using System.Collections.Generic;
using System.Text.Json.Serialization;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using Sozsoft.Mcp.Dtos;
using Volo.Abp.AspNetCore.Mvc;

namespace Sozsoft.Mcp.Controllers;

/// <summary>
/// Uzak MCP istemcilerinin baglanti kesfi. Istemci /mcp'den 401 alir, <c>WWW-Authenticate</c>
/// basligindaki meta veri adresinden yetkilendirme sunucusunu ogrenir, kayit ucundan istemci
/// kimligini alir ve kullaniciyi platformun giris ekranina yonlendirir.
/// Adresler ve yanit bicimi RFC'lerle sabittir; bu yuzden ABP'nin konvansiyonel uclari yerine
/// acik rotali bir controller kullanilir.
/// </summary>
[AllowAnonymous]
[IgnoreAntiforgeryToken]
[ApiExplorerSettings(IgnoreApi = true)]
public class McpOAuthController(
    IOptions<McpOAuthOptions> options,
    IMcpOAuthAppService oAuthAppService) : AbpControllerBase
{
    /// <summary>Korumali kaynak meta verisi (RFC 9728).</summary>
    [HttpGet(McpConsts.ProtectedResourceMetadataPath)]
    [HttpGet(McpConsts.ProtectedResourceMetadataPath + McpConsts.EndpointPath)]
    public IActionResult GetProtectedResourceMetadata()
    {
        var value = options.Value;

        return new JsonResult(new ProtectedResourceMetadata(
            value.ResourceUrl,
            [value.AuthorizationServer],
            McpConsts.OAuthScopes,
            ["header"],
            McpServerInfoDefaults.DisplayName));
    }

    /// <summary>Dinamik istemci kaydi (RFC 7591).</summary>
    [HttpPost(McpConsts.RegistrationEndpointPath)]
    public async Task<IActionResult> RegisterAsync([FromBody] ClientRegistrationRequest request)
    {
        var result = await oAuthAppService.RegisterClientAsync(new McpClientRegistrationRequestDto
        {
            ClientName = request.ClientName,
            RedirectUris = request.RedirectUris ?? []
        });

        if (result.Error is not null)
        {
            return new JsonResult(new ClientRegistrationError(result.Error, result.ErrorDescription))
            {
                StatusCode = StatusCodes.Status400BadRequest
            };
        }

        return new JsonResult(new ClientRegistrationResponse(
            result.ClientId!,
            result.ClientIdIssuedAt,
            result.ClientName,
            result.RedirectUris,
            result.GrantTypes,
            result.ResponseTypes,
            result.TokenEndpointAuthMethod,
            result.Scope))
        {
            StatusCode = StatusCodes.Status201Created
        };
    }

    // Protokol sozlesmeleri snake_case alan adlariyla sabittir; ABP'nin camelCase JSON
    // politikasina birakilmaz.

    public sealed record ClientRegistrationRequest(
        [property: JsonPropertyName("client_name")] string? ClientName,
        [property: JsonPropertyName("redirect_uris")] List<string>? RedirectUris);

    private sealed record ClientRegistrationResponse(
        [property: JsonPropertyName("client_id")] string ClientId,
        [property: JsonPropertyName("client_id_issued_at")] long ClientIdIssuedAt,
        [property: JsonPropertyName("client_name")] string? ClientName,
        [property: JsonPropertyName("redirect_uris")] IReadOnlyList<string> RedirectUris,
        [property: JsonPropertyName("grant_types")] IReadOnlyList<string> GrantTypes,
        [property: JsonPropertyName("response_types")] IReadOnlyList<string> ResponseTypes,
        [property: JsonPropertyName("token_endpoint_auth_method")] string TokenEndpointAuthMethod,
        [property: JsonPropertyName("scope")] string? Scope);

    private sealed record ClientRegistrationError(
        [property: JsonPropertyName("error")] string Error,
        [property: JsonPropertyName("error_description")] string? ErrorDescription);

    private sealed record ProtectedResourceMetadata(
        [property: JsonPropertyName("resource")] string Resource,
        [property: JsonPropertyName("authorization_servers")] IReadOnlyList<string> AuthorizationServers,
        [property: JsonPropertyName("scopes_supported")] IReadOnlyList<string> ScopesSupported,
        [property: JsonPropertyName("bearer_methods_supported")] IReadOnlyList<string> BearerMethodsSupported,
        [property: JsonPropertyName("resource_name")] string ResourceName);
}