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

namespace ScadaLink.StoreAndForward.Tests;

/// <summary>
/// WP-9: Tests for SQLite persistence layer.
/// Uses in-memory SQLite with a kept-alive connection for test isolation.
/// </summary>
public class StoreAndForwardStorageTests : IAsyncLifetime, IDisposable
{
    private readonly SqliteConnection _keepAlive;
    private readonly StoreAndForwardStorage _storage;
    private readonly string _dbName;

    public StoreAndForwardStorageTests()
    {
        _dbName = $"StorageTests_{Guid.NewGuid():N}";
        var connStr = $"Data Source={_dbName};Mode=Memory;Cache=Shared";
        // Keep one connection alive so the in-memory DB persists
        _keepAlive = new SqliteConnection(connStr);
        _keepAlive.Open();
        _storage = new StoreAndForwardStorage(connStr, NullLogger<StoreAndForwardStorage>.Instance);
    }

    public async Task InitializeAsync() => await _storage.InitializeAsync();

    public Task DisposeAsync() => Task.CompletedTask;

    public void Dispose()
    {
        _keepAlive.Dispose();
    }

    [Fact]
    public async Task EnqueueAsync_StoresMessage()
    {
        var message = CreateMessage("msg1", StoreAndForwardCategory.ExternalSystem);
        await _storage.EnqueueAsync(message);

        var retrieved = await _storage.GetMessageByIdAsync("msg1");
        Assert.NotNull(retrieved);
        Assert.Equal("msg1", retrieved!.Id);
        Assert.Equal(StoreAndForwardCategory.ExternalSystem, retrieved.Category);
        Assert.Equal("target1", retrieved.Target);
    }

    [Fact]
    public async Task EnqueueAsync_AllCategories()
    {
        await _storage.EnqueueAsync(CreateMessage("es1", StoreAndForwardCategory.ExternalSystem));
        await _storage.EnqueueAsync(CreateMessage("n1", StoreAndForwardCategory.Notification));
        await _storage.EnqueueAsync(CreateMessage("db1", StoreAndForwardCategory.CachedDbWrite));

        var es = await _storage.GetMessageByIdAsync("es1");
        var n = await _storage.GetMessageByIdAsync("n1");
        var db = await _storage.GetMessageByIdAsync("db1");

        Assert.Equal(StoreAndForwardCategory.ExternalSystem, es!.Category);
        Assert.Equal(StoreAndForwardCategory.Notification, n!.Category);
        Assert.Equal(StoreAndForwardCategory.CachedDbWrite, db!.Category);
    }

    [Fact]
    public async Task RemoveMessageAsync_RemovesSuccessfully()
    {
        await _storage.EnqueueAsync(CreateMessage("rm1", StoreAndForwardCategory.ExternalSystem));
        await _storage.RemoveMessageAsync("rm1");

        var retrieved = await _storage.GetMessageByIdAsync("rm1");
        Assert.Null(retrieved);
    }

    [Fact]
    public async Task UpdateMessageAsync_UpdatesFields()
    {
        var message = CreateMessage("upd1", StoreAndForwardCategory.ExternalSystem);
        await _storage.EnqueueAsync(message);

        message.RetryCount = 5;
        message.LastAttemptAt = DateTimeOffset.UtcNow;
        message.Status = StoreAndForwardMessageStatus.Parked;
        message.LastError = "Connection refused";
        await _storage.UpdateMessageAsync(message);

        var retrieved = await _storage.GetMessageByIdAsync("upd1");
        Assert.Equal(5, retrieved!.RetryCount);
        Assert.Equal(StoreAndForwardMessageStatus.Parked, retrieved.Status);
        Assert.Equal("Connection refused", retrieved.LastError);
    }

    [Fact]
    public async Task GetMessagesForRetryAsync_ReturnsOnlyPendingMessages()
    {
        var pending = CreateMessage("pend1", StoreAndForwardCategory.ExternalSystem);
        pending.Status = StoreAndForwardMessageStatus.Pending;
        await _storage.EnqueueAsync(pending);

        var parked = CreateMessage("park1", StoreAndForwardCategory.ExternalSystem);
        parked.Status = StoreAndForwardMessageStatus.Parked;
        await _storage.EnqueueAsync(parked);
        await _storage.UpdateMessageAsync(parked);

        var forRetry = await _storage.GetMessagesForRetryAsync();
        Assert.All(forRetry, m => Assert.Equal(StoreAndForwardMessageStatus.Pending, m.Status));
    }

    [Fact]
    public async Task GetMessagesForRetryAsync_NonZeroInterval_ExcludesNotYetDueIncludesDue()
    {
        // StoreAndForward-013: exercise the julianday elapsed-time comparison with a
        // non-zero retry interval. A message attempted just now must NOT be due; one
        // attempted long ago must be due.
        var notDue = CreateMessage("notdue", StoreAndForwardCategory.ExternalSystem);
        notDue.RetryIntervalMs = (long)TimeSpan.FromHours(1).TotalMilliseconds;
        notDue.LastAttemptAt = DateTimeOffset.UtcNow;
        await _storage.EnqueueAsync(notDue);

        var due = CreateMessage("due", StoreAndForwardCategory.ExternalSystem);
        due.RetryIntervalMs = (long)TimeSpan.FromMinutes(5).TotalMilliseconds;
        due.LastAttemptAt = DateTimeOffset.UtcNow.AddHours(-2);
        await _storage.EnqueueAsync(due);

        var neverAttempted = CreateMessage("never", StoreAndForwardCategory.ExternalSystem);
        neverAttempted.RetryIntervalMs = (long)TimeSpan.FromHours(1).TotalMilliseconds;
        neverAttempted.LastAttemptAt = null;
        await _storage.EnqueueAsync(neverAttempted);

        var forRetry = await _storage.GetMessagesForRetryAsync();
        var ids = forRetry.Select(m => m.Id).ToHashSet();

        Assert.DoesNotContain("notdue", ids);
        Assert.Contains("due", ids);
        Assert.Contains("never", ids);
    }

    [Fact]
    public async Task GetParkedMessagesAsync_ReturnsParkedOnly()
    {
        var msg = CreateMessage("prk1", StoreAndForwardCategory.Notification);
        msg.Status = StoreAndForwardMessageStatus.Parked;
        await _storage.EnqueueAsync(msg);
        await _storage.UpdateMessageAsync(msg);

        var (messages, total) = await _storage.GetParkedMessagesAsync();
        Assert.True(total > 0);
        Assert.All(messages, m => Assert.Equal(StoreAndForwardMessageStatus.Parked, m.Status));
    }

    [Fact]
    public async Task RetryParkedMessageAsync_MovesToPending()
    {
        var msg = CreateMessage("retry1", StoreAndForwardCategory.ExternalSystem);
        msg.Status = StoreAndForwardMessageStatus.Parked;
        msg.RetryCount = 10;
        await _storage.EnqueueAsync(msg);
        await _storage.UpdateMessageAsync(msg);

        var success = await _storage.RetryParkedMessageAsync("retry1");
        Assert.True(success);

        var retrieved = await _storage.GetMessageByIdAsync("retry1");
        Assert.Equal(StoreAndForwardMessageStatus.Pending, retrieved!.Status);
        Assert.Equal(0, retrieved.RetryCount);
    }

    [Fact]
    public async Task RetryParkedMessageAsync_ClearsLastAttemptAt_SoMessageIsImmediatelyDue()
    {
        // StoreAndForward-010: a re-queued parked message must be unambiguously due
        // for the next sweep regardless of its (stale) last_attempt_at. Use a large
        // retry interval so a leftover timestamp would otherwise exclude the message.
        var msg = CreateMessage("requeue1", StoreAndForwardCategory.ExternalSystem);
        msg.RetryIntervalMs = (long)TimeSpan.FromHours(1).TotalMilliseconds;
        msg.LastAttemptAt = DateTimeOffset.UtcNow; // recent attempt
        msg.Status = StoreAndForwardMessageStatus.Parked;
        await _storage.EnqueueAsync(msg);
        await _storage.UpdateMessageAsync(msg);

        var requeued = await _storage.RetryParkedMessageAsync("requeue1");
        Assert.True(requeued);

        var retrieved = await _storage.GetMessageByIdAsync("requeue1");
        Assert.Null(retrieved!.LastAttemptAt);

        // It must appear in the retry-due set even though the configured interval
        // (1 hour) has not elapsed since the original attempt.
        var due = await _storage.GetMessagesForRetryAsync();
        Assert.Contains(due, m => m.Id == "requeue1");
    }

    [Fact]
    public async Task DiscardParkedMessageAsync_RemovesMessage()
    {
        var msg = CreateMessage("disc1", StoreAndForwardCategory.ExternalSystem);
        msg.Status = StoreAndForwardMessageStatus.Parked;
        await _storage.EnqueueAsync(msg);
        await _storage.UpdateMessageAsync(msg);

        var success = await _storage.DiscardParkedMessageAsync("disc1");
        Assert.True(success);

        var retrieved = await _storage.GetMessageByIdAsync("disc1");
        Assert.Null(retrieved);
    }

    [Fact]
    public async Task GetBufferDepthByCategoryAsync_ReturnsCorrectCounts()
    {
        await _storage.EnqueueAsync(CreateMessage("bd1", StoreAndForwardCategory.ExternalSystem));
        await _storage.EnqueueAsync(CreateMessage("bd2", StoreAndForwardCategory.ExternalSystem));
        await _storage.EnqueueAsync(CreateMessage("bd3", StoreAndForwardCategory.Notification));

        var depth = await _storage.GetBufferDepthByCategoryAsync();
        Assert.True(depth.GetValueOrDefault(StoreAndForwardCategory.ExternalSystem) >= 2);
    }

    [Fact]
    public async Task GetMessageCountByOriginInstanceAsync_ReturnsCount()
    {
        var msg1 = CreateMessage("oi1", StoreAndForwardCategory.ExternalSystem);
        msg1.OriginInstanceName = "Pump1";
        await _storage.EnqueueAsync(msg1);

        var msg2 = CreateMessage("oi2", StoreAndForwardCategory.Notification);
        msg2.OriginInstanceName = "Pump1";
        await _storage.EnqueueAsync(msg2);

        var count = await _storage.GetMessageCountByOriginInstanceAsync("Pump1");
        Assert.Equal(2, count);
    }

    [Fact]
    public async Task GetParkedMessagesAsync_Pagination()
    {
        for (int i = 0; i < 5; i++)
        {
            var msg = CreateMessage($"page{i}", StoreAndForwardCategory.ExternalSystem);
            msg.Status = StoreAndForwardMessageStatus.Parked;
            await _storage.EnqueueAsync(msg);
            await _storage.UpdateMessageAsync(msg);
        }

        var (page1, total) = await _storage.GetParkedMessagesAsync(pageNumber: 1, pageSize: 2);
        Assert.Equal(2, page1.Count);
        Assert.True(total >= 5);

        var (page2, _) = await _storage.GetParkedMessagesAsync(pageNumber: 2, pageSize: 2);
        Assert.Equal(2, page2.Count);
    }

    [Fact]
    public async Task GetMessageCountByStatusAsync_ReturnsAccurateCount()
    {
        var msg = CreateMessage("cnt1", StoreAndForwardCategory.ExternalSystem);
        await _storage.EnqueueAsync(msg);

        var count = await _storage.GetMessageCountByStatusAsync(StoreAndForwardMessageStatus.Pending);
        Assert.True(count >= 1);
    }

    private static StoreAndForwardMessage CreateMessage(string id, StoreAndForwardCategory category)
    {
        return new StoreAndForwardMessage
        {
            Id = id,
            Category = category,
            Target = "target1",
            PayloadJson = """{"method":"Test","args":{}}""",
            RetryCount = 0,
            MaxRetries = 50,
            RetryIntervalMs = 30000,
            CreatedAt = DateTimeOffset.UtcNow,
            Status = StoreAndForwardMessageStatus.Pending
        };
    }

    [Fact]
    public async Task InitializeAsync_FileInMissingDirectory_CreatesDirectory()
    {
        // SQLite creates the database file on demand but not its parent directory;
        // the storage must create the directory itself or OpenAsync fails with
        // "unable to open database file" (the cause of the SiteActorPathTests failures).
        var directory = Path.Combine(Path.GetTempPath(), "sf-storage-test-" + Guid.NewGuid().ToString("N"));
        var dbPath = Path.Combine(directory, "store-and-forward.db");
        Assert.False(Directory.Exists(directory));

        try
        {
            var storage = new StoreAndForwardStorage(
                $"Data Source={dbPath}", NullLogger<StoreAndForwardStorage>.Instance);

            await storage.InitializeAsync();

            Assert.True(Directory.Exists(directory));
            Assert.True(File.Exists(dbPath));
        }
        finally
        {
            if (Directory.Exists(directory))
                Directory.Delete(directory, recursive: true);
        }
    }
}