using System.Text.Json;
using Fleet.Core;
using Fleet.Rpc;

namespace Fleet.Server;

public sealed record EnrollmentContext(string? RemoteIp, JsonElement? ProductMeta);

/// <summary>产品挂钩：节点注册成功之后调用。</summary>
public interface IEnrollmentHook
{
    ValueTask OnEnrolledAsync(NodeRecord node, EnrollmentContext context, CancellationToken ct);
}

public enum NodeEventKind
{
    Online,
    Offline,
    Hello,
    Heartbeat,
}

public sealed record NodeEvent(NodeEventKind Kind, NodeRecord Node, long AtMs, HelloParams? Hello = null, JsonElement? Extra = null);

public interface INodeEventSink
{
    ValueTask OnEventAsync(NodeEvent nodeEvent, CancellationToken ct);
}

/// <summary>期望状态提供者：为每个节点计算期望状态的完整快照（天然幂等）。</summary>
public interface IStateProvider
{
    /// <summary>状态文档类型，例如 <c>task_set</c>。</summary>
    string Type { get; }

    ValueTask<StateDocument?> GetAsync(NodeRecord node, CancellationToken ct);

    /// <summary>节点应用之后回调，<c>rejected[]</c> 带结构化原因。</summary>
    ValueTask OnAppliedAsync(NodeRecord node, long version, StateSyncResult result, CancellationToken ct);
}

public sealed record StateDocument(long Version, JsonElement Doc);

public enum InboxOutcome
{
    Stored,
    Duplicate,
    Rejected,
}

/// <summary>收件箱：持久化之后才返回 Stored，框架随后才回复 ACK。</summary>
public interface IInbox
{
    byte Channel { get; }

    ValueTask<InboxOutcome> HandleAsync(NodeRecord node, Guid msgId, ReadOnlyMemory<byte> payload, CancellationToken ct);
}

/// <summary>通知 Fleet：某个节点的期望状态变了，需要重新计算并推送。</summary>
public interface IStateNotifier
{
    void NotifyChanged(NodeId node);

    void NotifyAllChanged();
}