extends Node2D

# Formation slots come from GameState.formation (editable at a command
# centre) rather than being fixed here, so a layout the player arranged
# survives scene swaps and fleet rebuilds. Ships are always
# spawned programmatically (spawn_ships), using however many of these
# offsets are needed. The optional vessel-type list preserves the exact
# mixed fleet through scene swaps; a fresh start still defaults each slot
# to an interceptor.
# The fleet's cruise speed. This is the speed of the FLEET as a whole: the
# anchor below advances at exactly this rate, and individual ships are
# allowed to fly faster than it (Ship.max_speed) so they can close on their
# formation slot - which is what makes a pivot while under way look sharp
# instead of sluggish.
# #88: the whole game moves 1.5x faster. This is the figure the pace is
# actually set by - vessel max_speed and acceleration were scaled with it,
# and so were the enemies, so it is a change of TEMPO rather than a
# difficulty cut.
@export var cruise_speed: float = 390.0

# Per-scene neon palette for the fleet. PlanetSurface.tscn overrides these
# with darker values, since the lunar surface is bright grey and the default
# near-white core would wash out against it. See NeonDraw.
@export var ship_glow_color: Color = Color(0.25, 0.85, 1.0)
@export var ship_core_color: Color = Color(1.0, 1.0, 1.0)

var ship_scene: PackedScene = preload("res://vessels/Ship.tscn")

var ships: Array = []
var formation_offsets: Array = []
var fleet_target: Vector2 = Vector2.ZERO
# Formation centre while under joystick steering, and the heading it is
# travelling along. Zero heading means the fleet is not being steered.
var anchor: Vector2 = Vector2.ZERO
var steer_direction: Vector2 = Vector2.ZERO


func _ready() -> void:
	# Lets anything resolve "the fleet" without a hardcoded ../Fleet sibling
	# path - enemies parented under different hosts (e.g. a planet surface's
	# SurfaceFeatures) need this to find their target.
	add_to_group("player_fleet")
	# Researching a vessel upgrade improves the ships already flying, not
	# just the next one built (#5).
	GameState.vessel_upgraded.connect(_on_vessel_upgraded)


func _on_vessel_upgraded(_id: String) -> void:
	for ship in ships:
		if is_instance_valid(ship):
			ship.apply_vessel_stats()


func spawn_ships(count: int, center: Vector2 = Vector2.ZERO,
		vessel_types: PackedStringArray = PackedStringArray()) -> void:
	for ship in ships:
		if is_instance_valid(ship):
			ship.queue_free()
	ships.clear()
	formation_offsets.clear()

	var spawn_types: PackedStringArray = PackedStringArray()
	if vessel_types.is_empty():
		for i in range(count):
			spawn_types.append(GameState.VESSEL_INTERCEPTOR)
	else:
		for vessel_type in vessel_types:
			if GameState.vessel_is_fleet_eligible(vessel_type):
				spawn_types.append(vessel_type)
	if spawn_types.is_empty():
		spawn_types.append(GameState.VESSEL_INTERCEPTOR)
	var n: int = clamp(spawn_types.size(), 1, GameState.max_fleet_size())
	for i in range(n):
		var offset: Vector2 = GameState.formation[i]
		var ship: Area2D = ship_scene.instantiate()
		ship.vessel_type = spawn_types[i]
		ship.position = center + offset
		ship.glow_color = ship_glow_color
		ship.core_color = ship_core_color
		add_child(ship)
		ships.append(ship)
		formation_offsets.append(offset)
		if ship.has_signal("destroyed"):
			ship.destroyed.connect(_on_ship_destroyed.bind(ship))

	fleet_target = center
	_sync_composition_state()


func vessel_types() -> PackedStringArray:
	var result: PackedStringArray = PackedStringArray()
	for ship in ships:
		if is_instance_valid(ship):
			result.append(String(ship.vessel_type))
	return result


func _sync_composition_state() -> void:
	# #106: the Planning Center counts vessels across the whole game, and
	# the fleet is the one place it cannot see - the ships are scene nodes
	# and GameState outlives the scene. Pushed here rather than polled,
	# alongside the cargo capacity and distorder count that already are,
	# and for the same reason: composition changes are authoritative, and
	# this is the one function every one of them goes through.
	GameState.fleet_vessel_types = vessel_types()
	GameState.sync_fleet_cargo_capacity(vessel_types())
	# Composition changes are authoritative; scene teardown is not. Keeping
	# this out of SpeedFader prevents an outgoing scene's empty fleet from
	# resetting a boost while the same vessels are being restored on a surface.
	# Each distorder vessel past the first widens the speed ceiling, so the
	# COUNT matters, not merely whether one is present.
	GameState.set_distorder_vessel_count(count_ships_with_capability("distorder"))
	if not has_capability("distorder"):
		GameState.set_fleet_speed_multiplier(1.0)


func has_vessel_type(vessel_type: String) -> bool:
	for ship in ships:
		if is_instance_valid(ship) and String(ship.vessel_type) == vessel_type:
			return true
	return false


func first_vessel_of_type(vessel_type: String) -> Node2D:
	for ship in ships:
		if is_instance_valid(ship) and String(ship.vessel_type) == vessel_type:
			return ship
	return null


func has_capability(capability: String) -> bool:
	return first_ship_with_capability(capability) != null


func count_ships_with_capability(capability: String) -> int:
	var total: int = 0
	for ship in ships:
		if is_instance_valid(ship) and ship.has_capability(capability):
			total += 1
	return total


func first_ship_with_capability(capability: String) -> Node2D:
	for ship in ships:
		if is_instance_valid(ship) and ship.has_capability(capability):
			return ship
	return null


func add_ship(vessel_type: String = GameState.VESSEL_INTERCEPTOR) -> bool:
	# Adds one vessel in the next free formation slot (bought from a ship
	# crafter). Returns false when the wedge is already full.
	if not GameState.vessel_is_fleet_eligible(vessel_type) \
			or ships.size() >= GameState.max_fleet_size():
		return false
	var offset: Vector2 = GameState.formation[ships.size()]
	var ship: Area2D = ship_scene.instantiate()
	# Before add_child, so Ship._ready() builds the right vessel - the shield
	# ring is created there and only for a shield vessel.
	ship.vessel_type = vessel_type
	# From the formation origin, not the centroid: with a lopsided layout the
	# centroid is already displaced by the average offset, so adding the new
	# ship's own offset to it would drop it well outside the wedge.
	ship.position = get_formation_origin() + offset
	ship.glow_color = ship_glow_color
	ship.core_color = ship_core_color
	add_child(ship)
	ships.append(ship)
	formation_offsets.append(offset)
	if ship.has_signal("destroyed"):
		ship.destroyed.connect(_on_ship_destroyed.bind(ship))
	ship.set_move_target(fleet_target + offset)
	_sync_composition_state()
	return true


func store_ship(index: int) -> String:
	# A fleet always keeps one ship deployed. Removing the last one would trip
	# the wiped-out-fleet safety net on the next frame and immediately spawn a
	# replacement, which is the opposite of storing it at the mothership.
	if ships.size() <= 1 or index < 0 or index >= ships.size():
		return ""
	var ship: Node = ships[index]
	if not is_instance_valid(ship):
		return ""
	var vessel_type: String = String(ship.vessel_type)
	ships.remove_at(index)
	formation_offsets.remove_at(index)
	ship.queue_free()
	apply_formation()
	_sync_composition_state()
	return vessel_type


func apply_formation() -> void:
	# Re-seats the EXISTING ships into the current GameState.formation.
	# Without this, editing the layout at a command centre (or pivoting it)
	# only affected ships built later, which read as the edit doing nothing.
	for i in range(ships.size()):
		if i >= GameState.max_fleet_size():
			break
		formation_offsets[i] = GameState.formation[i]
	_assign_slot_targets()


func move_to(world_pos: Vector2) -> void:
	steer_direction = Vector2.ZERO
	fleet_target = world_pos
	anchor = world_pos
	_assign_slot_targets()


func move_in_direction(direction: Vector2) -> void:
	# Joystick steering. Sets the heading; _process advances the anchor.
	#
	# This used to park a target 2000 units ahead and let the ships chase
	# it. That made formation changes barely register while flying: with
	# the aim point that far away, a 60-unit formation offset moved a
	# ship's heading by under two degrees, so pivoting mid-flight looked
	# like it did almost nothing. Anchoring the formation and having each
	# ship hold its own slot relative to it fixes that.
	if direction == Vector2.ZERO:
		stop()
		return
	if steer_direction == Vector2.ZERO:
		anchor = get_formation_origin()
	steer_direction = direction.normalized()


func _process(delta: float) -> void:
	# #158: a building may pay a local cost out of the hold when the fleet is
	# actually standing at it, and the autoload has no other way to know
	# where that is. Written before the early return below - a parked fleet
	# is exactly the case that matters.
	GameState.fleet_position = get_centroid()
	if steer_direction == Vector2.ZERO:
		return
	# The anchor - the fleet's formation centre - travels at cruise_speed.
	# Ships may exceed it individually to reach their slots. #59: multiplied
	# at the point of use, not baked into cruise_speed itself, so the base
	# value stays stable regardless of the current boost.
	anchor += steer_direction * _effective_cruise_speed() * delta
	fleet_target = anchor
	_assign_slot_targets()


func _effective_cruise_speed() -> float:
	return cruise_speed * GameState.fleet_speed_multiplier


func _assign_slot_targets() -> void:
	var effective_cruise_speed: float = _effective_cruise_speed()
	for i in range(ships.size()):
		ships[i].set_move_target(fleet_target + formation_offsets[i])
		# Context, not a command: the ship adds this to its own velocity to
		# work out how it is really moving. See Ship.fleet_velocity.
		ships[i].fleet_velocity = steer_direction * effective_cruise_speed


func stop() -> void:
	steer_direction = Vector2.ZERO
	# Aim each ship at the point where its own braking curve brings it to
	# rest, so releasing the stick coasts to a halt instead of snapping to
	# a dead stop (which is what targeting the current position would do,
	# since that lands inside arrive_radius immediately).
	fleet_target = get_formation_origin()
	for ship in ships:
		# A ship's `velocity` is already its true motion, including the
		# fleet's travel, because Ship feeds the slot velocity forward into
		# its own steering rather than carrying it in a separate field. So
		# stopping is only a matter of telling it the slot has halted and
		# aiming it at the point its own braking curve reaches.
		#
		# This used to do `ship.velocity += ship.fleet_velocity` here, to
		# compensate for `velocity` reading zero while the ship was in fact
		# cruising (Ship snapped to its slot every tick and zeroed it). That
		# compensation was an unbounded ACCUMULATOR: every release added a
		# whole cruise velocity, the next steer refilled fleet_velocity, and
		# tapping a direction repeatedly stacked them up faster than
		# `acceleration` could bleed them off - so a vessel could be flung
		# along at many times its own top speed, and ships fell out of sync
		# because each bled off at a rate set by its own distance to its
		# slot. Ship now bounds its total speed every tick as well, so
		# neither half of that can come back.
		var motion: Vector2 = ship.velocity
		# The fleet is not cruising any more, so the slot is standing still.
		ship.fleet_velocity = Vector2.ZERO
		var speed: float = motion.length()
		if speed <= 0.001:
			ship.set_move_target(ship.position)
			continue
		var braking_distance: float = (speed * speed) / (2.0 * ship.acceleration)
		ship.set_move_target(ship.position + motion.normalized() * braking_distance)


func get_move_targets() -> Array:
	var result: Array = []
	for ship in ships:
		result.append(ship.move_target)
	return result


func restore(previous_fleet_target: Vector2, previous_move_targets: Array) -> void:
	fleet_target = previous_fleet_target
	for i in range(ships.size()):
		ships[i].move_target = previous_move_targets[i]


func _on_ship_destroyed(ship: Node) -> void:
	var idx: int = ships.find(ship)
	if idx != -1:
		ships.remove_at(idx)
		formation_offsets.remove_at(idx)
		_sync_composition_state()


func get_centroid() -> Vector2:
	if ships.is_empty():
		return fleet_target
	var sum: Vector2 = Vector2.ZERO
	for ship in ships:
		sum += ship.position
	return sum / ships.size()


func get_formation_origin() -> Vector2:
	# Where the anchor must be for the ships to be standing in their slots
	# right now. This is NOT the centroid: ships sit at anchor + offset, so
	# the centroid is anchor + the AVERAGE offset, and the two only coincide
	# when the layout happens to be balanced around its origin.
	#
	# The default wedge is balanced, which is why using the centroid as the
	# anchor looked fine - until a layout dragged off to one corner at a
	# command centre made the average offset large. Seeding the anchor from
	# the centroid then displaced every slot by that average the instant
	# steering began, so the fleet lurched towards the formation's own
	# lopsided side before the anchor caught up and it flew the right way.
	if ships.is_empty():
		return fleet_target
	var sum: Vector2 = Vector2.ZERO
	for offset in formation_offsets:
		sum += offset
	return get_centroid() - sum / formation_offsets.size()