using System.Collections.Generic;
using System.Linq;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Gott.Extensions;
using Gott.Models;
using Gott.Services;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.Configuration;

namespace Gott.Endpoints;

public static class ChatEndpoint
{
    public static void MapChatEndpoint(this IEndpointRouteBuilder app)
    {
        app.MapPost("/api/chat", HandleChat);
    }

    private static async Task HandleChat(HttpRequest req, HttpResponse res, IConfiguration config, ChatService chatService, DatabaseService db, StreamingTracker streamingTracker, AnthropicService anthropic, CancellationToken cancellationToken)
    {
        var body = await JsonSerializer.DeserializeAsync<ChatRequest>(req.Body);
        if (body == null || body.Messages == null || body.Messages.Count == 0)
        {
            res.StatusCode = 400;
            await res.WriteAsJsonAsync(new { error = "messages required" });
            return;
        }

        var sessionId = body.SessionId;
        if (string.IsNullOrEmpty(sessionId))
        {
            res.StatusCode = 400;
            await res.WriteAsJsonAsync(new { error = "sessionId required" });
            return;
        }

        var userId = req.HttpContext.GetUserId();
        var maxIterations = config.GetValue<int>("MaxIterations", 100);

        var ctx = await chatService.PrepareContext(sessionId, userId, maxIterations);
        if (ctx == null)
        {
            res.StatusCode = 400;
            await res.WriteAsJsonAsync(new { error = "Session/Agent nicht gefunden oder kein Agent ausgewählt" });
            return;
        }

        res.Headers["Content-Type"] = "text/event-stream";
        res.Headers["Cache-Control"] = "no-cache";
        res.Headers["Connection"] = "keep-alive";

        // Messages aus dem Request aufbereiten
        var messages = new List<object>();
        foreach (var msg in body.Messages)
        {
            JsonElement content = msg.Content;
            if (msg.Content.ValueKind == JsonValueKind.Array)
            {
                var node = System.Text.Json.Nodes.JsonNode.Parse(msg.Content.GetRawText());
                foreach (var block in node.AsArray())
                {
                    if (block is System.Text.Json.Nodes.JsonObject obj)
                        obj.Remove("_file_name");
                }
                content = JsonSerializer.Deserialize<JsonElement>(node.ToJsonString());
            }

            messages.Add(new Dictionary<string, JsonElement>
            {
                ["role"] = JsonSerializer.Deserialize<JsonElement>($"\"{msg.Role}\""),
                ["content"] = content
            });
        }

        // Nur die letzte User-Message speichern (= die neue)
        var lastUserMsg = body.Messages.LastOrDefault(m => m.Role == "user");
        if (lastUserMsg != null)
        {
            var textContent = lastUserMsg.GetTextContent();
            var attachmentBlocks = lastUserMsg.GetAttachmentBlocks();

            var attachmentRecords = attachmentBlocks.Select(b => new AttachmentRecord
            {
                Type = b.Type,
                MediaType = b.MediaType,
                FileName = b.FileName,
                Data = b.Data
            }).ToList();

            await db.SaveMessageWithAttachments(new MessageRecord
            {
                ChainId = ctx.ChainId,
                Iteration = 0,
                Role = "user",
                Type = "text",
                Content = textContent
            }, attachmentRecords);
        }

        streamingTracker.Start(sessionId, ctx.ChainId);
        try
        {
            await anthropic.StreamChat(res, ctx.ModelId, ctx.SystemPrompt, messages, ctx.ChainId, ctx.Workspace, sessionId, agentId: ctx.AgentId, useMemory: ctx.UseMemory, webSearchVersion: ctx.WebSearchVersion, maxIterations: ctx.MaxIterations, toolChoice: ctx.ToolChoice, cancellationToken: cancellationToken);
        }
        finally
        {
            streamingTracker.Stop(sessionId);
        }
    }
}