SnowflakeCommand.GroupBy.cs

//-----------------------------------------------------------------------
// <copyright file="SnowflakeCommand.GroupBy.cs" company="Jonas Schubert">
//     Copyright (c) Jonas Schubert. All rights reserved.
// </copyright>
// <author>Jonas Schubert</author>
//-----------------------------------------------------------------------

using TimeSpanXt;

namespace Snowflake.Data.Xt
{
  /// <summary>
  /// The snowflake command.
  /// </summary>
  /// <typeparam name="T">The generic type. This is used to parse properties for the query.</typeparam>
  public partial class SnowflakeCommand<T>
    where T : class
  {
    /// <summary>
    /// Adds a group by clause.
    /// https://docs.snowflake.com/en/sql-reference/constructs/group-by .
    /// </summary>
    /// <typeparam name="TGroupBy">The generic type.</typeparam>
    /// <param name="predicate">The group by predicate.</param>
    /// <returns>The snowflake command.</returns>
    /// <exception cref="InvalidOperationException">Command already has a group by clause.</exception>
    public SnowflakeCommand<T> GroupBy<TGroupBy>(Expression<Func<T, TGroupBy>> predicate)
    {
      if (this.Sql.Contains("GROUP BY", StringComparison.Ordinal))
      {
        throw new InvalidOperationException("Command already has a group by clause!");
      }

      var groupByBody = string.Join(", ", new Regex("new <>f__AnonymousType[0-9]{1,}`[0-9]{1,}", RegexOptions.None, 3.Seconds())
        .Replace(
          predicate.Body
            .ToString()
            .Replace($"{predicate.Parameters[0].Name}.", string.Empty, StringComparison.Ordinal), string.Empty)
        .Replace("(", string.Empty, StringComparison.Ordinal)
        .Replace(")", string.Empty, StringComparison.Ordinal)
        .Split(',')
        .Select(_ => _.Split("=")[0].Trim()));

      foreach (var property in this.Properties)
      {
        var propertyName = property.Value.Name;
        var propertyTableAlias = string.IsNullOrWhiteSpace(property.Value.Table)
          ? this.Table.Alias
          : this.Joins.Single(join => string.Equals(join.Table, property.Value.Table, StringComparison.Ordinal)).Alias;

        groupByBody = groupByBody.Replace($"{property.Key.Name}", $"{propertyTableAlias}.{propertyName}", StringComparison.Ordinal);
      }

      this.SqlBuilder.Append(CultureInfo.InvariantCulture, $" GROUP BY {groupByBody.Trim()}");

      return this;
    }

    /// <summary>
    /// Adds a group by clause.
    /// https://docs.snowflake.com/en/sql-reference/constructs/group-by .
    /// </summary>
    /// <param name="groupBy">The group by clause.</param>
    /// <returns>The snowflake command.</returns>
    /// <exception cref="InvalidOperationException">Command already has a group by clause.</exception>
    /// <exception cref="ArgumentNullException">Value for group by clause may not be empty.</exception>
    /// <exception cref="ArgumentException">Group By may only contain valid properties.</exception>
    [Obsolete("Use GroupBy<TGroupBy>(Expression<Func<T, TGroupBy>> predicate) instead.")]
    public SnowflakeCommand<T> GroupBy(string groupBy)
    {
      if (this.Sql.Contains("GROUP BY", StringComparison.Ordinal))
      {
        throw new InvalidOperationException("Command already has a group by clause!");
      }

      if (string.IsNullOrWhiteSpace(groupBy))
      {
        throw new ArgumentNullException(nameof(groupBy), "Value for group by clause may not be empty!");
      }

      var regexTestValue = groupBy.Replace("GROUP BY", string.Empty, StringComparison.Ordinal).Trim();
      if (!this.ValidPropertiesRegex.IsMatch(regexTestValue))
      {
        throw new ArgumentException($"Group By may only contain valid properties ({string.Join(", ", this.ValidProperties)})! \"{regexTestValue}\" is not allowed!");
      }

      this.SqlBuilder.Append(CultureInfo.InvariantCulture, $" {(groupBy.Trim().StartsWith("GROUP BY", ignoreCase: true, CultureInfo.InvariantCulture) ? groupBy.Trim() : $"GROUP BY {groupBy.Trim()}")}");

      return this;
    }
  }
}