using Elsa.AI.Abstractions.Contracts;
using Elsa.AI.Abstractions.Models;
using Elsa.Common.Multitenancy;
using Elsa.AI.Host.Options;
using Elsa.AI.Host.Streaming;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using ChatEndpoint = Elsa.AI.Host.Endpoints.AI.Chat.Endpoint;
using MicrosoftOptions = Microsoft.Extensions.Options.Options;

namespace Elsa.AI.IntegrationTests;

public class AIChatEndpointReconnectTests
{
    [Fact(DisplayName = "Chat endpoint marks the actual reconnect conversation as connected")]
    public async Task ChatEndpointMarksTheActualReconnectConversationAsConnected()
    {
        var sessionManager = new AIStreamSessionManager();
        sessionManager.MarkDisconnected("foreign-conversation", TimeSpan.FromMinutes(5));
        sessionManager.MarkDisconnected("actual-conversation", TimeSpan.FromMinutes(5));
        var endpoint = new ChatEndpoint(
            new ReassignedConversationOrchestrator(),
            sessionManager,
            MicrosoftOptions.Create(new AIHostOptions()));
        SetHttpContext(endpoint, new DefaultHttpContext
        {
            Response =
            {
                Body = new MemoryStream()
            }
        });

        await endpoint.HandleAsync(new AIChatRequest
        {
            ConversationId = "foreign-conversation",
            UserId = "user-1",
            Message = "Reconnect"
        }, CancellationToken.None);

        Assert.True(sessionManager.CanReconnect("foreign-conversation"));
        Assert.False(sessionManager.CanReconnect("actual-conversation"));
    }

    [Fact(DisplayName = "Chat endpoint releases reconnect reservation when no stream starts")]
    public async Task ChatEndpointReleasesReconnectReservationWhenNoStreamStarts()
    {
        var sessionManager = new AIStreamSessionManager();
        sessionManager.MarkDisconnected("conversation-1", TimeSpan.FromMinutes(5));
        var endpoint = new ChatEndpoint(
            new EmptyOrchestrator(),
            sessionManager,
            MicrosoftOptions.Create(new AIHostOptions()));
        SetHttpContext(endpoint, new DefaultHttpContext
        {
            Response =
            {
                Body = new MemoryStream()
            }
        });

        await endpoint.HandleAsync(new AIChatRequest
        {
            ConversationId = "conversation-1",
            UserId = "user-1",
            Message = "Reconnect"
        }, CancellationToken.None);

        Assert.True(sessionManager.CanReconnect("conversation-1"));
    }

    [Fact(DisplayName = "Chat endpoint resolves tenant from tenant accessor")]
    public async Task ChatEndpointResolvesTenantFromTenantAccessor()
    {
        var tenantAccessor = new DefaultTenantAccessor();
        using var tenantScope = tenantAccessor.PushContext(new Tenant { Id = "tenant-1", Name = "Tenant 1" });
        var services = new ServiceCollection();
        services.AddSingleton<ITenantAccessor>(tenantAccessor);
        await using var provider = services.BuildServiceProvider();
        var orchestrator = new CapturingRequestOrchestrator();
        var endpoint = new ChatEndpoint(
            orchestrator,
            new AIStreamSessionManager(),
            MicrosoftOptions.Create(new AIHostOptions()));
        SetHttpContext(endpoint, new DefaultHttpContext
        {
            RequestServices = provider,
            Response =
            {
                Body = new MemoryStream()
            }
        });

        await endpoint.HandleAsync(new AIChatRequest
        {
            ConversationId = "conversation-1",
            UserId = "user-1",
            Message = "Reconnect"
        }, CancellationToken.None);

        Assert.Equal("tenant-1", orchestrator.Request!.TenantId);
    }

    [Fact(DisplayName = "Chat endpoint clears unknown requested agents")]
    public async Task ChatEndpointClearsUnknownRequestedAgents()
    {
        var orchestrator = new CapturingRequestOrchestrator();
        var endpoint = new ChatEndpoint(
            orchestrator,
            new AIStreamSessionManager(),
            MicrosoftOptions.Create(new AIHostOptions()));
        SetHttpContext(endpoint, new DefaultHttpContext
        {
            Response =
            {
                Body = new MemoryStream()
            }
        });

        await endpoint.HandleAsync(new AIChatRequest
        {
            ConversationId = "conversation-1",
            UserId = "user-1",
            Agent = "privileged-agent",
            Message = "Use a privileged tool"
        }, CancellationToken.None);

        Assert.Null(orchestrator.Request!.Agent);
    }

    [Fact(DisplayName = "Chat endpoint forwards known requested agents")]
    public async Task ChatEndpointForwardsKnownRequestedAgents()
    {
        var orchestrator = new CapturingRequestOrchestrator();
        var endpoint = new ChatEndpoint(
            orchestrator,
            new AIStreamSessionManager(),
            MicrosoftOptions.Create(new AIHostOptions()));
        SetHttpContext(endpoint, new DefaultHttpContext
        {
            Response =
            {
                Body = new MemoryStream()
            }
        });

        await endpoint.HandleAsync(new AIChatRequest
        {
            ConversationId = "conversation-1",
            UserId = "user-1",
            Agent = "workflow-author",
            Message = "Use authoring tools"
        }, CancellationToken.None);

        Assert.Equal("workflow-author", orchestrator.Request!.Agent);
    }

    [Fact(DisplayName = "Chat endpoint clears client supplied provider names")]
    public async Task ChatEndpointClearsClientSuppliedProviderNames()
    {
        var orchestrator = new CapturingRequestOrchestrator();
        var endpoint = new ChatEndpoint(
            orchestrator,
            new AIStreamSessionManager(),
            MicrosoftOptions.Create(new AIHostOptions()));
        SetHttpContext(endpoint, new DefaultHttpContext
        {
            Response =
            {
                Body = new MemoryStream()
            }
        });

        await endpoint.HandleAsync(new AIChatRequest
        {
            ConversationId = "conversation-1",
            UserId = "user-1",
            ProviderName = "privileged-provider",
            Message = "Use a specific provider"
        }, CancellationToken.None);

        Assert.Null(orchestrator.Request!.ProviderName);
    }

    [Fact(DisplayName = "Chat endpoint normalizes explicit null request values")]
    public async Task ChatEndpointNormalizesExplicitNullRequestValues()
    {
        var orchestrator = new CapturingRequestOrchestrator();
        var endpoint = new ChatEndpoint(
            orchestrator,
            new AIStreamSessionManager(),
            MicrosoftOptions.Create(new AIHostOptions()));
        SetHttpContext(endpoint, new DefaultHttpContext
        {
            Response =
            {
                Body = new MemoryStream()
            }
        });

        await endpoint.HandleAsync(new AIChatRequest
        {
            ConversationId = "conversation-1",
            UserId = "user-1",
            Message = null!,
            Attachments = null!
        }, CancellationToken.None);

        Assert.Equal("", orchestrator.Request!.Message);
        Assert.Empty(orchestrator.Request.Attachments);
    }

    [Fact(DisplayName = "Chat endpoint generates conversation ID for blank values")]
    public async Task ChatEndpointGeneratesConversationIdForBlankValues()
    {
        var orchestrator = new CapturingRequestOrchestrator();
        var endpoint = new ChatEndpoint(
            orchestrator,
            new AIStreamSessionManager(),
            MicrosoftOptions.Create(new AIHostOptions()));
        SetHttpContext(endpoint, new DefaultHttpContext
        {
            Response =
            {
                Body = new MemoryStream()
            }
        });

        await endpoint.HandleAsync(new AIChatRequest
        {
            ConversationId = " ",
            UserId = "user-1",
            Message = "Start a conversation"
        }, CancellationToken.None);

        Assert.False(string.IsNullOrWhiteSpace(orchestrator.Request!.ConversationId));
        Assert.NotEqual(" ", orchestrator.Request.ConversationId);
    }

    private static void SetHttpContext(ChatEndpoint endpoint, HttpContext httpContext)
    {
        var property = typeof(ChatEndpoint)
            .GetProperty(nameof(ChatEndpoint.HttpContext), System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.NonPublic);
        property!.SetValue(endpoint, httpContext);
    }

    private class EmptyOrchestrator : IAIOrchestrator
    {
        public async IAsyncEnumerable<AIStreamEvent> ExecuteChatAsync(AIChatRequest request, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
        {
            await Task.Yield();
            yield break;
        }
    }

    private class ReassignedConversationOrchestrator : IAIOrchestrator
    {
        public async IAsyncEnumerable<AIStreamEvent> ExecuteChatAsync(AIChatRequest request, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
        {
            await Task.Yield();

            yield return new AIStreamEvent
            {
                Type = "conversation.started",
                ConversationId = "actual-conversation",
                Sequence = 0,
                Timestamp = DateTimeOffset.UtcNow
            };

            yield return new AIStreamEvent
            {
                Type = "conversation.completed",
                ConversationId = "actual-conversation",
                Sequence = 1,
                Timestamp = DateTimeOffset.UtcNow
            };
        }
    }

    private class CapturingRequestOrchestrator : IAIOrchestrator
    {
        public AIChatRequest? Request { get; private set; }

        public async IAsyncEnumerable<AIStreamEvent> ExecuteChatAsync(AIChatRequest request, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
        {
            Request = request;
            await Task.Yield();

            yield return new AIStreamEvent
            {
                Type = "conversation.completed",
                ConversationId = request.ConversationId!,
                Sequence = 0,
                Timestamp = DateTimeOffset.UtcNow
            };
        }
    }
}