using System.Threading;
using System.Threading.Tasks;
using MediatR;
using Microsoft.Extensions.Logging;
using CellularManagement.Application.Common;
using CellularManagement.Domain.Entities;
using CellularManagement.Domain.Repositories;
using CellularManagement.Domain.Common;
using System;

namespace CellularManagement.Application.Features.Permissions.Commands.CreatePermission;

/// <summary>
/// 创建权限命令处理器
/// </summary>
public sealed class CreatePermissionCommandHandler : IRequestHandler<CreatePermissionCommand, OperationResult<CreatePermissionResponse>>
{
    private readonly IPermissionRepository _permissionRepository;
    private readonly ILogger<CreatePermissionCommandHandler> _logger;

    /// <summary>
    /// 初始化处理器
    /// </summary>
    public CreatePermissionCommandHandler(
        IPermissionRepository permissionRepository,
        ILogger<CreatePermissionCommandHandler> logger)
    {
        _permissionRepository = permissionRepository;
        _logger = logger;
    }

    /// <summary>
    /// 处理创建权限请求
    /// </summary>
    public async Task<OperationResult<CreatePermissionResponse>> Handle(
        CreatePermissionCommand request,
        CancellationToken cancellationToken)
    {
        try
        {
            // 检查权限是否已存在
            var existingPermission = await _permissionRepository.GetByNameAsync(request.Name, cancellationToken);
            if (existingPermission != null)
            {
                _logger.LogWarning("权限 {PermissionName} 已存在", request.Name);
                return OperationResult<CreatePermissionResponse>.CreateFailure("权限已存在");
            }

            // 创建权限
            var permission = Permission.Create(request.Name, request.Description);
            var createdPermission = await _permissionRepository.AddAsync(permission, cancellationToken);

            _logger.LogInformation("权限 {PermissionName} 创建成功", request.Name);

            return OperationResult<CreatePermissionResponse>.CreateSuccess(
                new CreatePermissionResponse(createdPermission.Id));
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "创建权限 {PermissionName} 失败", request.Name);
            return OperationResult<CreatePermissionResponse>.CreateFailure("创建权限失败，请稍后重试");
        }
    }
}