using Microsoft.Data.Sqlite;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using ScadaLink.Commons.Types;
using ScadaLink.Commons.Types.Enums;
using ScadaLink.SiteRuntime.Tracking;

namespace ScadaLink.SiteRuntime.Tests.Tracking;

/// <summary>
/// Audit Log #23 (M3 Bundle A — Task A2) — schema + behaviour tests for the
/// site-local <see cref="OperationTrackingStore"/>. Each test uses a unique
/// shared-cache in-memory SQLite database so the store and the verifier share
/// the same store without touching disk.
/// </summary>
public class OperationTrackingStoreTests
{
    private static (OperationTrackingStore store, string dataSource) CreateStore(
        string testName)
    {
        var dataSource = $"file:{testName}-{Guid.NewGuid():N}?mode=memory&cache=shared";
        var connectionString = $"Data Source={dataSource};Cache=Shared";
        var options = new OperationTrackingOptions
        {
            ConnectionString = connectionString,
        };
        var store = new OperationTrackingStore(
            Options.Create(options),
            NullLogger<OperationTrackingStore>.Instance);
        return (store, dataSource);
    }

    private static SqliteConnection OpenVerifierConnection(string dataSource)
    {
        var connection = new SqliteConnection($"Data Source={dataSource};Cache=Shared");
        connection.Open();
        return connection;
    }

    [Fact]
    public void Constructor_CreatesOperationTracking_SchemaOnFirstUse()
    {
        var (store, dataSource) = CreateStore(nameof(Constructor_CreatesOperationTracking_SchemaOnFirstUse));
        using (store)
        {
            using var connection = OpenVerifierConnection(dataSource);
            using var cmd = connection.CreateCommand();
            cmd.CommandText = "PRAGMA table_info(OperationTracking);";
            using var reader = cmd.ExecuteReader();

            var columns = new List<(string Name, int Pk, int NotNull)>();
            while (reader.Read())
            {
                columns.Add((reader.GetString(1), reader.GetInt32(5), reader.GetInt32(3)));
            }

            var expected = new[]
            {
                "TrackedOperationId", "Kind", "TargetSummary", "Status",
                "RetryCount", "LastError", "HttpStatus", "CreatedAtUtc",
                "UpdatedAtUtc", "TerminalAtUtc", "SourceInstanceId", "SourceScript",
            };
            Assert.Equal(
                expected.OrderBy(n => n),
                columns.Select(c => c.Name).OrderBy(n => n));

            var pkColumns = columns.Where(c => c.Pk > 0).Select(c => c.Name).ToList();
            Assert.Single(pkColumns);
            Assert.Equal("TrackedOperationId", pkColumns[0]);
        }
    }

    [Fact]
    public async Task RecordEnqueueAsync_InsertsSubmittedRow_WithRetryCountZero()
    {
        var (store, dataSource) = CreateStore(nameof(RecordEnqueueAsync_InsertsSubmittedRow_WithRetryCountZero));
        await using var _ = store;

        var id = TrackedOperationId.New();
        await store.RecordEnqueueAsync(
            id,
            kind: nameof(AuditKind.ApiCallCached),
            targetSummary: "ERP.GetOrder",
            sourceInstanceId: "Plant.Pump42",
            sourceScript: "ScriptActor:OnTick");

        var snapshot = await store.GetStatusAsync(id);
        Assert.NotNull(snapshot);
        Assert.Equal(id, snapshot!.Id);
        Assert.Equal(nameof(AuditKind.ApiCallCached), snapshot.Kind);
        Assert.Equal("ERP.GetOrder", snapshot.TargetSummary);
        Assert.Equal(nameof(AuditStatus.Submitted), snapshot.Status);
        Assert.Equal(0, snapshot.RetryCount);
        Assert.Null(snapshot.LastError);
        Assert.Null(snapshot.HttpStatus);
        Assert.Null(snapshot.TerminalAtUtc);
        Assert.Equal("Plant.Pump42", snapshot.SourceInstanceId);
        Assert.Equal("ScriptActor:OnTick", snapshot.SourceScript);
        Assert.Equal(DateTimeKind.Utc, snapshot.CreatedAtUtc.Kind);
        Assert.Equal(DateTimeKind.Utc, snapshot.UpdatedAtUtc.Kind);
    }

    [Fact]
    public async Task RecordEnqueueAsync_Duplicate_IsNoOp_FirstWriteWins()
    {
        var (store, _) = CreateStore(nameof(RecordEnqueueAsync_Duplicate_IsNoOp_FirstWriteWins));
        await using var _store = store;

        var id = TrackedOperationId.New();
        await store.RecordEnqueueAsync(id, "ApiCallCached", "ERP.GetOrder", "Plant.Pump42", "ScriptActor:OnTick");
        await store.RecordEnqueueAsync(id, "ApiCallCached", "OtherTarget", "Other.Instance", "ScriptActor:Other");

        var snapshot = await store.GetStatusAsync(id);
        Assert.NotNull(snapshot);
        // First-write-wins: the second enqueue is ignored — Target/Source stay first.
        Assert.Equal("ERP.GetOrder", snapshot!.TargetSummary);
        Assert.Equal("Plant.Pump42", snapshot.SourceInstanceId);
        Assert.Equal("ScriptActor:OnTick", snapshot.SourceScript);
        Assert.Equal(nameof(AuditStatus.Submitted), snapshot.Status);
        Assert.Equal(0, snapshot.RetryCount);
    }

    [Fact]
    public async Task RecordAttemptAsync_AdvancesStatusAndRetryCount_OnNonTerminalRow()
    {
        var (store, _) = CreateStore(nameof(RecordAttemptAsync_AdvancesStatusAndRetryCount_OnNonTerminalRow));
        await using var _store = store;

        var id = TrackedOperationId.New();
        await store.RecordEnqueueAsync(id, "ApiCallCached", "ERP.GetOrder", null, null);

        await store.RecordAttemptAsync(
            id,
            status: nameof(AuditStatus.Attempted),
            retryCount: 1,
            lastError: "HTTP 503 from ERP",
            httpStatus: 503);

        var snapshot = await store.GetStatusAsync(id);
        Assert.NotNull(snapshot);
        Assert.Equal(nameof(AuditStatus.Attempted), snapshot!.Status);
        Assert.Equal(1, snapshot.RetryCount);
        Assert.Equal("HTTP 503 from ERP", snapshot.LastError);
        Assert.Equal(503, snapshot.HttpStatus);
        Assert.Null(snapshot.TerminalAtUtc);

        // UpdatedAtUtc advances past CreatedAtUtc.
        Assert.True(snapshot.UpdatedAtUtc >= snapshot.CreatedAtUtc);
    }

    [Fact]
    public async Task RecordAttemptAsync_OnTerminalRow_IsNoOp()
    {
        var (store, _) = CreateStore(nameof(RecordAttemptAsync_OnTerminalRow_IsNoOp));
        await using var _store = store;

        var id = TrackedOperationId.New();
        await store.RecordEnqueueAsync(id, "ApiCallCached", "ERP.GetOrder", null, null);
        await store.RecordTerminalAsync(
            id,
            status: nameof(AuditStatus.Delivered),
            lastError: null,
            httpStatus: 200);

        var terminalSnapshot = await store.GetStatusAsync(id);
        Assert.NotNull(terminalSnapshot);
        Assert.NotNull(terminalSnapshot!.TerminalAtUtc);

        // Late attempt telemetry must NOT overwrite the terminal row.
        await store.RecordAttemptAsync(
            id,
            status: nameof(AuditStatus.Attempted),
            retryCount: 5,
            lastError: "late attempt",
            httpStatus: 500);

        var afterLate = await store.GetStatusAsync(id);
        Assert.NotNull(afterLate);
        Assert.Equal(nameof(AuditStatus.Delivered), afterLate!.Status);
        Assert.Equal(0, afterLate.RetryCount);
        Assert.Null(afterLate.LastError);
        Assert.Equal(200, afterLate.HttpStatus);
        Assert.NotNull(afterLate.TerminalAtUtc);
    }

    [Fact]
    public async Task RecordTerminalAsync_FlipsToTerminal_WithTerminalAtUtcSet()
    {
        var (store, _) = CreateStore(nameof(RecordTerminalAsync_FlipsToTerminal_WithTerminalAtUtcSet));
        await using var _store = store;

        var id = TrackedOperationId.New();
        await store.RecordEnqueueAsync(id, "ApiCallCached", "ERP.GetOrder", null, null);

        var beforeTerminal = DateTime.UtcNow;
        await store.RecordTerminalAsync(
            id,
            status: nameof(AuditStatus.Parked),
            lastError: "HTTP 503 (max retries)",
            httpStatus: 503);

        var snapshot = await store.GetStatusAsync(id);
        Assert.NotNull(snapshot);
        Assert.Equal(nameof(AuditStatus.Parked), snapshot!.Status);
        Assert.NotNull(snapshot.TerminalAtUtc);
        Assert.Equal(DateTimeKind.Utc, snapshot.TerminalAtUtc!.Value.Kind);
        Assert.True(snapshot.TerminalAtUtc >= beforeTerminal.AddSeconds(-1));
        Assert.Equal("HTTP 503 (max retries)", snapshot.LastError);
        Assert.Equal(503, snapshot.HttpStatus);
    }

    [Fact]
    public async Task GetStatusAsync_Unknown_ReturnsNull()
    {
        var (store, _) = CreateStore(nameof(GetStatusAsync_Unknown_ReturnsNull));
        await using var _store = store;

        var unknown = TrackedOperationId.New();
        var snapshot = await store.GetStatusAsync(unknown);

        Assert.Null(snapshot);
    }

    [Fact]
    public async Task GetStatusAsync_ReturnsLatestSnapshot_AfterMultipleAttempts()
    {
        var (store, _) = CreateStore(nameof(GetStatusAsync_ReturnsLatestSnapshot_AfterMultipleAttempts));
        await using var _store = store;

        var id = TrackedOperationId.New();
        await store.RecordEnqueueAsync(id, "ApiCallCached", "ERP.GetOrder", null, null);
        await store.RecordAttemptAsync(id, nameof(AuditStatus.Attempted), 1, "first failure", 503);
        await store.RecordAttemptAsync(id, nameof(AuditStatus.Attempted), 2, "second failure", 503);
        await store.RecordAttemptAsync(id, nameof(AuditStatus.Attempted), 3, "third failure", 504);

        var snapshot = await store.GetStatusAsync(id);
        Assert.NotNull(snapshot);
        Assert.Equal(3, snapshot!.RetryCount);
        Assert.Equal("third failure", snapshot.LastError);
        Assert.Equal(504, snapshot.HttpStatus);
    }

    [Fact]
    public async Task PurgeTerminalAsync_RemovesOldTerminalRows_KeepsRecent_KeepsNonTerminal()
    {
        var (store, dataSource) = CreateStore(nameof(PurgeTerminalAsync_RemovesOldTerminalRows_KeepsRecent_KeepsNonTerminal));
        await using var _store = store;

        // Three rows:
        // (a) terminal, old   → should be purged
        // (b) terminal, fresh → should be kept
        // (c) non-terminal, ancient CreatedAt → should be kept (no TerminalAtUtc)
        var aId = TrackedOperationId.New();
        var bId = TrackedOperationId.New();
        var cId = TrackedOperationId.New();

        await store.RecordEnqueueAsync(aId, "ApiCallCached", "A", null, null);
        await store.RecordEnqueueAsync(bId, "ApiCallCached", "B", null, null);
        await store.RecordEnqueueAsync(cId, "ApiCallCached", "C", null, null);

        await store.RecordTerminalAsync(aId, nameof(AuditStatus.Delivered), null, 200);
        await store.RecordTerminalAsync(bId, nameof(AuditStatus.Delivered), null, 200);

        // Backdate the (a) row's TerminalAtUtc to 30 days ago via a direct UPDATE
        // — RecordTerminalAsync stamps DateTime.UtcNow which we cannot inject.
        // The verifier connection shares the same in-memory store thanks to
        // mode=memory&cache=shared.
        using (var connection = OpenVerifierConnection(dataSource))
        using (var cmd = connection.CreateCommand())
        {
            cmd.CommandText =
                "UPDATE OperationTracking SET TerminalAtUtc = $old WHERE TrackedOperationId = $id;";
            cmd.Parameters.AddWithValue("$old", DateTime.UtcNow.AddDays(-30).ToString("o"));
            cmd.Parameters.AddWithValue("$id", aId.ToString());
            cmd.ExecuteNonQuery();
        }

        // Purge anything terminal older than 7 days.
        var threshold = DateTime.UtcNow.AddDays(-7);
        await store.PurgeTerminalAsync(threshold);

        Assert.Null(await store.GetStatusAsync(aId));      // purged
        Assert.NotNull(await store.GetStatusAsync(bId));   // kept (recent terminal)
        Assert.NotNull(await store.GetStatusAsync(cId));   // kept (non-terminal)
    }
}