// Copyright 2024-2025 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Mirrors server/jetstream_versioning_test.go in the NATS server Go source.

using Shouldly;

namespace ZB.MOM.NatsNet.Server.Tests.JetStream;

/// <summary>
/// Unit tests for JetStream API level versioning helpers.
/// Mirrors server/jetstream_versioning_test.go.
/// Tests 1803–1808 (TestJetStreamMetadataMutations, TestJetStreamMetadataStreamRestoreAndRestart,
/// TestJetStreamMetadataStreamRestoreAndRestartCluster, TestJetStreamApiErrorOnRequiredApiLevel,
/// TestJetStreamApiErrorOnRequiredApiLevelDirectGet, TestJetStreamApiErrorOnRequiredApiLevelPullConsumerNextMsg)
/// all require a running JetStream server and are deferred.
/// </summary>
public sealed class JetStreamVersioningTests
{
    // -------------------------------------------------------------------------
    // Helpers (mirrors module-level helpers in Go test file)
    // -------------------------------------------------------------------------

    private static Dictionary<string, string> MetadataAtLevel(string featureLevel) =>
        new() { [JetStreamVersioning.JsRequiredLevelMetadataKey] = featureLevel };

    private static Dictionary<string, string> MetadataPrevious() =>
        new() { [JetStreamVersioning.JsRequiredLevelMetadataKey] = "previous-level" };

    // -------------------------------------------------------------------------
    // T:1791 — TestGetAndSupportsRequiredApiLevel
    // -------------------------------------------------------------------------

    [Fact] // T:1791
    public void GetAndSupportsRequiredApiLevel_VariousInputs_ReturnsExpected()
    {
        // getRequiredApiLevel
        JetStreamVersioning.GetRequiredApiLevel(null).ShouldBe(string.Empty);
        JetStreamVersioning.GetRequiredApiLevel(new Dictionary<string, string>()).ShouldBe(string.Empty);
        JetStreamVersioning.GetRequiredApiLevel(MetadataAtLevel("1")).ShouldBe("1");
        JetStreamVersioning.GetRequiredApiLevel(MetadataAtLevel("text")).ShouldBe("text");

        // supportsRequiredApiLevel
        JetStreamVersioning.SupportsRequiredApiLevel(null).ShouldBeTrue();
        JetStreamVersioning.SupportsRequiredApiLevel(new Dictionary<string, string>()).ShouldBeTrue();
        JetStreamVersioning.SupportsRequiredApiLevel(MetadataAtLevel("1")).ShouldBeTrue();
        JetStreamVersioning.SupportsRequiredApiLevel(
            MetadataAtLevel(JetStreamVersioning.JsApiLevel.ToString())).ShouldBeTrue();
        JetStreamVersioning.SupportsRequiredApiLevel(MetadataAtLevel("text")).ShouldBeFalse();
    }

    // -------------------------------------------------------------------------
    // T:1792 — TestJetStreamSetStaticStreamMetadata
    // -------------------------------------------------------------------------

    [Fact] // T:1792
    public void SetStaticStreamMetadata_VariousConfigs_SetsCorrectApiLevel()
    {
        var cases = new[]
        {
            ("empty",                        new StreamConfig(),                                                                   "0"),
            ("overwrite-user-provided",      new StreamConfig { Metadata = MetadataPrevious() },                                  "0"),
            ("AllowMsgTTL",                  new StreamConfig { AllowMsgTTL = true },                                             "1"),
            ("SubjectDeleteMarkerTTL",       new StreamConfig { SubjectDeleteMarkerTTL = TimeSpan.FromSeconds(1) },               "1"),
            ("AllowMsgCounter",              new StreamConfig { AllowMsgCounter = true },                                         "2"),
            ("AllowAtomicPublish",           new StreamConfig { AllowAtomicPublish = true },                                      "2"),
            ("AllowMsgSchedules",            new StreamConfig { AllowMsgSchedules = true },                                       "2"),
            ("AsyncPersistMode",             new StreamConfig { PersistMode = PersistModeType.AsyncPersistMode },                 "2"),
        };

        foreach (var (desc, cfg, expectedLevel) in cases)
        {
            JetStreamVersioning.SetStaticStreamMetadata(cfg);
            var level = cfg.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey];
            level.ShouldBe(expectedLevel, $"case: {desc}");

            // Ensure we do not exceed the server API level.
            int.Parse(level).ShouldBeLessThanOrEqualTo(JetStreamVersioning.JsApiLevel,
                customMessage: $"case: {desc}");
        }
    }

    // -------------------------------------------------------------------------
    // T:1793 — TestJetStreamSetStaticStreamMetadataRemoveDynamicFields
    // -------------------------------------------------------------------------

    [Fact] // T:1793
    public void SetStaticStreamMetadata_RemovesDynamicFields()
    {
        var cfg = new StreamConfig
        {
            Metadata = new Dictionary<string, string>
            {
                [JetStreamVersioning.JsServerVersionMetadataKey] = "dynamic-version",
                [JetStreamVersioning.JsServerLevelMetadataKey]   = "dynamic-level",
            }
        };

        JetStreamVersioning.SetStaticStreamMetadata(cfg);

        cfg.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerVersionMetadataKey);
        cfg.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerLevelMetadataKey);
        cfg.Metadata[JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("0");
    }

    // -------------------------------------------------------------------------
    // T:1794 — TestJetStreamSetDynamicStreamMetadata
    // -------------------------------------------------------------------------

    [Fact] // T:1794
    public void SetDynamicStreamMetadata_DoesNotMutateOriginal_AddsVersionFields()
    {
        var cfg = new StreamConfig { Metadata = MetadataAtLevel("0") };
        var newCfg = JetStreamVersioning.SetDynamicStreamMetadata(cfg);

        // Original must NOT have dynamic fields.
        cfg.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerVersionMetadataKey);
        cfg.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerLevelMetadataKey);

        // New copy must have dynamic fields.
        newCfg.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("0");
        newCfg.Metadata[JetStreamVersioning.JsServerVersionMetadataKey].ShouldBe(ServerConstants.Version);
        newCfg.Metadata[JetStreamVersioning.JsServerLevelMetadataKey]
              .ShouldBe(JetStreamVersioning.JsApiLevel.ToString());
    }

    // -------------------------------------------------------------------------
    // T:1795 — TestJetStreamCopyStreamMetadata
    // -------------------------------------------------------------------------

    [Fact] // T:1795
    public void CopyStreamMetadata_VariousScenarios_CopiesRequiredLevelKey()
    {
        // no-previous-ignore: when prevCfg is null, key must be absent
        var cfg1 = new StreamConfig { Metadata = MetadataAtLevel("-1") };
        JetStreamVersioning.CopyStreamMetadata(cfg1, null);
        (cfg1.Metadata?.ContainsKey(JetStreamVersioning.JsRequiredLevelMetadataKey) ?? false).ShouldBeFalse();

        // nil-previous-metadata-ignore: prevCfg has null Metadata
        var cfg2 = new StreamConfig { Metadata = MetadataAtLevel("-1") };
        JetStreamVersioning.CopyStreamMetadata(cfg2, new StreamConfig { Metadata = null });
        (cfg2.Metadata?.ContainsKey(JetStreamVersioning.JsRequiredLevelMetadataKey) ?? false).ShouldBeFalse();

        // nil-current-metadata-ignore: cfg has null Metadata — should not throw
        var cfg3 = new StreamConfig { Metadata = null };
        JetStreamVersioning.CopyStreamMetadata(cfg3, new StreamConfig { Metadata = MetadataPrevious() });
        cfg3.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("previous-level");

        // copy-previous: key from prevCfg is copied into cfg
        var cfg4 = new StreamConfig { Metadata = MetadataAtLevel("-1") };
        JetStreamVersioning.CopyStreamMetadata(cfg4, new StreamConfig { Metadata = MetadataPrevious() });
        cfg4.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("previous-level");

        // delete-missing-fields: prevCfg has empty metadata dict → key absent in cfg
        var cfg5 = new StreamConfig { Metadata = MetadataAtLevel("-1") };
        JetStreamVersioning.CopyStreamMetadata(cfg5, new StreamConfig { Metadata = new Dictionary<string, string>() });
        (cfg5.Metadata?.ContainsKey(JetStreamVersioning.JsRequiredLevelMetadataKey) ?? false).ShouldBeFalse();
    }

    // -------------------------------------------------------------------------
    // T:1796 — TestJetStreamCopyStreamMetadataRemoveDynamicFields
    // -------------------------------------------------------------------------

    [Fact] // T:1796
    public void CopyStreamMetadata_RemovesDynamicFields()
    {
        // Copy from null prevCfg — dynamic fields should be removed and key absent.
        var cfg = new StreamConfig
        {
            Metadata = new Dictionary<string, string>
            {
                [JetStreamVersioning.JsServerVersionMetadataKey] = "dynamic-version",
                [JetStreamVersioning.JsServerLevelMetadataKey]   = "dynamic-level",
            }
        };
        JetStreamVersioning.CopyStreamMetadata(cfg, null);
        cfg.Metadata.ShouldBeNull(); // all entries removed → null'd

        // Copy from prevCfg with req-level → dynamic fields removed, req-level preserved.
        var cfg2 = new StreamConfig
        {
            Metadata = new Dictionary<string, string>
            {
                [JetStreamVersioning.JsServerVersionMetadataKey] = "dynamic-version",
                [JetStreamVersioning.JsServerLevelMetadataKey]   = "dynamic-level",
            }
        };
        var prev = new StreamConfig { Metadata = MetadataAtLevel("0") };
        JetStreamVersioning.CopyStreamMetadata(cfg2, prev);
        cfg2.Metadata.ShouldNotBeNull();
        cfg2.Metadata!.ShouldNotContainKey(JetStreamVersioning.JsServerVersionMetadataKey);
        cfg2.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerLevelMetadataKey);
        cfg2.Metadata[JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("0");
    }

    // -------------------------------------------------------------------------
    // T:1797 — TestJetStreamSetStaticConsumerMetadata
    // -------------------------------------------------------------------------

    [Fact] // T:1797
    public void SetStaticConsumerMetadata_VariousConfigs_SetsCorrectApiLevel()
    {
        var pauseUntil     = new DateTime(1970, 1, 1, 0, 0, 1, DateTimeKind.Utc); // Unix(0, 0) = epoch+1s
        var pauseUntilZero = default(DateTime);

        var cases = new[]
        {
            ("empty",                new ConsumerConfig(),                                                                               "0"),
            ("overwrite-user-provided", new ConsumerConfig { Metadata = MetadataPrevious() },                                          "0"),
            ("PauseUntil/zero",      new ConsumerConfig { PauseUntil = pauseUntilZero },                                                "0"),
            ("PauseUntil",           new ConsumerConfig { PauseUntil = pauseUntil },                                                    "1"),
            ("Pinned",               new ConsumerConfig { PriorityPolicy = PriorityPolicy.PriorityPinnedClient,
                                                          PriorityGroups = new[] { "a" } },                                             "1"),
        };

        foreach (var (desc, cfg, expectedLevel) in cases)
        {
            JetStreamVersioning.SetStaticConsumerMetadata(cfg);
            var level = cfg.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey];
            level.ShouldBe(expectedLevel, $"case: {desc}");

            int.Parse(level).ShouldBeLessThanOrEqualTo(JetStreamVersioning.JsApiLevel,
                customMessage: $"case: {desc}");
        }
    }

    // -------------------------------------------------------------------------
    // T:1798 — TestJetStreamSetStaticConsumerMetadataRemoveDynamicFields
    // -------------------------------------------------------------------------

    [Fact] // T:1798
    public void SetStaticConsumerMetadata_RemovesDynamicFields()
    {
        var cfg = new ConsumerConfig
        {
            Metadata = new Dictionary<string, string>
            {
                [JetStreamVersioning.JsServerVersionMetadataKey] = "dynamic-version",
                [JetStreamVersioning.JsServerLevelMetadataKey]   = "dynamic-level",
            }
        };

        JetStreamVersioning.SetStaticConsumerMetadata(cfg);

        cfg.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerVersionMetadataKey);
        cfg.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerLevelMetadataKey);
        cfg.Metadata[JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("0");
    }

    // -------------------------------------------------------------------------
    // T:1799 — TestJetStreamSetDynamicConsumerMetadata
    // -------------------------------------------------------------------------

    [Fact] // T:1799
    public void SetDynamicConsumerMetadata_DoesNotMutateOriginal_AddsVersionFields()
    {
        var cfg = new ConsumerConfig { Metadata = MetadataAtLevel("0") };
        var newCfg = JetStreamVersioning.SetDynamicConsumerMetadata(cfg);

        // Original must NOT have dynamic fields.
        cfg.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerVersionMetadataKey);
        cfg.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerLevelMetadataKey);

        // New copy must have dynamic fields.
        newCfg.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("0");
        newCfg.Metadata[JetStreamVersioning.JsServerVersionMetadataKey].ShouldBe(ServerConstants.Version);
        newCfg.Metadata[JetStreamVersioning.JsServerLevelMetadataKey]
              .ShouldBe(JetStreamVersioning.JsApiLevel.ToString());
    }

    // -------------------------------------------------------------------------
    // T:1800 — TestJetStreamSetDynamicConsumerInfoMetadata
    // -------------------------------------------------------------------------

    [Fact] // T:1800
    public void SetDynamicConsumerInfoMetadata_DoesNotMutateOriginal_AddsVersionFields()
    {
        var ci = new ConsumerInfo { Config = new ConsumerConfig { Metadata = MetadataAtLevel("0") } };
        var newCi = JetStreamVersioning.SetDynamicConsumerInfoMetadata(ci);

        // Configs must not be reference-equal (we got a new object).
        ReferenceEquals(ci, newCi).ShouldBeFalse();

        // Original config must NOT have dynamic fields.
        ci.Config!.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerVersionMetadataKey);
        ci.Config.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerLevelMetadataKey);

        // New config must have dynamic fields.
        newCi.Config!.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("0");
        newCi.Config.Metadata[JetStreamVersioning.JsServerVersionMetadataKey].ShouldBe(ServerConstants.Version);
        newCi.Config.Metadata[JetStreamVersioning.JsServerLevelMetadataKey]
                    .ShouldBe(JetStreamVersioning.JsApiLevel.ToString());
    }

    // -------------------------------------------------------------------------
    // T:1801 — TestJetStreamCopyConsumerMetadata
    // -------------------------------------------------------------------------

    [Fact] // T:1801
    public void CopyConsumerMetadata_VariousScenarios_CopiesRequiredLevelKey()
    {
        // no-previous-ignore
        var cfg1 = new ConsumerConfig { Metadata = MetadataAtLevel("-1") };
        JetStreamVersioning.CopyConsumerMetadata(cfg1, null);
        (cfg1.Metadata?.ContainsKey(JetStreamVersioning.JsRequiredLevelMetadataKey) ?? false).ShouldBeFalse();

        // nil-previous-metadata-ignore
        var cfg2 = new ConsumerConfig { Metadata = MetadataAtLevel("-1") };
        JetStreamVersioning.CopyConsumerMetadata(cfg2, new ConsumerConfig { Metadata = null });
        (cfg2.Metadata?.ContainsKey(JetStreamVersioning.JsRequiredLevelMetadataKey) ?? false).ShouldBeFalse();

        // nil-current-metadata-ignore
        var cfg3 = new ConsumerConfig { Metadata = null };
        JetStreamVersioning.CopyConsumerMetadata(cfg3, new ConsumerConfig { Metadata = MetadataPrevious() });
        cfg3.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("previous-level");

        // copy-previous
        var cfg4 = new ConsumerConfig { Metadata = MetadataAtLevel("-1") };
        JetStreamVersioning.CopyConsumerMetadata(cfg4, new ConsumerConfig { Metadata = MetadataPrevious() });
        cfg4.Metadata![JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("previous-level");

        // delete-missing-fields
        var cfg5 = new ConsumerConfig { Metadata = MetadataAtLevel("-1") };
        JetStreamVersioning.CopyConsumerMetadata(cfg5,
            new ConsumerConfig { Metadata = new Dictionary<string, string>() });
        (cfg5.Metadata?.ContainsKey(JetStreamVersioning.JsRequiredLevelMetadataKey) ?? false).ShouldBeFalse();
    }

    // -------------------------------------------------------------------------
    // T:1802 — TestJetStreamCopyConsumerMetadataRemoveDynamicFields
    // -------------------------------------------------------------------------

    [Fact] // T:1802
    public void CopyConsumerMetadata_RemovesDynamicFields()
    {
        // Copy from null prevCfg → dynamic removed, key absent.
        var cfg = new ConsumerConfig
        {
            Metadata = new Dictionary<string, string>
            {
                [JetStreamVersioning.JsServerVersionMetadataKey] = "dynamic-version",
                [JetStreamVersioning.JsServerLevelMetadataKey]   = "dynamic-level",
            }
        };
        JetStreamVersioning.CopyConsumerMetadata(cfg, null);
        cfg.Metadata.ShouldBeNull();

        // Copy from prevCfg with req-level → dynamic removed, req-level preserved.
        var cfg2 = new ConsumerConfig
        {
            Metadata = new Dictionary<string, string>
            {
                [JetStreamVersioning.JsServerVersionMetadataKey] = "dynamic-version",
                [JetStreamVersioning.JsServerLevelMetadataKey]   = "dynamic-level",
            }
        };
        var prev = new ConsumerConfig { Metadata = MetadataAtLevel("0") };
        JetStreamVersioning.CopyConsumerMetadata(cfg2, prev);
        cfg2.Metadata.ShouldNotBeNull();
        cfg2.Metadata!.ShouldNotContainKey(JetStreamVersioning.JsServerVersionMetadataKey);
        cfg2.Metadata.ShouldNotContainKey(JetStreamVersioning.JsServerLevelMetadataKey);
        cfg2.Metadata[JetStreamVersioning.JsRequiredLevelMetadataKey].ShouldBe("0");
    }

    // -------------------------------------------------------------------------
    // T:1803 — TestJetStreamMetadataMutations — deferred: requires RunBasicJetStreamServer
    // -------------------------------------------------------------------------

    [Fact(Skip = "deferred: requires running JetStream server")] // T:1803
    public void JetStreamMetadataMutations_RequiresRunningServer() { }

    // -------------------------------------------------------------------------
    // T:1804 — TestJetStreamMetadataStreamRestoreAndRestart — deferred
    // -------------------------------------------------------------------------

    [Fact(Skip = "deferred: requires running JetStream server")] // T:1804
    public void JetStreamMetadataStreamRestoreAndRestart_RequiresRunningServer() { }

    // -------------------------------------------------------------------------
    // T:1805 — TestJetStreamMetadataStreamRestoreAndRestartCluster — deferred
    // -------------------------------------------------------------------------

    [Fact(Skip = "deferred: requires running JetStream cluster")] // T:1805
    public void JetStreamMetadataStreamRestoreAndRestartCluster_RequiresRunningServer() { }

    // -------------------------------------------------------------------------
    // T:1806 — TestJetStreamApiErrorOnRequiredApiLevel — deferred
    // -------------------------------------------------------------------------

    [Fact(Skip = "deferred: requires running JetStream server")] // T:1806
    public void JetStreamApiErrorOnRequiredApiLevel_RequiresRunningServer() { }

    // -------------------------------------------------------------------------
    // T:1807 — TestJetStreamApiErrorOnRequiredApiLevelDirectGet — deferred
    // -------------------------------------------------------------------------

    [Fact(Skip = "deferred: requires running JetStream server")] // T:1807
    public void JetStreamApiErrorOnRequiredApiLevelDirectGet_RequiresRunningServer() { }

    // -------------------------------------------------------------------------
    // T:1808 — TestJetStreamApiErrorOnRequiredApiLevelPullConsumerNextMsg — deferred
    // -------------------------------------------------------------------------

    [Fact(Skip = "deferred: requires running JetStream server")] // T:1808
    public void JetStreamApiErrorOnRequiredApiLevelPullConsumerNextMsg_RequiresRunningServer() { }
}