using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.Extensions.Localization;
using ModelContextProtocol;
using Sozsoft.Platform.Localization;
using Volo.Abp;
using Volo.Abp.Authorization;
using Volo.Abp.Authorization.Permissions;
using Volo.Abp.DependencyInjection;

namespace Sozsoft.Mcp;

/// <summary>
/// Arac hatalarini istemcinin gorebilecegi bicime cevirir. SDK yalnizca <see cref="McpException"/>
/// mesajini iletir; diger her istisna "An error occurred invoking" olarak gider ve model neden
/// reddedildigini bilemez. Yetki reddinde eksik yetkiler adiyla, is kurali hatasinda
/// (<see cref="UserFriendlyException"/>) zaten yerellestirilmis mesaj iletilir. Diger istisnalar
/// cevrilmez: ic ayrinti (SQL, yigin) istemciye sizmaz.
/// </summary>
public class McpToolErrorTranslator(
    IPermissionChecker permissionChecker,
    IStringLocalizer<PlatformResource> localizer) : ITransientDependency
{
    public static bool CanTranslate(Exception exception)
        => exception is AbpAuthorizationException or UserFriendlyException;

    public async Task<McpException> TranslateAsync(Exception exception, string? toolName)
        => exception is AbpAuthorizationException authorization
            ? new McpException(await DescribeMissingPermissionsAsync(authorization, toolName), exception)
            : new McpException(exception.Message, exception);

    /// <summary>
    /// <c>CheckAsync("...")</c> reddi yetki adini tasir; <c>[Authorize]</c> attribute'u tasimaz. Ikinci
    /// durumda aracin adi bilinen yetkileri kullanicinin yetkileriyle karsilastirilir.
    /// </summary>
    private async Task<string> DescribeMissingPermissionsAsync(AbpAuthorizationException exception, string? toolName)
    {
        var candidates = new List<string>(McpToolNames.KnownPermissionsOf(toolName));
        if (exception.Data["PolicyName"] is string policyName && !string.IsNullOrWhiteSpace(policyName))
        {
            candidates.Add(policyName);
        }

        var grants = await permissionChecker.IsGrantedAsync([.. candidates.Distinct(StringComparer.Ordinal)]);
        var missing = grants.Result
            .Where(result => result.Value != PermissionGrantResult.Granted)
            .Select(result => Describe(result.Key))
            .ToList();

        var target = toolName ?? McpConsts.EndpointPath;

        return missing.Count == 0
            ? localizer[McpErrorCodes.PermissionDeniedUnspecified, target]
            : localizer[McpErrorCodes.PermissionDenied, target, string.Join(", ", missing)];
    }

    /// <summary>Yetkinin gorunen adi ve kodu; rol ekraninda aranabilsin diye kod her zaman yazilir.</summary>
    private string Describe(string permissionName)
    {
        var displayName = localizer[permissionName];

        return displayName.ResourceNotFound || displayName.Value == permissionName
            ? permissionName
            : $"{displayName.Value} ({permissionName})";
    }
}