namespace pbi_local_mcp.Core;
/// <summary>
/// Result of truncation operation including metadata
/// </summary>
public class TruncationResult<T>
{
/// <summary>
/// The truncated data
/// </summary>
public required List<T> Data { get; init; }
/// <summary>
/// Total number of rows before truncation
/// </summary>
public required int TotalRows { get; init; }
/// <summary>
/// Number of rows in the truncated result
/// </summary>
public required int DisplayedRows { get; init; }
/// <summary>
/// Whether the data was truncated
/// </summary>
public required bool Truncated { get; init; }
/// <summary>
/// Whether there are more rows available
/// </summary>
public required bool HasMore { get; init; }
}
/// <summary>
/// Service for applying row limits and truncation to query results
/// </summary>
public class TruncationService
{
private readonly int _maxRows;
/// <summary>
/// Initializes a new instance of TruncationService
/// </summary>
/// <param name="maxRows">Maximum number of rows to return (default: 500)</param>
public TruncationService(int maxRows = 500)
{
if (maxRows <= 0)
throw new ArgumentException("MaxRows must be greater than 0", nameof(maxRows));
_maxRows = maxRows;
}
/// <summary>
/// Gets the configured maximum rows
/// </summary>
public int MaxRows => _maxRows;
/// <summary>
/// Applies truncation to a collection of data
/// </summary>
/// <typeparam name="T">Type of data items</typeparam>
/// <param name="data">The data to truncate</param>
/// <param name="requestedLimit">Optional requested limit (will be capped at MaxRows)</param>
/// <returns>Truncation result with metadata</returns>
public TruncationResult<T> ApplyTruncation<T>(
IEnumerable<T> data,
int? requestedLimit = null)
{
var dataList = data.ToList();
var totalRows = dataList.Count;
// Effective limit is the minimum of requested limit and max rows
var effectiveLimit = requestedLimit.HasValue
? Math.Min(requestedLimit.Value, _maxRows)
: _maxRows;
var truncatedData = dataList.Take(effectiveLimit).ToList();
return new TruncationResult<T>
{
Data = truncatedData,
TotalRows = totalRows,
DisplayedRows = truncatedData.Count,
Truncated = totalRows > truncatedData.Count,
HasMore = totalRows > truncatedData.Count
};
}
/// <summary>
/// Applies truncation and returns dictionary-based result with metadata
/// </summary>
/// <param name="rows">The row data</param>
/// <param name="columns">The column names</param>
/// <param name="requestedLimit">Optional requested limit</param>
/// <param name="executionTime">Optional execution time in milliseconds</param>
/// <returns>Dictionary containing rows, columns, and truncation metadata</returns>
public Dictionary<string, object?> ApplyTruncationWithMetadata(
List<Dictionary<string, object?>> rows,
List<string> columns,
int? requestedLimit = null,
double? executionTime = null)
{
var result = ApplyTruncation(rows, requestedLimit);
var response = new Dictionary<string, object?>
{
["rows"] = result.Data,
["columns"] = columns,
["rowCount"] = result.DisplayedRows, // Backward compatibility
["totalRows"] = result.TotalRows,
["displayedRows"] = result.DisplayedRows,
["truncated"] = result.Truncated,
["hasMore"] = result.HasMore
};
if (executionTime.HasValue)
{
response["executionTime"] = Math.Round(executionTime.Value, 2);
}
return response;
}
}
