using UnityEngine;
using UnityEngine.TextCore.Text;

namespace MegaKoop.Game.UI
{
    /// <summary>
    /// Preloads required characters into dynamic font atlases on the main thread to avoid runtime race conditions.
    /// Attach once to a bootstrap GameObject and assign all UI font assets used by UITK.
    /// </summary>
    public sealed class FontAssetPreloader : MonoBehaviour
    {
        [SerializeField] private FontAsset[] fontAssets;
        [SerializeField, TextArea(1, 4)] private string charactersToPreload = "…•-";

        private System.Collections.IEnumerator Start()
        {
            if (fontAssets == null || fontAssets.Length == 0)
            {
                yield break;
            }

            // Wait one frame to ensure the scene finished loading on the main thread.
            yield return null;

            foreach (FontAsset asset in fontAssets)
            {
                if (asset == null)
                {
                    continue;
                }

                // Try to add characters that are commonly generated at runtime (ellipsis, bullets, dashes, etc.).
                bool allAdded = asset.TryAddCharacters(charactersToPreload, out string missingCharacters);
                if (!allAdded && !string.IsNullOrEmpty(missingCharacters))
                {
                    Debug.LogWarning($"[FontAssetPreloader] Missing glyphs '{missingCharacters}' in font '{asset.name}'. Consider adding a fallback font.");
                }
            }
        }
    }
}