DodoSSH/src/DodoSSH.Client.Android/Views/PreferencesScreen.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:vm="using:DodoSSH.Client.Shell.ViewModels"
             x:Class="DodoSSH.Client.Android.Views.PreferencesScreen"
             x:DataType="vm:MainWindowViewModel"
             Background="{StaticResource Canvas}">

  <!--
    Design v2 — PREFERENCES, and the phone's counterpart of the desktop head's screen of the same name.

    It exists for one setting: whether this phone may open the keychain with a fingerprint. That is the
    setting the whole Android device key store was built for — AndroidDeviceKeyStore and BiometricGate have
    been in this head since it was written — and until this screen there was nowhere to turn it on. The
    lock screen offers UNLOCK WITH FINGERPRINT only when a device key exists, and nothing on the phone could
    make one, so on a phone that button could never appear. This is the missing half.

    Registering has to happen from an unlocked keychain and cannot happen from the lock screen, which is why
    it is here rather than beside the button it enables: sealing this phone's device key needs the vault
    open, and the wrap has to reach the server or it could never be revoked from a phone that was lost. See
    MainWindowViewModel.RegisterDeviceAsync.

    Everything the desktop's screen carries and this one does not is stated at the foot rather than left
    out, exactly as the desktop states its own gaps. A preferences screen that is silent about what it has
    not got reads as a product with one preference.
  -->

  <ScrollViewer>
    <StackPanel Margin="16,0,16,24" Spacing="0">

      <TextBlock Classes="section" Text="THIS PHONE" Margin="6,4,0,0" />

      <!--
        The offer and the withdrawal share this card and never show together: one is "there is no device key
        here", the other is "there is". Neither appears on a phone that cannot hold one at all — a handset
        with no screen lock — and that third case is the paragraph under them, because a card with nothing
        in it would read as a setting that failed to load.
      -->
      <Border Classes="card" Margin="0,10,0,0">
        <StackPanel Spacing="10">

          <StackPanel Orientation="Horizontal" Spacing="9">
            <!-- The lock screen draws the same ring beside its own fingerprint button. -->
            <Ellipse Width="16" Height="16" Stroke="{StaticResource Accent}" StrokeThickness="1.5"
                     VerticalAlignment="Center" />
            <TextBlock FontSize="14.5" FontWeight="SemiBold" Foreground="{StaticResource Text}" Text="Unlock with a fingerprint" />
          </StackPanel>

          <TextBlock Classes="body"
                     Text="Registers this phone so a later launch can open the keychain with your fingerprint — or this phone's PIN — instead of your passphrase. The key is held by the phone's secure hardware and never leaves it, and your passphrase keeps working." />

          <Button Classes="primary" Content="REGISTER THIS PHONE"
                  Command="{Binding RegisterDeviceCommand}"
                  IsEnabled="{Binding !IsBusy}"
                  IsVisible="{Binding CanRegisterDevice}" />

          <!--
            No confirmation, deliberately, and the desktop's button says the same in a tooltip this head has
            no room for — so the sentence above it carries it instead. Somebody pressing this has realised a
            phone is in the wrong hands, and the cost of a wrong press is one passphrase.
          -->
          <StackPanel Spacing="8" IsVisible="{Binding CanForgetDevice}">
            <TextBlock Classes="detail" TextWrapping="Wrap"
                       Text="registered · this phone can open the keychain without your passphrase" />
            <Button Classes="danger" Content="STOP UNLOCKING HERE"
                    Command="{Binding ForgetDeviceCommand}"
                    IsEnabled="{Binding !IsBusy}" />
          </StackPanel>

          <!--
            Neither flag is set on a phone with no screen lock, and that is worth saying: Android will
            generate a key that requires authentication on such a phone and then no gesture can ever release
            it, which is why AndroidDeviceKeyStore reports itself unavailable rather than offering one.
          -->
          <TextBlock Classes="body" IsVisible="{Binding HasNoDeviceKeyOption}"
                     Text="This phone has nowhere to keep a device key, so the keychain will keep asking for your passphrase. That needs a screen lock with a fingerprint or a PIN enrolled on the phone itself." />

        </StackPanel>
      </Border>

      <!-- Where registering, withdrawing and a declined prompt all answer. -->
      <TextBlock Classes="body" Margin="6,12,6,0" TextAlignment="Center"
                 Text="{Binding StatusMessage}" />

      <!-- ============ ◆ updates ============ -->
      <!--
        The phone's copy of the desktop's UPDATES section, over the same view model. What differs is the
        last step and only the last step: pressing INSTALL hands the package to Android's own installer
        rather than swapping files, so the platform draws a confirmation this application does not control
        and the answer may be no. Everything before that — the timer, the quiet background pass, the loud
        pressed one, the fetch — is shared. See AndroidUpdateChannel and ADR 0014.

        The version is a fact, printed, in the shape ACCOUNT uses on the desktop. It comes from the
        assembly's own informational version rather than from the updater, so it answers on a build run
        from a checkout too; see ClientVersion.Current.

        The sentence about where builds come from is ADR 0011 rule 2 in plain words, and it is on the head
        the rule was written for: no DodoSSH server will ever offer you the client, and one that does is not
        one to trust.
      -->
      <TextBlock Classes="section" Text="UPDATES" Margin="6,26,0,0" />

      <Border Classes="card" Margin="0,10,0,0">
        <StackPanel Spacing="10">
          <Grid ColumnDefinitions="Auto,*">
            <TextBlock Grid.Column="0" Classes="label" Text="VERSION" VerticalAlignment="Center" />
            <TextBlock Grid.Column="1" Classes="mono" FontSize="13" Margin="10,0,0,0"
                       HorizontalAlignment="Right" TextTrimming="CharacterEllipsis"
                       Text="{Binding Updates.CurrentVersion}" />
          </Grid>

          <StackPanel Spacing="10" IsVisible="{Binding Updates.IsSupported}">

            <CheckBox MinHeight="44" IsChecked="{Binding Updates.IsAutomatic}">
              <TextBlock Classes="mono" FontSize="11.5" TextWrapping="Wrap"
                         Text="Look for newer builds on their own" />
            </CheckBox>

            <TextBlock Classes="body"
                       Text="Checks come from the project's own release page and never from the server you sign in to. Nothing is installed without you saying so, and Android asks again in its own words before anything is replaced." />

            <!--
              The bar, copying the desktop's and the transfers screen's. Shown while fetching and not
              before: a bar at zero beside a button nobody has pressed is a screen that looks busy.
            -->
            <ProgressBar IsVisible="{Binding Updates.IsDownloading}" Height="4"
                         Minimum="0" Maximum="100" Value="{Binding Updates.DownloadPercent}" />

            <Button Classes="secondary" Height="44" Content="CHECK NOW"
                    Command="{Binding Updates.CheckNowCommand}"
                    IsEnabled="{Binding Updates.CanCheckNow}" />

            <!--
              INSTALL rather than the desktop's RESTART NOW, and the word is the honest one: this does not
              restart anything. It asks Android to install, and Android asks the user. What follows is the
              system's screen, not this one.
            -->
            <Button Classes="primary" Height="44" Content="INSTALL"
                    IsVisible="{Binding Updates.IsReady}"
                    Command="{Binding Updates.RestartNowCommand}" />

            <TextBlock Classes="body" IsVisible="{Binding Updates.IsReady}"
                       Text="{Binding Updates.RestartWarning}" />

            <TextBlock Classes="detail" TextWrapping="Wrap" Text="{Binding Updates.Status}"
                       IsVisible="{Binding Updates.Status, Converter={x:Static StringConverters.IsNotNullOrEmpty}}" />
          </StackPanel>

          <!--
            The build that cannot replace itself, which on this head is one an IDE deployed or one built
            from a checkout — see AndroidUpdateChannels.ForThisPhone. Said rather than shown as dead
            controls, following HasNoDeviceKeyOption above.
          -->
          <TextBlock Classes="body" IsVisible="{Binding Updates.IsUnsupported}"
                     Text="This build cannot replace itself — it was not installed from the project's release page. A newer DodoSSH is an APK from there, installed the way a released one would be. No DodoSSH server will ever offer you one, whatever it says; a server that does is not a server to trust." />
        </StackPanel>
      </Border>

      <TextBlock Classes="section" Text="NOT HERE" Margin="6,26,0,0" />

      <Border Classes="card" Margin="0,10,0,0">
        <StackPanel Spacing="9">
          <TextBlock Classes="body"
                     Text="Text size is on the terminal itself, where the text is — the phone puts A− and A+ in the shell's own bar rather than a step away from what they resize." />
          <TextBlock Classes="body"
                     Text="Importing an ~/.ssh/config has no meaning on Android: scoped storage means there is no such file for this application to read." />
          <TextBlock Classes="body"
                     Text="Importing a Hetzner Cloud project would work here — it is a token and a network request, not a file — and the wizard behind it is already shared. What is missing is a phone layout for it: the desktop draws a five-column table, and the screen it would become is not the desktop's with narrower columns. Until then it is a thing to do on a desktop; the hosts it makes sync here like any other." />
          <TextBlock Classes="body"
                     Text="Signing out is on the lock screen, where somebody who has forgotten their passphrase can reach it without unlocking anything first." />
        </StackPanel>
      </Border>

    </StackPanel>
  </ScrollViewer>

</UserControl>