using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Time.Testing;
using StellaOps.Notifier.Worker.Digest;

namespace StellaOps.Notifier.Tests.Digest;

public class InMemoryDigestSchedulerTests
{
    private readonly FakeTimeProvider _timeProvider;
    private readonly InMemoryDigestScheduler _scheduler;

    public InMemoryDigestSchedulerTests()
    {
        _timeProvider = new FakeTimeProvider(new DateTimeOffset(2024, 1, 15, 10, 0, 0, TimeSpan.Zero));
        _scheduler = new InMemoryDigestScheduler(
            _timeProvider,
            NullLogger<InMemoryDigestScheduler>.Instance);
    }

    [Fact]
    public async Task UpsertScheduleAsync_CreatesNewSchedule()
    {
        // Arrange
        var schedule = CreateTestSchedule("schedule-1");

        // Act
        var result = await _scheduler.UpsertScheduleAsync(schedule);

        // Assert
        Assert.NotNull(result);
        Assert.Equal("schedule-1", result.ScheduleId);
        Assert.NotNull(result.NextRunAt);
    }

    [Fact]
    public async Task UpsertScheduleAsync_UpdatesExistingSchedule()
    {
        // Arrange
        var schedule = CreateTestSchedule("schedule-1");
        await _scheduler.UpsertScheduleAsync(schedule);

        var updated = schedule with { Name = "Updated Name" };

        // Act
        var result = await _scheduler.UpsertScheduleAsync(updated);

        // Assert
        Assert.Equal("Updated Name", result.Name);
    }

    [Fact]
    public async Task GetScheduleAsync_ReturnsSchedule()
    {
        // Arrange
        var schedule = CreateTestSchedule("schedule-1");
        await _scheduler.UpsertScheduleAsync(schedule);

        // Act
        var result = await _scheduler.GetScheduleAsync("tenant1", "schedule-1");

        // Assert
        Assert.NotNull(result);
        Assert.Equal("schedule-1", result.ScheduleId);
    }

    [Fact]
    public async Task GetScheduleAsync_ReturnsNullForUnknown()
    {
        // Act
        var result = await _scheduler.GetScheduleAsync("tenant1", "unknown");

        // Assert
        Assert.Null(result);
    }

    [Fact]
    public async Task GetSchedulesAsync_ReturnsTenantSchedules()
    {
        // Arrange
        await _scheduler.UpsertScheduleAsync(CreateTestSchedule("schedule-1", "tenant1"));
        await _scheduler.UpsertScheduleAsync(CreateTestSchedule("schedule-2", "tenant1"));
        await _scheduler.UpsertScheduleAsync(CreateTestSchedule("schedule-3", "tenant2"));

        // Act
        var result = await _scheduler.GetSchedulesAsync("tenant1");

        // Assert
        Assert.Equal(2, result.Count);
        Assert.All(result, s => Assert.Equal("tenant1", s.TenantId));
    }

    [Fact]
    public async Task DeleteScheduleAsync_RemovesSchedule()
    {
        // Arrange
        await _scheduler.UpsertScheduleAsync(CreateTestSchedule("schedule-1"));

        // Act
        var deleted = await _scheduler.DeleteScheduleAsync("tenant1", "schedule-1");

        // Assert
        Assert.True(deleted);
        var result = await _scheduler.GetScheduleAsync("tenant1", "schedule-1");
        Assert.Null(result);
    }

    [Fact]
    public async Task DeleteScheduleAsync_ReturnsFalseForUnknown()
    {
        // Act
        var deleted = await _scheduler.DeleteScheduleAsync("tenant1", "unknown");

        // Assert
        Assert.False(deleted);
    }

    [Fact]
    public async Task GetDueSchedulesAsync_ReturnsDueSchedules()
    {
        // Arrange - create a schedule that should run every minute
        var schedule = CreateTestSchedule("schedule-1") with
        {
            CronExpression = "0 * * * * *" // Every minute
        };
        await _scheduler.UpsertScheduleAsync(schedule);

        // Advance time past next run
        _timeProvider.Advance(TimeSpan.FromMinutes(2));

        // Act
        var dueSchedules = await _scheduler.GetDueSchedulesAsync(_timeProvider.GetUtcNow());

        // Assert
        Assert.Single(dueSchedules);
        Assert.Equal("schedule-1", dueSchedules[0].ScheduleId);
    }

    [Fact]
    public async Task GetDueSchedulesAsync_ExcludesDisabledSchedules()
    {
        // Arrange
        var schedule = CreateTestSchedule("schedule-1") with
        {
            Enabled = false,
            CronExpression = "0 * * * * *"
        };
        await _scheduler.UpsertScheduleAsync(schedule);

        _timeProvider.Advance(TimeSpan.FromMinutes(2));

        // Act
        var dueSchedules = await _scheduler.GetDueSchedulesAsync(_timeProvider.GetUtcNow());

        // Assert
        Assert.Empty(dueSchedules);
    }

    [Fact]
    public async Task UpdateLastRunAsync_UpdatesTimestamps()
    {
        // Arrange
        var schedule = CreateTestSchedule("schedule-1") with
        {
            CronExpression = "0 0 * * * *" // Every hour
        };
        await _scheduler.UpsertScheduleAsync(schedule);

        var runTime = _timeProvider.GetUtcNow();

        // Act
        await _scheduler.UpdateLastRunAsync("tenant1", "schedule-1", runTime);

        // Assert
        var updated = await _scheduler.GetScheduleAsync("tenant1", "schedule-1");
        Assert.NotNull(updated);
        Assert.Equal(runTime, updated.LastRunAt);
        Assert.NotNull(updated.NextRunAt);
        Assert.True(updated.NextRunAt > runTime);
    }

    [Fact]
    public async Task UpsertScheduleAsync_CalculatesNextRunWithTimezone()
    {
        // Arrange
        var schedule = CreateTestSchedule("schedule-1") with
        {
            CronExpression = "0 0 9 * * *", // 9 AM every day
            Timezone = "America/New_York"
        };

        // Act
        var result = await _scheduler.UpsertScheduleAsync(schedule);

        // Assert
        Assert.NotNull(result.NextRunAt);
    }

    [Fact]
    public async Task UpsertScheduleAsync_HandlesInvalidCron()
    {
        // Arrange
        var schedule = CreateTestSchedule("schedule-1") with
        {
            CronExpression = "invalid-cron"
        };

        // Act
        var result = await _scheduler.UpsertScheduleAsync(schedule);

        // Assert
        Assert.Null(result.NextRunAt);
    }

    [Fact]
    public async Task GetSchedulesAsync_OrdersByName()
    {
        // Arrange
        await _scheduler.UpsertScheduleAsync(CreateTestSchedule("schedule-c") with { Name = "Charlie" });
        await _scheduler.UpsertScheduleAsync(CreateTestSchedule("schedule-a") with { Name = "Alpha" });
        await _scheduler.UpsertScheduleAsync(CreateTestSchedule("schedule-b") with { Name = "Bravo" });

        // Act
        var result = await _scheduler.GetSchedulesAsync("tenant1");

        // Assert
        Assert.Equal(3, result.Count);
        Assert.Equal("Alpha", result[0].Name);
        Assert.Equal("Bravo", result[1].Name);
        Assert.Equal("Charlie", result[2].Name);
    }

    private DigestSchedule CreateTestSchedule(string id, string tenantId = "tenant1")
    {
        return new DigestSchedule
        {
            ScheduleId = id,
            TenantId = tenantId,
            Name = $"Test Schedule {id}",
            Enabled = true,
            CronExpression = "0 0 8 * * *", // 8 AM daily
            DigestType = DigestType.Daily,
            Format = DigestFormat.Html,
            CreatedAt = _timeProvider.GetUtcNow(),
            Recipients =
            [
                new DigestRecipient { Type = "email", Address = "test@example.com" }
            ]
        };
    }
}