using Authentication;
using FileShare_Common.Core;
using FileShare_Services.Core;
using FileShare_Services.Services.AuthService;
using System;
using System.Threading.Tasks;

namespace FileShare_PC.Authentication
{
    /// <summary>
    /// PC 端鉴权端点服务，实现 <see cref="IPcAuthEndpointService"/>，
    /// 处理授权码登录、Token 刷新和登出操作。
    /// </summary>
    public sealed class PcAuthEndpointService(PcGlobalTokenService tokenService) : IPcAuthEndpointService
    {
        /// <inheritdoc />
        public async Task<IApiResponse> AuthorizeAsync(PcAuthorizeRequest request, ServiceEndpointContext ctx)
        {
            var token = await tokenService.AuthorizeAsync(request.AuthorizationCode);
            if (token is null)
            {
                ctx.StatusCode = 401;
                return ResponseHelper.Failure(401, "授权失败");
            }

            return ResponseHelper.Ok(token, "授权成功");
        }

        /// <inheritdoc />
        public async Task<IApiResponse> RefreshAsync(PcRefreshRequest request, ServiceEndpointContext ctx)
        {
            var token = request.Token ?? ExtractBearerToken(ctx.GetHeader("Authorization"));
            var refreshed = await tokenService.RefreshAsync(token);
            if (refreshed is null)
            {
                ctx.StatusCode = 401;
                return ResponseHelper.Failure(401, "授权已失效");
            }

            return ResponseHelper.Ok(refreshed, "刷新成功");
        }

        /// <inheritdoc />
        public Task<IApiResponse> LogoutAsync(PcLogoutRequest request, ServiceEndpointContext ctx)
        {
            var token = request.Token ?? ExtractBearerToken(ctx.GetHeader("Authorization"));
            tokenService.Logout(token);
            return Task.FromResult<IApiResponse>(ResponseHelper.Succeed("退出成功"));
        }

        /// <summary>
        /// 从 Authorization 头中提取 Bearer Token。
        /// </summary>
        /// <param name="authorization">Authorization 头的值。</param>
        /// <returns>提取的 Token 字符串；若无法提取则返回 null。</returns>
        private static string? ExtractBearerToken(string? authorization)
        {
            if (string.IsNullOrWhiteSpace(authorization))
            {
                return null;
            }

            /// <summary>
        /// Bearer Token 的前缀常量。
        /// </summary>
        const string prefix = "Bearer ";
            return authorization.StartsWith(prefix, StringComparison.OrdinalIgnoreCase)
                ? authorization[prefix.Length..].Trim()
                : authorization.Trim();
        }
    }
}