namespace Syntriax.Engine.StateMachine;

public class State : IState
{
    public event IState.StateUpdateEventHandler? OnStateUpdate = null;
    public event IState.StateTransitionedFromEventHandler? OnStateTransitionedFrom = null;
    public event IState.StateTransitionedToEventHandler? OnStateTransitionedTo = null;
    public event IState.StateTransitionReadyEventHandler? OnStateTransitionReady = null;

    private readonly List<StateTransition> transitions = [];
    private readonly Dictionary<string, StateTransition> possibleTransitions = [];

    public string Name { get; set; } = "Default State Name";
    public IReadOnlyList<StateTransition> Transitions => transitions;
    public IReadOnlyDictionary<string, StateTransition> PossibleTransitions => possibleTransitions;

    public void RemoveTransition(string name)
    {
        if (!possibleTransitions.TryGetValue(name, out StateTransition stateTransition))
            return;

        transitions.Remove(stateTransition);
        possibleTransitions.Remove(name);
    }

    public void AddTransition(string name, StateTransition stateTransition)
    {
        if (transitions.Contains(stateTransition))
            return;

        transitions.Add(stateTransition);
        possibleTransitions.Add(name, stateTransition);
    }

    public void Update()
    {
        if (GetNextState() is IState transitionState)
            OnStateTransitionReady?.Invoke(this, transitionState);
        OnStateUpdate?.Invoke(this);
    }

    public void TransitionTo(IState from) => OnStateTransitionedTo?.Invoke(this, from);
    public void TransitionFrom(IState to) => OnStateTransitionedFrom?.Invoke(this, to);

    public IState? GetNextState()
    {
        foreach (StateTransition stateTransition in transitions)
            if (stateTransition.CanTransition)
                return stateTransition.State;
        return null;
    }
}