extends Node2D
## Composition root. Shows the start menu, then runs a session as host or as
## guest with the map view, the figures, the HUD and the files on disk.

## Seed of a new world until the slice ships its chosen seed.
const NEW_WORLD_SEED := 2026
## How far the pickaxe reaches, in tiles from the figure to the tile centre.
const REACH_TILES := 2.5
## Ticks between two automatic saves: two minutes.
const AUTOSAVE_TICKS := 2 * 60 * GwSession.TICKS_PER_SECOND
const CAMERA_ZOOM := Vector2(3.0, 3.0)
## Most ticks a guest runs in one frame. A guest that fell behind catches up
## within a few frames without freezing.
const MAX_GUEST_TICKS_PER_FRAME := 20
## Seconds between two position updates of the own figure.
const FIGURE_SECONDS := 0.1
## The text for every reason a host gives for turning a guest away.
const REFUSAL_TEXTS := {
	GwSession.REFUSED_OTHER_PROTOCOL: "REFUSED_OTHER_PROTOCOL",
	GwSession.REFUSED_OTHER_RULES: "REFUSED_OTHER_RULES",
	GwSession.REFUSED_WORLD_FULL: "REFUSED_WORLD_FULL",
	GwSession.REFUSED_TOO_MANY_PLAYERS: "REFUSED_TOO_MANY_PLAYERS",
	GwSession.REFUSED_ALREADY_PLAYING: "REFUSED_ALREADY_PLAYING",
}

## Folder for the player key, the save and the recordings. If it is empty,
## the command line decides; tests set a folder of their own.
@export var storage_dir := ""
## Network interface an open world listens on. Tests use the loopback one.
var listen_address := "*"
## The command line arguments after "--". Tools and tests may set their own
## before the scene enters the tree.
var command_line := OS.get_cmdline_user_args()

var options: LaunchOptions
var store: SaveStore
## The running session, or null in the menu. A guest's session has no world
## until the host sent it.
var session: GwSession
## The network connection of an open world or a guest, or null.
var link: SessionLink
var clock: TickClock
var menu: Menu
var map_view: MapView
var marker: TileMarker
var avatar: Avatar
var figures: Figures
var hud: Hud
## How often a guest's world diverged and was replaced by the host's.
var resyncs := 0

var _player_key: PackedByteArray
var _next_dig_tick := 0
## True while an unusable save could not be set aside. Saving is refused
## then, so that the unusable save is never overwritten.
var _save_blocked := false
var _figure_wait := 0.0
## The address a guest is joining, for messages.
var _joining := ""
## The host's accepted guests when _process last looked. A new one ends a
## pause.
var _known_guests := 0


func _ready() -> void:
	I18n.install()
	InputSetup.install()
	options = LaunchOptions.parse(command_line)
	for argument in options.ignored:
		push_warning("ignored command line argument: %s" % argument)
	if storage_dir.is_empty():
		storage_dir = options.storage_dir()
	store = SaveStore.new(storage_dir)
	_player_key = store.player_key()
	if _player_key.is_empty():
		push_warning("the player key cannot be read: %s" % error_string(store.last_read_error))
	clock = TickClock.new(GwSession.TICKS_PER_SECOND)
	map_view = MapView.new()
	add_child(map_view)
	marker = TileMarker.new()
	add_child(marker)
	figures = Figures.new()
	add_child(figures)
	avatar = Avatar.new()
	add_child(avatar)
	var camera := Camera2D.new()
	camera.zoom = CAMERA_ZOOM
	avatar.add_child(camera)
	hud = Hud.new()
	add_child(hud)
	menu = Menu.new()
	add_child(menu)
	menu.name_field.text = options.player_name if not options.player_name.is_empty() else store.player_name()
	menu.address_field.text = options.address if not options.address.is_empty() else store.last_address()
	menu.play_chosen.connect(play)
	menu.join_chosen.connect(join)
	_show_menu("")
	match options.start:
		"solo":
			play(false)
		"host":
			play(true)
		"join":
			join(options.address)


## Plays the saved world, or a new one, as its host. With `open`, guests may
## join. Returns false if it could not start; the menu then says why.
func play(open: bool) -> bool:
	if not _can_start():
		return false
	var next := GwSession.new()
	var set_aside := false
	if store.has_save():
		var save := store.read_save()
		if store.last_read_error != OK:
			_show_menu(tr("SAVE_UNREADABLE"))
			return false
		set_aside = not _load(next, save)
	if not next.is_running():
		next.start_new(NEW_WORLD_SEED)
	if open:
		var net := NetLink.new()
		if net.host(options.port, listen_address) != OK:
			_show_menu(tr("OPEN_FAILED") % options.port)
			return false
		link = SessionLink.new(next, net)
	session = next
	session.join(_player_key, _player_name())
	_run_tick()
	_show_world()
	if set_aside:
		hud.flash("LOAD_FAILED")
	return true


## Starts joining the host at `address`, "host" or "host:port". The world
## arrives later; until then the menu says that it is connecting.
func join(address: String) -> void:
	if not _can_start():
		return
	var target := NetLink.split_address(address)
	if target.is_empty():
		_show_menu(tr("ADDRESS_INVALID") % address)
		return
	var net := NetLink.new()
	if net.join(target[0], target[1]) != OK:
		_show_menu(tr("CONNECT_FAILED") % address)
		return
	session = GwSession.new()
	session.start_guest(_player_key, _player_name())
	link = SessionLink.new(session, net)
	_joining = address
	store.set_last_address(address)
	_show_menu(tr("CONNECTING") % address)


func _can_start() -> bool:
	if session != null:
		return false
	if _player_key.is_empty():
		_show_menu(tr("KEY_UNREADABLE"))
		return false
	store.set_player_name(menu.player_name())
	return true


func _player_name() -> String:
	var typed := menu.player_name()
	return typed if not typed.is_empty() else tr("DEFAULT_NAME")


## Starts `next` from `save`. If the save is unusable, it is set aside so
## that the next save does not overwrite it, and false is returned.
func _load(next: GwSession, save: PackedByteArray) -> bool:
	if next.start_loaded(save):
		_save_blocked = false
		return true
	var aside := store.set_aside_save()
	if aside.is_empty():
		_save_blocked = true
		push_warning("save not usable (%s) and could not be set aside; saving is off" % next.last_error())
	else:
		push_warning("save not usable (%s), kept as %s" % [next.last_error(), aside])
	return false


func _show_menu(status: String) -> void:
	menu.show_status(status)
	menu.show()
	hud.hide()
	for node: Node2D in [avatar, marker, figures]:
		node.hide()


## Shows the world of the session and puts the figure on the spawn.
func _show_world() -> void:
	menu.hide()
	hud.show()
	for node: Node2D in [avatar, marker, figures]:
		node.show()
	map_view.session = session
	map_view.queue_redraw()
	figures.session = session
	figures.clear()
	avatar.is_walkable = session.is_walkable
	avatar.position = GridMotion.tile_center(session.spawn_point())
	hud.show_stone(session.item_count(GwSession.ITEM_STONE))
	_update_status()
	_next_dig_tick = 0


## Says in the status line how the game is shared, and with how many.
func _update_status() -> void:
	if link == null:
		hud.show_status("")
	elif session.is_host():
		hud.show_status(tr("STATUS_HOST") % [link.link.local_port(), session.online_players().size()])
	else:
		hud.show_status(tr("STATUS_GUEST") % [_joining, session.online_players().size()])


## Ends a guest's session and goes back to the menu with `message`.
func _leave(message: String) -> void:
	if session == null:
		return
	_write_recording()
	if link != null:
		link.link.close()
	link = null
	session = null
	map_view.session = null
	map_view.queue_redraw()
	avatar.is_walkable = Callable()
	figures.clear()
	_show_menu(message)


## A broken session runs no more ticks. Instead of leaving the others
## waiting, a host closes its world to guests and a guest leaves.
func _stop_sharing() -> void:
	if not session.is_host():
		_leave(tr("SIMULATION_STOPPED"))
		return
	link.link.close()
	link = null
	figures.clear()
	_update_status()


## Ends a pause once the host accepted a guest: the guest joins in the next
## tick, and a paused world would keep it waiting. A connection that has not
## greeted yet is no guest.
func _end_pause_for_new_guests() -> void:
	var guests := session.guest_count()
	if guests > _known_guests and clock.paused:
		_set_paused(false)
	_known_guests = guests


func _process(delta: float) -> void:
	if link != null:
		for notice in link.pump(delta):
			_on_notice(notice)
	if session != null and session.is_broken() and link != null:
		_stop_sharing()
	if session == null or not session.is_running() or session.is_broken():
		return
	_end_pause_for_new_guests()
	_update_marker()
	if Input.is_action_pressed("dig") and not clock.paused:
		_try_dig()
	if session.is_host():
		for i in clock.advance(delta):
			_run_tick()
	else:
		for i in mini(session.pending_ticks(), MAX_GUEST_TICKS_PER_FRAME):
			_apply(session.step())
	if link != null:
		link.flush()
		_figure_wait -= delta
		if _figure_wait <= 0.0:
			_figure_wait = FIGURE_SECONDS
			link.send_figure(avatar.position)


func _on_notice(notice: Dictionary) -> void:
	# An earlier notice of the same batch may have ended the session.
	if session == null:
		return
	match notice["type"]:
		"world_received":
			if notice["resync"]:
				resyncs += 1
				_keep_diverged_recording()
				map_view.queue_redraw()
				hud.show_stone(session.item_count(GwSession.ITEM_STONE))
				hud.flash("RESYNCED")
			else:
				_show_world()
		"refused":
			_leave(tr(REFUSAL_TEXTS.get(notice["reason"], "PROTOCOL_ERROR")))
		"protocol_error":
			push_warning("broken message from the host: %s" % session.last_error())
			_leave(tr("PROTOCOL_ERROR"))
		"host_lost":
			_leave(tr("HOST_LEFT"))
		"failed":
			_leave(tr("CONNECT_FAILED") % _joining)
		"divergence":
			push_warning("guest %d diverged at tick %d with state %s" % [notice["peer"], notice["tick"], notice["hash"]])
		"figure":
			figures.place(notice["player"], notice["position"])


## Keeps the recording of a guest's world that diverged from the host's, so
## that the divergence can be replayed.
func _keep_diverged_recording() -> void:
	var path := store.write_recording(session.take_diverged_recording())
	push_warning("the world diverged from the host's; its recording is %s" % path)


func _unhandled_input(event: InputEvent) -> void:
	if session == null or not session.is_running():
		return
	if event.is_action_pressed("save_game"):
		if session.is_host():
			hud.flash("SAVED" if save_game() else "SAVE_FAILED")
		else:
			hud.flash("HOST_SAVES")
	elif event.is_action_pressed("load_game"):
		_reload()
	elif event.is_action_pressed("toggle_pause"):
		# Ending a pause is always allowed, starting one only alone.
		if clock.paused or (session.is_host() and session.guest_count() == 0):
			_set_paused(not clock.paused)
		else:
			hud.flash("PAUSE_ONLY_ALONE")


## Goes back to the saved world. Only when playing alone: guests would no
## longer have the host's world.
func _reload() -> void:
	if link != null:
		hud.flash("LOAD_ONLY_ALONE")
		return
	var save := store.read_save()
	if store.last_read_error != OK:
		hud.flash("LOAD_FAILED")
		return
	var next := GwSession.new()
	if not _load(next, save):
		hud.flash("LOAD_FAILED")
		return
	_write_recording()
	session = next
	session.join(_player_key, _player_name())
	_run_tick()
	_show_world()
	hud.flash("LOADED")


func _set_paused(paused: bool) -> void:
	clock.paused = paused
	avatar.set_process(not paused)
	hud.show_paused(paused)


func _notification(what: int) -> void:
	if what != NOTIFICATION_WM_CLOSE_REQUEST or session == null:
		return
	if session.is_running():
		if session.is_host() and not save_game():
			push_warning("the game could not be saved on close")
		_write_recording()
	if link != null:
		link.link.close()


func _run_tick() -> void:
	_apply(session.step())
	if session.tick() % AUTOSAVE_TICKS == 0 and not save_game():
		hud.flash("SAVE_FAILED")
		push_warning("the automatic save failed")


func _apply(events: Array[Dictionary]) -> void:
	var local := session.local_player()
	for event in events:
		match event["type"]:
			"tile_hit", "tile_changed":
				map_view.queue_redraw()
			"item_gained":
				if event["player"] == local:
					hud.show_stone(session.item_count(GwSession.ITEM_STONE))
			"inventory_full":
				if event["player"] == local:
					hud.flash("INVENTORY_FULL")
			"player_joined":
				if event["player"] != local:
					hud.flash("PLAYER_JOINED", [session.player_name(event["player"])])
				_update_status()
			"player_left":
				figures.forget(event["player"])
				hud.flash("PLAYER_LEFT", [session.player_name(event["player"])])
				_update_status()
	if session.is_broken():
		hud.flash("SIMULATION_STOPPED")
		push_error(session.last_error())


func _update_marker() -> void:
	var tile := GridMotion.tile_of(get_global_mouse_position())
	var distance := avatar.position.distance_to(GridMotion.tile_center(tile))
	marker.show_tile(tile, distance <= REACH_TILES * GridMotion.TILE_SIZE)


func _try_dig() -> void:
	if marker.in_reach:
		dig_at(marker.tile)


## Queues a pickaxe hit on `tile`, at most once per cooldown. The caller must
## check the reach: figures move outside the lockstep, so the core does not
## know where the figure is. The core checks the cooldown, the tile, its
## terrain, the tool tier and the free space in the inventory.
func dig_at(tile: Vector2i) -> void:
	if session.tick() < _next_dig_tick:
		return
	session.dig(tile.x, tile.y)
	_next_dig_tick = session.tick() + GwSession.DIG_COOLDOWN_TICKS


## Writes the running world as the save. Returns false if nothing was
## written: for a guest, whose world belongs to the host, and while an
## unusable save could not be set aside.
func save_game() -> bool:
	if _save_blocked or not session.is_host():
		return false
	return store.write_save(session.save())


func _write_recording() -> void:
	store.write_recording(session.recording_bytes())