namespace LaaProduction.SQL
{
    using LaaProduction.SQL.Interfaces;
    
    using System;
    using System.Data.SqlClient;

    public class SQLReader : ISQLReader, IDisposable
    {
        private readonly SqlDataReader sqlDataReader;

        private int index;

        private SQLReader(SqlDataReader sqlDataReader) 
            => this.sqlDataReader = sqlDataReader.EnsureNotNull(nameof(sqlDataReader));

        public void Dispose()
        {
            this.sqlDataReader.Close();
            this.sqlDataReader.Dispose();
        }

        public T GetValue<T>()
        {
            this.index++;

            if (!this.sqlDataReader.IsDBNull(this.index))
            {
                var value = this.sqlDataReader.GetValue(this.index);
                var type = Nullable.GetUnderlyingType(typeof(T));

                if (type is null)
                {
                    type = typeof(T);
                }

                try
                {
                    value = Convert.ChangeType(value, type);
                }
                catch (Exception)
                {
                    // TODO:
                }

                if (value is T _value)
                {
                    return _value;
                }
            }

            return default(T);
        }

        public object GetValue(string column)
        {
            column.EnsureNotNullOrWhiteSpace(nameof(column));

            var colIndex = this.sqlDataReader.GetOrdinal(column);

            if (0 <= colIndex && colIndex < this.sqlDataReader.FieldCount)
            {
                if (!this.sqlDataReader.IsDBNull(colIndex))
                {
                    return this.sqlDataReader.GetValue(colIndex);
                }
            }

            return default(object);
        }

        internal bool Read()
        {
            this.index = -1;

            return this.sqlDataReader.Read();
        }

        public static implicit operator SQLReader(SqlDataReader sqlDataReader)
            => new SQLReader(sqlDataReader);
    }
}