using System;

namespace Hylasoft.Opc.Common
{
    /// <summary>
    /// Useful extension methods for OPC Clients
    /// </summary>
    public static class ClientExtensions
    {
        /// <summary>
        /// Reads a tag from the OPC. If for whatever reason the read fails (Tag doesn't exist, server not available) returns a default value
        /// </summary>
        /// <param name="client">the opc client to use for the read</param>
        /// <param name="tag">The fully qualified identifier of the tag</param>
        /// <param name="defaultValue">the default value to read if the read fails</param>
        /// <returns></returns>
        public static ReadEvent<T> ReadOrdefault<T>(this IClient<Node> client, string tag, T defaultValue = default(T))
        {
            try
            {
                return client.Read<T>(tag);
            }
            catch (OpcException)
            {
                var readEvent = new ReadEvent<T>();
                readEvent.Quality = Quality.Good;
                readEvent.Value = defaultValue;
                readEvent.SourceTimestamp = DateTime.Now;
                readEvent.ServerTimestamp = DateTime.Now;
                return readEvent;
            }
        }
    }
}