extends Node

const NetCodec = preload("res://scripts/net_codec.gd")
const ServerControlScript = preload("res://scripts/server_control.gd")
const AgonesSDKScript = preload("res://scripts/agones_sdk.gd")
const AssignmentState = preload("res://scripts/assignment_state.gd")

# Headless dedicated server entry point (task 1.6). Parses CLI args, hosts
# via NetworkManager, logs structured lines, and watches for physics-tick
# overrun (§9 gotcha 9: Engine.max_physics_steps_per_frame defaults to 8;
# a tick overrunning 16.7ms backs up the accumulator and the next frame
# runs multiple ticks, spiking CPU further — worth logging, not just
# silently absorbing).
#
# Run: godot --headless --path Game res://scenes/server_boot.tscn -- --port=7777
#
# Dedicated *exports* reach this scene without the CLI argument above, via the
# `run/main_scene.dedicated_server` feature override in project.godot — the same
# project-setting mechanism the training export uses for training.tscn. That
# override is deliberately uncommented in project.godot: Godot's ConfigFile
# writer does not round-trip comments, and a `#` block directly above a setting
# can be spliced into the setting's own line on rewrite, silently commenting it
# out and sending dedicated builds to the interactive main menu instead of here.
# `tests/cases/test_project_settings.gd` fails loudly if that ever happens.
#
# Deliberately does not spawn a match yet — that's Phase 2's networked_match
# scene. This is just the process shell: listen, log, idle cheaply.

var _last_physics_frame := 0
var config: ServerConfig = null
var _watchdog_armed := false   # skip the first _process(): engine startup scheduling can batch several physics frames before the first idle frame runs, which isn't a real overrun
var _control: ServerControl = null
var _match_loop: ServerMatchLoop = null
var _agones = null
var _drain_requested := false
var _connection_reports_inflight: Dictionary = {}
var _connection_reports_complete: Dictionary = {}


func _ready() -> void:
	Engine.max_fps = 60   # a server never renders; this just caps the idle-frame poll rate so it doesn't spin

	# Task 6.3. This process owns the whole command line, so it parses STRICTLY:
	# an unknown flag or an out-of-range value stops the server with a message
	# rather than starting one that silently ignores half of what it was told.
	config = ServerConfig.parse(OS.get_cmdline_user_args())
	if config.help_requested:
		print(ServerConfig.help_text())
		get_tree().quit(0)
		return
	if not config.is_valid():
		# Straight to stderr-ish plain print rather than through _log: the log
		# level itself may be one of the things that failed to parse, and an
		# operator running this by hand needs to see every problem at once, not
		# the first one.
		printerr("cosmic-clash-server: refusing to start")
		for problem in config.errors:
			printerr("  %s" % problem)
		printerr("try --help")
		get_tree().quit(1)
		return
	ServerLog.configure(String(config.get_value("log-level")))
	var port := int(config.get_value("port"))
	var max_clients := int(config.get_value("max-clients"))
	var allocated_mode := bool(config.get_value("allocated-mode"))
	var assigned_transport := String(config.get_value("transport"))
	# Hosted SDR is not wired into the Godot transport layer yet. Refuse the
	# allocated launch rather than silently opening an ENet endpoint that does
	# not match the signed assignment's transport contract.
	if allocated_mode and assigned_transport != NetworkManager.TRANSPORT_ENET:
		printerr("cosmic-clash-server: allocated transport '%s' is not supported by this build" % assigned_transport)
		get_tree().quit(1)
		return
	if allocated_mode:
		var roster_file := String(config.get_value("join-authorisations-file"))
		var key_file := String(config.get_value("join-authorisations-key-file"))
		var roster_json := FileAccess.get_file_as_string(roster_file)
		var signing_key := FileAccess.get_file_as_bytes(key_file)
		var roster_tokens = JSON.parse_string(roster_json)
		if not roster_tokens is Array or roster_tokens.is_empty() or signing_key.is_empty() or not MatchNet.configure_join_authorisations(roster_tokens, {
			"match_id": String(config.get_value("match-id")),
			"server_id": String(config.get_value("server-id")),
			"protocol": str(NetCodec.PROTOCOL_VERSION),
			"protocol_version": NetCodec.PROTOCOL_VERSION,
		}, signing_key) or MatchNet.assigned_player_slots().size() != roster_tokens.size():
			printerr("cosmic-clash-server: refusing to start with invalid join-authorisations-file")
			get_tree().quit(1)
			return
		_control = ServerControlScript.new()
		# An allocated process owns exactly the roster issued for this match.
		# Never let the general-purpose direct-server default (one player) start
		# an allocated match with only a partial assignment admitted.
		config.values["min-players"] = required_min_players(true, roster_tokens.size(), int(config.get_value("min-players")))
		_control.name = "ServerControl"
		_control.drain_requested.connect(_on_drain_requested)
		_control.initial_connect_ready.connect(_on_initial_connect_ready)
		get_tree().root.add_child.call_deferred(_control)
		var control_err := _control.start(int(config.get_value("readiness-port")), OS.get_environment(String(config.get_value("drain-token-env"))))
		if control_err != OK:
			printerr("cosmic-clash-server: refusing to start with invalid readiness control port")
			get_tree().quit(1)
			return
		_agones = AgonesSDKScript.new()
		_agones.name = "AgonesSDK"
		get_tree().root.add_child.call_deferred(_agones)
		if _agones.configure_from_environment():
			_agones.start_health()

	NetworkManager.client_connected.connect(_on_client_connected)
	NetworkManager.client_disconnected.connect(_on_client_disconnected)
	MatchNet.player_joined.connect(_on_player_joined)
	MatchNet.player_left.connect(_on_player_left)

	var err := NetworkManager.host(port, max_clients)
	if err != OK:
		ServerLog.error("server_boot_failed", {"port": port, "error": error_string(err)})
		get_tree().quit(1)
		return
	if _control != null:
		_control.set_process_ready(true)
	_install_match_loop()
	ServerLog.info("server_started", {
		"port": port, "max_clients": max_clients, "log_level": ServerLog.level_name(),
		"min_players": int(config.get_value("min-players")),
		"max_matches": 1 if allocated_mode else int(config.get_value("max-matches")),
		"arena_rotation": String(config.get_value("arena-rotation")),
		"allocated_mode": allocated_mode,
		"match_id": String(config.get_value("match-id")) if allocated_mode else "",
		"server_id": String(config.get_value("server-id")) if allocated_mode else "",
		"region": String(config.get_value("region")) if allocated_mode else "",
		"transport": assigned_transport if allocated_mode else NetworkManager.TRANSPORT_ENET,
	})
	_last_physics_frame = Engine.get_physics_frames()


# Task 6.5. Parented to the ROOT rather than to this node: the loop calls
# change_scene_to_file, which frees the current scene — and this boot scene IS
# the current scene, so a loop parented here would be freed by the first match
# it started. Same constraint the smoke-test hooks document.
func _install_match_loop() -> void:
	var loop := ServerMatchLoop.new()
	_match_loop = loop
	loop.name = "ServerMatchLoop"
	loop.min_players = int(config.get_value("min-players"))
	loop.start_countdown_seconds = float(config.get_value("start-countdown"))
	loop.max_matches = 1 if bool(config.get_value("allocated-mode")) else int(config.get_value("max-matches"))
	loop.rotation_mode = String(config.get_value("arena-rotation"))
	loop.allocated_mode = bool(config.get_value("allocated-mode"))
	loop.allocated_playlist = String(config.get_value("playlist"))
	loop.allocated_roster_size = MatchNet.assigned_player_slots().size() if loop.allocated_mode else 0
	loop.allocated_arena_path = String(config.get_value("arena-path"))
	# The backend's fair timeout starts only after durable assignment-ready.
	# When a control plane is present, the supervisor arms this loop through
	# the authenticated local control endpoint after that transition commits.
	loop.allocated_admission_armed = not loop.allocated_mode or OS.get_environment("COSMIC_CLASH_INITIAL_CONNECT_SIGNAL_REQUIRED") != "1"
	get_tree().root.add_child.call_deferred(loop)


func _process(_delta: float) -> void:
	NetworkManager.poll()
	if _drain_requested:
		var scene := get_tree().current_scene
		if not (is_instance_valid(scene) and scene.is_in_group("game")) and MatchNet.roster.is_empty():
			get_tree().quit(0)
	var current := Engine.get_physics_frames()
	var steps := current - _last_physics_frame
	_last_physics_frame = current
	# §9 gotcha 6: with physics_jitter_fix = 0.0, frames legitimately
	# alternate between 0 and 2 ticks even on an idle, healthy server —
	# that's expected quantisation, not backlog. A real overrun is the
	# accumulator failing to drain back down, i.e. 3+ ticks in one frame.
	if steps > 2 and _watchdog_armed:
		ServerLog.warn("physics_overrun", {"steps": steps})
	_watchdog_armed = true


func _physics_process(_delta: float) -> void:
	NetworkManager.poll()


func _on_client_connected(peer_id: int) -> void:
	ServerLog.debug("peer_connected", {"peer_id": peer_id})


func _on_client_disconnected(peer_id: int) -> void:
	ServerLog.debug("peer_disconnected", {"peer_id": peer_id})


func _on_player_joined(peer_id: int, player_name: String) -> void:
	ServerLog.info("player_joined", {"peer_id": peer_id, "name": player_name, "roster": MatchNet.roster.size()})
	if config != null and bool(config.get_value("allocated-mode")):
		_report_player_connected(MatchNet.player_identity(peer_id))


func _on_player_left(peer_id: int) -> void:
	ServerLog.info("player_left", {"peer_id": peer_id, "roster": MatchNet.roster.size()})


func _on_drain_requested() -> void:
	_drain_requested = true
	MatchNet.admissions_open = false
	MatchNet.broadcast_server_shutdown("server_draining")
	ServerLog.info("server_draining", {"reason": "control_request"})


func _on_initial_connect_ready() -> void:
	if _match_loop != null and is_instance_valid(_match_loop):
		_match_loop.arm_allocated_admission()
		ServerLog.info("initial_connect_window_started", {"match_id": String(config.get_value("match-id"))})


func _report_player_connected(player_id: String) -> void:
	var base_url := OS.get_environment("COSMIC_CLASH_CONTROL_PLANE_URL").strip_edges().trim_suffix("/")
	var workload_token := OS.get_environment("COSMIC_CLASH_WORKLOAD_TOKEN").strip_edges()
	var server_id := String(config.get_value("server-id"))
	var match_id := String(config.get_value("match-id"))
	if not valid_connection_report_configuration(base_url, workload_token, match_id, server_id, player_id) or _connection_reports_inflight.has(player_id) or _connection_reports_complete.has(player_id):
		return
	_connection_reports_inflight[player_id] = true
	var endpoint := "%s/v1/servers/%s/connect" % [base_url, server_id.uri_encode()]
	# A player can join many matches. Scope the durable key to this match so a
	# later valid report cannot conflict with an earlier match's stored digest.
	var idempotency_key := "server-connect-" + (match_id + "\n" + player_id).sha256_text()
	var payload := JSON.stringify({"player_id": player_id})
	for attempt in range(5):
		var request := HTTPRequest.new()
		request.timeout = 5.0
		add_child(request)
		var start_error := request.request(endpoint, [
			"Authorization: Bearer " + workload_token,
			"Content-Type: application/json",
			"Idempotency-Key: " + idempotency_key,
		], HTTPClient.METHOD_POST, payload)
		var response_code := 0
		if start_error == OK:
			var response: Array = await request.request_completed
			response_code = int(response[1])
		request.queue_free()
		if response_code == 204:
			_connection_reports_complete[player_id] = true
			_connection_reports_inflight.erase(player_id)
			ServerLog.debug("player_connection_recorded", {"player_id": player_id})
			return
		if response_code in [400, 401, 404, 409, 422]:
			break
		if attempt < 4 and is_inside_tree():
			await get_tree().create_timer(1.0).timeout
	_connection_reports_inflight.erase(player_id)
	ServerLog.warn("player_connection_report_failed", {"player_id": player_id})


static func valid_connection_report_configuration(base_url: String, workload_token: String, match_id: String, server_id: String, player_id: String) -> bool:
	if not (base_url.begins_with("http://") or base_url.begins_with("https://")) or base_url.contains("\n") or base_url.contains("\r") or base_url.contains("?") or base_url.contains("#"):
		return false
	if workload_token.is_empty() or workload_token.contains("\n") or workload_token.contains("\r"):
		return false
	return AssignmentState.is_valid_opaque_id(match_id) and AssignmentState.is_valid_opaque_id(server_id) and AssignmentState.is_valid_opaque_id(player_id)


static func required_min_players(allocated: bool, roster_size: int, configured: int) -> int:
	if allocated and roster_size > 0:
		return roster_size
	return configured