using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
using ZB.MOM.WW.OtOpcUa.ControlPlane.AdminOperations;
using ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.Harness;
using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;

namespace ZB.MOM.WW.OtOpcUa.ControlPlane.Tests;

/// <summary>
///     End-to-end contract between the two halves of #520 stage 4: <see cref="ConfigComposer"/> writes the
///     API keys + ACL grants into the artifact, and <see cref="DeploymentArtifact.ParseDataPlaneAuthority"/>
///     reads them back out on the node.
/// </summary>
/// <remarks>
///     These deliberately compose a REAL artifact rather than hand-writing the JSON. A hand-written fixture
///     pins the parser against my own idea of the format, not against the producer — the failure it would
///     miss is exactly the one that matters here: someone changes how the composer serialises (a naming
///     policy, a <c>JsonStringEnumConverter</c>) and every key and grant silently stops arriving at the
///     node, with no error anywhere and no test going red.
/// </remarks>
public sealed class DataPlaneAuthorityArtifactTests : ControlPlaneActorTestBase
{
    private const string NodeA = "node-a:4840";
    private const string NodeB = "node-b:4840";

    [Fact]
    public async Task A_key_survives_the_round_trip_through_a_composed_artifact()
    {
        var f = NewInMemoryDbFactory();
        await using (var db = f.CreateDbContext())
        {
            db.ServerClusters.Add(NewCluster("cluster-a"));
            db.ApiKeys.Add(NewKey("abc123", "scadabridge-dcl"));
            await db.SaveChangesAsync();
        }

        var artifact = await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext());
        var parsed = DeploymentArtifact.ParseDataPlaneAuthority(artifact.Blob, NodeA);

        var key = parsed.Keys.ShouldHaveSingleItem();
        key.ApiKeyId.ShouldBe("abc123");
        key.Principal.ShouldBe("scadabridge-dcl");
        key.SecretHash.ShouldBe("hash-of-abc123");
        key.Enabled.ShouldBeTrue();
    }

    [Fact]
    public async Task A_grant_survives_the_round_trip_with_its_scope_kind_and_permission_flags()
    {
        // The enum fields are the fragile part: ConfigComposer writes them as NUMBERS, so the parser reads
        // int. If that ever diverges the grant is dropped and a key silently authenticates with no
        // permissions — which looks exactly like a correctly-unprivileged key.
        var f = NewInMemoryDbFactory();
        await using (var db = f.CreateDbContext())
        {
            db.ServerClusters.Add(NewCluster("cluster-a"));
            db.NodeAcls.Add(NewAcl("acl-1", "cluster-a", "scadabridge-dcl",
                NodeAclScopeKind.Cluster, NodePermissions.Read | NodePermissions.WriteOperate));
            await db.SaveChangesAsync();
        }

        var artifact = await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext());
        var parsed = DeploymentArtifact.ParseDataPlaneAuthority(artifact.Blob, NodeA);

        var grant = parsed.Grants.ShouldHaveSingleItem();
        grant.Principal.ShouldBe("scadabridge-dcl");
        grant.ScopeKind.ShouldBe(NodeAclScopeKind.Cluster);
        grant.PermissionFlags.ShouldBe(NodePermissions.Read | NodePermissions.WriteOperate);
    }

    [Fact]
    public async Task A_non_cluster_scope_kind_round_trips_as_itself()
    {
        // Falsifies "the enum happens to work because Cluster is 0". Equipment is 4, so a broken
        // enum read would surface as Cluster here rather than as a dropped row.
        var f = NewInMemoryDbFactory();
        await using (var db = f.CreateDbContext())
        {
            db.ServerClusters.Add(NewCluster("cluster-a"));
            var acl = NewAcl("acl-1", "cluster-a", "p", NodeAclScopeKind.Equipment, NodePermissions.Read);
            acl.ScopeId = "EQ-1";
            db.NodeAcls.Add(acl);
            await db.SaveChangesAsync();
        }

        var artifact = await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext());
        var parsed = DeploymentArtifact.ParseDataPlaneAuthority(artifact.Blob, NodeA);

        var grant = parsed.Grants.ShouldHaveSingleItem();
        grant.ScopeKind.ShouldBe(NodeAclScopeKind.Equipment);
        grant.ScopeId.ShouldBe("EQ-1");
    }

    [Fact]
    public async Task An_expiry_round_trips_as_the_same_UTC_instant()
    {
        // Covers the round trip only. It does NOT cover the timezone hazard: the in-memory EF provider
        // preserves DateTimeKind.Utc, so the composer writes a "Z" here and the parser's Unspecified
        // branch never runs — verified by breaking that branch and watching this test still pass. SQL
        // Server's datetime2 DOES materialise as Unspecified, so the branch is real in production and is
        // pinned directly at the parser by
        // DeploymentArtifactDataPlaneAuthorityTests.An_expiry_written_without_an_offset_is_read_as_UTC.
        var expires = new DateTime(2030, 6, 15, 12, 0, 0, DateTimeKind.Utc);
        var f = NewInMemoryDbFactory();
        await using (var db = f.CreateDbContext())
        {
            db.ServerClusters.Add(NewCluster("cluster-a"));
            var key = NewKey("abc123", "p");
            key.ExpiresUtc = expires;
            db.ApiKeys.Add(key);
            await db.SaveChangesAsync();
        }

        var artifact = await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext());
        var parsed = DeploymentArtifact.ParseDataPlaneAuthority(artifact.Blob, NodeA);

        var parsedKey = parsed.Keys.ShouldHaveSingleItem();
        parsedKey.ExpiresUtc.ShouldNotBeNull();
        parsedKey.ExpiresUtc!.Value.ShouldBe(expires);
        parsedKey.ExpiresUtc!.Value.Kind.ShouldBe(DateTimeKind.Utc);
    }

    [Fact]
    public async Task Grants_are_scoped_to_the_nodes_own_cluster_but_keys_are_not()
    {
        // Multi-cluster artifact: node-a belongs to cluster-a, so it must not receive cluster-b's grants.
        // Keys carry no ClusterId — a key is a fleet-wide credential, and it is the ACL rows that decide
        // what it can reach — so BOTH keys arrive.
        var f = NewInMemoryDbFactory();
        await using (var db = f.CreateDbContext())
        {
            db.ServerClusters.Add(NewCluster("cluster-a"));
            db.ServerClusters.Add(NewCluster("cluster-b"));
            db.ClusterNodes.Add(NewNode(NodeA, "cluster-a"));
            db.ClusterNodes.Add(NewNode(NodeB, "cluster-b"));
            db.ApiKeys.Add(NewKey("key-a", "principal-a"));
            db.ApiKeys.Add(NewKey("key-b", "principal-b"));
            db.NodeAcls.Add(NewAcl("acl-a", "cluster-a", "principal-a", NodeAclScopeKind.Cluster, NodePermissions.Read));
            db.NodeAcls.Add(NewAcl("acl-b", "cluster-b", "principal-b", NodeAclScopeKind.Cluster, NodePermissions.Read));
            await db.SaveChangesAsync();
        }

        var artifact = await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext());
        var parsed = DeploymentArtifact.ParseDataPlaneAuthority(artifact.Blob, NodeA);

        parsed.ClusterId.ShouldBe("cluster-a");
        parsed.Grants.ShouldHaveSingleItem().NodeAclId.ShouldBe("acl-a");
        parsed.Keys.Select(k => k.ApiKeyId).OrderBy(x => x).ShouldBe(["key-a", "key-b"]);
    }

    [Fact]
    public async Task A_node_absent_from_a_multi_cluster_artifact_receives_no_grants()
    {
        // ResolveClusterScope reads an unlisted node as Suppress — it was not deployed to. Handing it
        // another cluster's grants would be the worst possible reading of that.
        var f = NewInMemoryDbFactory();
        await using (var db = f.CreateDbContext())
        {
            db.ServerClusters.Add(NewCluster("cluster-a"));
            db.ServerClusters.Add(NewCluster("cluster-b"));
            db.ClusterNodes.Add(NewNode(NodeB, "cluster-b"));
            db.NodeAcls.Add(NewAcl("acl-b", "cluster-b", "principal-b", NodeAclScopeKind.Cluster, NodePermissions.Read));
            await db.SaveChangesAsync();
        }

        var artifact = await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext());
        var parsed = DeploymentArtifact.ParseDataPlaneAuthority(artifact.Blob, "node-nowhere:4840");

        parsed.Grants.ShouldBeEmpty();
    }

    [Fact]
    public async Task A_revoked_key_still_ships_so_the_node_can_see_the_revocation()
    {
        // Filtering revoked keys out of the artifact would make a revocation indistinguishable from a key
        // that was never deployed — and worse, would leave the node's previous snapshot as the last word
        // on that id. The key ships with Enabled=false and the lookup denies it.
        var f = NewInMemoryDbFactory();
        await using (var db = f.CreateDbContext())
        {
            db.ServerClusters.Add(NewCluster("cluster-a"));
            var key = NewKey("abc123", "p");
            key.Enabled = false;
            db.ApiKeys.Add(key);
            await db.SaveChangesAsync();
        }

        var artifact = await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext());
        var parsed = DeploymentArtifact.ParseDataPlaneAuthority(artifact.Blob, NodeA);

        parsed.Keys.ShouldHaveSingleItem().Enabled.ShouldBeFalse();
    }

    [Fact]
    public void An_empty_or_malformed_blob_yields_nothing()
    {
        DeploymentArtifact.ParseDataPlaneAuthority(ReadOnlySpan<byte>.Empty, NodeA)
            .Keys.ShouldBeEmpty();
        DeploymentArtifact.ParseDataPlaneAuthority("not json at all"u8, NodeA)
            .Grants.ShouldBeEmpty();
    }

    [Fact]
    public async Task Adding_a_key_changes_the_revision_hash()
    {
        // The node's generation stamp is driven by this hash, so a key change that did not move it would
        // leave the node believing it had already applied the new authorization inputs.
        var f = NewInMemoryDbFactory();
        await using (var db = f.CreateDbContext())
        {
            db.ServerClusters.Add(NewCluster("cluster-a"));
            await db.SaveChangesAsync();
        }
        var before = (await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext())).RevisionHash;

        await using (var db = f.CreateDbContext())
        {
            db.ApiKeys.Add(NewKey("abc123", "p"));
            await db.SaveChangesAsync();
        }
        var after = (await ConfigComposer.SnapshotAndFlattenAsync(f.CreateDbContext())).RevisionHash;

        after.ShouldNotBe(before);
    }

    private static readonly DateTime FixedTimestamp = new(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);

    private static ServerCluster NewCluster(string id) => new()
    {
        ClusterId = id,
        Name = id,
        Enterprise = "ent",
        Site = "site",
        RedundancyMode = RedundancyMode.None,
        CreatedBy = "test",
        CreatedAt = FixedTimestamp,
    };

    private static ClusterNode NewNode(string nodeId, string clusterId) => new()
    {
        NodeId = nodeId,
        ClusterId = clusterId,
        Host = nodeId.Split(':')[0],
        ApplicationUri = $"urn:{nodeId}",
        CreatedBy = "test",
        CreatedAt = FixedTimestamp,
    };

    private static ApiKey NewKey(string apiKeyId, string principal) => new()
    {
        ApiKeyRowId = Guid.NewGuid(),
        ApiKeyId = apiKeyId,
        Name = $"key {apiKeyId}",
        SecretHash = $"hash-of-{apiKeyId}",
        Principal = principal,
        Enabled = true,
        CreatedUtc = FixedTimestamp,
    };

    private static NodeAcl NewAcl(
        string id, string clusterId, string principal, NodeAclScopeKind scopeKind, NodePermissions flags) => new()
    {
        NodeAclRowId = Guid.NewGuid(),
        NodeAclId = id,
        ClusterId = clusterId,
        Principal = principal,
        ScopeKind = scopeKind,
        PermissionFlags = flags,
    };
}