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.Application.Services;

namespace Sozsoft.Mcp;

/// <summary>
/// MCP uygulama servislerinin ortak tabani. Kullaniciya gorunen metinler platformun
/// <c>PlatformResource</c> kaynagindan okunur; sunucu kaydini cozme ve arac kapisi her
/// serviste ayni davranir.
/// </summary>
public abstract class McpAppService : ApplicationService
{
    protected IMcpServerConfigProvider ServerConfigProvider { get; }

    protected McpAppService(IMcpServerConfigProvider serverConfigProvider)
    {
        ServerConfigProvider = serverConfigProvider;
        LocalizationResource = typeof(PlatformResource);
    }

    /// <summary>Etkin sunucu kaydinin DTO hali; kayit yoksa null.</summary>
    protected async Task<McpServerConfigDto?> ResolveServerConfigAsync()
    {
        var server = await ServerConfigProvider.GetEffectiveServerAsync();
        if (server is null)
        {
            return null;
        }

        return new McpServerConfigDto
        {
            Name = server.Name,
            Url = server.Url,
            AllowedTools = [.. ServerConfigProvider.SplitMultiValue(server.AllowedTools)],
            MaxRows = server.MaxRows,
            Description = server.Description,
            TenantName = CurrentTenant.Name
        };
    }

    /// <summary>
    /// Kapali bir araca yapilan cagriyi reddeder: sunucu kaydi yoksa, arac sunucu kaydinda kapaliysa
    /// ya da kullanicinin uygulamada karsilik gelen yetkisi yoksa. Arac listesini suzmek tek basina
    /// yeterli degildir — istemci listede olmayan bir araci da cagirabilir.
    /// </summary>
    protected async Task<McpOutcome<McpServerConfigDto>> EnsureToolAllowedAsync(string toolName)
    {
        var config = await ResolveServerConfigAsync();
        if (config is null)
        {
            return Problem(McpErrorCodes.NoServerRecord);
        }

        if (CurrentTenant.IsAvailable && !McpToolNames.TenantTools.Contains(toolName, StringComparer.Ordinal))
        {
            return Problem(McpErrorCodes.TenantToolDisabled, toolName);
        }

        if (!McpToolPolicy.IsAllowed(true, CurrentTenant.IsAvailable, config.AllowedTools, toolName))
        {
            return Problem(McpErrorCodes.ToolDisabled, toolName, config.Name);
        }

        if (McpToolNames.RequiredPermissions.TryGetValue(toolName, out var permission) &&
            await CheckPermissionAsync(toolName, permission) is { } denied)
        {
            return denied;
        }

        return config;
    }

    /// <summary>
    /// Yetkiyi adiyla ister; eksikse istemcinin rol ekraninda arayabilecegi ad ve kodla reddeder.
    /// <c>AuthorizationService.CheckAsync</c> istisna atar, bu yuzden MCP'de kullanilmaz.
    /// </summary>
    protected async Task<McpProblem?> CheckPermissionAsync(string toolName, string permission)
        => await AuthorizationService.IsGrantedAsync(permission)
            ? null
            : Problem(McpErrorCodes.PermissionDenied, toolName, McpPermissionText.Describe(L, permission));

    protected McpProblem Problem(string name, params object[] arguments)
        => McpProblem.From(L, name, arguments);

    /// <summary>Istenen satir sayisini sunucu kaydindaki tavana kirpar.</summary>
    protected static int ResolveMaxRows(McpServerConfigDto config, int requested)
    {
        var ceiling = config.MaxRows > 0 ? config.MaxRows : McpConsts.DefaultMaxRows;

        return requested > 0 ? Math.Min(requested, ceiling) : ceiling;
    }
}