using System;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Sozsoft.Mcp.Dtos;
using Sozsoft.Mcp.Services;
using Sozsoft.Platform.Localization;
using Volo.Abp;
using Volo.Abp.Application.Services;

namespace Sozsoft.Mcp;

/// <summary>
/// Dinamik istemci kaydi (RFC 7591). Uc kimlik dogrulamasizdir; istemci ne alirsa alsin token
/// kullanicinin kendi girisiyle ve kendi yetkileriyle uretilir. Kural ve kayit
/// <see cref="IMcpOAuthClientManager"/> icindedir.
/// </summary>
[AllowAnonymous]
public class McpOAuthAppService : ApplicationService, IMcpOAuthAppService
{
    private const string AuthorizationCodeGrant = "authorization_code";
    private const string RefreshTokenGrant = "refresh_token";

    private readonly IMcpOAuthClientManager clientManager;

    public McpOAuthAppService(IMcpOAuthClientManager clientManager)
    {
        this.clientManager = clientManager;
        LocalizationResource = typeof(PlatformResource);
    }

    public async Task<McpClientRegistrationResultDto> RegisterClientAsync(McpClientRegistrationRequestDto input)
    {
        Check.NotNull(input, nameof(input));

        var redirectUris = (input.RedirectUris ?? []).Distinct(StringComparer.Ordinal).ToList();
        var registration = await clientManager.RegisterAsync(input.ClientName, redirectUris);

        return registration.Error switch
        {
            McpClientRegistrationError.InvalidRedirectUri => new McpClientRegistrationResultDto
            {
                Error = "invalid_redirect_uri",
                ErrorDescription = L[McpErrorCodes.RedirectUriNotAllowed, registration.ErrorValue ?? string.Empty]
            },
            McpClientRegistrationError.LimitReached => new McpClientRegistrationResultDto
            {
                Error = "invalid_client_metadata",
                ErrorDescription = L[McpErrorCodes.RegistrationLimitReached, registration.ErrorValue ?? string.Empty]
            },
            _ => new McpClientRegistrationResultDto
            {
                ClientId = registration.ClientId,
                ClientName = input.ClientName,
                RedirectUris = redirectUris,
                // Istemci hangi akislari isterse istesin gecerli olanlar bunlardir; RFC 7591
                // sunucunun istenen degerleri daraltmasina izin verir.
                GrantTypes = [AuthorizationCodeGrant, RefreshTokenGrant],
                ResponseTypes = ["code"],
                Scope = string.Join(' ', McpConsts.OAuthScopes),
                ClientIdIssuedAt = DateTimeOffset.UtcNow.ToUnixTimeSeconds()
            }
        };
    }
}