namespace GB5Shared.ChangeTracking
{
    /// <summary>
    /// Represents a single field-level change detected during an entity UPDATE.
    /// Serialized to JSON and carried in <see cref="GB5Shared.DTO.PubSub.OutboxEventMessage.Changes"/>.
    /// Stored individually in TEVENTLOGCHANGE by EventLogSubBLL after the event is consumed.
    /// Not written for INSERT operations — full snapshot is in TEVENTLOG.DATA.
    /// </summary>
    public sealed class ChangeRecordDTO
    {
        public ChangeRecordDTO() { }

        public ChangeRecordDTO(string fieldName, string? oldValue, string? newValue)
        {
            FieldName = fieldName;
            OldValue  = oldValue;
            NewValue  = newValue;
        }

        /// <summary>Property name from the DTO (e.g. "Amount", "Status").</summary>
        public string  FieldName { get; set; } = string.Empty;

        /// <summary>String representation of the value before the update; null if not previously set.</summary>
        public string? OldValue  { get; set; }

        /// <summary>String representation of the value after the update.</summary>
        public string? NewValue  { get; set; }
    }
}