using System.Text.Json;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using ZB.MOM.WW.CBDDC.Core;
using ZB.MOM.WW.CBDDC.Core.Network;
using ZB.MOM.WW.CBDDC.Core.Storage;
using ZB.MOM.WW.CBDDC.Core.Sync;
using ZB.MOM.WW.CBDDC.Persistence;
using ZB.MOM.WW.CBDDC.Persistence.Surreal;

namespace ZB.MOM.WW.CBDDC.Sample.Console.Tests;

[Collection("SurrealCdcDurability")]
public class SurrealCdcDurabilityTests
{
    /// <summary>
    ///     Verifies checkpoints persist latest local changes per consumer across restarts.
    /// </summary>
    [Fact]
    public async Task CheckpointPersistence_ShouldTrackLatestLocalChange_AndPersistPerConsumer()
    {
        string dbPath = CreateTemporaryDatabasePath();
        const string nodeId = "node-checkpoint";
        const string defaultConsumer = "consumer-default";
        const string secondaryConsumer = "consumer-secondary";

        try
        {
            HlcTimestamp expectedTimestamp = default;
            string expectedHash = "";
            DateTimeOffset previousUpdatedUtc = DateTimeOffset.MinValue;

            await using (var harness = await CdcTestHarness.OpenWithRetriesAsync(dbPath, nodeId, defaultConsumer))
            {
                var user = CreateUser("checkpoint-user", "Alice", 30, "Austin");
                await harness.Context.Users.InsertAsync(user);
                await harness.Context.SaveChangesAsync();
                await harness.PollAsync();

                user.Age = 31;
                user.Address = new Address { City = "Dallas" };
                await harness.Context.Users.UpdateAsync(user);
                await harness.Context.SaveChangesAsync();
                await harness.PollAsync();

                await WaitForConditionAsync(
                    async () => (await harness.GetEntriesByKeyAsync("Users", "checkpoint-user")).Count >= 2,
                    "Timed out waiting for checkpoint-user oplog entries.");
                var entries = await harness.GetEntriesByKeyAsync("Users", "checkpoint-user");
                entries.Count.ShouldBe(2);

                expectedTimestamp = entries[^1].Timestamp;
                expectedHash = entries[^1].Hash;

                var checkpoint = await harness.CheckpointPersistence.GetCheckpointAsync();
                checkpoint.ShouldNotBeNull();
                checkpoint!.Timestamp.ShouldBe(expectedTimestamp);
                checkpoint.LastHash.ShouldBe(expectedHash);
                previousUpdatedUtc = checkpoint.UpdatedUtc;

                await harness.CheckpointPersistence.UpsertCheckpointAsync(
                    entries[0].Timestamp,
                    entries[0].Hash,
                    secondaryConsumer);

                var secondary = await harness.CheckpointPersistence.GetCheckpointAsync(secondaryConsumer);
                secondary.ShouldNotBeNull();
                secondary!.Timestamp.ShouldBe(entries[0].Timestamp);
                secondary.LastHash.ShouldBe(entries[0].Hash);
            }

            await using (var restarted = await CdcTestHarness.OpenWithRetriesAsync(dbPath, nodeId, defaultConsumer))
            {
                var restoredDefault = await restarted.CheckpointPersistence.GetCheckpointAsync();
                restoredDefault.ShouldNotBeNull();
                restoredDefault!.Timestamp.ShouldBe(expectedTimestamp);
                restoredDefault.LastHash.ShouldBe(expectedHash);
                restoredDefault.UpdatedUtc.ShouldBe(previousUpdatedUtc);

                var restoredSecondary = await restarted.CheckpointPersistence.GetCheckpointAsync(secondaryConsumer);
                restoredSecondary.ShouldNotBeNull();
                restoredSecondary!.LastHash.ShouldNotBe(restoredDefault.LastHash);
            }
        }
        finally
        {
            await DeleteDirectoryWithRetriesAsync(dbPath);
        }
    }

    /// <summary>
    ///     Verifies recovery resumes from a persisted checkpoint and advances after catch-up.
    /// </summary>
    [Fact]
    public async Task RestartRecovery_ShouldResumeCatchUpFromPersistedCheckpoint_InRocksDb()
    {
        string dbPath = CreateTemporaryDatabasePath();
        const string nodeId = "node-resume";
        const string consumerId = "consumer-resume";
        HlcTimestamp resumeTimestamp = default;
        string resumeHash = "";
        string expectedFinalHash = "";

        try
        {
            await using (var initial = await CdcTestHarness.OpenWithRetriesAsync(dbPath, nodeId, consumerId))
            {
                await initial.Context.Users.InsertAsync(CreateUser("resume-1", "User One", 18, "Rome"));
                await initial.Context.SaveChangesAsync();
                await initial.PollAsync();
                await initial.Context.Users.InsertAsync(CreateUser("resume-2", "User Two", 19, "Milan"));
                await initial.Context.SaveChangesAsync();
                await initial.PollAsync();

                await WaitForConditionAsync(
                    async () => (await initial.GetEntriesByCollectionAsync("Users")).Count >= 2,
                    "Timed out waiting for resume oplog entries.");
                var entries = await initial.GetEntriesByCollectionAsync("Users");
                entries.Count.ShouldBe(2);

                resumeTimestamp = entries[0].Timestamp;
                resumeHash = entries[0].Hash;
                expectedFinalHash = entries[1].Hash;

                await initial.CheckpointPersistence.UpsertCheckpointAsync(resumeTimestamp, resumeHash);
            }

            await using (var restarted = await CdcTestHarness.OpenWithRetriesAsync(dbPath, nodeId, consumerId))
            {
                var checkpoint = await restarted.CheckpointPersistence.GetCheckpointAsync();
                checkpoint.ShouldNotBeNull();
                checkpoint!.Timestamp.ShouldBe(resumeTimestamp);
                checkpoint.LastHash.ShouldBe(resumeHash);

                var catchUp = (await restarted.OplogStore.GetOplogAfterAsync(checkpoint.Timestamp))
                    .OrderBy(e => e.Timestamp.PhysicalTime)
                    .ThenBy(e => e.Timestamp.LogicalCounter)
                    .ToList();

                catchUp.Count.ShouldBe(1);
                catchUp[0].Hash.ShouldBe(expectedFinalHash);

                await restarted.CheckpointPersistence.AdvanceCheckpointAsync(catchUp[0]);
            }

            await using (var recovered = await CdcTestHarness.OpenWithRetriesAsync(dbPath, nodeId, consumerId))
            {
                var finalCheckpoint = await recovered.CheckpointPersistence.GetCheckpointAsync();
                finalCheckpoint.ShouldNotBeNull();
                finalCheckpoint!.LastHash.ShouldBe(expectedFinalHash);

                var remaining = await recovered.OplogStore.GetOplogAfterAsync(finalCheckpoint.Timestamp);
                remaining.ShouldBeEmpty();
            }
        }
        finally
        {
            await DeleteDirectoryWithRetriesAsync(dbPath);
        }
    }

    /// <summary>
    ///     Verifies duplicate remote apply windows are idempotent without loopback entries.
    /// </summary>
    [Fact]
    public async Task RemoteApply_ShouldBeIdempotentAcrossDuplicateWindow_WithoutLoopbackEntries()
    {
        string dbPath = CreateTemporaryDatabasePath();
        const string localNodeId = "node-local";
        const string remoteNodeId = "node-remote";

        try
        {
            await using var harness = await CdcTestHarness.OpenWithRetriesAsync(
                dbPath,
                localNodeId,
                "consumer-loopback");

            await harness.Context.Users.InsertAsync(CreateUser("loopback-user", "Loopback", 40, "Boston"));
            await harness.Context.SaveChangesAsync();
            await harness.PollAsync();

            await WaitForConditionAsync(
                async () => (await harness.GetEntriesByKeyAsync("Users", "loopback-user")).Count >= 1,
                "Timed out waiting for loopback-user insert oplog entry.");
            var localEntries = await harness.GetEntriesByKeyAsync("Users", "loopback-user");
            localEntries.Count.ShouldBe(1);
            localEntries[0].Operation.ShouldBe(OperationType.Put);
            localEntries[0].Timestamp.NodeId.ShouldBe(localNodeId);

            var remoteDelete = new OplogEntry(
                "Users",
                "loopback-user",
                OperationType.Delete,
                null,
                new HlcTimestamp(localEntries[0].Timestamp.PhysicalTime + 10, 0, remoteNodeId),
                localEntries[0].Hash);

            var duplicateWindow = new[] { remoteDelete, remoteDelete };

            await harness.OplogStore.ApplyBatchAsync(duplicateWindow);
            await harness.OplogStore.ApplyBatchAsync(duplicateWindow);

            harness.Context.Users.FindById("loopback-user").ShouldBeNull();

            var allEntries = await harness.GetEntriesByKeyAsync("Users", "loopback-user");
            allEntries.Count(e => e.Hash == remoteDelete.Hash).ShouldBe(1);
            allEntries.Count(e => e.Operation == OperationType.Delete && e.Timestamp.NodeId == localNodeId)
                .ShouldBe(0);
            allEntries.Count(e => e.Operation == OperationType.Delete && e.Timestamp.NodeId == remoteNodeId)
                .ShouldBe(1);
        }
        finally
        {
            await DeleteDirectoryWithRetriesAsync(dbPath);
        }
    }

    /// <summary>
    ///     Verifies local deletes persist tombstone metadata and advance checkpoints.
    /// </summary>
    [Fact]
    public async Task LocalDelete_ShouldPersistTombstoneMetadata_AndAdvanceCheckpoint()
    {
        string dbPath = CreateTemporaryDatabasePath();
        const string nodeId = "node-tombstone";

        try
        {
            await using var harness = await CdcTestHarness.OpenWithRetriesAsync(
                dbPath,
                nodeId,
                "consumer-tombstone");

            await harness.Context.Users.InsertAsync(CreateUser("tombstone-user", "Before Delete", 28, "Turin"));
            await harness.Context.SaveChangesAsync();
            await harness.PollAsync();
            await harness.Context.Users.DeleteAsync("tombstone-user");
            await harness.Context.SaveChangesAsync();
            await harness.PollAsync();

            harness.Context.Users.FindById("tombstone-user").ShouldBeNull();

            await WaitForConditionAsync(
                async () => (await harness.GetEntriesByKeyAsync("Users", "tombstone-user")).Count >= 2,
                "Timed out waiting for tombstone-user oplog entries.");
            var entries = await harness.GetEntriesByKeyAsync("Users", "tombstone-user");
            entries.Count.ShouldBe(2);
            var deleteEntry = entries.Last(e => e.Operation == OperationType.Delete);

            var metadata = await harness.MetadataStore.GetMetadataAsync("Users", "tombstone-user");
            metadata.ShouldNotBeNull();
            metadata!.IsDeleted.ShouldBeTrue();
            metadata.UpdatedAt.ShouldBe(deleteEntry.Timestamp);

            var checkpoint = await harness.CheckpointPersistence.GetCheckpointAsync();
            checkpoint.ShouldNotBeNull();
            checkpoint!.LastHash.ShouldBe(deleteEntry.Hash);
            checkpoint.Timestamp.ShouldBe(deleteEntry.Timestamp);
        }
        finally
        {
            await DeleteDirectoryWithRetriesAsync(dbPath);
        }
    }

    private static User CreateUser(string id, string name, int age, string city)
    {
        return new User
        {
            Id = id,
            Name = name,
            Age = age,
            Address = new Address { City = city }
        };
    }

    private static string CreateTemporaryDatabasePath()
    {
        return Path.Combine(Path.GetTempPath(), $"cbddc-cdc-{Guid.NewGuid():N}.rocksdb");
    }

    private static async Task DeleteDirectoryWithRetriesAsync(string path)
    {
        for (var attempt = 0; attempt < 5; attempt++)
            try
            {
                if (Directory.Exists(path)) Directory.Delete(path, true);
                return;
            }
            catch when (attempt < 4)
            {
                await Task.Delay(50);
            }
    }

    private static async Task WaitForConditionAsync(
        Func<Task<bool>> predicate,
        string failureMessage,
        int timeoutMs = 6000,
        int pollMs = 50)
    {
        DateTimeOffset deadline = DateTimeOffset.UtcNow.AddMilliseconds(timeoutMs);
        while (DateTimeOffset.UtcNow < deadline)
        {
            if (await predicate()) return;
            await Task.Delay(pollMs);
        }

        throw new TimeoutException(failureMessage);
    }
}

[CollectionDefinition("SurrealCdcDurability", DisableParallelization = true)]
public sealed class SurrealCdcDurabilityCollection;

internal sealed class CdcTestHarness : IAsyncDisposable
{
    private readonly VectorClockService _vectorClock;
    private readonly CBDDCSurrealEmbeddedOptions _options;

    private CdcTestHarness(string databasePath, string nodeId, string consumerId)
    {
        _options = new CBDDCSurrealEmbeddedOptions
        {
            Cdc = new CBDDCSurrealCdcOptions
            {
                Enabled = true,
                ConsumerId = consumerId,
                CheckpointTable = "cbddc_cdc_checkpoint"
            }
        };

        Context = new SampleDbContext(databasePath);
        _vectorClock = new VectorClockService();

        var configProvider = Substitute.For<IPeerNodeConfigurationProvider>();
        configProvider.GetConfiguration().Returns(new PeerNodeConfiguration
        {
            NodeId = nodeId,
            AuthToken = "test-token",
            TcpPort = 0
        });

        CheckpointPersistence = new SurrealCdcCheckpointPersistence(
            Context.SurrealEmbeddedClient,
            Context.SchemaInitializer,
            _options);

        DocumentStore = new CheckpointedSampleDocumentStore(
            Context,
            configProvider,
            _vectorClock,
            CheckpointPersistence,
            _options,
            NullLogger<CheckpointedSampleDocumentStore>.Instance);

        OplogStore = new SurrealOplogStore(
            Context.SurrealEmbeddedClient,
            Context.SchemaInitializer,
            DocumentStore,
            new LastWriteWinsConflictResolver(),
            _vectorClock,
            null,
            NullLogger<SurrealOplogStore>.Instance);

        MetadataStore = new SurrealDocumentMetadataStore(
            Context.SurrealEmbeddedClient,
            Context.SchemaInitializer,
            NullLogger<SurrealDocumentMetadataStore>.Instance);
    }

    /// <summary>
    ///     Gets the sample database context.
    /// </summary>
    public SampleDbContext Context { get; }

    /// <summary>
    ///     Gets the checkpointed sample document store.
    /// </summary>
    public CheckpointedSampleDocumentStore DocumentStore { get; }

    /// <summary>
    ///     Gets the oplog store used by the harness.
    /// </summary>
    public SurrealOplogStore OplogStore { get; }

    /// <summary>
    ///     Gets the document metadata store.
    /// </summary>
    public SurrealDocumentMetadataStore MetadataStore { get; }

    /// <summary>
    ///     Gets checkpoint persistence used for CDC progress tracking.
    /// </summary>
    public ISurrealCdcCheckpointPersistence CheckpointPersistence { get; }

    /// <summary>
    ///     Polls CDC once through the document store.
    /// </summary>
    public async Task PollAsync()
    {
        await DocumentStore.PollCdcOnceAsync();
    }

    /// <summary>
    ///     Creates a harness instance with retries for transient RocksDB lock contention.
    /// </summary>
    /// <param name="databasePath">Database directory path.</param>
    /// <param name="nodeId">Node identifier.</param>
    /// <param name="consumerId">CDC consumer identifier.</param>
    /// <returns>Initialized test harness.</returns>
    public static async Task<CdcTestHarness> OpenWithRetriesAsync(
        string databasePath,
        string nodeId,
        string consumerId)
    {
        for (var attempt = 0; attempt < 8; attempt++)
            try
            {
                return new CdcTestHarness(databasePath, nodeId, consumerId);
            }
            catch (Exception ex) when (IsLockContention(ex) && attempt < 7)
            {
                await Task.Delay(75);
            }

        throw new InvalidOperationException("Unable to acquire RocksDB lock for test harness.");
    }

    /// <summary>
    ///     Gets oplog entries for a collection ordered by timestamp.
    /// </summary>
    /// <param name="collection">Collection name.</param>
    /// <returns>Ordered oplog entries.</returns>
    public async Task<List<OplogEntry>> GetEntriesByCollectionAsync(string collection)
    {
        return (await OplogStore.ExportAsync())
            .Where(e => string.Equals(e.Collection, collection, StringComparison.Ordinal))
            .OrderBy(e => e.Timestamp.PhysicalTime)
            .ThenBy(e => e.Timestamp.LogicalCounter)
            .ToList();
    }

    /// <summary>
    ///     Gets oplog entries for a collection key ordered by timestamp.
    /// </summary>
    /// <param name="collection">Collection name.</param>
    /// <param name="key">Document key.</param>
    /// <returns>Ordered oplog entries.</returns>
    public async Task<List<OplogEntry>> GetEntriesByKeyAsync(string collection, string key)
    {
        return (await OplogStore.ExportAsync())
            .Where(e => string.Equals(e.Collection, collection, StringComparison.Ordinal) &&
                        string.Equals(e.Key, key, StringComparison.Ordinal))
            .OrderBy(e => e.Timestamp.PhysicalTime)
            .ThenBy(e => e.Timestamp.LogicalCounter)
            .ToList();
    }

    /// <inheritdoc />
    public async ValueTask DisposeAsync()
    {
        DocumentStore.Dispose();
        Context.Dispose();
        await Task.Delay(75);
    }

    private static bool IsLockContention(Exception exception)
    {
        return exception.ToString().Contains("No locks available", StringComparison.OrdinalIgnoreCase);
    }
}

internal sealed class CheckpointedSampleDocumentStore : SurrealDocumentStore<SampleDbContext>
{
    private const string UsersCollection = "Users";
    private const string TodoListsCollection = "TodoLists";

    /// <summary>
    ///     Initializes a new instance of the <see cref="CheckpointedSampleDocumentStore"/> class.
    /// </summary>
    /// <param name="context">Sample database context.</param>
    /// <param name="configProvider">Peer configuration provider.</param>
    /// <param name="vectorClockService">Vector clock service.</param>
    /// <param name="checkpointPersistence">Checkpoint persistence implementation.</param>
    /// <param name="surrealOptions">Optional Surreal embedded options.</param>
    /// <param name="logger">Optional logger.</param>
    public CheckpointedSampleDocumentStore(
        SampleDbContext context,
        IPeerNodeConfigurationProvider configProvider,
        IVectorClockService vectorClockService,
        ISurrealCdcCheckpointPersistence checkpointPersistence,
        CBDDCSurrealEmbeddedOptions? surrealOptions = null,
        ILogger<CheckpointedSampleDocumentStore>? logger = null)
        : base(
            context,
            context.SurrealEmbeddedClient,
            context.SchemaInitializer,
            configProvider,
            vectorClockService,
            new LastWriteWinsConflictResolver(),
            checkpointPersistence,
            BuildPollingOptions(surrealOptions),
            logger)
    {
        WatchCollection(UsersCollection, context.Users, u => u.Id, subscribeForInMemoryEvents: false);
        WatchCollection(TodoListsCollection, context.TodoLists, t => t.Id, subscribeForInMemoryEvents: false);
    }

    /// <inheritdoc />
    protected override async Task ApplyContentToEntityAsync(
        string collection,
        string key,
        JsonElement content,
        CancellationToken cancellationToken)
    {
        await UpsertEntityAsync(collection, key, content, cancellationToken);
    }

    /// <inheritdoc />
    protected override async Task ApplyContentToEntitiesBatchAsync(
        IEnumerable<(string Collection, string Key, JsonElement Content)> documents,
        CancellationToken cancellationToken)
    {
        foreach ((string collection, string key, var content) in documents)
            await UpsertEntityAsync(collection, key, content, cancellationToken);
    }

    /// <inheritdoc />
    protected override async Task<JsonElement?> GetEntityAsJsonAsync(
        string collection,
        string key,
        CancellationToken cancellationToken)
    {
        return collection switch
        {
            UsersCollection => SerializeEntity(await _context.Users.FindByIdAsync(key, cancellationToken)),
            TodoListsCollection => SerializeEntity(await _context.TodoLists.FindByIdAsync(key, cancellationToken)),
            _ => null
        };
    }

    /// <inheritdoc />
    protected override async Task RemoveEntityAsync(
        string collection,
        string key,
        CancellationToken cancellationToken)
    {
        await DeleteEntityAsync(collection, key, cancellationToken);
    }

    /// <inheritdoc />
    protected override async Task RemoveEntitiesBatchAsync(
        IEnumerable<(string Collection, string Key)> documents,
        CancellationToken cancellationToken)
    {
        foreach ((string collection, string key) in documents)
            await DeleteEntityAsync(collection, key, cancellationToken);
    }

    /// <inheritdoc />
    protected override async Task<IEnumerable<(string Key, JsonElement Content)>> GetAllEntitiesAsJsonAsync(
        string collection,
        CancellationToken cancellationToken)
    {
        return collection switch
        {
            UsersCollection => (await _context.Users.FindAllAsync(cancellationToken))
                .Select(u => (u.Id, SerializeEntity(u)!.Value))
                .ToList(),
            TodoListsCollection => (await _context.TodoLists.FindAllAsync(cancellationToken))
                .Select(t => (t.Id, SerializeEntity(t)!.Value))
                .ToList(),
            _ => []
        };
    }

    private async Task UpsertEntityAsync(
        string collection,
        string key,
        JsonElement content,
        CancellationToken cancellationToken)
    {
        switch (collection)
        {
            case UsersCollection:
                var user = content.Deserialize<User>() ??
                           throw new InvalidOperationException("Failed to deserialize user.");
                user.Id = key;
                if (await _context.Users.FindByIdAsync(key, cancellationToken) == null)
                    await _context.Users.InsertAsync(user, cancellationToken);
                else
                    await _context.Users.UpdateAsync(user, cancellationToken);
                break;

            case TodoListsCollection:
                var todo = content.Deserialize<TodoList>() ??
                           throw new InvalidOperationException("Failed to deserialize todo list.");
                todo.Id = key;
                if (await _context.TodoLists.FindByIdAsync(key, cancellationToken) == null)
                    await _context.TodoLists.InsertAsync(todo, cancellationToken);
                else
                    await _context.TodoLists.UpdateAsync(todo, cancellationToken);
                break;

            default:
                throw new NotSupportedException($"Collection '{collection}' is not supported for sync.");
        }
    }

    private async Task DeleteEntityAsync(string collection, string key, CancellationToken cancellationToken)
    {
        switch (collection)
        {
            case UsersCollection:
                await _context.Users.DeleteAsync(key, cancellationToken);
                break;

            case TodoListsCollection:
                await _context.TodoLists.DeleteAsync(key, cancellationToken);
                break;
        }
    }

    private static JsonElement? SerializeEntity<T>(T? entity) where T : class
    {
        return entity == null ? null : JsonSerializer.SerializeToElement(entity);
    }

    private static SurrealCdcPollingOptions? BuildPollingOptions(CBDDCSurrealEmbeddedOptions? options)
    {
        if (options == null) return null;

        return new SurrealCdcPollingOptions
        {
            Enabled = options.Cdc.Enabled,
            PollInterval = options.Cdc.PollingInterval,
            BatchSize = options.Cdc.BatchSize,
            EnableLiveSelectAccelerator = options.Cdc.EnableLiveSelectAccelerator,
            LiveSelectReconnectDelay = options.Cdc.LiveSelectReconnectDelay
        };
    }
}