using MediatR;
using Microsoft.Extensions.Logging;
using CellularManagement.Domain.Common;
using CellularManagement.Domain.Entities;
using CellularManagement.Domain.Repositories;

namespace CellularManagement.Application.Features.Devices.Commands.CreateDevice;

/// <summary>
/// 创建设备命令处理器
/// </summary>
public class CreateDeviceCommandHandler : IRequestHandler<CreateDeviceCommand, OperationResult<Device>>
{
    private readonly IDeviceRepository _deviceRepository;
    private readonly ILogger<CreateDeviceCommandHandler> _logger;

    /// <summary>
    /// 初始化命令处理器
    /// </summary>
    public CreateDeviceCommandHandler(
        IDeviceRepository deviceRepository,
        ILogger<CreateDeviceCommandHandler> logger)
    {
        _deviceRepository = deviceRepository;
        _logger = logger;
    }

    /// <summary>
    /// 处理创建设备命令
    /// </summary>
    public async Task<OperationResult<Device>> Handle(CreateDeviceCommand request, CancellationToken cancellationToken)
    {
        try
        {
            _logger.LogInformation("Creating new device with serial number: {SerialNumber}", request.SerialNumber);

            // 检查序列号是否已存在
            if (await _deviceRepository.ExistsBySerialNumberAsync(request.SerialNumber, cancellationToken: cancellationToken))
            {
                _logger.LogWarning("Device with serial number {SerialNumber} already exists", request.SerialNumber);
                return OperationResult<Device>.CreateFailure($"设备序列号 {request.SerialNumber} 已存在");
            }

            // 创建设备实体
            var device = new Device
            {
                DeviceID = Guid.NewGuid().ToString(),
                DeviceName = request.DeviceName,
                ProtocolVersion = request.ProtocolVersion,
                SupportBands = request.SupportBands,
                HardwareVersion = request.HardwareVersion,
                SerialNumber = request.SerialNumber,
                Comment = request.Comment,
                IPAddress = request.IPAddress,
                IsDisabled = false,
                CreatedAt = DateTime.UtcNow,
                UpdatedAt = DateTime.UtcNow
            };

            // 保存设备
            await _deviceRepository.CreateAsync(device, cancellationToken);

            _logger.LogInformation("Successfully created device with ID: {DeviceId}", device.DeviceID);
            return OperationResult<Device>.CreateSuccess("设备创建成功", device);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error creating device with serial number: {SerialNumber}", request.SerialNumber);
            return OperationResult<Device>.CreateFailure($"创建设备时发生错误: {ex.Message}");
        }
    }
}