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

namespace Fleet.Server;

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

/// <summary>
/// 服务器的身份密钥：操作员用 passkey 把它的公钥签进操作员集合。有它的时候，认证挑战会带上服务器的签名，节点据此确认对面是真的服务器，
/// 并在这条链路上用应用层加密。没有注册就是旧的行为（没有服务器身份）。
/// </summary>
public interface IServerIdentity
{
    byte[] PublicKeySpki { get; }

    /// <summary>对一段内容签名（<c>Fleet.Identity.ServerHello.Payload</c> 给出的）。</summary>
    byte[] Sign(ReadOnlySpan<byte> payload);
}

/// <summary>操作员集合的链（passkey 签的，创世在前）。没有初始化信任根时是空的。节点注册时用它确认「这个面板确实是我的操作员的」。</summary>
/// <summary>节点握手时自述的二进制（旧节点没有）。</summary>
public sealed record BinaryEvidence(string? Sha256, string? Manifest, string? Signature);

/// <summary>是否让这个节点继续：不放行时 <c>Reason</c> 会原样告诉节点（这是它自己的信息，不是秘密）。</summary>
public sealed record BinaryDecision(bool Accept, string Reason = "");

/// <summary>
/// 服务端对节点二进制的把关：节点第一次握手成功的那一刻绑定它的二进制哈希，之后哈希对不上、又不在 CI 签名的更新清单里，就不让它继续运行。
/// 没有注册实现时不做任何检查。
/// </summary>
public interface IBinaryAttestor
{
    ValueTask<BinaryDecision> CheckAsync(NodeRecord node, BinaryEvidence evidence, CancellationToken ct);
}

public interface IOperatorTrustSource
{
    ValueTask<IReadOnlyList<SignedStatementDto>> ChainAsync(CancellationToken ct);
}

/// <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();
}