using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.Auth.Abstractions.ApiKeys;
using ZB.MOM.WW.Auth.ApiKeys.SqlServer;
using ZB.MOM.WW.ScadaBridge.Host;

namespace ZB.MOM.WW.ScadaBridge.Host.Tests;

/// <summary>
/// Unit tests for <see cref="InboundApiKeyStoreImportService"/> — the one-shot copy of a node's
/// legacy per-node SQLite key file into the shared SQL Server store (register row 108).
/// The real importer is replaced by <see cref="FakeImporter"/> so every case runs without a
/// SQL Server: the behaviour under test is path selection, the rename-on-success, the single
/// PK-violation retry, and the "never take the node down" exception posture.
/// </summary>
public sealed class InboundApiKeyStoreImportServiceTests : IDisposable
{
    private readonly string _dir;

    public InboundApiKeyStoreImportServiceTests()
    {
        _dir = Path.Combine(Path.GetTempPath(), $"sb_apikey_import_{Guid.NewGuid():N}");
        Directory.CreateDirectory(_dir);
    }

    public void Dispose()
    {
        try
        {
            Directory.Delete(_dir, recursive: true);
        }
        catch (IOException)
        {
            // Best-effort temp cleanup; a locked file must not fail the suite.
        }
    }

    [Fact]
    public async Task StartAsync_FilePresent_ImportsThenRenamesFileAndSidecars()
    {
        var path = WriteFile("inbound-api-keys.sqlite");
        WriteFile("inbound-api-keys.sqlite-wal");
        WriteFile("inbound-api-keys.sqlite-shm");

        var importer = new FakeImporter();
        var service = CreateService(importer, sqlitePath: path);

        await service.StartAsync(CancellationToken.None);

        Assert.Equal(new[] { path }, importer.Calls);
        Assert.False(File.Exists(path));
        Assert.True(File.Exists(path + ".imported"));
        Assert.False(File.Exists(path + "-wal"));
        Assert.True(File.Exists(path + "-wal.imported"));
        Assert.False(File.Exists(path + "-shm"));
        Assert.True(File.Exists(path + "-shm.imported"));
    }

    [Fact]
    public async Task StartAsync_FileAbsent_DoesNotCallImporter()
    {
        var importer = new FakeImporter();
        var service = CreateService(importer, sqlitePath: Path.Combine(_dir, "missing.sqlite"));

        await service.StartAsync(CancellationToken.None);

        Assert.Empty(importer.Calls);
    }

    [Fact]
    public async Task StartAsync_BlankPath_DoesNotCallImporter()
    {
        var importer = new FakeImporter();
        var service = CreateService(importer, sqlitePath: "   ");

        await service.StartAsync(CancellationToken.None);

        Assert.Empty(importer.Calls);
    }

    [Fact]
    public async Task StartAsync_ImportFromSqlitePath_OverridesApiKeyOptionsPath()
    {
        var apiKeyPath = WriteFile("api-key-options.sqlite");
        var overridePath = WriteFile("explicit-override.sqlite");

        var importer = new FakeImporter();
        var service = CreateService(importer, sqlitePath: apiKeyPath, importFrom: overridePath);

        await service.StartAsync(CancellationToken.None);

        Assert.Equal(new[] { overridePath }, importer.Calls);
        Assert.True(File.Exists(apiKeyPath));           // untouched
        Assert.True(File.Exists(overridePath + ".imported"));
    }

    [Fact]
    public async Task StartAsync_ImporterThrows_DoesNotThrowAndLeavesFileInPlace()
    {
        var path = WriteFile("inbound-api-keys.sqlite");

        var importer = new FakeImporter { ThrowOnCall = _ => new InvalidOperationException("boom") };
        var service = CreateService(importer, sqlitePath: path);

        await service.StartAsync(CancellationToken.None);

        Assert.Single(importer.Calls);
        Assert.True(File.Exists(path));                 // left for the next boot to retry
        Assert.False(File.Exists(path + ".imported"));
    }

    [Fact]
    public async Task StartAsync_PrimaryKeyViolation_RetriesOnceThenSucceeds()
    {
        var path = WriteFile("inbound-api-keys.sqlite");

        var importer = new FakeImporter
        {
            ThrowOnCall = call => call == 1 ? FabricateSqlException("duplicate key", number: 2627) : null,
        };
        var service = CreateService(importer, sqlitePath: path);

        await service.StartAsync(CancellationToken.None);

        Assert.Equal(2, importer.Calls.Count);
        Assert.True(File.Exists(path + ".imported"));
    }

    [Fact]
    public async Task StartAsync_PrimaryKeyViolationTwice_DoesNotThrowAndLeavesFileInPlace()
    {
        var path = WriteFile("inbound-api-keys.sqlite");

        var importer = new FakeImporter
        {
            ThrowOnCall = _ => FabricateSqlException("duplicate key", number: 2627),
        };
        var service = CreateService(importer, sqlitePath: path);

        await service.StartAsync(CancellationToken.None);

        Assert.Equal(2, importer.Calls.Count);
        Assert.True(File.Exists(path));
    }

    [Fact]
    public async Task StartAsync_NonPrimaryKeySqlException_DoesNotRetry()
    {
        var path = WriteFile("inbound-api-keys.sqlite");

        var importer = new FakeImporter
        {
            ThrowOnCall = _ => FabricateSqlException("login failed", number: 18456),
        };
        var service = CreateService(importer, sqlitePath: path);

        await service.StartAsync(CancellationToken.None);

        Assert.Single(importer.Calls);
        Assert.True(File.Exists(path));
    }

    [Fact]
    public async Task StartAsync_StaleImportedFilePresent_IsOverwritten()
    {
        var path = WriteFile("inbound-api-keys.sqlite", content: "fresh");
        WriteFile("inbound-api-keys.sqlite.imported", content: "stale");

        var importer = new FakeImporter();
        var service = CreateService(importer, sqlitePath: path);

        await service.StartAsync(CancellationToken.None);

        Assert.False(File.Exists(path));
        Assert.Equal("fresh", File.ReadAllText(path + ".imported"));
    }

    [Fact]
    public async Task StopAsync_IsANoOp()
    {
        var importer = new FakeImporter();
        var service = CreateService(importer, sqlitePath: Path.Combine(_dir, "missing.sqlite"));

        await service.StopAsync(CancellationToken.None);

        Assert.Empty(importer.Calls);
    }

    // --- helpers ---

    private string WriteFile(string name, string content = "x")
    {
        var path = Path.Combine(_dir, name);
        File.WriteAllText(path, content);
        return path;
    }

    private static InboundApiKeyStoreImportService CreateService(
        IInboundApiKeyStoreImporter importer, string sqlitePath, string? importFrom = null)
        => new(
            importer,
            Options.Create(new InboundApiKeyStoreOptions
            {
                Provider = InboundApiKeyStoreProvider.SqlServer,
                ImportFromSqlitePath = importFrom,
            }),
            Options.Create(new ApiKeyOptions { SqlitePath = sqlitePath }),
            NullLogger<InboundApiKeyStoreImportService>.Instance);

    private sealed class FakeImporter : IInboundApiKeyStoreImporter
    {
        private int _calls;

        public List<string> Calls { get; } = new();

        /// <summary>Given the 1-based call number, returns the exception to throw, or null to succeed.</summary>
        public Func<int, Exception?>? ThrowOnCall { get; init; }

        public Task<ApiKeyImportResult> ImportAsync(string sqlitePath, CancellationToken ct)
        {
            Calls.Add(sqlitePath);
            var call = ++_calls;
            var toThrow = ThrowOnCall?.Invoke(call);
            if (toThrow is not null)
            {
                return Task.FromException<ApiKeyImportResult>(toThrow);
            }

            return Task.FromResult(new ApiKeyImportResult(1, 0, 2, 0, SourceFound: true));
        }
    }

    /// <summary>
    /// Fabricates a <see cref="Microsoft.Data.SqlClient.SqlException"/> with a given message and
    /// error number via the driver's internal <c>CreateException</c> factory (the type has no
    /// public constructor). Same recipe as <c>DatabaseGatewayTests.FabricateSqlException</c>;
    /// duplicated because the two suites share no test-support assembly.
    /// </summary>
    private static Microsoft.Data.SqlClient.SqlException FabricateSqlException(string message, int number)
    {
        var errorCtor = typeof(Microsoft.Data.SqlClient.SqlError).GetConstructors(
            System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic)
            .First(c => c.GetParameters().Length == 8
                && c.GetParameters()[7].ParameterType == typeof(Exception));
        var sqlError = (Microsoft.Data.SqlClient.SqlError)errorCtor.Invoke(
            new object?[] { number, (byte)0, (byte)0, "server", message, "procedure", 0, null });

        var collectionCtor = typeof(Microsoft.Data.SqlClient.SqlErrorCollection).GetConstructors(
            System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic).First();
        var collection = (Microsoft.Data.SqlClient.SqlErrorCollection)collectionCtor.Invoke(Array.Empty<object?>());
        typeof(Microsoft.Data.SqlClient.SqlErrorCollection)
            .GetMethod("Add", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic)!
            .Invoke(collection, new object?[] { sqlError });

        var createException = typeof(Microsoft.Data.SqlClient.SqlException).GetMethod(
            "CreateException",
            System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic,
            new[] { typeof(Microsoft.Data.SqlClient.SqlErrorCollection), typeof(string) })!;
        return (Microsoft.Data.SqlClient.SqlException)createException.Invoke(
            null, new object?[] { collection, "6.0.0" })!;
    }
}