using DodoSSH.Client.Domain;
using DodoSSH.Client.Storage;
using DodoSSH.Crypto;

namespace DodoSSH.Client.Sync.Tests;

/// <summary>
/// One machine: its own cache, its own outbox, its own view of the vault.
/// </summary>
/// <remarks>
/// A separate SQLite database per device, because the whole subject of these tests is two caches
/// diverging and being reconciled. Sharing one would make every conflict test vacuous.
/// </remarks>
internal sealed class SyncDevice : IDisposable
{
    private readonly ClientCacheFactory factory;
    private readonly MasterKey master;
    private readonly LocalCacheProtector protector;

    private SyncDevice(
        string name,
        ClientCacheFactory factory,
        MasterKey master,
        LocalCacheProtector protector,
        VaultKeyring keyring,
        FakeVaultServer server,
        SyncOptions options)
    {
        Name = name;
        this.factory = factory;
        this.master = master;
        this.protector = protector;
        Keyring = keyring;

        Items = new ItemStore(factory, protector);
        Outbox = new OutboxStore(factory, protector, TimeProvider.System);
        SyncState = new SyncStateStore(factory);
        Conflicts = new ConflictStore(factory, protector, TimeProvider.System);
        Hosts = new HostRepository(Items, Outbox, keyring);

        Engine = new SyncEngine(
            server, Items, Outbox, SyncState, Conflicts, keyring, TimeProvider.System, options);
    }

    internal string Name { get; }

    internal VaultKeyring Keyring { get; }

    internal ItemStore Items { get; }

    internal OutboxStore Outbox { get; }

    internal SyncStateStore SyncState { get; }

    internal ConflictStore Conflicts { get; }

    internal HostRepository Hosts { get; }

    internal SyncEngine Engine { get; }

    internal static async Task<SyncDevice> CreateAsync(
        string name,
        UserSecretBundle bundle,
        StoredVault vault,
        FakeVaultServer server,
        SyncOptions options)
    {
        var cache = ClientCacheFactory.ForMemory($"sync-{name}-{Guid.CreateVersion7():N}");

        try
        {
            await cache.MigrateAsync(TestContext.Current.CancellationToken);

            var derived = MasterKey.Derive(
                $"passphrase-{name}", new byte[CryptoSpec.SaltSize], SyncHarness.CheapProfile);

            // Opened through the real grant, so the keyring, the wrap and the AAD are all exercised.
            var keyring = VaultKeyring.Open(bundle, [vault]);

            return new SyncDevice(
                name, cache, derived, LocalCacheProtector.From(derived), keyring, server, options);
        }
        catch
        {
            cache.Dispose();
            throw;
        }
    }

    internal Task<SyncReport> SyncAsync() =>
        Engine.SyncAsync(SyncHarness.VaultId, TestContext.Current.CancellationToken);

    internal Task<HostListing> ListAsync() =>
        Hosts.ListAsync(SyncHarness.VaultId, TestContext.Current.CancellationToken);

    internal async Task<IReadOnlyList<HostSecret>> HostsSortedAsync()
    {
        var listing = await ListAsync();

        return [.. listing.Hosts.Select(h => h.Host).OrderBy(h => h.Label, StringComparer.Ordinal)];
    }

    internal async Task<VaultHost> FindAsync(Guid entityId)
    {
        var listing = await ListAsync();

        return listing.Hosts.SingleOrDefault(host => host.EntityId == entityId)
            ?? throw new InvalidOperationException($"{Name} cannot see host {entityId}.");
    }

    internal Task<Guid> CreateAsync(HostSecret host) =>
        Hosts.CreateAsync(SyncHarness.VaultId, host, TestContext.Current.CancellationToken);

    internal Task UpdateAsync(Guid entityId, HostSecret host) =>
        Hosts.UpdateAsync(SyncHarness.VaultId, entityId, host, TestContext.Current.CancellationToken);

    internal Task DeleteAsync(Guid entityId) =>
        Hosts.DeleteAsync(SyncHarness.VaultId, entityId, TestContext.Current.CancellationToken);

    internal Task<IReadOnlyList<StoredConflict>> ConflictsAsync() =>
        Conflicts.ListAsync(SyncHarness.VaultId, false, TestContext.Current.CancellationToken);

    /// <inheritdoc />
    public void Dispose()
    {
        Keyring.Dispose();
        protector.Dispose();
        master.Dispose();
        factory.Dispose();
    }
}

/// <summary>
/// One user, one vault, two machines and a server.
/// </summary>
/// <remarks>
/// Both devices share the identity bundle, which is what a single user on a laptop and a desktop
/// actually looks like: one enrolled key pair, one vault grant, two independent local caches. That is
/// also the cheapest realistic setup in which every conflict case can be produced.
/// </remarks>
internal sealed class SyncHarness : IDisposable
{
    internal static readonly Argon2Profile CheapProfile =
        Argon2Profile.FromStoredParameters(memoryKibibytes: 8 * 1024, passes: 1, parallelism: 1);

    private readonly UserSecretBundle bundle;

    private SyncHarness(UserSecretBundle bundle, FakeVaultServer server, SyncDevice first, SyncDevice second)
    {
        this.bundle = bundle;
        Server = server;
        First = first;
        Second = second;
    }

    internal static Guid VaultId { get; } = Guid.Parse("0192f0c8-7777-7c3d-8e4f-5a6b7c8d9e0f");

    internal FakeVaultServer Server { get; }

    /// <summary>The laptop.</summary>
    internal SyncDevice First { get; }

    /// <summary>The desktop.</summary>
    internal SyncDevice Second { get; }

    internal static async Task<SyncHarness> CreateAsync(SyncOptions? options = null)
    {
        var effective = options ?? SyncOptions.Default;

        var identity = UserSecretBundle.Create(DateTimeOffset.FromUnixTimeSeconds(1_700_000_000));

        try
        {
            var vaultKey = VaultKeys.Create();
            var wrapped = VaultKeys.WrapTo(vaultKey, identity.EncryptionPublicKey, VaultId, 1);

            // The plaintext key is not retained: each device unwraps the grant itself, as it would after
            // an ordinary unlock.
            System.Security.Cryptography.CryptographicOperations.ZeroMemory(vaultKey);

            var vault = new StoredVault(
                VaultId, "Personal", IsPersonal: true, TeamId: null, KeyGeneration: 1,
                Permissions: 31, wrapped, RekeyRequired: false);

            var server = new FakeVaultServer(VaultId);

            var first = await SyncDevice.CreateAsync("laptop", identity, vault, server, effective);

            try
            {
                var second = await SyncDevice.CreateAsync("desktop", identity, vault, server, effective);
                return new SyncHarness(identity, server, first, second);
            }
            catch
            {
                first.Dispose();
                throw;
            }
        }
        catch
        {
            identity.Dispose();
            throw;
        }
    }

    /// <summary>Brings both devices up to date, twice, so the result is a settled state.</summary>
    /// <remarks>
    /// Twice because one pass per device is not enough for a change made on one to be merged on the
    /// other and then pushed back. Asserting on a settled state rather than on an intermediate one is
    /// what makes "the two devices converge" a meaningful claim.
    /// </remarks>
    internal async Task SettleAsync()
    {
        for (var round = 0; round < 2; round++)
        {
            await First.SyncAsync();
            await Second.SyncAsync();
        }
    }

    /// <inheritdoc />
    public void Dispose()
    {
        First.Dispose();
        Second.Dispose();
        bundle.Dispose();
    }

    // ---- Builders ----

    internal static HostSecret Host(
        string label,
        string hostname = "db.internal",
        int port = 22,
        string? username = "deploy",
        string? notes = null,
        (string Name, string Value)[]? options = null,
        bool relayEnabled = false) =>
        new()
        {
            Label = label,
            Hostname = hostname,
            Port = port,
            Username = username,
            Notes = notes,
            Options = options is null
                ? HostOptions.Empty
                : HostOptions.Create(options.Select(o => new HostOption(o.Name, o.Value))),
            RelayEnabled = relayEnabled,
        };
}