using DodoSSH.Client.Session;

namespace DodoSSH.Client.Shell.ViewModels;

/// <summary>
/// The shell's half of a link from Spelunk: holding it until there is a vault to act on it.
/// </summary>
internal sealed partial class MainWindowViewModel
{
    /// <summary>
    /// Acts on a <c>dodossh://spelunk/connect</c> link now, or as soon as a vault is open.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Called by the head, on the UI thread, for a link this launch was started with, a link a second launch
    /// passed down the doorbell, or one the platform delivered to the running application. The link has
    /// already been checked by <see cref="SpelunkLink.TryParse"/>; what it may do is decided by
    /// <see cref="VaultViewModel.OpenSpelunkLinkAsync"/>, which never starts a sign-in by itself, and only
    /// connects through a Spelunk this device is already signed in to.
    /// </para>
    /// <para>
    /// <b>A locked application keeps it rather than dropping it.</b> Clicking a server in Spelunk and being
    /// asked for the passphrase is the ordinary first half of this; losing the click at the second half would
    /// make the button look broken. It is not kept across a restart.
    /// </para>
    /// </remarks>
    internal void OpenLink(SpelunkLink link)
    {
        ArgumentNullException.ThrowIfNull(link);

        pendingLink = link;

        if (State is ShellState.Unlocked && Vault is not null)
        {
            DeliverPendingLink();
            return;
        }

        if (State is ShellState.Locked)
        {
            StatusMessage = $"Unlock to open {link.Name} from Spelunk.";
        }
    }

    /// <summary>Hands a waiting link to the open vault, on the Hosts screen where its answer appears.</summary>
    private void DeliverPendingLink()
    {
        if (pendingLink is not { } link || Vault is not { } vault)
        {
            return;
        }

        pendingLink = null;

        ShowScreen(ShellScreen.Hosts);

        // Not awaited: a connect reports its own progress and failures on the vault's status line and in its
        // tab, as a tap on the row does, and this is called from places that must not wait on a handshake.
        _ = vault.OpenSpelunkLinkAsync(link);
    }
}