using ZB.MOM.WW.ScadaBridge.CentralUI.Components.Dialogs;
using ZB.MOM.WW.ScadaBridge.CentralUI.Services;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Sites;
using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Protocol;

namespace ZB.MOM.WW.ScadaBridge.CentralUI.Components.Pages.Deployment;

/// <summary>
/// Code-behind for <c>InstanceCreate.razor</c> — the Connection Bindings card
/// (design 2026-08-21). The card flattens the chosen template AGAINST the chosen
/// site through <c>IFlatteningPipeline.PreviewAsync</c> (no instance row exists yet),
/// groups the data-sourced attributes with the same <see cref="BindingGroupBuilder"/>
/// the Configure page uses, and collects one connection + Object per group. The pure
/// prefill / tail-strip / binding-list logic lives in <see cref="CreateBindingPlanner"/>
/// so it is unit-pinned without rendering the page.
/// </summary>
public partial class InstanceCreate
{
    // --- Connection Bindings card state (design 2026-08-21) ---
    private IReadOnlyList<BindingGroup> _groups = Array.Empty<BindingGroup>();
    private int _rowCount;
    private List<DataConnection> _siteConnections = new();
    private readonly Dictionary<string, CreateBindingPlanner.GroupInput> _inputs = new(StringComparer.Ordinal);
    private int _rootConnectionId;
    private string? _rootObject;
    private bool _skipBindings;
    private bool _previewLoading;
    private string? _previewError;
    private string? _siteIdentifier;

    private bool BindingsCardVisible => _createTemplateId > 0 && _createSiteId > 0;

    private int UnboundGroups => _groups.Count(g => !IsGroupBound(g));

    private bool IsGroupBound(BindingGroup g)
        => _inputs.TryGetValue(g.Key, out var i) && i.ConnectionId > 0 && !string.IsNullOrWhiteSpace(i.Object);

    private int BoundRowCount => _groups.Where(IsGroupBound).Sum(g => g.Members.Count);

    /// <summary>
    /// Called from the Template and Site selects' <c>@onchange</c>; re-runs the preview
    /// flatten and rebuilds the groups. No-ops until both a template and a site are chosen.
    /// </summary>
    private async Task OnTemplateOrSiteChangedAsync()
    {
        _groups = Array.Empty<BindingGroup>();
        _inputs.Clear();
        _previewError = null;
        _rowCount = 0;
        if (!BindingsCardVisible) return;

        _previewLoading = true;
        try
        {
            var site = _sites.FirstOrDefault(s => s.Id == _createSiteId);
            _siteIdentifier = site?.SiteIdentifier;
            _siteConnections = (await SiteRepository.GetDataConnectionsBySiteIdAsync(_createSiteId)).ToList();

            var preview = await FlatteningPipeline.PreviewAsync(_createTemplateId, _createSiteId);
            if (preview.IsFailure)
            {
                _previewError = preview.Error;
                return;
            }

            // Same predicate as the deploy gate (ValidateConnectionBindingCompleteness:
            // DataSourceReference != null), so every row the gate will check has a row here.
            var rows = preview.Value.Attributes
                .Where(a => a.DefaultDataSourceReference is not null || a.DataSourceReference is not null)
                .Select(a => new BindingRow(a.CanonicalName, a.DefaultDataSourceReference ?? a.DataSourceReference, null, null))
                .ToList();
            _rowCount = rows.Count;
            _groups = BindingGroupBuilder.Build(rows, _siteConnections.Select(c => c.Id).ToHashSet());

            // Groups whose defaults already carry an object prefix start "from template" —
            // the connection is still the operator's to pick.
            foreach (var g in _groups)
            {
                if (!g.IsInstanceGroup && g.InferredObject is { Length: > 0 })
                    _inputs[g.Key] = new CreateBindingPlanner.GroupInput(0, g.InferredObject);
            }
        }
        catch (Exception ex)
        {
            _previewError = ex.Message;
        }
        finally
        {
            _previewLoading = false;
        }
    }

    private void PrefillGroups()
    {
        foreach (var kv in CreateBindingPlanner.Prefill(_groups, _inputs, _rootConnectionId, _rootObject))
            _inputs[kv.Key] = kv.Value;
    }

    private void SetGroupConnection(BindingGroup g, int id)
        => _inputs[g.Key] = (_inputs.GetValueOrDefault(g.Key) ?? new CreateBindingPlanner.GroupInput(0, null))
            with { ConnectionId = id };

    private void SetGroupObject(BindingGroup g, string? obj)
        => _inputs[g.Key] = (_inputs.GetValueOrDefault(g.Key) ?? new CreateBindingPlanner.GroupInput(0, null))
            with { Object = obj, Suggested = false };

    // ── Address-space browser ───────────────────────────────────────────────

    /// <summary>Object as well as Variable: a module group binds to a container node.</summary>
    private static readonly BrowseNodeClass[] ObjectAndVariable = [BrowseNodeClass.Object, BrowseNodeClass.Variable];

    private NodeBrowserDialog? _browserRef;
    private string _browserConnectionName = "";
    private string? _browserInitial;
    private BindingGroup? _browserTarget; // null = the "Bind all to" root picker

    /// <summary>
    /// True when the selected data connection supports address-space browsing. OPC UA
    /// and MxGateway both implement <c>IBrowsableDataConnection</c> site-side; other
    /// protocols return a NotBrowsable failure, so the button stays disabled for them.
    /// (Mirrors the Configure page's identical gate.)
    /// </summary>
    private bool IsBrowsable(int connectionId)
    {
        if (connectionId <= 0) return false;
        var protocol = _siteConnections.FirstOrDefault(c => c.Id == connectionId)?.Protocol;
        return string.Equals(protocol, "OpcUa", StringComparison.OrdinalIgnoreCase)
            || string.Equals(protocol, "MxGateway", StringComparison.OrdinalIgnoreCase);
    }

    /// <summary>
    /// Opens the picker for one group, or for the root object when
    /// <paramref name="target"/> is null. Remembers the target so
    /// <see cref="OnBrowserSelected"/> writes the pick back to the right input.
    /// </summary>
    private async Task OpenBrowser(BindingGroup? target)
    {
        var connId = target is null ? _rootConnectionId : _inputs.GetValueOrDefault(target.Key)?.ConnectionId ?? 0;
        var conn = _siteConnections.FirstOrDefault(c => c.Id == connId);
        if (conn is null) return;

        _browserTarget = target;
        _browserConnectionName = conn.Name;
        _browserInitial = string.IsNullOrWhiteSpace(_rootObject) ? null : _rootObject;

        if (_browserRef is not null)
            await _browserRef.ShowAsync(_siteIdentifier ?? "", conn.Name, _browserInitial);
    }

    /// <summary>
    /// A group pick is normalised through <see cref="CreateBindingPlanner.ObjectFromPick"/>,
    /// so selecting a leaf tag under the module still yields the module's object.
    /// </summary>
    private void OnBrowserSelected(string nodeId)
    {
        if (_browserTarget is null) _rootObject = nodeId;
        else SetGroupObject(_browserTarget, CreateBindingPlanner.ObjectFromPick(_browserTarget, nodeId));
        _browserTarget = null;
    }
}