using DodoSSH.Client.App.ViewModels;
using DodoSSH.Client.Session;

// FakeDeviceKeyStore is compiled into this assembly from a source link and keeps its original namespace;
// see the csproj for why it is shared rather than reimplemented.
using DodoSSH.Client.Session.Tests;
using DodoSSH.Client.Ssh;
using DodoSSH.Client.Storage;
using DodoSSH.Client.Terminal;
using DodoSSH.Crypto;

namespace DodoSSH.Client.App.Tests;

/// <summary>
/// Teams, from the side that holds the keys: create one, add somebody, and wrap a vault key to them.
/// </summary>
/// <remarks>
/// <para>
/// The reason this suite exists rather than leaving teams to the server's own tests is that the
/// interesting half is not on the server. Adding a member is a row; <b>sharing is a decision the client
/// makes about whether to trust a public key the server just handed it</b>, and that decision is what
/// stands between an end-to-end encrypted vault and one the operator can read by answering a directory
/// lookup with a key of their own.
/// </para>
/// <para>
/// So the fake server keeps a real key log — chained with the same <c>KeyLogChain</c> the server uses —
/// and can be told to corrupt it. A test that only ever saw a well-formed log would be checking that
/// sharing works, not that verification does.
/// </para>
/// </remarks>
public sealed class TeamSharingTests : IAsyncLifetime
{
    private const string Passphrase = "a sufficiently long passphrase";

    private static readonly Argon2Profile CheapProfile =
        Argon2Profile.FromStoredParameters(memoryKibibytes: 8 * 1024, passes: 1, parallelism: 1);

    private readonly FakeVaultServer server = new();
    private readonly FakeSshConnectionFactory ssh = new();

    private string directory = null!;
    private ClientCacheFactory caches = null!;
    private TerminalWorkspace workspace = null!;
    private VaultKnownHostStore knownHosts = null!;
    private FakeDeviceKeyStore deviceKeys = null!;
    private MainWindowViewModel shell = null!;

    private static CancellationToken Token => TestContext.Current.CancellationToken;

    /// <inheritdoc />
    public ValueTask InitializeAsync()
    {
        directory = Path.Combine(Path.GetTempPath(), $"dodossh-teams-{Guid.CreateVersion7():N}");

        var paths = new ClientPaths(directory);

        caches = ClientCacheFactory.ForFile(paths.CacheFile);
        knownHosts = new VaultKnownHostStore();
        deviceKeys = new FakeDeviceKeyStore();

        workspace = new TerminalWorkspace(
            new InMemoryTerminalAssetProvider(
                new Dictionary<string, TerminalAsset>(StringComparer.Ordinal)),
            ssh,
            TimeProvider.System);

        shell = new MainWindowViewModel(
            paths,
            caches,
            workspace,
            knownHosts,
            deviceKeys,
            (_, _) => Task.FromResult<IVaultServer>(server),
            TimeProvider.System,
            NSubstitute.Substitute.For<ISftpSessionFactory>(),
            CheapProfile);

        return ValueTask.CompletedTask;
    }

    /// <inheritdoc />
    public async ValueTask DisposeAsync()
    {
        await shell.DisposeAsync();
        knownHosts.Close();
        await workspace.DisposeAsync();
        caches.Dispose();

        try
        {
            Directory.Delete(directory, recursive: true);
        }
        catch (IOException)
        {
            // A cache file the process has not finished releasing. The directory is under the temp path
            // and named per run, so leaving it costs a few kilobytes and never collides.
        }
    }

    /// <remarks>
    /// The whole point of a team, in one test. Note what the status line says after the add and before
    /// the share: adding somebody grants them nothing readable, and the interface has to say so rather
    /// than let a user believe the credential is already with their colleague.
    /// </remarks>
    [Fact]
    public async Task CreatingATeamAndSharingItsVault_WrapsTheKeyToTheOtherMember()
    {
        await UnlockedAsync();

        var teams = shell.Teams;
        var colleague = server.AddAccount("bob@example.com", "Bob Example");

        await CreateTeamAsync(teams, "Platform", "platform");

        await teams.CreateVaultCommand.ExecuteAsync(null);
        teams.Vaults.Count.ShouldBe(1, teams.Status);

        teams.InviteEmail = "bob@example.com";
        await teams.AddMemberCommand.ExecuteAsync(null);

        teams.Members.Count.ShouldBe(2, teams.Status);
        teams.Status.ShouldContain("cannot read anything yet");

        teams.SelectedMember = teams.Members.Single(member => member.UserId == colleague);
        teams.SelectedVault = teams.Vaults[0];

        await teams.ShareVaultCommand.ExecuteAsync(null);

        var vaultId = teams.Vaults[0].VaultId;

        server.IssuedGrants.ShouldContainKey((vaultId, colleague));
        teams.Status.ShouldContain("Shared");

        // The one thing verification cannot promise, said in the same breath as the success.
        teams.Status.ShouldContain("fingerprint", Case.Insensitive);
    }

    /// <remarks>
    /// <para>
    /// The test this whole design exists for. A server that wants to read a team's vault only has to
    /// answer one directory lookup with a key it holds the private half of — so the client reads the
    /// append-only key log, verifies its chain, and refuses to wrap anything unless the key it was
    /// offered is in there unchanged.
    /// </para>
    /// <para>
    /// Nothing may be sent. A refusal that still issued the grant, or that issued it on a retry, would be
    /// worse than no check at all, because the interface would have said it was verified.
    /// </para>
    /// </remarks>
    [Fact]
    public async Task ATamperedKeyLog_StopsTheShareRatherThanWarningAboutIt()
    {
        await UnlockedAsync();

        var teams = shell.Teams;
        var colleague = server.AddAccount("mallory@example.com", "Mallory Example");

        await CreateTeamAsync(teams, "Platform", "platform");
        await teams.CreateVaultCommand.ExecuteAsync(null);

        teams.InviteEmail = "mallory@example.com";
        await teams.AddMemberCommand.ExecuteAsync(null);

        teams.SelectedMember = teams.Members.Single(member => member.UserId == colleague);
        teams.SelectedVault = teams.Vaults[0];

        server.CorruptKeyLog = true;

        await teams.ShareVaultCommand.ExecuteAsync(null);

        server.IssuedGrants.ShouldBeEmpty();
        teams.Status.ShouldContain("Did not share");
        teams.Status.ShouldContain("key log");
    }

    /// <remarks>
    /// A vault created here is usable here, without a relock. The key was generated in this process, so
    /// making the user lock and unlock to reach the vault they just made would be asking them to work
    /// around bookkeeping.
    /// </remarks>
    [Fact]
    public async Task ATeamVaultCreatedHere_IsImmediatelyReadableAndWritable()
    {
        await UnlockedAsync();

        var teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");
        await teams.CreateVaultCommand.ExecuteAsync(null);

        var vaultId = teams.Vaults[0].VaultId;
        var session = shell.Vault!.Session;

        session.ReadableVaults.Select(vault => vault.VaultId).ShouldContain(vaultId);

        // And it is offered as somewhere to file a new item, which is what makes it worth having.
        await shell.Vault.LoadAsync(Token);

        shell.Vault.TargetVaults.Select(choice => choice.VaultId).ShouldContain(vaultId);
        shell.Vault.HasVaultChoice.ShouldBeTrue();
    }

    /// <remarks>
    /// Filing into a team vault has to be chosen and has to stick. The bug this guards is the obvious
    /// one: an editor that read the picker at save time rather than at open time, so changing the picker
    /// with a half-typed host on screen would move it.
    /// </remarks>
    [Fact]
    public async Task AHostFiledIntoATeamVault_StaysThere()
    {
        await UnlockedAsync();

        var teams = shell.Teams;

        await CreateTeamAsync(teams, "Platform", "platform");
        await teams.CreateVaultCommand.ExecuteAsync(null);

        var vault = shell.Vault!;
        var teamVaultId = teams.Vaults[0].VaultId;

        await vault.LoadAsync(Token);

        vault.SelectedTargetVault =
            vault.TargetVaults.Single(choice => choice.VaultId == teamVaultId);

        vault.NewHostCommand.Execute(null);
        vault.EditorLabel = "prod-db";
        vault.EditorHostname = "db.internal";
        vault.EditorUsername = "deploy";

        // Moved back after the editor opened. The host must still land in the team's vault.
        vault.SelectedTargetVault =
            vault.TargetVaults.First(choice => choice.VaultId != teamVaultId);

        await vault.SaveHostCommand.ExecuteAsync(null);

        var row = vault.Hosts.Single(
            host => string.Equals(host.Label, "prod-db", StringComparison.Ordinal));
        row.VaultId.ShouldBe(teamVaultId);
    }

    private async Task CreateTeamAsync(TeamsViewModel teams, string name, string slug)
    {
        await teams.LoadAsync(Token);

        teams.NewTeamCommand.Execute(null);
        teams.NewTeamName = name;
        teams.NewTeamSlug = slug;

        await teams.CreateTeamCommand.ExecuteAsync(null);

        teams.SelectedTeam.ShouldNotBeNull(teams.Status);
    }

    /// <remarks>
    /// The whole path rather than a shortcut into the unlocked state, because sharing needs an identity
    /// key that was really enrolled: the fake server publishes it into its key log during enrollment, and
    /// that entry is what the client verifies its own directory answer against.
    /// </remarks>
    private async Task UnlockedAsync()
    {
        await shell.StartAsync(Token);
        await shell.SignInCommand.ExecuteAsync(null);

        shell.Passphrase = Passphrase;
        shell.ConfirmPassphrase = Passphrase;
        await shell.EnrollCommand.ExecuteAsync(null);

        shell.RecoveryCodeWrittenDown = true;
        shell.ConfirmRecoveryCodeCommand.Execute(null);

        shell.Passphrase = Passphrase;
        await shell.UnlockCommand.ExecuteAsync(null);

        shell.State.ShouldBe(ShellState.Unlocked, shell.StatusMessage);
    }
}