using Syntriax.Engine.Core;
using Syntriax.Engine.Core.Abstract;

namespace Syntriax.Engine.Systems.Time;

public class TimerBehaviour : Behaviour, ITimer
{
    public event IReadOnlyTimer.TimerEventHandler? OnStarted = null;
    public event IReadOnlyTimer.TimerDeltaEventHandler? OnDelta = null;
    public event IReadOnlyTimer.TimerEventHandler? OnStopped = null;
    public event IReadOnlyTimer.TimerEventHandler? OnPaused = null;
    public event IReadOnlyTimer.TimerEventHandler? OnResumed = null;

    public TimerState State { get; protected set; } = TimerState.Idle;
    public double StartTime { get; protected set; } = 0f;
    public float Percentage => (float)(1f - (Remaining / StartTime));

    private double _remaining = 0f;
    public double Remaining
    {
        get => _remaining;
        protected set
        {
            if (value < .0f)
                value = .0f;

            _remaining = value;
        }
    }

    private bool shouldBeTicking = false;
    private bool hasStartedTickingBefore = false;

    public virtual void Start(double time)
    {
        StartTime = time;
        Remaining = time;

        shouldBeTicking = true;
        hasStartedTickingBefore = false;

        if (IsActive)
            StartTimer();
    }

    public virtual void Stop()
    {
        if (!shouldBeTicking)
            return;

        shouldBeTicking = false;

        State = TimerState.Stopped;
        OnStopped?.Invoke(this);
    }

    protected override void OnUpdate()
    {
        if (State is not TimerState.Ticking)
            return;

        double delta = GameManager.Time.DeltaSpan.TotalSeconds;

        Remaining -= delta;
        OnDelta?.Invoke(this, delta);

        if (Remaining <= .0f)
            Stop();
    }

    protected override void OnEnteredHierarchy(IGameManager gameManager)
    {
        if (!shouldBeTicking || State is TimerState.Ticking)
            return;

        if (hasStartedTickingBefore)
            Resume();
        else
            StartTimer();
    }

    protected override void OnExitedHierarchy(IGameManager gameManager)
    {
        if (!shouldBeTicking || State is not TimerState.Ticking)
            return;

        Pause();
    }

    public virtual void Pause()
    {
        State = TimerState.Paused;
        OnPaused?.Invoke(this);
    }

    public virtual void Resume()
    {
        State = TimerState.Ticking;
        OnResumed?.Invoke(this);
    }

    private void StartTimer()
    {
        hasStartedTickingBefore = true;

        State = TimerState.Ticking;
        OnStarted?.Invoke(this);
    }

    protected override void OnFinalize()
    {
        StartTime = 0f;
        Remaining = 0f;
        State = TimerState.Idle;
        shouldBeTicking = false;
        hasStartedTickingBefore = false;
    }
}