using System.ComponentModel.DataAnnotations;
using RestSharp;
using Store.Management.Api.Transport;

namespace Store.Management.Api.Authentication;

public sealed class LoginRequest
{
    [Required] public string UserName { get; set; } = "";
    /// <summary>服务端要求的 UTF-8 密码的 32 位大写 MD5，由调用方计算。</summary>
    [Required] public string Password { get; set; } = "";
    [StringLength(100)] public string? DeviceId { get; set; }
    [StringLength(100)] public string? DeviceName { get; set; }
}

public sealed class LoginResult
{
    public string TokenType { get; init; } = "Bearer";
    public string Token { get; init; } = "";
    public uint ExpiresInMinutes { get; init; }
}

public sealed record CurrentUser(string UserName, string? NickName);

public interface IAuthApi
{
    Task<LoginResult> LoginAsync(LoginRequest request, CancellationToken cancellationToken = default);
    Task LogoutAsync(CancellationToken cancellationToken = default);
    Task<CurrentUser> MeAsync(CancellationToken cancellationToken = default);
}

internal sealed class AuthApi(ApiTransport transport, TokenSession session) : IAuthApi
{
    // 登录和退出串行执行，避免迟到的登录响应覆盖退出操作。
    private readonly SemaphoreSlim _gate = new(1, 1);

    public async Task<LoginResult> LoginAsync(LoginRequest request, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(request);
        await _gate.WaitAsync(cancellationToken).ConfigureAwait(false);
        try
        {
            LoginResult result = await transport.GetRequiredAsync<LoginResult>("Auth/Login", Method.Post, request,
                authenticated: false, cancellationToken: cancellationToken).ConfigureAwait(false);
            if (string.IsNullOrWhiteSpace(result.Token) || result.Token.Contains('\r') || result.Token.Contains('\n') ||
                !string.Equals(result.TokenType, "Bearer", StringComparison.OrdinalIgnoreCase))
            {
                throw new ApiException(ApiErrorKind.InvalidResponse, "登录响应缺少有效的 Bearer Token。");
            }
            session.Set(result.Token);
            return result;
        }
        finally
        {
            _gate.Release();
        }
    }

    public async Task LogoutAsync(CancellationToken cancellationToken = default)
    {
        await _gate.WaitAsync(cancellationToken).ConfigureAwait(false);
        string? token = session.Token;
        try
        {
            if (token is not null)
            {
                await transport.SendAsync<object>("Auth/Logout", Method.Post, cancellationToken: cancellationToken).ConfigureAwait(false);
            }
        }
        finally
        {
            session.ClearIfCurrent(token);
            _gate.Release();
        }
    }

    public Task<CurrentUser> MeAsync(CancellationToken cancellationToken = default)
        => transport.GetRequiredAsync<CurrentUser>("Auth/Me", Method.Get, cancellationToken: cancellationToken);
}