using System;

namespace HotUpdate.UI
{
    /// <summary>编辑器生成与运行时加载共用的目录约定。</summary>
    public static class UiAtlasPaths
    {
        public const string TextureRoot = "Assets/Bundles/UI/Texture";
        public const string AtlasRoot = "Assets/Bundles/UI/Atlas";
        public const string AtlasNamePrefix = "UI_";

        public static bool IsTexturePath(string path)
        {
            return path != null && path.Replace('\\', '/').StartsWith(TextureRoot + "/", StringComparison.Ordinal);
        }

        public static string GetAtlasName(string relativeFolder)
        {
            if (relativeFolder == null) throw new ArgumentNullException(nameof(relativeFolder));
            relativeFolder = relativeFolder.Replace('\\', '/').Trim('/');
            if (relativeFolder.Length == 0) return AtlasNamePrefix + "__RootAtlas";
            foreach (string segment in relativeFolder.Split('/'))
                if (segment.Length == 0 || segment == "." || segment == "..")
                    throw new ArgumentException("Invalid UI texture folder: " + relativeFolder);
            // 转义下划线与路径分隔符，避免 A/B 与 A_B 生成同名图集。
            return AtlasNamePrefix + relativeFolder.Replace("_", "_u").Replace("/", "_s") + "Atlas";
        }

        public static string GetAtlasPath(string relativeFolder)
        {
            return AtlasRoot + "/" + GetAtlasName(relativeFolder) + ".spriteatlas";
        }

        public static string GetAtlasPathForTexture(string texturePath)
        {
            texturePath = texturePath?.Replace('\\', '/');
            if (!IsTexturePath(texturePath)) throw new ArgumentException("Not a UI texture: " + texturePath);
            int lastSlash = texturePath.LastIndexOf('/');
            string folder = lastSlash == TextureRoot.Length ? "" :
                texturePath.Substring(TextureRoot.Length + 1, lastSlash - TextureRoot.Length - 1);
            return GetAtlasPath(folder);
        }
    }
}