using ChatBot.Models;
using ChatBot.Services;
using ChatBot.Tests.TestUtilities;
using FluentAssertions;

namespace ChatBot.Tests.Services;

public class InMemorySessionStorageTests
{
    private readonly InMemorySessionStorage _sessionStorage;

    public InMemorySessionStorageTests()
    {
        _sessionStorage = new InMemorySessionStorage(
            TestDataBuilder.Mocks.CreateLoggerMock<InMemorySessionStorage>().Object
        );
    }

    [Fact]
    public void GetOrCreate_ShouldReturnExistingSession_WhenSessionExists()
    {
        // Arrange
        _sessionStorage.GetOrCreate(12345, "private", "Test Chat");

        // Act
        var result = _sessionStorage.GetOrCreate(12345, "private", "Test Chat");

        // Assert
        result.Should().NotBeNull();
        result.ChatId.Should().Be(12345);
        result.ChatType.Should().Be("private");
    }

    [Fact]
    public void GetOrCreate_ShouldCreateNewSession_WhenSessionDoesNotExist()
    {
        // Act
        var result = _sessionStorage.GetOrCreate(12345, "group", "Test Group");

        // Assert
        result.Should().NotBeNull();
        result.ChatId.Should().Be(12345);
        result.ChatType.Should().Be("group");
        result.ChatTitle.Should().Be("Test Group");
    }

    [Fact]
    public void GetOrCreate_ShouldUseDefaultValues_WhenParametersNotProvided()
    {
        // Act
        var result = _sessionStorage.GetOrCreate(12345);

        // Assert
        result.Should().NotBeNull();
        result.ChatId.Should().Be(12345);
        result.ChatType.Should().Be("private");
        result.ChatTitle.Should().BeEmpty();
    }

    [Fact]
    public void Get_ShouldReturnSession_WhenSessionExists()
    {
        // Arrange
        var session = _sessionStorage.GetOrCreate(12345, "private", "Test Chat");

        // Act
        var result = _sessionStorage.Get(12345);

        // Assert
        result.Should().BeSameAs(session);
    }

    [Fact]
    public void Get_ShouldReturnNull_WhenSessionDoesNotExist()
    {
        // Act
        var result = _sessionStorage.Get(99999);

        // Assert
        result.Should().BeNull();
    }

    [Fact]
    public async Task SaveSessionAsync_ShouldUpdateExistingSession()
    {
        // Arrange
        var session = _sessionStorage.GetOrCreate(12345, "private", "Original Title");
        session.ChatTitle = "Updated Title";
        session.LastUpdatedAt = DateTime.UtcNow;

        // Act
        await _sessionStorage.SaveSessionAsync(session);

        // Assert
        var savedSession = _sessionStorage.Get(12345);
        savedSession.Should().NotBeNull();
        savedSession!.ChatTitle.Should().Be("Updated Title");
    }

    [Fact]
    public async Task SaveSessionAsync_ShouldAddNewSession()
    {
        // Arrange
        var session = _sessionStorage.GetOrCreate(12345, "private", "Original Title");
        session.ChatTitle = "New Session";

        // Act
        await _sessionStorage.SaveSessionAsync(session);

        // Assert
        var savedSession = _sessionStorage.Get(12345);
        savedSession.Should().NotBeNull();
        savedSession!.ChatTitle.Should().Be("New Session");
    }

    [Fact]
    public void Remove_ShouldReturnTrue_WhenSessionExists()
    {
        // Arrange
        _sessionStorage.GetOrCreate(12345, "private", "Test Chat");

        // Act
        var result = _sessionStorage.Remove(12345);

        // Assert
        result.Should().BeTrue();
        _sessionStorage.Get(12345).Should().BeNull();
    }

    [Fact]
    public void Remove_ShouldReturnFalse_WhenSessionDoesNotExist()
    {
        // Act
        var result = _sessionStorage.Remove(99999);

        // Assert
        result.Should().BeFalse();
    }

    [Fact]
    public void GetActiveSessionsCount_ShouldReturnCorrectCount()
    {
        // Arrange
        _sessionStorage.GetOrCreate(12345, "private", "Chat 1");
        _sessionStorage.GetOrCreate(67890, "group", "Chat 2");
        _sessionStorage.GetOrCreate(11111, "private", "Chat 3");

        // Act
        var count = _sessionStorage.GetActiveSessionsCount();

        // Assert
        count.Should().Be(3);
    }

    [Fact]
    public void GetActiveSessionsCount_ShouldReturnZero_WhenNoSessions()
    {
        // Act
        var count = _sessionStorage.GetActiveSessionsCount();

        // Assert
        count.Should().Be(0);
    }

    [Fact]
    public void CleanupOldSessions_ShouldDeleteOldSessions()
    {
        // Arrange
        var oldSession = _sessionStorage.GetOrCreate(99999, "private", "Old Chat");
        // Manually set CreatedAt to 2 days ago using test method
        oldSession.SetCreatedAtForTesting(DateTime.UtcNow.AddDays(-2));

        var recentSession = _sessionStorage.GetOrCreate(88888, "private", "Recent Chat");
        // Manually set CreatedAt to 30 minutes ago using test method
        recentSession.SetCreatedAtForTesting(DateTime.UtcNow.AddMinutes(-30));

        // Act
        _sessionStorage.CleanupOldSessions(1); // Delete sessions older than 1 day

        // Assert
        _sessionStorage.Get(99999).Should().BeNull(); // Old session should be deleted
        _sessionStorage.Get(88888).Should().NotBeNull(); // Recent session should remain
    }

    [Fact]
    public void CleanupOldSessions_ShouldNotDeleteRecentSessions()
    {
        // Arrange
        var recentSession1 = _sessionStorage.GetOrCreate(12345, "private", "Recent 1");
        recentSession1.CreatedAt = DateTime.UtcNow.AddHours(-1);

        var recentSession2 = _sessionStorage.GetOrCreate(67890, "private", "Recent 2");
        recentSession2.CreatedAt = DateTime.UtcNow.AddMinutes(-30);

        // Act
        var deletedCount = _sessionStorage.CleanupOldSessions(24); // Delete sessions older than 24 hours

        // Assert
        deletedCount.Should().Be(0);
        _sessionStorage.Get(12345).Should().NotBeNull();
        _sessionStorage.Get(67890).Should().NotBeNull();
    }

    [Fact]
    public void CleanupOldSessions_ShouldReturnZero_WhenNoSessions()
    {
        // Act
        var deletedCount = _sessionStorage.CleanupOldSessions(1);

        // Assert
        deletedCount.Should().Be(0);
    }

    [Fact]
    public void GetOrCreate_ShouldCreateSessionWithCorrectTimestamp()
    {
        // Act
        var session = _sessionStorage.GetOrCreate(12345, "private", "Test Chat");

        // Assert
        session.CreatedAt.Should().BeCloseTo(DateTime.UtcNow, TimeSpan.FromMinutes(1));
        session.LastUpdatedAt.Should().BeCloseTo(DateTime.UtcNow, TimeSpan.FromMinutes(1));
    }

    [Fact]
    public async Task SaveSessionAsync_ShouldUpdateLastUpdatedAt()
    {
        // Arrange
        var session = _sessionStorage.GetOrCreate(12345, "private", "Test Chat");
        var originalTime = session.LastUpdatedAt;

        // Wait a bit to ensure time difference
        await Task.Delay(10);

        session.ChatTitle = "Updated Title";

        // Act
        await _sessionStorage.SaveSessionAsync(session);

        // Assert
        var savedSession = _sessionStorage.Get(12345);
        savedSession!.LastUpdatedAt.Should().BeAfter(originalTime);
    }

    [Fact]
    public async Task GetOrCreate_ShouldHandleConcurrentAccess()
    {
        // Arrange
        var tasks = new List<Task<ChatSession>>();

        // Act - Create sessions concurrently
        for (int i = 0; i < 100; i++)
        {
            var chatId = 1000 + i;
            tasks.Add(
                Task.Run(() => _sessionStorage.GetOrCreate(chatId, "private", $"Chat {chatId}"))
            );
        }

        await Task.WhenAll(tasks);

        // Assert
        _sessionStorage.GetActiveSessionsCount().Should().Be(100);

        // Verify all sessions were created
        for (int i = 0; i < 100; i++)
        {
            var chatId = 1000 + i;
            var session = _sessionStorage.Get(chatId);
            session.Should().NotBeNull();
            session!.ChatId.Should().Be(chatId);
        }
    }

    [Fact]
    public void Remove_ShouldDecreaseActiveSessionsCount()
    {
        // Arrange
        _sessionStorage.GetOrCreate(12345, "private", "Chat 1");
        _sessionStorage.GetOrCreate(67890, "private", "Chat 2");
        _sessionStorage.GetOrCreate(11111, "private", "Chat 3");

        // Act
        _sessionStorage.Remove(67890);

        // Assert
        _sessionStorage.GetActiveSessionsCount().Should().Be(2);
        _sessionStorage.Get(12345).Should().NotBeNull();
        _sessionStorage.Get(67890).Should().BeNull();
        _sessionStorage.Get(11111).Should().NotBeNull();
    }
}