using System;
using System.IO;
using Godot;

namespace TBL.GodotSharp.Content;

/// <summary>
/// 内容模块扩展功能类
/// </summary>
public static class Content
{
    /// <summary>
    /// 考虑依赖项打开文件流
    /// </summary>
    /// <param name="package">要打开的内容包</param>
    /// <param name="path">要打开的路径</param>
    /// <returns>打开的文件流</returns>
    public static Stream OpenFileStreamWithDependency(
        this Package package, string path)
    {
        var stream = package.OpenFileStream(path);

        // 直接打开成功的场合
        if (stream != null)
            return stream;

        // 在同级节点中寻找依赖项
        Node container;
        if (null != (container = package.GetParent()))
        {
            for (int i = 0, count = container.GetChildCount();
                 i < count; 
                 i++)
            {
                if (container.GetChild(i) is not Package dependency)
                    continue;
                // 遍历依赖项信息
                foreach (var info in package.Dependencies)
                {
                    // 符合依赖项的包将会被试图追溯
                    if (dependency.SelfInfo.IsCompatibleWith(info))
                    {
                        stream = dependency.OpenFileStreamWithDependency(path);
                        
                        // 直接打开成功的场合
                        if (stream != null)
                            return stream;
                    }
                }
            }
        }

        // 打开失败的场合
        return null;
    }
    
    /// <summary>
    /// 判断 <paramref name="actualVersion"/> 能否满足 <paramref name="targetVersion"/> 的版本要求
    /// <para>用于内容包之间的依赖可用性检测</para>
    /// </summary>
    /// <param name="actualVersion">当前版本</param>
    /// <param name="targetVersion">要求的版本</param>
    /// <param name="level">兼容级别</param>
    public static bool IsCompatibleWith(Version actualVersion, Version targetVersion, int level)
    {
        // 主版本号
        if (actualVersion.Major != targetVersion.Major)
            return false;
        if (level < 1)
            return true;
        // 次版本号
        if (actualVersion.Minor != targetVersion.Minor)
            return false;
        if (level < 2)
            return true;
        // 构建版本号
        if (actualVersion.Build != targetVersion.Build)
            return false;
        return true;
    }
}