using System.IO.Compression;
using System.Security.Cryptography;
using System.Text.Json;
using Microsoft.EntityFrameworkCore;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Configuration;
using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
using ZB.MOM.WW.OtOpcUa.Configuration.Validation;
using ZB.MOM.WW.OtOpcUa.ControlPlane.AdminOperations;
using ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.Harness;

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

/// <summary>
///     Fix round 1 minor — revision-hash stability across the R03:3.2 refactor. The pre-change composer read
///     every table with a SQL <c>ORDER BY</c> (the database's case-INSENSITIVE collation); the refactor re-sorted
///     in memory with an ORDINAL comparer, which orders mixed-case keys differently ("B-1" before "a-2"). The
///     same configuration would then hash differently after the upgrade: drift detection reports every node
///     drifted, and a re-deploy of an unchanged config shows a "new" revision. This pins the composer's output
///     BYTE-identical to a verbatim replica of the pre-change composer on the real provider.
/// </summary>
[Trait("Category", "SchemaCompliance")]
public sealed class ConfigComposerSqlServerHashStabilityTests
{
    [Fact]
    public async Task Composer_output_is_byte_identical_to_the_pre_change_composer_for_mixed_case_keys()
    {
        using var sql = new SqlServerTestDatabase();
        await using (var seed = sql.NewContext())
        {
            // Collation order a-2, B-1, c-3; ordinal order B-1, a-2, c-3.
            foreach (var id in new[] { "c-3", "B-1", "a-2" })
                seed.Scripts.Add(new Script { ScriptId = id, Name = id, SourceCode = "return 1;", SourceHash = id });
            await seed.SaveChangesAsync();
        }

        await using var legacyDb = sql.NewContext();
        var legacy = await LegacySnapshotAndFlattenAsync(legacyDb);

        await using var viaDb = sql.NewContext();
        var current = await ConfigComposer.SnapshotAndFlattenAsync(viaDb);
        current.Blob.ShouldBe(legacy.Blob);
        current.RevisionHash.ShouldBe(legacy.RevisionHash);

        // The deploy path's form (validate + compose from ONE snapshot) must agree too.
        await using var deployDb = sql.NewContext();
        var viaSnapshot = ConfigComposer.Compose(await DraftSnapshotFactory.FromConfigDbAsync(deployDb));
        viaSnapshot.RevisionHash.ShouldBe(legacy.RevisionHash);
    }

    /// <summary>Verbatim replica of <c>ConfigComposer.SnapshotAndFlattenAsync</c> before R03:3.2 (ad2b5c40).</summary>
    private static async Task<(byte[] Blob, string RevisionHash)> LegacySnapshotAndFlattenAsync(OtOpcUaConfigDbContext db)
    {
        var ct = CancellationToken.None;
        var snapshot = new
        {
            Clusters = await db.ServerClusters.AsNoTracking().OrderBy(x => x.ClusterId).ToListAsync(ct),
            Nodes = await db.ClusterNodes.AsNoTracking().OrderBy(x => x.NodeId).ToListAsync(ct),
            RawFolders = await db.RawFolders.AsNoTracking().OrderBy(x => x.RawFolderId).ToListAsync(ct),
            DriverInstances = await db.DriverInstances.AsNoTracking().OrderBy(x => x.DriverInstanceId).ToListAsync(ct),
            Devices = await db.Devices.AsNoTracking().OrderBy(x => x.DeviceId).ToListAsync(ct),
            TagGroups = await db.TagGroups.AsNoTracking().OrderBy(x => x.TagGroupId).ToListAsync(ct),
            Equipment = await db.Equipment.AsNoTracking().OrderBy(x => x.EquipmentId).ToListAsync(ct),
            Tags = await db.Tags.AsNoTracking().OrderBy(x => x.TagId).ToListAsync(ct),
            UnsTagReferences = await db.UnsTagReferences.AsNoTracking().OrderBy(x => x.UnsTagReferenceId).ToListAsync(ct),
            PollGroups = await db.PollGroups.AsNoTracking().OrderBy(x => x.PollGroupId).ToListAsync(ct),
            UnsAreas = await db.UnsAreas.AsNoTracking().OrderBy(x => x.UnsAreaId).ToListAsync(ct),
            UnsLines = await db.UnsLines.AsNoTracking().OrderBy(x => x.UnsLineId).ToListAsync(ct),
            NodeAcls = await db.NodeAcls.AsNoTracking().OrderBy(x => x.NodeAclId).ToListAsync(ct),
            ApiKeys = await db.ApiKeys.AsNoTracking().OrderBy(x => x.ApiKeyId).ToListAsync(ct),
            Scripts = await db.Scripts.AsNoTracking().OrderBy(x => x.ScriptId).ToListAsync(ct),
            VirtualTags = await db.VirtualTags.AsNoTracking().OrderBy(x => x.VirtualTagId).ToListAsync(ct),
            ScriptedAlarms = await db.ScriptedAlarms.AsNoTracking().OrderBy(x => x.ScriptedAlarmId).ToListAsync(ct),
        };
        var json = JsonSerializer.SerializeToUtf8Bytes(snapshot, new JsonSerializerOptions
        {
            WriteIndented = false,
            DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.Never,
        });
        using var output = new MemoryStream(json.Length / 8);
        using (var gzip = new GZipStream(output, CompressionLevel.Fastest, leaveOpen: true))
            gzip.Write(json, 0, json.Length);
        var blob = output.ToArray();
        return (blob, Convert.ToHexStringLower(SHA256.HashData(blob)));
    }
}