using Avalonia;
using Avalonia.Controls;
using Avalonia.Controls.Primitives;
using Avalonia.Input;
using Avalonia.Interactivity;
using Avalonia.VisualTree;
using DodoSSH.Client.Shell.ViewModels;
namespace DodoSSH.Client.App.Views;
///
/// The flat board of host cards, and everything on it that is a gesture rather than a binding.
///
///
///
/// ◆ v5: THE GRID OF GROUP CARDS AND THE BREADCRUMB TRAIL ARE GONE, AND SO IS THE DRAG. The desktop
/// used to hold one level of the group tree at a time — a wrap of group cards above the hosts, opened by a
/// double-click, with a trail above it saying where you were — the way a directory pane holds one directory.
/// That model is retired outright rather than folded into the new board: every group is now a heading, in
/// label order, all of them at once, exactly the flattening the phone's SidebarRows has always drawn.
/// A host is filed under a group through the group's own picker in its editor, or through the "Change
/// group…" entry the chosen-hosts menu already carried — dragging a card onto another card had exactly one
/// destination, a group card, and that card is what left. See VaultViewModel.HostSections.
///
///
/// ◆ ONE SECTION, ONE ListBox. The two shapes worth weighing were a single mixed list of
/// header rows and host rows in one WrapPanel, or an ItemsControl of sections each holding its
/// own card list. The first is what the phone's single flat list already is, and reusing it here would have
/// meant a header row pretending to be as wide as the row it sits on so the wrap panel breaks a line before
/// and after it — a real technique, and a fragile one to get right at every width this window can be resized
/// to. The second costs a real thing: there is no longer one ListBox owning one SelectedItem,
/// so multi-select and the marquee have to be taught to reach across however many section lists are on
/// screen. That is what most of this file now does. It was chosen anyway, because a WrapPanel that
/// only ever holds cards of one kind is the ordinary, well-trodden case, and "reach across N lists instead
/// of one" is a bounded, mechanical problem — enumerate every list, not the fixed one named in the markup —
/// where "make a wrap panel break a line for one specific child" is a harder one to be sure of without a
/// custom panel this application does not otherwise need.
///
///
/// ◆ SELECTION IS ONE-WAY INTO EVERY SECTION AND WRITTEN BY HAND ON THE WAY OUT. Each section's
/// ListBox binds SelectedItem from VaultViewModel.SelectedSidebarRow so the right card
/// lights up wherever it lives, but not back — a two-way binding shared by several independently-rebuilt
/// lists would have each list's own Reset (one per filter keystroke, one per background sync) racing
/// to null the one shared property, which is the same hazard VaultViewModel.RebuildVisibleHosts
/// already documents for a single list and multiplies it by the section count. So a card being pressed is
/// what actually moves the selection, here in code, exactly as a Ctrl or Shift modifier already had to be —
/// see .
///
///
/// ◆ THERE ARE STILL TWO SELECTIONS ON THIS SCREEN, AND THEY ARE STILL NOT THE SAME THING.
/// SelectedHost is the card the drawer, CONNECT and the ordinary menu are about; the chosen set is
/// what Ctrl, Shift and the band build on top of it, as IsChosen on the row. Every handler below that
/// reads a modifier is about keeping the two from being confused for one another, on the same terms this
/// screen has always used — see VaultViewModel.ChooseHosts and Android's HostsScreen.
///
///
/// Its data context is the VaultViewModel, as 's is. The window hands it
/// over; see .
///
///
internal sealed partial class HostsScreen : UserControl
{
/// How far the pointer has to travel before a press on the empty space becomes a band.
///
/// A threshold, because a press on the space around the cards is nearly always a click that drops the
/// chosen set — see . Starting a band on the press itself would turn every one
/// of those into a rectangle nobody asked for.
///
private const double DragThreshold = 5;
/// Where a Shift-click measures its run from: the last card pressed without one.
///
/// Kept here rather than in the vault because it is a fact about the gesture rather than about the
/// keychain — it is what the pointer last touched, and it means nothing to the phone or to any command.
/// Null until something has been pressed, which is what a Shift-click into an untouched board falls back
/// to the selected card for.
///
private HostRowViewModel? anchor;
/// Whether a band is being dragged out over the board right now.
private bool banding;
/// The corner it was started from, in the scroller's own coordinates.
private Point bandFrom;
/// Whether that band adds to the set rather than being the whole of it.
///
/// Read once, when the band starts, rather than per move. A modifier picked up halfway through a drag
/// would change what the rectangle already crossed means, which is a selection nobody could predict.
///
private bool bandAdds;
public HostsScreen()
{
InitializeComponent();
// Wired here rather than in the markup because it is a gesture rather than a binding, which is how
// the transfers screen opens a directory too. Attached to the board rather than to any one section's
// list, since double-tapping a card in any of them means the same thing and DoubleTapped bubbles.
Board.DoubleTapped += OnHostActivated;
// Tunnelled, so the card under the pointer is read before whichever section's ListBox has answered
// the press itself. Bubbling would work for a plain click but not for the menu or for Ctrl/Shift: by
// the time either reaches this control the list has already decided what it thinks is selected.
Board.AddHandler(PointerPressedEvent, OnPointerPressed, RoutingStrategies.Tunnel);
Board.AddHandler(ContextRequestedEvent, OnContextRequested, RoutingStrategies.Tunnel);
WireTheBand();
}
/// The band's own wiring, and the two keys that go with a set.
///
/// Split out of the constructor rather than sitting in it, and only because the constructor is at the
/// length this repository's analyser allows for one. Everything here arrived together: it is the whole
/// of choosing more than one card with a pointer.
///
private void WireTheBand()
{
// Esc and Ctrl+A, on the board rather than on the window: both are ordinary editing keys that mean
// something else everywhere else, and Ctrl+A in the find box above has to go on selecting the text
// in it. The board takes focus on a press, so the keys work from the moment anything has been
// touched; see KeyboardTarget for the other half of who has the keyboard on this screen.
Board.KeyDown += OnGridKey;
// The arrows' half of the selection, which the pointer's half writes by hand in OnPointerPressed. See
// OnCardSelectionChanged for why this is not simply a two-way binding.
Board.AddHandler(SelectingItemsControl.SelectionChangedEvent, OnCardSelectionChanged);
// Tunnelled, because a section's list answers Enter itself and nothing bubbles past it.
Board.AddHandler(KeyDownEvent, OnCardEnter, RoutingStrategies.Tunnel);
// ◆ The band is the scroller's rather than any one section list's, because the space it is dragged
// out over is mostly not a list's: a WrapPanel of cards is exactly as tall as its cards, and the gaps
// between sections and below the last one belong to the stack around them. Tunnelled for the reason
// the board's own press is, and it runs first, so it has to recognise a press on a card and leave it
// alone.
Scroll.AddHandler(PointerPressedEvent, OnBandPressed, RoutingStrategies.Tunnel);
Scroll.PointerMoved += OnBandMoved;
Scroll.PointerReleased += OnBandReleased;
Scroll.PointerCaptureLost += OnBandCaptureLost;
}
///
/// Null before the window has handed one over, and while the previewer is showing this control with no
/// data context at all. Every handler below checks rather than assuming.
///
private VaultViewModel? Vault => DataContext as VaultViewModel;
///
/// Where the keyboard should land when the terminal hands it back.
///
///
///
/// Exposed as a property rather than left for the window to find by name, because the name is inside
/// this control's template and the window cannot see it.
///
///
/// It has to be a control the keyboard can actually go to. Focus() on a collapsed control is
/// measurably a no-op and is not replayed when the control is revealed, so handing the keyboard to
/// something that is not there would swallow it. Board is focusable and holds every section, so it
/// answers as long as one card is on it; an empty board is what a filter matching nothing produces, and
/// the find box is the answer then — it is where they were typing.
///
///
internal IInputElement KeyboardTarget =>
Vault is { HasHostBoardEntries: true } ? Board : HostFilter;
///
/// Fire-and-forget, as the transfers screen's is: the command reports its own failures onto the status
/// line — an unknown host key, a refused password — and awaiting it here would mean an event handler
/// returning a task nothing observes.
///
private void OnHostActivated(object? sender, TappedEventArgs e)
{
// Only over a card. A double-tap on the space around them, or on a section heading, must not connect
// to whichever host was selected before — which is what an unguarded handler would do, on a machine
// the user is not even pointing at.
if (Vault is { } vault && RowUnder(e.Source) is HostRowViewModel)
{
_ = vault.ConnectCommand.ExecuteAsync(null);
}
}
///
/// Points the menu at whatever was right-clicked.
///
///
///
/// The menu's commands read the vault's host selection, and a right click does not move it — which would
/// mean a menu that quietly acted on whichever host happened to be selected instead of the one under the
/// pointer. Deleting the wrong machine is the version of that mistake worth designing against.
///
///
/// ◆ A right click outside the ticked set drops the set, and one inside it keeps it. That is the
/// same rule as the plain press below, and it is what makes the two halves of the menu safe to draw from
/// one markup: the entries about a set and the entries about a selection are never both meaningful, so
/// Delete… can never be a question about the card under the pointer asked while six others sit ticked
/// behind the menu.
///
///
/// Cancelled outright over the space around the cards, or on a section heading. Neither is a host, and a
/// menu offering Connect, Edit and Delete over either would be entries that either do nothing or act on
/// something else entirely.
///
///
private void OnContextRequested(object? sender, ContextRequestedEventArgs e)
{
if (Vault is not { } vault || RowUnder(e.Source) is not HostRowViewModel row)
{
e.Handled = true;
return;
}
if (vault.IsChoosingHosts && !row.IsChosen)
{
vault.ClearHostChoiceCommand.Execute(null);
}
if (!vault.IsChoosingHosts)
{
vault.SelectedHost = row;
}
}
///
/// Ticks cards, or moves the selection.
///
///
///
/// ◆ Ctrl and Shift are answered here and go no further. Both mark the event handled, which is
/// what stops whichever section's ListBox the press landed in from moving its own selection onto
/// the card: a Ctrl-click that also selected would light the card it had just unticked, and the drawer
/// would open on a machine the user was removing from a set. Handled on the way down is the only place
/// that can be said — by the time the press bubbles the control has already answered it.
///
///
/// A plain press moves the selection and drops the chosen set, which is every file manager's rule
/// and the reason the two selections on this screen can never disagree: after an ordinary click there is
/// exactly one card in play. Not marked handled — the section list's own native selection is left to
/// follow along, which is harmless now that it is only OneWay bound: whatever it shows locally is
/// overwritten the moment 's change reaches every section again.
///
///
/// Nothing here refuses while the drawer's editor is open, and the phone's own ChooseHost does.
/// The difference is real: there a sheet is over the list and the row under the finger is not what was
/// aimed at, where the board sits beside the editor in plain view. Ticking is free anyway — the seven
/// things that can then be done to a set each refuse for themselves, and say so.
///
///
private void OnPointerPressed(object? sender, PointerPressedEventArgs e)
{
if (Vault is not { } vault
|| !e.GetCurrentPoint(Board).Properties.IsLeftButtonPressed
|| RowUnder(e.Source) is not HostRowViewModel row)
{
return;
}
var control = e.KeyModifiers.HasFlag(KeyModifiers.Control);
if (e.KeyModifiers.HasFlag(KeyModifiers.Shift))
{
vault.ChooseHostRun(anchor ?? vault.SelectedHost, row, replacing: !control);
Board.Focus();
e.Handled = true;
return;
}
if (control)
{
// Extend rather than toggle: the set this starts has the lit card in it, which is the half a
// plain toggle left out. See VaultViewModel.ExtendHostChoice.
vault.ExtendHostChoiceCommand.Execute(row);
anchor = row;
Board.Focus();
e.Handled = true;
return;
}
anchor = row;
if (vault.IsChoosingHosts)
{
vault.ClearHostChoiceCommand.Execute(null);
}
vault.SelectedHost = row;
}
///
/// Esc drops the set, and Ctrl+A is every card on the board.
///
///
///
/// Every card on the board: , which is every section
/// with whatever the find box and the two toolbar flyouts have already narrowed it to, and every card a
/// fold has not hidden. Ctrl+A over a filtered board that quietly ticked machines it is not showing would
/// be the worst possible input to Delete.
///
///
/// Handled only when they did something. Esc has other jobs on this window — it closes the palette, and
/// it cancels the terminal's own things — and swallowing it here while nothing is ticked would take it
/// away from whichever of those the user meant.
///
///
private void OnGridKey(object? sender, KeyEventArgs e)
{
if (Vault is not { } vault)
{
return;
}
if (e.Key is Key.Escape && vault.IsChoosingHosts)
{
vault.ClearHostChoiceCommand.Execute(null);
e.Handled = true;
return;
}
// An arrow with the board itself focused — which is where this screen puts the keyboard, see
// KeyboardTarget — goes into the cards: onto the selected one, or the first. Otherwise no arrow ever
// reaches a section's list, since none of them has the keyboard until a card has been clicked.
if (e.Key is Key.Up or Key.Down or Key.Left or Key.Right && ReferenceEquals(e.Source, Board))
{
e.Handled = EnterTheCards(vault);
return;
}
if (e.Key is Key.A && e.KeyModifiers.HasFlag(KeyModifiers.Control) && vault.HasHostBoardEntries)
{
var order = vault.HostBoardOrder.ToList();
vault.ChooseHosts(order, replacing: true);
anchor = order[0];
e.Handled = true;
}
}
///
/// Starts a band on the empty space between and below the cards.
///
///
///
/// ◆ Only where there is nothing to press. The scroller holds every section heading, every card
/// list and whichever panel the set's menu raised, and a rectangle dragged out from inside any of those
/// would be a gesture aimed at hosts started on something that is not one. is
/// the guard, and it is ancestor-based rather than naming one control, which is what lets it work
/// regardless of how many section lists happen to be realized.
///
///
/// The pointer is captured, because a band is nearly always dragged past the edge of the control it
/// started in — down onto the status bar, or off the window entirely — and without capture the moves
/// stop arriving and the release lands somewhere else, leaving a rectangle painted over the board with
/// nothing left to take it down.
///
///
/// Nothing is ticked or unticked here. A press is not yet a band and may never become one; what a click
/// on the empty space means is decided on the release. See .
///
///
/// Enter on a card is the double-press, for somebody who got there with the arrows.
///
/// Only on a card, for the reason gives: Enter with the board itself focused
/// would connect to whatever was selected before, which is not something anyone is looking at. And not
/// while cards are ticked, where the selection is not what the set is about.
///
private void OnCardEnter(object? sender, KeyEventArgs e)
{
if (e.Key is not Key.Enter
|| e.KeyModifiers != KeyModifiers.None
|| Vault is not { IsChoosingHosts: false } vault
|| RowUnder(e.Source) is not HostRowViewModel row)
{
return;
}
vault.SelectedHost = row;
_ = vault.ConnectCommand.ExecuteAsync(null);
e.Handled = true;
}
/// Writes a selection the arrows made in one section's list back to the vault.
///
///
/// The cards' SelectedItem is one-way, for the reason the markup gives: several lists rebuilt
/// independently would each null the vault's selection on every filter keystroke and every sync pass. So
/// the pointer writes it by hand, and until this nothing wrote it for the arrows — a card lit by the
/// keyboard was not the one the drawer's CONNECT and DELETE then acted on, which is the same mistake the
/// right-click handler exists to prevent.
///
///
/// ◆ Only from the list that has the keyboard, and only for a card. A rebuild's reset arrives as a change
/// to nothing, and the binding's own refills of the lists nobody is in arrive without the keyboard — both
/// are exactly the writes the one-way binding keeps out, and they stay out. A click arrives here too, after
/// has already written the same card, and changes nothing.
///
///
private void OnCardSelectionChanged(object? sender, SelectionChangedEventArgs e)
{
if (Vault is not { } vault
|| e.Source is not ListBox { IsKeyboardFocusWithin: true, SelectedItem: HostRowViewModel row }
|| ReferenceEquals(row, vault.SelectedHost))
{
return;
}
if (vault.IsChoosingHosts)
{
vault.ClearHostChoiceCommand.Execute(null);
}
anchor = row;
vault.SelectedHost = row;
}
/// Hands the keyboard from the board to a card: the selected one if it is drawn, else the first.
private bool EnterTheCards(VaultViewModel vault)
{
var cards = Board.GetVisualDescendants().OfType().Where(card => card.IsEffectivelyVisible).ToList();
var card = cards.Find(card => ReferenceEquals(card.DataContext, vault.SelectedHost)) ?? cards.FirstOrDefault();
if (card?.DataContext is not HostRowViewModel row)
{
return false;
}
vault.SelectedHost = row;
anchor = row;
return card.Focus(NavigationMethod.Directional);
}
private void OnBandPressed(object? sender, PointerPressedEventArgs e)
{
EndBand();
if (Vault is null
|| !e.GetCurrentPoint(Scroll).Properties.IsLeftButtonPressed
|| TakesThePress(e.Source))
{
return;
}
banding = true;
bandFrom = e.GetPosition(Scroll);
bandAdds = e.KeyModifiers.HasFlag(KeyModifiers.Control);
e.Pointer.Capture(Scroll);
Board.Focus();
}
///
/// The rectangle is drawn and the set is rewritten on every move, so what is ticked is what the band is
/// over at that moment — including the cards it has just been pulled back off. A band that only ever
/// added would make overshooting it unrecoverable without starting again. Ctrl is the exception and is
/// the reason it is a mode read once: with it held the band adds to what was already ticked, which is how
/// a second run is picked up without losing the first.
///
private void OnBandMoved(object? sender, PointerEventArgs e)
{
if (!banding || Vault is not { } vault)
{
return;
}
if (!e.GetCurrentPoint(Scroll).Properties.IsLeftButtonPressed)
{
EndBand();
return;
}
var at = e.GetPosition(Scroll);
var box = new Rect(
Math.Min(bandFrom.X, at.X),
Math.Min(bandFrom.Y, at.Y),
Math.Abs(at.X - bandFrom.X),
Math.Abs(at.Y - bandFrom.Y));
if (box.Width < DragThreshold && box.Height < DragThreshold)
{
return;
}
Band.Margin = new Thickness(box.X, box.Y, 0, 0);
Band.Width = box.Width;
Band.Height = box.Height;
Band.IsVisible = true;
vault.ChooseHosts(CardsIn(box), replacing: !bandAdds);
}
///
/// A press and a release with no band between them is a click on the space around the cards, and that
/// drops the set — the same thing a plain click on a card does, and the way out of selection mode for
/// anybody who never finds Esc. Where a band was drawn the moves have already said what is
/// ticked, and re-applying it here would only repeat the last one.
///
private void OnBandReleased(object? sender, PointerReleasedEventArgs e)
{
if (!banding)
{
return;
}
var drawn = Band.IsVisible;
EndBand();
e.Pointer.Capture(null);
if (!drawn && Vault is { IsChoosingHosts: true } vault)
{
vault.ClearHostChoiceCommand.Execute(null);
}
}
///
/// The band is taken down and nothing is decided. Capture is lost when a menu opens over the drag, when
/// the window is deactivated, and when the platform simply takes it — none of which is the user saying
/// what they wanted; leaving the rectangle up would be the only visible consequence.
///
private void OnBandCaptureLost(object? sender, PointerCaptureLostEventArgs e) => EndBand();
private void EndBand()
{
banding = false;
Band.IsVisible = false;
}
/// The hosts whose cards a rectangle over the scroller touches.
///
/// Touches rather than contains, which is what makes a band usable at all: a rectangle that had to
/// swallow a card whole would tick nothing for a band drawn down the middle of a column. Gathered from
/// every section's own list — see — rather than one named control, since
/// a band drawn across two sections has to touch cards in both.
///
private List CardsIn(Rect box)
{
var hit = new List();
foreach (var container in AllCardContainers())
{
if (container.DataContext is HostRowViewModel row
&& container.TranslatePoint(default, Scroll) is { } corner
&& box.Intersects(new Rect(corner, container.Bounds.Size)))
{
hit.Add(row);
}
}
return hit;
}
/// Every realized card, across every section's own list.
///
/// A section is a ListBox of its own — see the type's remarks — so there is no single control
/// whose GetRealizedContainers() would answer for the whole board. Found by class rather than by
/// name, because how many sections exist is a fact about the keychain rather than the markup: a flat
/// keychain draws one, a filed one draws several, and neither shape is known until the vault says so.
///
private List AllCardContainers() =>
[.. this.GetVisualDescendants()
.OfType()
.Where(list => list.Classes.Contains("sectioncards"))
.SelectMany(list => list.GetRealizedContainers())
.OfType()];
/// Whether what was pressed is something that answers a press itself.
///
/// Everything a band must not start from, asked as "is this inside one" rather than by hit-testing a
/// rectangle: the cards, the scrollbar, and the controls on whichever panel is up or in a section's own
/// heading. Missing the scrollbar is the one that would be felt every day — dragging the thumb would
/// paint a band down the board and tick everything it passed.
///
private static bool TakesThePress(object? source) => source is Visual visual
&& visual.GetSelfAndVisualAncestors().Any(element =>
element is ListBoxItem or ScrollBar or Button or ComboBox or TextBox);
/// The view model of the grid item an event happened on, if it happened on a host card.
private static HostRowViewModel? RowUnder(object? source) =>
Container(source)?.DataContext as HostRowViewModel;
///
/// Walks up from whatever was actually hit — a text block, a border, the card's own grid — because that
/// is what an event's source is. Anything not inside a card, which includes a section's own heading and
/// the space around them, yields null.
///
private static ListBoxItem? Container(object? source) => source is Visual visual
? visual.FindAncestorOfType(includeSelf: true)
: null;
}