using ChatBot.Models;
using ChatBot.Models.Dto;
using FluentAssertions;
using OllamaSharp.Models.Chat;

namespace ChatBot.Tests.Models;

public class ChatSessionTests
{
    [Fact]
    public void Constructor_ShouldInitializeProperties()
    {
        // Arrange & Act
        var session = new ChatSession();

        // Assert
        session.ChatId.Should().Be(0);
        session.SessionId.Should().NotBeNullOrEmpty();
        session.ChatType.Should().Be("private");
        session.ChatTitle.Should().Be(string.Empty);
        session.Model.Should().Be(string.Empty);
        session.CreatedAt.Should().BeCloseTo(DateTime.UtcNow, TimeSpan.FromSeconds(1));
        session.LastUpdatedAt.Should().BeCloseTo(DateTime.UtcNow, TimeSpan.FromSeconds(1));
        session.GetAllMessages().Should().NotBeNull();
        session.GetAllMessages().Should().BeEmpty();
    }

    [Fact]
    public void AddUserMessage_ShouldAddMessageToSession()
    {
        // Arrange
        var session = new ChatSession();
        var content = "Hello";
        var username = "testuser";

        // Act
        session.AddUserMessage(content, username);

        // Assert
        session.GetAllMessages().Should().HaveCount(1);
        var message = session.GetAllMessages().First();
        message.Role.Should().Be(ChatRole.User);
        message.Content.Should().Be(content);
    }

    [Fact]
    public void AddAssistantMessage_ShouldAddMessageToSession()
    {
        // Arrange
        var session = new ChatSession();
        var content = "Hello! How can I help you?";

        // Act
        session.AddAssistantMessage(content);

        // Assert
        session.GetAllMessages().Should().HaveCount(1);
        var message = session.GetAllMessages().First();
        message.Role.Should().Be(ChatRole.Assistant);
        message.Content.Should().Be(content);
    }

    [Fact]
    public void AddMessage_ShouldAddMessageToSession()
    {
        // Arrange
        var session = new ChatSession();
        var content = "You are a helpful assistant.";
        var message = new ChatMessage { Role = ChatRole.System, Content = content };

        // Act
        session.AddMessage(message);

        // Assert
        session.GetAllMessages().Should().HaveCount(1);
        var addedMessage = session.GetAllMessages().First();
        addedMessage.Role.Should().Be(ChatRole.System);
        addedMessage.Content.Should().Be(content);
    }

    [Fact]
    public void ClearHistory_ShouldRemoveAllMessages()
    {
        // Arrange
        var session = new ChatSession();
        session.AddUserMessage("Hello", "testuser");
        session.AddAssistantMessage("Hi there!");

        // Act
        session.ClearHistory();

        // Assert
        session.GetAllMessages().Should().BeEmpty();
    }

    [Fact]
    public void GetMessageCount_ShouldReturnCorrectCount()
    {
        // Arrange
        var session = new ChatSession();
        session.AddUserMessage("Hello", "testuser");
        session.AddAssistantMessage("Hi there!");
        session.AddUserMessage("How are you?", "testuser");

        // Act
        var count = session.GetMessageCount();

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

    [Fact]
    public void GetLastMessage_ShouldReturnLastMessage()
    {
        // Arrange
        var session = new ChatSession();
        session.AddUserMessage("Hello", "testuser");
        session.AddAssistantMessage("Hi there!");
        session.AddUserMessage("How are you?", "testuser");

        // Act
        var messages = session.GetAllMessages();
        var lastMessage = messages.LastOrDefault();

        // Assert
        lastMessage.Should().NotBeNull();
        lastMessage!.Content.Should().Be("How are you?");
        lastMessage.Role.Should().Be(ChatRole.User);
    }

    [Fact]
    public void GetLastMessage_ShouldReturnNull_WhenNoMessages()
    {
        // Arrange
        var session = new ChatSession();

        // Act
        var messages = session.GetAllMessages();
        var lastMessage = messages.LastOrDefault();

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

    [Fact]
    public void AddMessage_ShouldUpdateLastUpdatedAt()
    {
        // Arrange
        var session = new ChatSession();
        var originalTime = session.LastUpdatedAt;
        var message = new ChatMessage { Role = ChatRole.User, Content = "Test" };

        // Act
        session.AddMessage(message);

        // Assert
        session.LastUpdatedAt.Should().BeAfter(originalTime);
    }

    [Fact]
    public void GetMessageCount_ShouldReturnZero_WhenNoMessages()
    {
        // Arrange
        var session = new ChatSession();

        // Act
        var count = session.GetMessageCount();

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

    [Fact]
    public void GetMessageCount_ShouldReturnCorrectCount_WhenHasMessages()
    {
        // Arrange
        var session = new ChatSession();
        session.AddUserMessage("Hello", "testuser");

        // Act
        var count = session.GetMessageCount();

        // Assert
        count.Should().Be(1);
    }
}