common/Logic/Common.Logic.Extensions.SQL/SQLCommand.cs

namespace Common.Logic.Extensions.SQL
{
    using Common.Logic.Extensions.SQL.Interfaces;

    using System;
    using System.Collections.Generic;
    using System.Data.SqlClient;
    using System.Linq;

    public class SQLCommand : ISQLCommand
    {
        private readonly SQLConnection sqlConnection;
        private readonly IDictionary<String, SqlParameter> parameters;

        public SQLCommand(SQLConnection sqlConnection, String commandText)
        {
            this.sqlConnection = sqlConnection.EnsureNotNull(nameof(sqlConnection));
            this.CommandText = commandText.EnsureNotNullOrWhiteSpace(nameof(commandText));
            this.parameters = new Dictionary<String, SqlParameter>();
        }

        internal String CommandText { get; }

        internal SqlParameter[] Parameters 
            => this.parameters.Values.ToArray();

        public Int32 ExecuteNonQuery()
            => this.sqlConnection.ExecuteNonQuery(this);

        public IEnumerable<T> ExecuteReader<T>(Func<ISQLReader, T> expression)
        {
            foreach (var result in this.sqlConnection.ExecuteReader(this, expression))
            {
                yield return result;
            }
        }

        public void ExecuteReader(Action<ISQLReader> expression)
        {
            expression.ThrowIfNull(nameof(expression));

            this.sqlConnection.ExecuteReader(this, reader =>
            {
                while (reader.Read())
                {
                    expression(reader);
                }
            });
        }

        public T ExecuteScalar<T>(Func<ISQLReader, T> expression)
            => this.sqlConnection.ExecuteScalar(this, expression);

        public T FirstOrDefault<T>(Func<ISQLReader, T> expression)
            => this.sqlConnection.FirstOrDefault(this, expression);

        public ISQLCommand SetParameter(String name, Object value)
        {
            name.ThrowIfNullOrWhiteSpace(nameof(name));

            if (value is null)
            {
                value = DBNull.Value;
            }

            this.parameters[name] = new SqlParameter(name, value);

            return this;
        }

        public ISQLCommand SetParameter(String name, DateTime value)
        {
            name.ThrowIfNullOrWhiteSpace(nameof(name));

            var sqlDate = new DateTime(1753, 1, 1, 12, 0, 0);

            if (value < sqlDate)
            {
                value = sqlDate;
            }

            this.parameters[name] = new SqlParameter(name, value);

            return this;
        }
    }
}