Godot Turn System

# skills/turn-system/scripts/active_time_battle.gd
extends Node

## Active Time Battle (ATB) Expert Pattern
## Async-aware ATB system managing unit charge, actions, and wait states.

class_name ActiveTimeBattle

signal turn_ready(unit: Node)
signal turn_ended(unit: Node)

enum State { CHARGING, WAIT_FOR_INPUT, EXECUTING }

@export var max_charge: float = 100.0
@export var fill_rate_multiplier: float = 1.0

var units: Array[Node] = [] # Expects units to have 'speed' and 'charge' properties
var current_state: State = State.CHARGING
var active_unit: Node

func _process(delta: float) -> void:
	if current_state == State.CHARGING:
		_process_charging(delta)

func _process_charging(delta: float) -> void:
	for unit in units:
		if is_instance_valid(unit):
			# Logic: Speed * Multiplier * Delta
			var speed = unit.get("speed") if "speed" in unit else 10.0
			var current = unit.get("charge") if "charge" in unit else 0.0
			
			current += speed * fill_rate_multiplier * delta
			unit.set("charge", current)
			
			if current >= max_charge:
				_start_turn(unit)
				return # Process one turn start per frame to avoid conflicts

func _start_turn(unit: Node) -> void:
	current_state = State.WAIT_FOR_INPUT
	active_unit = unit
	turn_ready.emit(unit)
	
	# Pause charging for others if "Wait" mode is desired
	# set_process(false) 

func submit_action(action_lambda: Callable) -> void:
	if current_state != State.WAIT_FOR_INPUT:
		return
		
	current_state = State.EXECUTING
	
	# Execute async action
	await action_lambda.call()
	
	_end_turn()

func _end_turn() -> void:
	if is_instance_valid(active_unit):
		active_unit.set("charge", 0.0)
		turn_ended.emit(active_unit)
	
	active_unit = null
	current_state = State.CHARGING
	# set_process(true)

## EXPERT USAGE:
## atb.turn_ready.connect(func(u): show_menu(u))
## atb.submit_action(func(): await u.attack(target))

# skills/turn-system/code/timeline_turn_manager.gd
extends Node

## Turn System Expert Pattern
## Implements Timeline-Based Initiative (CTB) and State Interrupts.

class Combatant:
    var name: String
    var speed: float = 10.0
    var energy: float = 0.0 # Energy accumulates based on speed
    var is_active: bool = true

var _combatants: Array[Combatant] = []
var _current_unit: Combatant = null

# 1. Timeline-Based Initiative
func process_timeline() -> Combatant:
    # Expert logic: Accumulate energy until someone hits the 100 threshold.
    while true:
        for unit in _combatants:
            if not unit.is_active: continue
            
            unit.energy += unit.speed
            if unit.energy >= 100.0:
                unit.energy -= 100.0
                _current_unit = unit
                return unit

# 2. Interruption Mechanics (State Stack Logic)
func inject_interrupt(interrupt_unit: Combatant) -> void:
    # Professional pattern: Temporarily halt the current turn 
    # to process a reaction or counter-attack.
    print("Interrupt! ", interrupt_unit.name, " is reacting.")
    var original_unit = _current_unit
    
    _current_unit = interrupt_unit
    # Process interrupt logic...
    
    _current_unit = original_unit
    print("Resuming turn for ", _current_unit.name)

# 3. Dynamic Turn Prediction
func get_predicted_order(steps: int = 10) -> Array[String]:
    # Professional protocol: Simulate the timeline to show the player 
    # who moves next.
    var prediction = []
    var temp_energy = {}
    for c in _combatants: temp_energy[c] = c.energy
    
    for i in range(steps):
        var next_unit = _simulate_next(temp_energy)
        prediction.append(next_unit.name)
    
    return prediction

func _simulate_next(energy_map: Dictionary) -> Combatant:
    while true:
        for unit in _combatants:
            energy_map[unit] += unit.speed
            if energy_map[unit] >= 100.0:
                energy_map[unit] -= 100.0
                return unit

## EXPERT NOTE:
## Use 'Signal-Based Turn Sync': Emit 'turn_started(unit)' and 
## 'turn_ended(unit)' signals to the UI. The UI should NEVER poll 
## the TurnManager; it only reacts to these signals.
## For 'turn-system', implement 'Asynchronous Sequence Execution': 
## Allow multiple units with identical initiative to perform animations 
## simultaneously to prevent "Turn Lag" in large battles.
## NEVER assume a combatant index will persist; if a unit dies 
## during a round, use 'Combatant.is_active = false' and cleanup 
## the array only at the start of a clear tick.

# turn_system_patterns.gd
extends Node

# 1. State Machine Pattern Matching
# EXPERT NOTE: Use Godot 4's advanced match syntax for clean, high-performance turn-phase logic.
func process_turn_logic(state: StringName) -> void:
    match state:
        &"player_turn":
            await _handle_player_turn()
        &"enemy_turn":
            await _handle_enemy_turn()
        &"resolution":
            await _resolve_effects()
        _:
            push_error("Invalid turn state.")

# 2. Awaiting Player Input Safely
# EXPERT NOTE: Yield execution until a UI signal fires, preventing thread lock.
func wait_for_selection() -> void:
    print("Awaiting player decision...")
    # await some_ui_signal.pressed
    pass

# 3. Robust Undo/Redo Turn History
# EXPERT NOTE: Uses the engine's built-in UndoRedo for historical state management.
var turn_undo_redo := UndoRedo.new()
func execute_unit_move(unit: Node2D, new_pos: Vector2) -> void:
    turn_undo_redo.create_action("Move Unit")
    turn_undo_redo.add_do_method(unit, &"set_position", new_pos)
    turn_undo_redo.add_undo_method(unit, &"set_position", unit.position)
    turn_undo_redo.commit_action()

# 4. Typed Dictionaries for Grid Board State
# EXPERT NOTE: Guarantees a rigid data structure for mapping coordinates to occupants.
var board_occupants: Dictionary[Vector2i, Node2D] = {}

# 5. Mapping Grid to Local Visual Space
# EXPERT NOTE: Safely maps logical array points to visual world space using TileMapLayer.
func snap_to_grid(layer: TileMapLayer, coords: Vector2i, entity: Node2D) -> void:
    entity.position = layer.map_to_local(coords)

# 6. AStarGrid2D Fast Pathfinding
# EXPERT NOTE: Instantiates a high-speed grid navigation map bypassing physical nodes.
var astar_grid := AStarGrid2D.new()
func setup_astar(region_sz: Rect2i) -> void:
    astar_grid.region = region_sz
    astar_grid.diagonal_mode = AStarGrid2D.DIAGONAL_MODE_NEVER
    astar_grid.update()

# 7. Duck-Typing Turn Interfaces
# EXPERT NOTE: Use has_method to verify if an object can participate in a turn cycle.
func trigger_turn_if_capable(entity: Node) -> void:
    if entity.has_method(&"take_turn"):
        entity.call(&"take_turn")

# 8. Functional Condition Checks
# EXPERT NOTE: Uses optimized C++ lambdas (all/any) to evaluate combat win/loss states.
func check_victory(entities: Array[Node]) -> bool:
    return entities.all(func(e): return e.get("is_dead") == true)

# 9. Dynamic Parameter Binding for UI
# EXPERT NOTE: Wire UI buttons to specific logic without extra wrapper functions.
func setup_action_button(btn: Button, target: Vector2i) -> void:
    btn.pressed.connect(_on_action_performed.bind(target))

func _on_action_performed(_coords: Vector2i) -> void:
    pass

# 10. Group Refreshing (Action Points)
# EXPERT NOTE: Instantly resets stats for all pertinent units in the scene tree.
func refresh_all_action_points() -> void:
    get_tree().call_group(&"units", &"reset_ap")

func _handle_player_turn(): pass
func _handle_enemy_turn(): pass
func _resolve_effects(): pass