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

namespace OpcUaCli.Commands;

[Command("alarms", Description = "Subscribe to alarm events on a node")]
public class AlarmsCommand : ICommand
{
    /// <summary>
    /// Gets the OPC UA endpoint URL for the server whose alarm stream should be monitored.
    /// </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 node to subscribe to for event notifications, typically a source object or the server node.
    /// </summary>
    [CommandOption("node", 'n', Description = "Node ID to monitor for events (default: Server node)")]
    public string? NodeId { get; init; }

    /// <summary>
    /// Gets the requested publishing and sampling interval for the alarm subscription.
    /// </summary>
    [CommandOption("interval", 'i', Description = "Publishing interval in milliseconds")]
    public int Interval { get; init; } = 1000;

    /// <summary>
    /// Gets a value indicating whether the command should request a retained-condition refresh after subscribing.
    /// </summary>
    [CommandOption("refresh", Description = "Request a ConditionRefresh after subscribing")]
    public bool Refresh { get; init; }

    /// <summary>
    /// Connects to the target server and streams alarm or condition events to the operator console.
    /// </summary>
    /// <param name="console">The CLI console used for cancellation and alarm-event 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 nodeId = string.IsNullOrEmpty(NodeId)
            ? ObjectIds.Server
            : new NodeId(NodeId);

        var subscription = new Subscription(session.DefaultSubscription)
        {
            PublishingInterval = Interval,
            DisplayName = "CLI Alarm Subscription"
        };

        var item = new MonitoredItem(subscription.DefaultItem)
        {
            StartNodeId = nodeId,
            DisplayName = "AlarmMonitor",
            SamplingInterval = Interval,
            NodeClass = NodeClass.Object,
            AttributeId = Attributes.EventNotifier,
            Filter = CreateEventFilter()
        };

        item.Notification += (_, e) =>
        {
            if (e.NotificationValue is EventFieldList eventFields)
            {
                PrintAlarmEvent(eventFields);
            }
        };

        subscription.AddItem(item);
        session.AddSubscription(subscription);
        await subscription.CreateAsync();

        Console.WriteLine($"Subscribed to alarm events on {nodeId} (interval: {Interval}ms). Press Ctrl+C to stop.");
        Console.Out.Flush();

        if (Refresh)
        {
            try
            {
                await subscription.ConditionRefreshAsync();
                Console.WriteLine("Condition refresh requested.");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Condition refresh not supported: {ex.Message}");
            }
            Console.Out.Flush();
        }

        var ct = console.RegisterCancellationHandler();

        while (!ct.IsCancellationRequested)
        {
            await Task.Delay(2000, ct).ContinueWith(_ => { });
        }

        await console.Output.WriteLineAsync("Unsubscribed.");
    }

    private static EventFilter CreateEventFilter()
    {
        var filter = new EventFilter();
        // 0: EventId
        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.EventId);
        // 1: EventType
        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.EventType);
        // 2: SourceName
        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.SourceName);
        // 3: Time
        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.Time);
        // 4: Message
        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.Message);
        // 5: Severity
        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.Severity);
        // 6: ConditionName
        filter.AddSelectClause(ObjectTypeIds.ConditionType, BrowseNames.ConditionName);
        // 7: Retain
        filter.AddSelectClause(ObjectTypeIds.ConditionType, BrowseNames.Retain);
        // 8: AckedState/Id
        filter.AddSelectClause(ObjectTypeIds.AcknowledgeableConditionType, "AckedState/Id");
        // 9: ActiveState/Id
        filter.AddSelectClause(ObjectTypeIds.AlarmConditionType, "ActiveState/Id");
        // 10: EnabledState/Id
        filter.AddSelectClause(ObjectTypeIds.AlarmConditionType, "EnabledState/Id");
        // 11: SuppressedOrShelved
        filter.AddSelectClause(ObjectTypeIds.AlarmConditionType, "SuppressedOrShelved");
        return filter;
    }

    private static void PrintAlarmEvent(EventFieldList eventFields)
    {
        var fields = eventFields.EventFields;
        if (fields == null || fields.Count < 6)
            return;

        var time = fields.Count > 3 ? fields[3].Value as DateTime? : null;
        var sourceName = fields.Count > 2 ? fields[2].Value as string : null;
        var message = fields.Count > 4 ? (fields[4].Value as LocalizedText)?.Text : null;
        var severity = fields.Count > 5 ? fields[5].Value : null;
        var conditionName = fields.Count > 6 ? fields[6].Value as string : null;
        var retain = fields.Count > 7 ? fields[7].Value as bool? : null;
        var ackedState = fields.Count > 8 ? fields[8].Value as bool? : null;
        var activeState = fields.Count > 9 ? fields[9].Value as bool? : null;
        var enabledState = fields.Count > 10 ? fields[10].Value as bool? : null;
        var suppressed = fields.Count > 11 ? fields[11].Value as bool? : null;

        Console.WriteLine($"[{time:O}] ALARM  {sourceName}");

        if (conditionName != null)
            Console.WriteLine($"  Condition: {conditionName}");

        if (activeState.HasValue || ackedState.HasValue)
        {
            var state = FormatAlarmState(activeState, ackedState);
            Console.WriteLine($"  State:     {state}");
        }

        if (enabledState.HasValue)
            Console.WriteLine($"  Enabled:   {enabledState.Value}");

        Console.WriteLine($"  Severity:  {severity}");

        if (!string.IsNullOrEmpty(message))
            Console.WriteLine($"  Message:   {message}");

        if (retain.HasValue)
            Console.WriteLine($"  Retain:    {retain.Value}");

        if (suppressed == true)
            Console.WriteLine($"  Suppressed/Shelved: True");

        Console.WriteLine();
    }

    private static string FormatAlarmState(bool? active, bool? acked)
    {
        var activePart = active == true ? "Active" : "Inactive";
        var ackedPart = acked == true ? "Acknowledged" : "Unacknowledged";
        return $"{activePart}, {ackedPart}";
    }
}