using System;
using System.Collections.Generic;
using System.Threading.Tasks;

namespace Hylasoft.Opc.Common
{
    /// <summary>
    /// Client interface to perform basic Opc tasks, like discovery, monitoring, reading/writing tags,
    /// </summary>
    public interface IClient<out TNode> : IDisposable
    where TNode : Node
    {
        /// <summary>
        /// Connect the client to the OPC Server
        /// </summary>
        Task Connect();

        /// <summary>
        /// Gets the current status of the OPC Client
        /// </summary>
        OpcStatus Status { get; }

        /// <summary>
        /// Gets the datatype of an OPC tag
        /// </summary>
        /// <param name="tag">Tag to get datatype of</param>
        /// <returns>System Type</returns>
        System.Type GetDataType(string tag);

        /// <summary>
        /// Read a tag
        /// </summary>
        /// <typeparam name="T">The type of tag to read</typeparam>
        /// <param name="tag">The fully-qualified identifier of the tag. You can specify a subfolder by using a comma delimited name.
        /// E.g: the tag `foo.bar` reads the tag `bar` on the folder `foo`</param>
        /// <returns>The value retrieved from the OPC</returns>
        ReadEvent<T> Read<T>(string tag);

        /// <summary>
        /// Write a value on the specified opc tag
        /// </summary>
        /// <typeparam name="T">The type of tag to write on</typeparam>
        /// <param name="tag">The fully-qualified identifier of the tag. You can specify a subfolder by using a comma delimited name.
        /// E.g: the tag `foo.bar` writes on the tag `bar` on the folder `foo`</param>
        /// <param name="item"></param>
        void Write<T>(string tag, T item);

        /// <summary>
        /// Monitor the specified tag for changes
        /// </summary>
        /// <typeparam name="T">the type of tag to monitor</typeparam>
        /// <param name="tag">The fully-qualified identifier of the tag. You can specify a subfolder by using a comma delimited name.
        /// E.g: the tag `foo.bar` monitors the tag `bar` on the folder `foo`</param>
        /// <param name="callback">the callback to execute when the value is changed.
        /// The first parameter is the new value of the node, the second is an `unsubscribe` function to unsubscribe the callback</param>
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an async method.")]
        void Monitor<T>(string tag, Action<ReadEvent<T>, Action> callback);

        /// <summary>
        /// Finds a node on the Opc Server
        /// </summary>
        /// <param name="tag">The fully-qualified identifier of the tag. You can specify a subfolder by using a comma delimited name.
        /// E.g: the tag `foo.bar` finds the tag `bar` on the folder `foo`</param>
        /// <returns>If there is a tag, it returns it, otherwise it throws an </returns>
        TNode FindNode(string tag);

        /// <summary>
        /// Gets the root node of the server
        /// </summary>
        TNode RootNode { get; }

        /// <summary>
        /// Explore a folder on the Opc Server
        /// </summary>
        /// <param name="tag">The fully-qualified identifier of the tag. You can specify a subfolder by using a comma delimited name.
        /// E.g: the tag `foo.bar` finds the sub nodes of `bar` on the folder `foo`</param>
        /// <returns>The list of sub-nodes</returns>
        IEnumerable<TNode> ExploreFolder(string tag);

        /// <summary>
        /// Read a tag asynchronusly
        /// </summary>
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an async method.")]
        Task<ReadEvent<T>> ReadAsync<T>(string tag);

        /// <summary>
        /// Write a value on the specified opc tag asynchronously
        /// </summary>
        Task WriteAsync<T>(string tag, T item);

        /// <summary>
        /// Finds a node on the Opc Server asynchronously
        /// </summary>
        Task<Node> FindNodeAsync(string tag);

        /// <summary>
        /// Explore a folder on the Opc Server asynchronously
        /// </summary>
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures",
          Justification = "Task")]
        Task<IEnumerable<Node>> ExploreFolderAsync(string tag);
    }
}