namespace AcDream.App.UI.Layout;

/// <summary>
/// Retained-mode port of retail <c>DialogFactory @ 0x004773C0..0x00478470</c>.
/// It owns dialog contexts, independent FIFO queue groups, nonqueued dialogs,
/// priority preemption, callback delivery, close notices, and fresh catalog roots.
/// </summary>
public sealed class RetailDialogFactory : IDisposable
{
    public const uint DefaultQueueKey = 2u;
    public const uint NonQueuedKey = 1u;

    private sealed class DialogInfo
    {
        public required RetailDialogData Data { get; init; }
        public required uint Context { get; init; }
        public required uint QueueKey { get; init; }
        public Action<RetailDialogData>? Callback { get; init; }
        public IRetailDialogView? View { get; set; }
    }

    private readonly UiRoot _host;
    private readonly Func<RetailDialogType, ImportedLayout?> _createLayout;
    private readonly Dictionary<uint, DialogInfo> _activeQueued = new();
    private readonly Dictionary<uint, DialogInfo> _activeNonQueued = new();
    private readonly Dictionary<uint, LinkedList<DialogInfo>> _pending = new();
    private readonly List<DialogInfo> _openOrder = new();
    private uint _globalContext;
    private bool _resetting;
    private bool _disposed;

    public RetailDialogFactory(
        UiRoot host,
        Func<RetailDialogType, ImportedLayout?> createLayout)
    {
        _host = host ?? throw new ArgumentNullException(nameof(host));
        _createLayout = createLayout ?? throw new ArgumentNullException(nameof(createLayout));
    }

    /// <summary>
    /// Retail's global close-dialog notice, raised after the per-context callback and
    /// before the live root is removed from its parent.
    /// </summary>
    public event Action<uint, RetailDialogData>? DialogClosed;

    public event Action<uint>? DialogOpened;

    public bool IsOpen => _activeQueued.Count != 0 || _activeNonQueued.Count != 0;

    public int ActiveCount => _activeQueued.Count + _activeNonQueued.Count;

    public int PendingCount => _pending.Values.Sum(static queue => queue.Count);

    /// <summary>Exact root-element switch from <c>CreateDialog_ @ 0x00477AD0</c>.</summary>
    public static uint RootElementId(RetailDialogType type)
        => type switch
        {
            RetailDialogType.Confirmation => 0x15u,
            RetailDialogType.Wait => 0x31u,
            RetailDialogType.Message => 0x24u,
            RetailDialogType.TextInput => 0x28u,
            RetailDialogType.ConfirmationTextInput => 0x2Cu,
            RetailDialogType.Menu => 0x1Bu,
            RetailDialogType.ConfirmationMenu => 0x1Fu,
            _ => 0u,
        };

    public uint MakeDialog(RetailDialogData data)
        => MakeDialog(data, callback: null);

    /// <summary>
    /// Retail <c>MakeCallbackDialogInCurrentUI @ 0x00478430</c>.
    /// </summary>
    public uint MakeDialog(RetailDialogData data, Action<RetailDialogData>? callback)
    {
        ObjectDisposedException.ThrowIf(_disposed, this);
        ArgumentNullException.ThrowIfNull(data);

        uint context = NextContext();
        RetailDialogData ownedData = data.Clone();
        uint queueKey = ownedData.GetUInt32(RetailDialogProperty.QueueKey, DefaultQueueKey);
        if (queueKey == 0u)
            queueKey = DefaultQueueKey;

        var info = new DialogInfo
        {
            Data = ownedData,
            Context = context,
            QueueKey = queueKey,
            Callback = callback,
        };

        if (queueKey == NonQueuedKey)
        {
            _activeNonQueued.Add(context, info);
            CreateDialog(info);
            return context;
        }

        if (!_activeQueued.TryGetValue(queueKey, out DialogInfo? current))
        {
            _activeQueued.Add(queueKey, info);
            CreateDialog(info);
            return context;
        }

        LinkedList<DialogInfo> queue = PendingQueue(queueKey);
        if (!ownedData.GetBoolean(RetailDialogProperty.Priority))
        {
            queue.AddLast(info);
            UpdatePendingDialogDisplays();
            return context;
        }

        // MakeDialog's 0x8D branch removes the active root without completing the
        // DialogInfo, inserts that current info at the front, then displays the
        // priority request in its place.
        Suspend(current);
        queue.AddFirst(current);
        _activeQueued[queueKey] = info;
        CreateDialog(info);
        return context;
    }

    public uint MakeConfirmation(
        string message,
        Action<RetailDialogData>? callback = null,
        uint queueKey = DefaultQueueKey,
        bool priority = false)
    {
        RetailDialogData data = RetailDialogData.Confirmation(message)
            .Set(RetailDialogProperty.QueueKey, queueKey);
        if (priority)
            data.Set(RetailDialogProperty.Priority, true);
        return MakeDialog(data, callback);
    }

    /// <summary>
    /// Text-only wait dialog (type 2), closed by the caller via
    /// <see cref="CloseDialog"/>. Property shape mirrors
    /// <c>UIOption_ActionKeyMap::OpenMapWarnDialog @ 0x00488A00</c>: type 2,
    /// caller-chosen queue key, element attribute 0x40 set, message text.
    /// </summary>
    public uint MakeWait(string message, uint queueKey = DefaultQueueKey)
    {
        RetailDialogData data = RetailDialogData.Wait(message)
            .Set(RetailDialogProperty.QueueKey, queueKey);
        return MakeDialog(data, callback: null);
    }

    public uint MakeMessage(
        string message,
        Action<RetailDialogData>? callback = null,
        uint queueKey = DefaultQueueKey)
    {
        RetailDialogData data = RetailDialogData.Message(message)
            .Set(RetailDialogProperty.QueueKey, queueKey);
        return MakeDialog(data, callback);
    }

    public uint MakeConfirmationTextInput(
        string message,
        Action<RetailDialogData>? callback = null,
        uint queueKey = DefaultQueueKey)
    {
        RetailDialogData data = RetailDialogData.ConfirmationTextInput(message)
            .Set(RetailDialogProperty.QueueKey, queueKey);
        return MakeDialog(data, callback);
    }

    /// <summary>
    /// Retail <c>CloseDialog @ 0x00478160</c>. The context can identify an active
    /// nonqueued dialog, an active queued dialog, or an item still pending in a queue.
    /// </summary>
    public bool CloseDialog(uint context)
    {
        if (context == 0u)
            return false;

        if (_activeNonQueued.Remove(context, out DialogInfo? nonQueued))
        {
            DialogDone(nonQueued);
            return true;
        }

        foreach ((uint queueKey, DialogInfo active) in _activeQueued.ToArray())
        {
            if (active.Context != context)
                continue;

            _activeQueued.Remove(queueKey);
            DialogDone(active);
            OpenNextDialog(queueKey);
            return true;
        }

        foreach ((uint queueKey, LinkedList<DialogInfo> queue) in _pending.ToArray())
        {
            LinkedListNode<DialogInfo>? node = queue.First;
            while (node is not null && node.Value.Context != context)
                node = node.Next;
            if (node is null)
                continue;

            DialogInfo pending = node.Value;
            queue.Remove(node);
            if (queue.Count == 0)
                _pending.Remove(queueKey);
            DialogDone(pending);
            UpdatePendingDialogDisplays();
            return true;
        }

        return false;
    }

    public void Tick()
    {
        foreach (DialogInfo info in _openOrder.ToArray())
            info.View?.Tick();
    }

    /// <summary>
    /// Retail <c>DialogFactory::Reset @ 0x00477950</c> completes active and pending
    /// infos before clearing the factory.
    /// </summary>
    public void Reset()
    {
        if (_resetting)
            return;

        _resetting = true;
        List<Exception>? failures = null;
        try
        {
            while (true)
            {
                DialogInfo[] infos = _activeNonQueued.Values
                    .Concat(_activeQueued.Values)
                    .Concat(_pending.Values.SelectMany(static queue => queue))
                    .Distinct()
                    .ToArray();
                if (infos.Length == 0)
                    break;

                // Callbacks may synchronously create another dialog. Retire
                // this exact snapshot, then loop until those reentrant infos
                // have also completed through DialogDone.
                _activeNonQueued.Clear();
                _activeQueued.Clear();
                _pending.Clear();
                foreach (DialogInfo info in infos)
                {
                    try { DialogDone(info); }
                    catch (Exception error) { (failures ??= []).Add(error); }
                }
            }
        }
        finally
        {
            _resetting = false;
            RefreshModal();
        }

        if (failures is not null)
            throw new AggregateException(
                "One or more dialogs failed while the factory reset.",
                failures);
    }

    public void Dispose()
    {
        if (_disposed) return;
        _disposed = true;
        Reset();
    }

    private uint NextContext()
    {
        _globalContext++;
        if (_globalContext == 0u)
            _globalContext++;
        return _globalContext;
    }

    private LinkedList<DialogInfo> PendingQueue(uint queueKey)
    {
        if (_pending.TryGetValue(queueKey, out LinkedList<DialogInfo>? queue))
            return queue;
        queue = new LinkedList<DialogInfo>();
        _pending.Add(queueKey, queue);
        return queue;
    }

    private void CreateDialog(DialogInfo info)
    {
        RetailDialogType type = (RetailDialogType)info.Data.GetUInt32(RetailDialogProperty.Type);
        if (type is not (RetailDialogType.Confirmation
            or RetailDialogType.Wait
            or RetailDialogType.Message
            or RetailDialogType.ConfirmationTextInput))
            throw new NotSupportedException(
                $"Retail dialog type {(uint)type} does not have a ported presenter yet.");

        ImportedLayout layout = _createLayout(type)
            ?? throw new InvalidOperationException(
                $"Retail dialog catalog could not create type {(uint)type}.");
        IRetailDialogView view = type switch
        {
            RetailDialogType.Wait => new RetailWaitDialogView(_host, layout, info.Data),
            RetailDialogType.Message => new RetailMessageDialogView(
                _host, layout, info.Data, info.Context,
                context => CloseDialog(context)),
            RetailDialogType.ConfirmationTextInput =>
                new RetailConfirmationTextInputDialogView(
                    _host, layout, info.Data, info.Context,
                    context => CloseDialog(context)),
            _ => new RetailConfirmationDialogView(
                _host, layout, info.Data, info.Context,
                context => CloseDialog(context)),
        };
        info.View = view;
        _host.AddChild(view.Root);
        _host.BringToFront(view.Root);
        _openOrder.Add(info);
        _host.Modal = view.Root;
        view.Tick();
        UpdatePendingDialogDisplays();
        DialogOpened?.Invoke(info.Context);
    }

    private void Suspend(DialogInfo info)
    {
        if (info.View is null)
            return;
        IRetailDialogView view = info.View;
        info.View = null;
        view.DetachHandlers();
        _openOrder.Remove(info);
        _host.RemoveChild(view.Root);
        RefreshModal();
    }

    private void DialogDone(DialogInfo info)
    {
        // DialogDone @ 0x004773C0 delivers the registered callback first, then
        // broadcasts the CloseDialog notice, and only then removes the root.
        try
        {
            info.Callback?.Invoke(info.Data);
            DialogClosed?.Invoke(info.Context, info.Data);
        }
        finally
        {
            RemoveView(info);
        }
    }

    private void RemoveView(DialogInfo info)
    {
        if (info.View is { } view)
        {
            view.DetachHandlers();
            _host.RemoveChild(view.Root);
            info.View = null;
            _openOrder.Remove(info);
        }
        RefreshModal();
    }

    private void OpenNextDialog(uint queueKey)
    {
        // A callback invoked from DialogDone (above, in CloseDialog) may
        // synchronously make a new dialog under this same queue key before
        // control returns here — MakeDialog's queued branch will have
        // already re-occupied _activeQueued[queueKey]. Retail's HashTable::add
        // tolerates the duplicate; Dictionary.Add does not. Bail out: the
        // re-entrant dialog's own eventual CloseDialog will drain the
        // pending queue via its own OpenNextDialog call.
        if (_activeQueued.ContainsKey(queueKey))
            return;

        if (!_pending.TryGetValue(queueKey, out LinkedList<DialogInfo>? queue)
            || queue.First is null)
            return;

        DialogInfo next = queue.First.Value;
        queue.RemoveFirst();
        if (queue.Count == 0)
            _pending.Remove(queueKey);
        _activeQueued.Add(queueKey, next);
        CreateDialog(next);
    }

    private void UpdatePendingDialogDisplays()
    {
        foreach ((uint queueKey, DialogInfo active) in _activeQueued)
        {
            int count = _pending.TryGetValue(queueKey, out LinkedList<DialogInfo>? queue)
                ? queue.Count
                : 0;
            active.View?.SetPendingCount(count);
        }
    }

    private void RefreshModal()
    {
        _host.Modal = _openOrder.Count == 0 ? null : _openOrder[^1].View?.Root;
    }
}