using CliFx;
using CliFx.Attributes;
using CliFx.Infrastructure;
using Opc.Ua;
using Opc.Ua.Client;

namespace OpcUaCli.Commands;

[Command("browse", Description = "Browse the OPC UA address space")]
public class BrowseCommand : ICommand
{
    /// <summary>
    /// Gets the OPC UA endpoint URL to connect to before browsing.
    /// </summary>
    [CommandOption("url", 'u', Description = "OPC UA server endpoint URL", IsRequired = true)]
    public string Url { get; init; } = default!;

    [CommandOption("username", 'U', Description = "Username for authentication")]
    public string? Username { get; init; }

    [CommandOption("password", 'P', Description = "Password for authentication")]
    public string? Password { get; init; }

    [CommandOption("security", 'S', Description = "Transport security: none, sign, encrypt (default: none)")]
    public string Security { get; init; } = "none";

    [CommandOption("failover-urls", 'F', Description = "Comma-separated failover endpoint URLs for redundancy")]
    public string? FailoverUrls { get; init; }

    /// <summary>
    /// Gets the optional node identifier to browse from; defaults to the OPC UA Objects folder.
    /// </summary>
    [CommandOption("node", 'n', Description = "Node ID to browse (default: Objects folder)")]
    public string? NodeId { get; init; }

    /// <summary>
    /// Gets the maximum browse depth when recursive traversal is enabled.
    /// </summary>
    [CommandOption("depth", 'd', Description = "Maximum browse depth")]
    public int Depth { get; init; } = 1;

    /// <summary>
    /// Gets a value indicating whether browse recursion should continue into child objects.
    /// </summary>
    [CommandOption("recursive", 'r', Description = "Browse recursively (uses --depth as max depth)")]
    public bool Recursive { get; init; }

    /// <summary>
    /// Connects to the OPC UA endpoint and writes the browse tree to the console.
    /// </summary>
    /// <param name="console">The console used to emit browse output.</param>
    public async ValueTask ExecuteAsync(IConsole console)
    {
        var urls = FailoverUrlParser.Parse(Url, FailoverUrls);
        using var failover = new OpcUaFailoverHelper(urls, Username, Password, Security);
        using var session = await failover.ConnectAsync();

        var startNode = string.IsNullOrEmpty(NodeId)
            ? ObjectIds.ObjectsFolder
            : new NodeId(NodeId);

        var maxDepth = Recursive ? Depth : 1;
        await BrowseNodeAsync(session, console, startNode, maxDepth, 0);
    }

    private static async Task BrowseNodeAsync(
        ISession session, IConsole console, NodeId nodeId, int maxDepth, int currentDepth)
    {
        var indent = new string(' ', currentDepth * 2);

        var (_, continuationPoint, references) = await session.BrowseAsync(
            null,
            null,
            nodeId,
            0u,
            BrowseDirection.Forward,
            ReferenceTypeIds.HierarchicalReferences,
            true,
            (uint)NodeClass.Object | (uint)NodeClass.Variable | (uint)NodeClass.Method);

        if (references == null) return;

        // Handle continuation points for large result sets
        while (references.Count > 0)
        {
            foreach (var reference in references)
            {
                var nodeClass = reference.NodeClass;
                var marker = nodeClass switch
                {
                    NodeClass.Object => "[Object]",
                    NodeClass.Variable => "[Variable]",
                    NodeClass.Method => "[Method]",
                    _ => $"[{nodeClass}]"
                };

                await console.Output.WriteLineAsync(
                    $"{indent}{marker} {reference.DisplayName} (NodeId: {reference.NodeId})");

                if (currentDepth + 1 < maxDepth && nodeClass == NodeClass.Object)
                {
                    var childNodeId = ExpandedNodeId.ToNodeId(
                        reference.NodeId, session.NamespaceUris);
                    await BrowseNodeAsync(session, console, childNodeId, maxDepth, currentDepth + 1);
                }
            }

            // Follow continuation point if present
            if (continuationPoint != null && continuationPoint.Length > 0)
            {
                var (_, nextCp, nextRefs) = await session.BrowseNextAsync(
                    null, false, continuationPoint);
                continuationPoint = nextCp;
                references = nextRefs;
            }
            else
            {
                break;
            }
        }
    }
}