using Fido2NetLib;
using Fido2NetLib.Objects;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace CloudBuilder.Security.Service
{
    /// <summary>
    /// 登录阶段，下发给前端的断言选项模型，对应 CredentialGetOptions
    /// </summary>
    public sealed class AssertionOptionsModel
    {
        [JsonPropertyName("challenge")]
        public string Challenge { get; init; }

        /// <summary>
        /// 依赖方ID，域名，例如 localhost / example.com
        /// </summary>
        [JsonPropertyName("rpId")]
        public string RpId { get; init; }

        /// <summary>
        /// 允许使用的凭证列表，告诉浏览器该用户有哪些已绑定凭证
        /// </summary>
        [JsonPropertyName("allowCredentials")]
        public PublicKeyCredentialDescriptor[] AllowCredentials { get; init; }

        /// <summary>
        /// 用户验证策略：preferred｜required｜discouraged
        /// </summary>
        [JsonPropertyName("userVerification")]
        public UserVerificationRequirement UserVerification { get; init; }

        /// <summary>
        /// 超时毫秒
        /// </summary>
        [JsonPropertyName("timeout")]
        public ulong Timeout { get; init; }

        // 可选扩展字段，如果业务用到可以加上
        //[JsonPropertyName("extensions")]
        //public AuthenticationExtensionsClientInputs? Extensions { get; init; }


        /// <summary>
        /// 和Fido2NetLib原生风格对齐，从JSON字符串反序列化对象
        /// </summary>
        /// <param name="json">后端输出给前端的原始json</param>
        /// <returns></returns>
        public static AssertionOptionsModel FromJson(string json)
        {
            var opt = new JsonSerializerOptions
            {
                Converters = { new Base64UrlConverter() },
                PropertyNameCaseInsensitive = false
            };
            return JsonSerializer.Deserialize<AssertionOptionsModel>(json, opt)!;
        }

        /// <summary>
        /// 序列化为给前端消费的JSON（challenge/id自动Base64Url编码）
        /// </summary>
        public string ToJson()
        {
            var opt = new JsonSerializerOptions
            {
                Converters = { new Base64UrlConverter() },
                WriteIndented = false
            };
            return JsonSerializer.Serialize(this, opt);
        }
    }
}