using AibisDream.Utility;
using UnityEngine;

namespace AibisDream.SaveSystem
{
    /// <summary>
    /// 存档槽位缩略图捕获工具。
    /// <para>
    /// 使用主相机渲染到 RenderTexture 后读像素并编码为 PNG。
    /// 捕获失败时安全返回 null，不会阻塞存档流程。
    /// </para>
    /// </summary>
    public static class SlotThumbnailCapture
    {
        /// <summary>捕获当前画面的 PNG 字节数组。</summary>
        public static byte[] CapturePng()
        {
            var cam = Camera.main;
            if (cam == null)
            {
                Debug.LogWarning("[SlotThumbnailCapture] 未找到 Camera.main，跳过截图。");
                return null;
            }

            var width = ConstRef.SaveThumbnailWidth;
            var height = ConstRef.SaveThumbnailHeight;

            var rt = RenderTexture.GetTemporary(width, height, 24, RenderTextureFormat.Default);
            var prevTarget = cam.targetTexture;
            cam.targetTexture = rt;
            cam.Render();
            cam.targetTexture = prevTarget;

            RenderTexture.active = rt;
            var tex = new Texture2D(width, height, TextureFormat.RGB24, false);
            tex.ReadPixels(new Rect(0, 0, width, height), 0, 0);
            tex.Apply();
            RenderTexture.active = null;

            var bytes = tex.EncodeToPNG();

            Object.Destroy(tex);
            RenderTexture.ReleaseTemporary(rt);

            return bytes;
        }
    }
}