namespace XFEExtension.NetCore.ServerInteractive.Utilities.Helpers;

/// <summary>
/// 路由通配符匹配辅助类
/// </summary>
internal static class RouteMatchHelper
{
    /// <summary>
    /// 判断路由是否包含通配符
    /// </summary>
    /// <param name="pattern">路由模式</param>
    /// <returns>是否包含通配符</returns>
    public static bool IsWildcardRoute(string pattern) => pattern.Split('/').Any(segment => segment is "*" or "**");

    /// <summary>验证通配符必须独占路径段，且双星号只能出现在末尾。</summary>
    public static void ValidatePattern(string pattern)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(pattern);
        var segments = pattern.Split('/');
        if (segments.Any(segment => segment.Length == 0 || segment.Contains('*') && segment is not ("*" or "**")) ||
            Array.IndexOf(segments, "**") is var catchAllIndex && catchAllIndex >= 0 && catchAllIndex != segments.Length - 1)
            throw new ArgumentException($"路由模式无效：'{pattern}'。* 必须匹配一个完整路径段，** 只能作为最后一个路径段。", nameof(pattern));
    }

    /// <summary>
    /// 将路由模式与实际路由进行通配符匹配
    /// <para>支持的通配符：</para>
    /// <para>- <c>*</c>：匹配一个路径段</para>
    /// <para>- <c>**</c>：匹配零个或多个剩余路径段，且只能位于末尾</para>
    /// <para>- <c>v1/*</c>：匹配 v1/ 后跟一个路径段</para>
    /// <para>- <c>v1/*/test</c>：匹配 v1/ 后跟任意一个段再跟 /test</para>
    /// </summary>
    /// <param name="pattern">包含通配符的路由模式</param>
    /// <param name="route">实际请求路由</param>
    /// <returns>是否匹配</returns>
    public static bool MatchWildcardRoute(string pattern, string route)
    {
        var patternSegments = pattern.Split('/', StringSplitOptions.RemoveEmptyEntries);
        var routeSegments = route.Split('/', StringSplitOptions.RemoveEmptyEntries);
        var catchAllIndex = Array.IndexOf(patternSegments, "**");
        if (catchAllIndex >= 0 && catchAllIndex != patternSegments.Length - 1)
            return false;
        if (catchAllIndex < 0 && patternSegments.Length != routeSegments.Length)
            return false;
        if (catchAllIndex >= 0 && routeSegments.Length < catchAllIndex)
            return false;

        var comparisonLength = catchAllIndex >= 0 ? catchAllIndex : patternSegments.Length;
        for (var index = 0; index < comparisonLength; index++)
        {
            if (patternSegments[index] == "*") continue;
            if (!patternSegments[index].Equals(routeSegments[index], StringComparison.Ordinal)) return false;
        }
        return true;
    }

    /// <summary>
    /// 计算路由模式的优先级，优先级规则如下
    /// </summary>
    /// <param name="pattern"></param>
    /// <returns></returns>
    public static int GetWildcardPatternPriority(string pattern)
    {
        var segments = pattern.Split('/', StringSplitOptions.RemoveEmptyEntries);
        var literalSegmentCount = 0;
        var wildcardSegmentCount = 0;
        foreach (var segment in segments)
        {
            if (segment is "*" or "**")
                wildcardSegmentCount++;
            else
                literalSegmentCount++;
        }
        return (literalSegmentCount * 1000) - (wildcardSegmentCount * 10) + pattern.Length;
    }
}