using Fleet.Core;
using Monitor.Protocol;

namespace Monitor.Backend.Application;

/// <summary><c>monitor.event</c>：Agent 报告的事件（Probe 连上/断开、端点变化、时钟跳变、缺口、CPU 饱和）。</summary>
public sealed class AgentEventService
{
    private readonly AgentRuntime _runtime;
    private readonly IEventStore _events;
    private readonly TimeProvider _time;
    private readonly NodeInfoService _nodes;

    public AgentEventService(AgentRuntime runtime, IEventStore events, TimeProvider time, NodeInfoService nodes)
    {
        _runtime = runtime;
        _events = events;
        _time = time;
        _nodes = nodes;
    }

    public async ValueTask OnEventAsync(NodeId agent, AgentEventParams e, CancellationToken ct)
    {
        if (!AgentEventKinds.All.Contains(e.Kind))
        {
            return;
        }

        // 节点上报的时间可能有偏差：限制在合理范围内，避免污染事件时间线
        long now = _time.GetUtcNow().ToUnixTimeMilliseconds();
        long at = Math.Abs(e.AtUtcMs - now) > 24L * 3600 * 1000 ? now : e.AtUtcMs;

        AgentRuntimeState state = _runtime.Get(agent);
        switch (e.Kind)
        {
            case AgentEventKinds.ProbeConnected when !string.IsNullOrEmpty(e.Detail):
                state.AddProbe(e.Probe is { } p ? new ConnectedProbeInfo(e.Detail, p.Version, p.Remote, p.SinceUtcMs > 0 ? p.SinceUtcMs : at) : new ConnectedProbeInfo(e.Detail, null, null, at));
                _nodes.ObserveProbeInBackground(e.Detail, e.Probe?.Remote);
                break;
            case AgentEventKinds.ProbeDisconnected when !string.IsNullOrEmpty(e.Detail):
                state.RemoveProbe(e.Detail);
                break;
            case AgentEventKinds.EndpointChanged:
                state.CountEndpointChange();
                break;
        }

        string? detail = e.Detail is { Length: > 512 } ? e.Detail[..512] : e.Detail;
        await _events.AddAsync(agent, e.Kind, at, detail, ct);
    }
}