using System.Text;
using ClaudeDo.Data;
using ClaudeDo.Data.Models;
using ClaudeDo.Data.Repositories;
using ClaudeDo.Worker.Config;
using ClaudeDo.Worker.Hub;
using ClaudeDo.Worker.Runner;
using ClaudeDo.Worker.Runner.Interfaces;
using Microsoft.EntityFrameworkCore;

namespace ClaudeDo.Worker.Planning;

public sealed class InteractiveSessionService
{
    private readonly IDbContextFactory<ClaudeDoDbContext> _dbFactory;
    private readonly WorkerConfig _cfg;
    private readonly HubBroadcaster _broadcaster;
    private readonly LiveSessionRegistry _registry;
    private readonly ILoggerFactory _loggerFactory;

    // Optional factory for tests. Signature: (onLine) -> (session, waitForExitTask).
    // The waitForExitTask completes when the underlying process has exited.
    private readonly Func<string, IReadOnlyList<string>, Func<string, Task>, (ILiveSession session, Task exitTask)>? _sessionFactory;

    public InteractiveSessionService(
        IDbContextFactory<ClaudeDoDbContext> dbFactory,
        WorkerConfig cfg,
        HubBroadcaster broadcaster,
        LiveSessionRegistry registry,
        ILoggerFactory loggerFactory,
        Func<string, IReadOnlyList<string>, Func<string, Task>, (ILiveSession session, Task exitTask)>? sessionFactory = null)
    {
        _dbFactory = dbFactory;
        _cfg = cfg;
        _broadcaster = broadcaster;
        _registry = registry;
        _loggerFactory = loggerFactory;
        _sessionFactory = sessionFactory;
    }

    public async Task StartAsync(string taskId, CancellationToken ct)
    {
        if (_registry.TryGet(taskId, out _))
            throw new InvalidOperationException("An interactive session is already running for this task.");

        await using var ctx = _dbFactory.CreateDbContext();
        var tasks = new TaskRepository(ctx);
        var lists = new ListRepository(ctx);

        var task = await tasks.GetByIdAsync(taskId, ct)
            ?? throw new InvalidOperationException($"Task {taskId} not found.");
        var list = await lists.GetByIdAsync(task.ListId, ct)
            ?? throw new InvalidOperationException($"List {task.ListId} not found.");

        var workingDir = list.WorkingDir;
        if (string.IsNullOrWhiteSpace(workingDir) || !Directory.Exists(workingDir))
            throw new InvalidOperationException(
                $"List '{list.Name}' has no valid working directory configured.");

        var seededPrompt = BuildInteractivePrompt(task);

        var args = new[]
        {
            "-p",
            "--input-format", "stream-json",
            "--output-format", "stream-json",
            "--verbose",
            "--replay-user-messages",
            "--model", ModelRegistry.PlanningAlias,
            "--permission-mode", "auto",
        };

        Func<string, Task> onLine = line => _broadcaster.TaskMessage(taskId, "[stdout] " + line);

        ILiveSession session;
        Task exitTask;

        if (_sessionFactory is not null)
        {
            // Factory is responsible for providing a ready-to-use session and its exit signal.
            (session, exitTask) = _sessionFactory(workingDir, args, onLine);
        }
        else
        {
            var transport = new ProcessClaudeStreamTransport(
                _cfg,
                _loggerFactory.CreateLogger<ProcessClaudeStreamTransport>());
            var streamingSession = new StreamingClaudeSession(
                transport,
                onLine,
                _loggerFactory.CreateLogger<StreamingClaudeSession>(),
                onQueueChanged: pending => _ = _broadcaster.InteractiveQueueChanged(taskId, pending),
                onUserMessageSent: text => _ = _broadcaster.InteractiveMessageSent(taskId, text));
            await streamingSession.StartAsync(args, workingDir, seededPrompt, ct);
            session = streamingSession;
            exitTask = transport.WaitForExitAsync();
        }
        _registry.Register(taskId, session);
        await _broadcaster.InteractiveSessionStarted(taskId);

        var logger = _loggerFactory.CreateLogger<InteractiveSessionService>();
        _ = WatchExitAsync(taskId, exitTask, logger);
    }

    private async Task WatchExitAsync(string taskId, Task exitTask, ILogger logger)
    {
        try
        {
            await exitTask;
        }
        catch (Exception ex)
        {
            logger.LogWarning(ex, "Interactive session exit watcher caught an exception for task {task_id}", taskId);
        }
        finally
        {
            _registry.Unregister(taskId);
            try { await _broadcaster.InteractiveSessionEnded(taskId); }
            catch (Exception ex) { logger.LogWarning(ex, "InteractiveSessionEnded broadcast failed for task {task_id}", taskId); }
        }
    }

    public async Task SendAsync(string taskId, string text, CancellationToken ct)
    {
        if (!_registry.TryGet(taskId, out var session))
            throw new InvalidOperationException("No interactive session is running for this task.");
        await session.SendUserMessageAsync(text, ct);
    }

    public async Task InterruptAsync(string taskId, CancellationToken ct)
    {
        if (_registry.TryGet(taskId, out var session))
            await session.InterruptAsync(ct);
    }

    public async Task StopAsync(string taskId, CancellationToken ct)
    {
        // StopAsync removes from registry and kills the session.
        // The exit watcher will fire InteractiveSessionEnded once the process exits,
        // so we don't broadcast here — the watcher is the single authoritative source.
        await _registry.StopAsync(taskId);
    }

    private static string BuildInteractivePrompt(TaskEntity task)
    {
        var sb = new StringBuilder();
        sb.AppendLine($"# Task: {task.Title}");
        if (!string.IsNullOrWhiteSpace(task.Description))
        {
            sb.AppendLine();
            sb.AppendLine(task.Description);
        }
        return sb.ToString();
    }
}