using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using System;
using System.Collections;

// Holds a graphic target with its own normal and highlighted colors
[Serializable]
public class TargetColorPair
{
    public Graphic Target;
    public Color NormalColor = Color.white;
    public Color HighlightedColor = Color.grey;
}

public class MultiTargetButton : MonoBehaviour,
    IPointerEnterHandler, IPointerExitHandler, IPointerClickHandler,
    ISelectHandler, IDeselectHandler
{
    public TargetColorPair[] Targets;
    public float FadeDuration = 0.15f;

    // When enabled, the last hovered button stays highlighted
    // until another button takes over (mouse or gamepad)
    public bool PersistLastHovered = false;

    // Static so all instances share the same "last hovered" reference
    private static MultiTargetButton _lastHovered;

    void Awake() {
        foreach (var t in Targets) t.Target.color = t.NormalColor;
    }

    void SetHighlight(bool highlighted) {
        foreach (var t in Targets)
            StartCoroutine(FadeTo(t.Target, highlighted ? t.HighlightedColor : t.NormalColor));
    }

    // Lerps color over FadeDuration — stops any previous coroutine implicitly
    // since we start a new one on the same graphic each time
    IEnumerator FadeTo(Graphic graphic, Color target) {
        Color start = graphic.color;
        float elapsed = 0f;
        while (elapsed < FadeDuration) {
            elapsed += Time.deltaTime;
            graphic.color = Color.Lerp(start, target, elapsed / FadeDuration);
            yield return null;
        }
        graphic.color = target;
    }

    // Shared logic for both mouse enter and gamepad select —
    // steals persistence from whoever had it before
    void Activate() {
        if (PersistLastHovered && _lastHovered != null && _lastHovered != this)
            _lastHovered.SetHighlight(false);
        SetHighlight(true);
        if (PersistLastHovered) _lastHovered = this;
    }

    // Mouse
    public void OnPointerEnter(PointerEventData e) => Activate();
    public void OnPointerExit(PointerEventData e) {
        // If persist is on, do nothing on exit — next Activate() will clean up
        if (!PersistLastHovered) SetHighlight(false);
    }
    public void OnPointerClick(PointerEventData e) { }

    // Gamepad / keyboard — mirrors exact same logic as mouse
    public void OnSelect(BaseEventData e) => Activate();
    public void OnDeselect(BaseEventData e) {
        if (!PersistLastHovered) SetHighlight(false);
    }

    public static void ClearPersistence() {
        if (_lastHovered != null) {
            _lastHovered.StopAllCoroutines();
            foreach (var t in _lastHovered.Targets)
                t.Target.color = t.NormalColor;
            _lastHovered = null;
        }
    }
}