using UnityEngine;
using UnityEngine.UI;

namespace AOT.UI
{
    /// <summary>Fill the screen without stretching the portrait illustration.</summary>
    [RequireComponent(typeof(Image))]
    public sealed class BootArtworkCover : MonoBehaviour
    {
        void OnEnable() => Fit();
        void LateUpdate() => Fit();
        void OnRectTransformDimensionsChange() => Fit();

        void Fit()
        {
            var image = GetComponent<Image>();
            if (image == null || image.sprite == null || transform.parent == null) return;
            var parent = transform.parent as RectTransform;
            if (parent == null || parent.rect.width <= 0 || parent.rect.height <= 0) return;
            var rect = (RectTransform)transform;
            float aspect = image.sprite.rect.width / image.sprite.rect.height;
            float width = Mathf.Max(parent.rect.width, parent.rect.height * aspect);
            Vector2 size = new Vector2(width, width / aspect);
            rect.anchorMin = rect.anchorMax = rect.pivot = new Vector2(.5f, .5f);
            rect.anchoredPosition = Vector2.zero;
            if ((rect.sizeDelta - size).sqrMagnitude > .01f) rect.sizeDelta = size;
        }
    }
}