using System;
using System.Security.Claims;
using Dpz.Core.EnumLibrary;

namespace Dpz.Core.Infrastructure;

public static class UserExtensions
{
    extension(ClaimsPrincipal? principal)
    {
        /// <summary>
        /// 账号 用户ID
        /// </summary>
        public string? NameIdentifier => principal?.FindFirst(ClaimTypes.NameIdentifier)?.Value;

        /// <summary>
        /// 严格获取用户ID
        /// <exception cref="CurrentUserRequiredException">如果用户未登录，将会引发此异常</exception>
        /// </summary>
        public string RequiredNameIdentifier =>
            principal?.NameIdentifier ?? throw new CurrentUserRequiredException();

        /// <summary>
        /// SessionId
        /// </summary>
        public string? SessionId =>
            principal?.FindFirst(UserSessionKeys.SessionIdClaim)?.Value
            ?? principal?.FindFirst(UserSessionKeys.SessionIdProperty)?.Value;

        /// <summary>
        /// 权限
        /// </summary>
        public Permissions? Permissions => principal.ParsePermissions();

        /// <summary>
        /// 是否具有系统权限
        /// </summary>
        public bool HasSystem => principal.HasSystemPermission();

        private Permissions? ParsePermissions()
        {
            var permissionClaim = principal?.FindFirst("Permissions")?.Value;
            if (permissionClaim is null)
            {
                return null;
            }
            if (Enum.TryParse<Permissions>(permissionClaim, ignoreCase: true, out var permissions))
            {
                return permissions;
            }
            return null;
        }

        private bool HasSystemPermission()
        {
            var permissions = principal?.ParsePermissions();
            return permissions.HasValue
                && (permissions.Value & Permissions.System) == Permissions.System;
        }

        /// <summary>
        /// 是否已认证
        /// </summary>
        public bool Authenticated => principal?.Identity?.IsAuthenticated == true;
    }
}