CellularManagement/src/CellularManagement.Application/Features/Devices/Queries/GetDevices/GetDevicesQueryHandler.cs

using MediatR;
using Microsoft.Extensions.Logging;
using CellularManagement.Domain.Common;
using CellularManagement.Domain.Entities;
using CellularManagement.Domain.Repositories;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace CellularManagement.Application.Features.Devices.Queries.GetDevices;

/// <summary>
/// 获取设备列表查询处理器
/// </summary>
public class GetDevicesQueryHandler : IRequestHandler<GetDevicesQuery, OperationResult<GetDevicesResponse>>
{
    private readonly IDeviceRepository _deviceRepository;
    private readonly ILogger<GetDevicesQueryHandler> _logger;

    /// <summary>
    /// 初始化查询处理器
    /// </summary>
    public GetDevicesQueryHandler(
        IDeviceRepository deviceRepository,
        ILogger<GetDevicesQueryHandler> logger)
    {
        _deviceRepository = deviceRepository;
        _logger = logger;
    }

    /// <summary>
    /// 处理获取设备列表查询
    /// </summary>
    public async Task<OperationResult<GetDevicesResponse>> Handle(GetDevicesQuery request, CancellationToken cancellationToken)
    {
        try
        {
            // 验证请求参数
            var validationContext = new ValidationContext(request);
            var validationResults = new List<ValidationResult>();
            if (!Validator.TryValidateObject(request, validationContext, validationResults, true))
            {
                var errorMessages = validationResults.Select(r => r.ErrorMessage).ToList();
                _logger.LogWarning("Invalid request parameters: {Errors}", string.Join(", ", errorMessages));
                return OperationResult<GetDevicesResponse>.CreateFailure(errorMessages);
            }

            _logger.LogInformation("Getting devices with page: {PageNumber}, size: {PageSize}, search: {SearchTerm}, isDisabled: {IsDisabled}",
                request.PageNumber, request.PageSize, request.SearchTerm, request.IsDisabled);

            // 获取分页数据
            var (totalCount, items) = await _deviceRepository.GetPagedAsync(
                request.PageNumber,
                request.PageSize,
                request.SearchTerm,
                request.IsDisabled,
                cancellationToken);

            // 构建响应
            var response = new GetDevicesResponse
            {
                TotalCount = totalCount,
                PageNumber = request.PageNumber,
                PageSize = request.PageSize,
                TotalPages = (int)Math.Ceiling(totalCount / (double)request.PageSize),
                HasPreviousPage = request.PageNumber > 1,
                HasNextPage = request.PageNumber < (int)Math.Ceiling(totalCount / (double)request.PageSize),
                Items = items.Select(d => new DeviceDto
                {
                    DeviceId = d.DeviceID,
                    DeviceName = d.DeviceName,
                    ProtocolVersion = d.ProtocolVersion,
                    SupportBands = d.SupportBands,
                    HardwareVersion = d.HardwareVersion,
                    SerialNumber = d.SerialNumber,
                    Comment = d.Comment,
                    IPAddress = d.IPAddress,
                    IsDisabled = d.IsDisabled,
                    CreatedAt = d.CreatedAt,
                    UpdatedAt = d.UpdatedAt
                }).ToList()
            };

            _logger.LogInformation("Successfully retrieved {Count} devices", items.Count());
            return OperationResult<GetDevicesResponse>.CreateSuccess(response);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error getting devices");
            return OperationResult<GetDevicesResponse>.CreateFailure($"获取设备列表时发生错误: {ex.Message}");
        }
    }
}