tactical-shooter/scripts/weapons/rollback_hitscan_manager.gd

## RollbackHitscanManager — rollback-safe hitscan weapon with lag compensation.
##
## Uses netfox RewindableAction to track fire state per tick inside the
## rollback loop, enabling server-authoritative hit detection with physics
## rewound to the exact tick when the client fired.
##
## Key capabilities:
##   - Server-authoritative raycast at the rewound tick (lag compensation)
##   - Per-limb damage system (head/chest/waist/legs) via collision groups
##   - RewindableAction for fire state sync across the rollback loop
##   - Client prediction support via fire_performed signal
##
## Usage:
##   Place as a child of the Player node (sibling of RollbackSynchronizer).
##   Call process_fire() from _rollback_tick() every tick.
##   Call record_fire() from input gathering when shoot is pressed.
##
## Headless safety:
##   - No class_name references — uses load() + has_method() duck-typing
##   - Graceful degradation when netfox types are unavailable
##   - Falls back to direct input-based firing without RewindableAction

extends Node

# ---------------------------------------------------------------------------
# Signals
# ---------------------------------------------------------------------------
## Emitted when a shot connects on the server or for client prediction.
signal hit_registered(tick: int, hit_position: Vector3, hit_normal: Vector3, collider: Object, final_damage: int)

## Emitted when a shot misses entirely.
signal shot_missed(tick: int)

## Emitted on any fire attempt (hit or miss) — for muzzle flash, sound, etc.
signal weapon_fired(tick: int, origin: Vector3, direction: Vector3)

# ---------------------------------------------------------------------------
# Weapon configuration
# ---------------------------------------------------------------------------
## Weapon data (WeaponData resource) — set when weapon switches
var current_weapon_data: Resource = null

## Maximum raycast distance — updated from current_weapon_data
var max_distance: float = 1000.0

## Eye height above player origin for reconstructing fire origin
var eye_height: float = 1.7

# ---------------------------------------------------------------------------
# RewindableAction reference
# ---------------------------------------------------------------------------
var _fire_action: Node = null
var _has_rewindable_action: bool = false

# ---------------------------------------------------------------------------
# Server-side state
# ---------------------------------------------------------------------------
## Tracks which ticks have already had damage applied, preventing
## double-processing during rollback re-simulation.
var _processed_damage_ticks: Dictionary = {}

# ---------------------------------------------------------------------------
# Player reference (cached parent)
# ---------------------------------------------------------------------------
var _player_node: Node3D = null

# ---------------------------------------------------------------------------
# Lifecycle
# ---------------------------------------------------------------------------

func _ready() -> void:
	_player_node = get_parent() as Node3D
	if _player_node == null:
		push_warning("[RollbackHitscan] Parent is not a Node3D")
		return
	_setup_fire_action()

## Create the RewindableAction child node for per-tick fire tracking.
func _setup_fire_action() -> void:
	if not Engine.has_singleton(&"NetworkRollback"):
		push_warning("[RollbackHitscan] NetworkRollback not available — falling back to direct fire tracking")
		return

	var ActionScript = load("res://addons/netfox/rewindable-action.gd")
	if ActionScript == null:
		push_warning("[RollbackHitscan] RewindableAction script not found")
		return

	_fire_action = ActionScript.new()
	if _fire_action == null:
		return
	_fire_action.name = "HitscanFireAction"
	add_child(_fire_action, true)
	_has_rewindable_action = true
	print("[RollbackHitscan] RewindableAction created for %s" % _player_node.name)

# ---------------------------------------------------------------------------
# Public API — called from input gathering
# ---------------------------------------------------------------------------

## Record a fire event for the given tick.
##
## Called during input gathering (before the tick) when the client presses
## shoot. Stores the precise fire origin and direction as context in the
## RewindableAction so it survives rollback re-simulation.
##
## Parameters:
##   tick:      The network tick when the shot occurred
##   origin:    World-space raycast origin (typically camera/eye position)
##   direction: World-space normalized raycast direction
func record_fire(tick: int, origin: Vector3, direction: Vector3) -> void:
	if _has_rewindable_action and _fire_action != null:
		_fire_action.set_active(true, tick)
		_fire_action.set_context({
			"origin": origin,
			"direction": direction,
		}, tick)

# ---------------------------------------------------------------------------
# Public API — called from _rollback_tick()
# ---------------------------------------------------------------------------

## Process weapon firing for the given tick.
##
## This is the core method called from the player's _rollback_tick() every
## network tick. On the server, it performs a lag-compensated raycast and
## applies per-limb damage. On all peers, it emits signals for effects.
##
## Returns: Dictionary with hit result (empty if no hit or no shot).
##   - {collider, position, normal, ...} from PhysicsDirectSpaceState3D.intersect_ray
##   - empty dict if no shot was fired this tick
##
## Parameters:
##   tick:       The current network tick
##   is_server:  Whether this peer is the server (authority)
##   input_node: The PlayerNetInput node (must have .shoot, .look_yaw, .look_pitch)
##   weapon_data: WeaponData resource for this tick (nil = use current_weapon_data)
func process_fire(tick: int, is_server: bool, input_node: Node, weapon_data: Resource = null) -> Dictionary:
	if _player_node == null:
		return {}

	# Use passed-in weapon data or fall back to current
	var wd: Resource = weapon_data if weapon_data != null else current_weapon_data
	var effective_max_dist: float = max_distance
	if wd != null and wd.has_method(&"get") and wd.get("max_distance") != null:
		effective_max_dist = wd.get("max_distance")

	# Check if the player is trying to shoot this tick
	var shoot: bool = _is_shooting(tick, input_node)
	if not shoot:
		return {}

	# Prevent double-processing damage during re-simulation.
	# On the server, we only apply damage once per tick per shot.
	if is_server and _processed_damage_ticks.has(tick):
		return {}

	# Reconstruct fire origin and direction
	var origin: Vector3
	var direction: Vector3
	var fire_params: Dictionary = _get_fire_params(tick, input_node, effective_max_dist)
	origin = fire_params.get("origin", _player_node.global_position + Vector3(0, eye_height, 0))
	direction = fire_params.get("direction", -_player_node.global_basis.z)

	# Perform the physics raycast
	var space_state: PhysicsDirectSpaceState3D = null
	if _player_node.get_world_3d() != null:
		space_state = _player_node.get_world_3d().direct_space_state

	var hit: Dictionary = {}
	if space_state != null:
		hit = _perform_raycast(space_state, origin, direction, effective_max_dist)

	# Emit fire event for effects
	weapon_fired.emit(tick, origin, direction)

	# Server-authoritative damage application
	if is_server:
		_processed_damage_ticks[tick] = true

		if not hit.is_empty():
			var final_damage: int = _apply_damage(hit, wd)
			hit_registered.emit(tick, hit.get("position", Vector3.ZERO),
				hit.get("normal", Vector3.UP), hit.get("collider"), final_damage)
		else:
			shot_missed.emit(tick)

	return hit

# ---------------------------------------------------------------------------
# Internal helpers
# ---------------------------------------------------------------------------

## Check if the player is shooting this tick.
## Uses RewindableAction if available, otherwise falls back to input_node.shoot.
func _is_shooting(tick: int, input_node: Node) -> bool:
	# Prefer RewindableAction for accurate per-tick tracking
	if _has_rewindable_action and _fire_action != null:
		if _fire_action.has_method(&"is_active"):
			return _fire_action.is_active(tick)

	# Fallback: check raw input
	if input_node != null and input_node.has_method(&"get"):
		return input_node.get(&"shoot") or false
	return false

## Get fire parameters (origin, direction) for the given tick.
## Uses RewindableAction context if available, otherwise reconstructs from
## player position + camera yaw/pitch at the tick.
func _get_fire_params(tick: int, input_node: Node, max_dist: float) -> Dictionary:
	# Try RewindableAction context first (most precise)
	if _has_rewindable_action and _fire_action != null:
		if _fire_action.has_method(&"get_context"):
			var ctx = _fire_action.get_context(tick)
			if ctx != null and typeof(ctx) == TYPE_DICTIONARY:
				var o = ctx.get("origin")
				var d = ctx.get("direction")
				if o != null and d != null:
					return {"origin": o, "direction": d}

	# Reconstruct from player position + look angles
	var yaw: float = 0.0
	var pitch: float = 0.0
	if input_node != null:
		yaw = input_node.get(&"look_yaw") if input_node.has_method(&"get") else 0.0
		pitch = input_node.get(&"look_pitch") if input_node.has_method(&"get") else 0.0

	var origin := _player_node.global_position + Vector3(0, eye_height, 0)
	var direction := _yaw_pitch_to_dir(yaw, pitch)
	return {"origin": origin, "direction": direction}

## Perform a physics raycast with the given parameters.
func _perform_raycast(space_state: PhysicsDirectSpaceState3D, origin: Vector3,
		direction: Vector3, max_dist: float) -> Dictionary:
	var params = PhysicsRayQueryParameters3D.new()
	if params == null:
		return {}

	params.from = origin
	params.to = origin + direction * max_dist
	params.collision_mask = 0xFFFFFFFF

	# Exclude the shooter's own collision body
	var exclude_list: Array[RID] = []
	exclude_list.append_array(_get_player_collision_r_ids())
	if exclude_list.size() > 0:
		params.exclude = exclude_list

	return space_state.intersect_ray(params)

## Get RIDs of collision shapes on the player node to exclude from raycast.
func _get_player_collision_r_ids() -> Array[RID]:
	var rids: Array[RID] = []
	if _player_node == null:
		return rids

	for child in _player_node.get_children():
		if child is CollisionShape3D and child.shape != null:
			rids.append(child.shape.get_rid())
		elif child is CollisionPolygon3D:
			rids.append(child.get_rid())

	return rids

## Apply per-limb damage to the hit player.
## Returns the final damage amount applied.
func _apply_damage(hit: Dictionary, wd: Resource) -> int:
	var collider = hit.get("collider")
	if collider == null or wd == null:
		return 0

	var multiplier: float = _get_limb_multiplier(collider, wd)
	var base_damage: int = wd.get("damage") if wd.has_method(&"get") else 0
	var final_damage := int(base_damage * multiplier)

	# Find the player node from the collider
	var hit_player = _find_player(collider)
	if hit_player == null:
		return 0
	if not hit_player.has_method(&"apply_damage"):
		return 0

	var owner_id: int = 0
	if _player_node != null and _player_node.has_method(&"get"):
		owner_id = _player_node.get(&"peer_id") if _player_node.get(&"peer_id") != null else 0

	var weapon_id: int = wd.get("weapon_id") if wd.has_method(&"get") else 0

	hit_player.apply_damage(final_damage, owner_id, weapon_id)
	print("[RollbackHitscan] Tick %d: %d dmg (%d base x %.1f) to %s by peer %d" % [
		Engine.get_singleton(&"NetworkTime").tick if Engine.has_singleton(&"NetworkTime") else -1,
		final_damage, base_damage, multiplier, hit_player.name, owner_id])

	return final_damage

## Determine the damage multiplier for the hit limb.
##
## Colliders should be in collision groups:
##   "head"  → headshot_multiplier
##   "chest" → chest_multiplier (default)
##   "waist" → waist_multiplier
##   "legs"  → leg_multiplier
func _get_limb_multiplier(collider: Node, wd: Resource) -> float:
	if wd == null:
		return 1.0

	var head: float = wd.get("headshot_multiplier") if wd.has_method(&"get") else 2.0
	var chest: float = wd.get("chest_multiplier") if wd.has_method(&"get") else 1.0
	var waist: float = wd.get("waist_multiplier") if wd.has_method(&"get") else 0.75
	var legs: float = wd.get("leg_multiplier") if wd.has_method(&"get") else 0.5

	if collider.is_in_group(&"head"):
		return head
	elif collider.is_in_group(&"chest"):
		return chest
	elif collider.is_in_group(&"waist"):
		return waist
	elif collider.is_in_group(&"legs"):
		return legs

	return chest

## Walk up the scene tree from a collider to find a player node.
func _find_player(node: Node) -> Node:
	var current = node
	while current != null:
		if current.has_method(&"apply_damage") or current.is_in_group(&"players"):
			return current
		current = current.get_parent()
	return null

## Convert yaw (radians) and pitch (radians) to a forward direction vector.
## Uses standard FPS convention: yaw around Y axis, pitch around X axis.
static func _yaw_pitch_to_dir(yaw: float, pitch: float) -> Vector3:
	var cos_pitch := cos(pitch)
	return Vector3(
		cos_pitch * sin(yaw),
		sin(pitch),
		cos_pitch * cos(yaw)
	)

# ---------------------------------------------------------------------------
# State management
# ---------------------------------------------------------------------------

## Reset processed ticks history (e.g. on round restart).
## Also resets the RewindableAction state.
func reset() -> void:
	_processed_damage_ticks.clear()

## Update weapon data when the player switches weapons.
func set_weapon_data(wd: Resource) -> void:
	current_weapon_data = wd
	if wd != null and wd.has_method(&"get"):
		var md = wd.get("max_distance")
		if md != null:
			max_distance = md

## Get the RewindableAction node (for external inspection, e.g. debug UI).
func get_fire_action():
	return _fire_action