using System.Collections.Concurrent;
using System.Threading;

namespace Gott.Services;

public class StreamingTracker
{
    private readonly ConcurrentDictionary<string, StreamingState> _streaming = new ConcurrentDictionary<string, StreamingState>();

    public StreamingTokens Start(string sessionId, string chainId)
    {
        var stopCts = new CancellationTokenSource();
        var hardCts = new CancellationTokenSource();
        var state = new StreamingState(chainId, stopCts, hardCts);
        _streaming[sessionId] = state;
        return new StreamingTokens(stopCts.Token, hardCts.Token);
    }

    public void Stop(string sessionId)
    {
        if (_streaming.TryRemove(sessionId, out var state))
        {
            state.StopCts.Dispose();
            state.HardCts.Dispose();
        }
    }

    /// <summary>
    /// Cancels the running stream for a session.
    /// First call = graceful (laufende Iteration wird fertig).
    /// Second call = hard (sofortiger Abbruch aus while-Loop).
    /// Returns "graceful", "hard" or null if not streaming.
    /// </summary>
    public string Cancel(string sessionId)
    {
        if (_streaming.TryGetValue(sessionId, out var state))
        {
            if (!state.StopCts.IsCancellationRequested)
            {
                // Erster Klick → graceful stop
                try { state.StopCts.Cancel(); } catch { }
                return "graceful";
            }
            else if (!state.HardCts.IsCancellationRequested)
            {
                // Zweiter Klick → hard stop
                try { state.HardCts.Cancel(); } catch { }
                return "hard";
            }
            return "hard"; // Bereits beides gecancelled
        }
        return null;
    }

    public bool IsStreaming(string sessionId) => _streaming.ContainsKey(sessionId);

    public string GetChainId(string sessionId) => _streaming.TryGetValue(sessionId, out var state) ? state.ChainId : null;

    public record StreamingTokens(CancellationToken StopToken, CancellationToken HardToken);

    private record StreamingState(string ChainId, CancellationTokenSource StopCts, CancellationTokenSource HardCts);
}