namespace Application;

/// <summary>
/// 导入类型
/// </summary>
public enum ImportType
{
    /// <summary>
    /// 支付宝
    /// </summary>
    Alipay,

    /// <summary>
    /// 微信
    /// </summary>
    WeChat
}

/// <summary>
/// 导入应用服务接口
/// </summary>
public interface IImportApplication
{
    /// <summary>
    /// 导入支付宝账单
    /// </summary>
    Task<ImportResponse> ImportAlipayAsync(ImportRequest request);

    /// <summary>
    /// 导入微信账单
    /// </summary>
    Task<ImportResponse> ImportWeChatAsync(ImportRequest request);
}

/// <summary>
/// 导入应用服务实现
/// </summary>
public class ImportApplication(
    IImportService importService,
    ILogger<ImportApplication> logger
) : IImportApplication
{
    private static readonly string[] AllowedExtensions = { ".csv", ".xlsx", ".xls" };
    private const long MaxFileSize = 10 * 1024 * 1024; // 10MB


    public async Task<ImportResponse> ImportAlipayAsync(ImportRequest request)
    {
        ValidateRequest(request);

        var (ok, message) = await importService.ImportAlipayAsync(
            (MemoryStream)request.FileStream, 
            request.FileExtension
        );

        if (!ok)
        {
            throw new BusinessException(message);
        }

        logger.LogInformation("支付宝账单导入成功: {Message}", message);
        return new ImportResponse { Message = message };
    }

    public async Task<ImportResponse> ImportWeChatAsync(ImportRequest request)
    {
        ValidateRequest(request);

        var (ok, message) = await importService.ImportWeChatAsync(
            (MemoryStream)request.FileStream, 
            request.FileExtension
        );

        if (!ok)
        {
            throw new BusinessException(message);
        }

        logger.LogInformation("微信账单导入成功: {Message}", message);
        return new ImportResponse { Message = message };
    }

    /// <summary>
    /// 验证导入请求
    /// </summary>
    private static void ValidateRequest(ImportRequest request)
    {
        // 验证文件流
        if (request.FileStream == null || request.FileStream.Length == 0)
        {
            throw new ValidationException("请选择要上传的文件");
        }

        // 验证文件扩展名
        if (string.IsNullOrWhiteSpace(request.FileExtension))
        {
            throw new ValidationException("文件扩展名不能为空");
        }

        var extension = request.FileExtension.ToLowerInvariant();
        if (!AllowedExtensions.Contains(extension))
        {
            throw new ValidationException("只支持 CSV 或 Excel 文件格式");
        }

        // 验证文件大小
        if (request.FileSize > MaxFileSize)
        {
            throw new ValidationException("文件大小不能超过 10MB");
        }
    }
}