class_name FakeHttpTransport
extends HttpTransport
## Stands in for the MusicServer in tests.
##
## Register canned responses per path with [method respond_json] or
## [method respond_bytes], then install it with [method install]. Requests to paths
## without a response get a 404. Responses are delivered immediately.
##
## Paths are relative to the API, e.g. [code]/music/list[/code] for
## [code]<Settings.default_path>/api/v1/music/list[/code].
##
## Like the real server it hands out tokens on [code]POST /token[/code] and answers 401
## to requests without a valid one. Token requests are counted in
## [member token_requests], not in [member requested_paths].
##
## Set [member queue_id] to answer with an [code]X-Queue-Id[/code] header, like the
## server's music endpoints.

## Paths that need no token, like on the real server.
const OPEN_PATHS: Array[String] = ["/token", "/health"]

## Paths requested so far, relative to the API.
var requested_paths: Array[String] = []
## HTTP method of each request, in the same order as [member requested_paths].
var requested_methods: Array[int] = []
## Headers of each request, in the same order as [member requested_paths].
var requested_headers: Array[PackedStringArray] = []
## The body of each request as text, e.g. its JSON, empty for none, in the same order as
## [member requested_paths].
var requested_bodies: Array[String] = []
## The body of each request as bytes, e.g. an uploaded picture, in the same order as
## [member requested_paths].
var requested_raw_bodies: Array[PackedByteArray] = []
## Whether each request followed redirects, in the same order as
## [member requested_paths].
var requested_follow_redirects: Array[bool] = []
## How many tokens have been asked for.
var token_requests: int = 0
## The JSON body of the last token request.
var last_token_request: Dictionary = {}
## Sent in an X-Queue-Id header with every answer that is not about a token, unless empty.
var queue_id: String = ""

var _responses: Dictionary = {}
var _successes_left: Dictionary = {}
var _failures_left: Dictionary = {}
var _held_paths: Dictionary = {}
var _previous_transport: HttpTransport
var _previous_queue_ids: Dictionary[String, String]
var _valid_tokens: Array[String] = []


func _init() -> void:
	super(null)


## Replaces the MusicServerClient transport with this fake.
func install() -> FakeHttpTransport:
	_previous_transport = MusicServerClient.transport
	MusicServerClient.transport = self
	MusicServerClient.clear_token()
	_previous_queue_ids = Settings.queue_ids.duplicate()
	Settings.queue_ids.clear()
	return self


## Restores the transport that was active before [method install].
func uninstall() -> void:
	MusicServerClient.transport = _previous_transport
	MusicServerClient.clear_token()
	Settings.queue_ids = _previous_queue_ids


## Answers requests to [param path] with a redirect to [param location], like the
## server's download routes. Requests that follow redirects get an empty 200 instead, as
## if they had followed it.
func respond_redirect(path: String, location: String) -> void:
	_responses[path] = {"code": 302, "body": PackedByteArray(), "location": location}
	_successes_left.erase(path)


## Answers requests to [param path] with [param data] encoded as JSON.
func respond_json(path: String, data: Variant, response_code: int = 200) -> void:
	respond_bytes(path, JSON.stringify(data).to_utf8_buffer(), response_code)


## Answers requests to [param path] with [param body] as-is.
func respond_bytes(path: String, body: PackedByteArray, response_code: int = 200) -> void:
	_responses[path] = {"code": response_code, "body": body}
	_successes_left.erase(path)


## Answers the next [param failures] requests to [param path] with a 503, then as usual.
func fail_first(path: String, failures: int) -> void:
	_failures_left[path] = failures


## Lets [param successes] more requests to [param path] succeed, then answers 503 until
## a new response is registered for the path.
func fail_after(path: String, successes: int) -> void:
	_successes_left[path] = successes


## Holds back responses to [param path] until [method release] is called, like a slow
## server.
func hold(path: String) -> void:
	_held_paths[path] = []


## Delivers the responses held back for [param path] and stops holding it.
func release(path: String) -> void:
	var waiting: Array = _held_paths.get(path, [])
	_held_paths.erase(path)
	for pending: Callable in waiting:
		pending.call()


## Returns how many times [param path] has been requested.
func count(path: String) -> int:
	return requested_paths.count(path)


## Makes every token handed out so far invalid, like after 24 hours or a server restart.
func expire_tokens() -> void:
	_valid_tokens.clear()


func request(
		url: String,
		method: int,
		on_complete: Callable,
		headers: PackedStringArray = PackedStringArray(),
		body: PackedByteArray = PackedByteArray(),
		follow_redirects: bool = true,
) -> void:
	var path: String = url.trim_prefix(Settings.default_path + MusicServerClient.API_PATH)
	if path == "/token" && method == HTTPClient.METHOD_POST:
		token_requests += 1
		if _held_paths.has(path):
			_held_paths[path].append(
					_answer_token_request.bind(body.get_string_from_utf8(), on_complete))
			return
		_answer_token_request(body.get_string_from_utf8(), on_complete)
		return
	requested_paths.append(path)
	requested_methods.append(method)
	requested_headers.append(headers)
	requested_bodies.append(body.get_string_from_utf8())
	requested_raw_bodies.append(body)
	requested_follow_redirects.append(follow_redirects)
	if !OPEN_PATHS.has(path.get_slice("?", 0)) && !_has_valid_token(headers):
		on_complete.call(401, JSON.stringify({"error": "Unauthorized"}).to_utf8_buffer(),
				PackedStringArray())
		return
	if _held_paths.has(path):
		_held_paths[path].append(_answer.bind(path, on_complete, follow_redirects))
		return
	_answer(path, on_complete, follow_redirects)


func _answer(path: String, on_complete: Callable, follow_redirects: bool = true) -> void:
	var headers: PackedStringArray = []
	if !queue_id.is_empty() && path != "/token":
		headers.append("X-Queue-Id: " + queue_id)
	if _failures_left.get(path, 0) > 0:
		_failures_left[path] -= 1
		on_complete.call(503, PackedByteArray(), headers)
		return
	if _successes_left.has(path):
		if _successes_left[path] == 0:
			on_complete.call(503, PackedByteArray(), headers)
			return
		_successes_left[path] -= 1
	if _responses.has(path) && _responses[path].has("location"):
		if follow_redirects:
			on_complete.call(200, PackedByteArray(), headers)
		else:
			headers.append("Location: " + _responses[path].location)
			on_complete.call(302, PackedByteArray(), headers)
	elif _responses.has(path):
		on_complete.call(_responses[path].code, _responses[path].body, headers)
	else:
		on_complete.call(404, PackedByteArray(), headers)


func _answer_token_request(body: String, on_complete: Callable) -> void:
	var data: Variant = JSON.parse_string(body)
	last_token_request = data if data is Dictionary else {}
	if _responses.has("/token"):
		# A token from a registered response is valid too
		var registered: Dictionary = _responses["/token"]
		var response: Variant = JSON.parse_string(registered.body.get_string_from_utf8())
		if registered.code == 200 && response is Dictionary:
			_valid_tokens.append(str(response.get("token", "")))
		_answer("/token", on_complete)
		return
	var token: String = "fake-token-%d" % token_requests
	_valid_tokens.append(token)
	on_complete.call(200, JSON.stringify({
		"token": token, "expires_at": "2026-10-07T12:00:00Z", "client_type": "godot",
	}).to_utf8_buffer(), PackedStringArray())


func _has_valid_token(headers: PackedStringArray) -> bool:
	for header: String in headers:
		if header.begins_with("Authorization: Bearer "):
			return _valid_tokens.has(header.trim_prefix("Authorization: Bearer "))
	return false