dictionary = Protocol.decode_inbound(encoded.value)
	assert_str(inbound["kind"]).is_equal("step_canvas")


func test_decode_inbound_still_classifies_plain_atlas_response() -> void:
	var raw := {"body_id": "GJ380c", "status": "Ready"}
	var encoded = Messagepack.encode(raw)
	var inbound: Dictionary = Protocol.decode_inbound(encoded.value)
	assert_str(inbound["kind"]).is_equal("atlas")


# =============================================================================
# EncodedStepCanvas — the PNG-per-field array-of-int wire shape
# (step_canvas.rs's png_bytes: Vec<u8> with NO serde_bytes anywhere in this
# codebase serializes via serialize_seq, a msgpack ARRAY of ints, never a
# `bin` blob — decode_png_field()/​_decode_encoded_canvas() must repack that
# Array into a PackedByteArray, not expect messagepack.gd's bin_8/16/32 path).
# =============================================================================


func test_decode_png_field_repacks_array_of_ints_to_packed_byte_array() -> void:
	# A 1x1 all-black L8 PNG's real byte stream, as it would arrive already
	# decoded off the wire (a plain Array of ints, one per byte) — using real
	# PNG magic bytes so a downstream Image.load_png_from_buffer() call
	# would also succeed, not just this repack step in isolation.
	var png_bytes := PackedByteArray([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a])
	var as_array: Array = []
	for b in png_bytes:
		as_array.append(b)
	var field_raw := {"png_bytes": as_array}
	var result: PackedByteArray = Protocol.step_canvas_response_from_raw(
		{
			"body_id": "GJ380c",
			"rung": "Chunk",
			"status": "Ready",
			"canvas":
			{
				"width": 1,
				"height": 1,
				"morphology": field_raw,
				"elev_q": {},
				"temp_dc": {"values": []},
				"moisture_q": {},
				"vegetation": {},
				"settlement_id": {"values": []},
				"glaciation": {},
				"flooded_q": {},
				"courses": [],
				"cliffs": [],
			},
		}
	)["canvas"]["morphology"]
	assert_that(result).is_equal(png_bytes)


func test_decode_encoded_canvas_passes_through_temp_dc_and_settlement_id_as_arrays() -> void:
	var raw := {
		"body_id": "GJ380c",
		"rung": "Chunk",
		"status": "Ready",
		"canvas":
		{
			"width": 2,
			"height": 1,
			"morphology": {},
			"elev_q": {},
			"temp_dc": {"values": [120, -32768]},
			"moisture_q": {},
			"vegetation": {},
			"settlement_id": {"values": [0, 7]},
			"glaciation": {},
			"flooded_q": {},
			"courses": [],
			"cliffs": [],
		},
	}
	var decoded = Protocol.step_canvas_response_from_raw(raw)
	var canvas: Dictionary = decoded["canvas"]
	assert_that(canvas["temp_dc"]).is_equal([120, -32768])
	assert_that(canvas["settlement_id"]).is_equal([0, 7])


func test_decode_encoded_canvas_passes_through_courses_and_cliffs_unshaped() -> void:
	var courses := [{"edge_id": 1, "class": 2, "points": [[0, 0], [100, 100]], "terminus": "Mouth"}]
	var cliffs := [{"point": [5, 5], "channel_depth_dm": 10, "cliff_edge": true}]
	var raw := {
		"body_id": "GJ380c",
		"rung": "Chunk",
		"status": "Ready",
		"canvas":
		{
			"width": 1,
			"height": 1,
			"morphology": {},
			"elev_q": {},
			"temp_dc": {"values": []},
			"moisture_q": {},
			"vegetation": {},
			"settlement_id": {"values": []},
			"glaciation": {},
			"flooded_q": {},
			"courses": courses,
			"cliffs": cliffs,
		},
	}
	var decoded = Protocol.step_canvas_response_from_raw(raw)
	var canvas: Dictionary = decoded["canvas"]
	assert_that(canvas["courses"]).is_equal(courses)
	assert_that(canvas["cliffs"]).is_equal(cliffs)


func test_decode_png_field_malformed_input_returns_empty_packed_byte_array() -> void:
	assert_that(Protocol._scp().decode_png_field(null)).is_equal(PackedByteArray())
	assert_that(Protocol._scp().decode_png_field({"png_bytes": "not an array"})).is_equal(
		PackedByteArray()
	)