namespace HSchool.Protocol;

/// <summary>
/// First frame from the client. <paramref name="Locale"/> is <see cref="ProtocolConstants.LocaleRussian"/>
/// or <see cref="ProtocolConstants.LocaleEnglish"/> — the same language the catalog HTTP API uses.
/// </summary>
public readonly record struct ClientHelloMessage(byte ProtocolVersion, byte Locale);

/// <summary>Round-trip probe; the server mirrors <paramref name="ClientTimeMs"/> back untouched.</summary>
public readonly record struct ClientPingMessage(long ClientTimeMs);

/// <summary>Asks for clock updates of one school. Starts its calendar running.</summary>
public readonly record struct ClientOpenSchoolMessage(int SchoolId);

/// <summary>
/// Play or pause the open school. Running and speed are separate messages on purpose: a button
/// that also resent the other field would clobber it with whatever the client last saw.
/// </summary>
public readonly record struct ClientSetRunningMessage(bool Running);

/// <summary>Change the speed of the open school without touching whether it runs.</summary>
public readonly record struct ClientSetSpeedMessage(byte SpeedIndex);

/// <summary>Sent once per connection, before anything else.</summary>
public readonly record struct ServerWelcomeMessage(byte ProtocolVersion, byte TickRate, byte MaxSchools);

/// <summary>Answer to <see cref="ClientPingMessage"/>, carrying the current server tick.</summary>
public readonly record struct ServerPongMessage(long ClientTimeMs, uint ServerTick);

/// <summary>
/// State of the open school's calendar, sent every tick.
/// <paramref name="GameTimeUnixMs"/> is the in-game date as milliseconds since the Unix epoch,
/// interpreted as UTC — the game calendar has no time zone.
/// </summary>
public readonly record struct ServerClockMessage(
    int SchoolId,
    long GameTimeUnixMs,
    bool Running,
    byte SpeedIndex);

/// <summary>The open school no longer exists (deleted from another tab); the client returns to the menu.</summary>
public readonly record struct ServerSchoolGoneMessage(int SchoolId);

/// <summary>
/// Tree node in a map snapshot. Kind is <c>0</c> territory, <c>1</c> building, <c>2</c> floor, <c>3</c> room.
/// <paramref name="ParentId"/> is empty for the yard.
/// <paramref name="PupilSlots"/> is how many pupils can take a lesson here — summed from things
/// on the server, not by the client.
/// <paramref name="ActivitySubject"/> and <paramref name="ActivityClass"/> are empty when the
/// room is free. <paramref name="Characters"/> are the people the timetable puts there right now.
/// </summary>
public sealed record MapSnapshotNode(
    byte Kind,
    string Id,
    string ParentId,
    string Name,
    ushort PupilSlots,
    IReadOnlyList<MapSnapshotItem> Items,
    IReadOnlyList<string> Positions,
    string ActivitySubject = "",
    string ActivityClass = "",
    IReadOnlyList<string>? Characters = null)
{
    public IReadOnlyList<string> Present => Characters ?? [];
}

/// <summary>One stacked thing in a room. <paramref name="Count"/> is 1–255.</summary>
public sealed record MapSnapshotItem(string Name, byte Count);

/// <summary>
/// One school's map, labelled in the Hello locale. Sent when that school is opened and again
/// when the current lesson slot changes. Occupancy is computed from the timetable and the clock.
/// </summary>
public sealed record ServerMapSnapshotMessage(int SchoolId, IReadOnlyList<MapSnapshotNode> Nodes);