acdream/src/AcDream.App/Streaming/LandblockStreamJob.cs

using System.Collections.Generic;
using AcDream.Core.Terrain;
using AcDream.Core.World;

namespace AcDream.App.Streaming;

/// <summary>
/// A job posted to <see cref="LandblockStreamer"/>'s inbox. Either a load
/// (fetch this landblock from the dats and build its CPU-side mesh data)
/// or an unload (release any state tied to this landblock on the render
/// thread's next Tick drain).
/// </summary>
public abstract record LandblockStreamJob(uint LandblockId)
{
    public sealed record Load(
        uint LandblockId,
        LandblockStreamJobKind Kind,
        ulong Generation = 0,
        LandblockBuildOrigin Origin = default) : LandblockStreamJob(LandblockId)
    {
        public LandblockBuildRequest Request =>
            new(LandblockId, Kind, Generation, Origin);
    }
    public sealed record Unload(
        uint LandblockId,
        ulong Generation = 0) : LandblockStreamJob(LandblockId);

    /// <summary>
    /// Control job: drop every queued (not-yet-started) Load from the worker's
    /// priority queues, keeping Unloads. Posted by
    /// <see cref="LandblockStreamer.ClearPendingLoads"/> when the player enters a
    /// dungeon and the in-flight outdoor/neighbor window load must be cancelled
    /// (#133 FPS — dungeons have no adjacent landblocks). LandblockId is 0 by
    /// convention; readers pattern-match on the type.
    /// </summary>
    public sealed record ClearLoads() : LandblockStreamJob(0);
}

/// <summary>
/// Outbox record the render thread drains. Either a successful load, a
/// failed load (logged and ignored until region recenters off/back), or
/// an unload notification (tells the render thread to release GPU state
/// for this landblock id).
/// </summary>
public abstract record LandblockStreamResult(uint LandblockId, ulong Generation)
{
    /// <summary>
    /// A landblock load completed. <see cref="Tier"/> distinguishes Far
    /// (terrain only) from Near (terrain + entities). <see cref="MeshData"/>
    /// is built off the render thread on the streaming worker.
    /// </summary>
    public sealed record Loaded(
        uint LandblockId,
        LandblockStreamTier Tier,
        LandblockBuild Build,
        LandblockMeshData MeshData,
        ulong Generation = 0
    ) : LandblockStreamResult(LandblockId, Generation)
    {
        public Loaded(
            uint landblockId,
            LandblockStreamTier tier,
            LoadedLandblock landblock,
            LandblockMeshData meshData,
            ulong generation = 0)
            : this(landblockId, tier, new LandblockBuild(landblock), meshData, generation)
        {
        }

        public LoadedLandblock Landblock => Build.Landblock;
    }

    /// <summary>
    /// A previously-Far-resident landblock was promoted to Near. The result
    /// carries the full near landblock plus mesh data so the render thread can
    /// run the same near-tier side effects as a fresh LoadNear: cell visibility,
    /// building registries, EnvCell finalization, lighting, and static collision.
    /// GpuWorldState still merges only the entity layer so live entities already
    /// attached to the landblock are preserved.
    /// </summary>
    public sealed record Promoted(
        uint LandblockId,
        LandblockBuild Build,
        LandblockMeshData MeshData,
        ulong Generation = 0
    ) : LandblockStreamResult(LandblockId, Generation)
    {
        public Promoted(
            uint landblockId,
            LoadedLandblock landblock,
            LandblockMeshData meshData,
            ulong generation = 0)
            : this(landblockId, new LandblockBuild(landblock), meshData, generation)
        {
        }

        public LoadedLandblock Landblock => Build.Landblock;
        public IReadOnlyList<WorldEntity> Entities => Landblock.Entities;
    }

    public sealed record Failed(
        uint LandblockId,
        string Error,
        ulong Generation = 0) : LandblockStreamResult(LandblockId, Generation);
    public sealed record Unloaded(
        uint LandblockId,
        ulong Generation = 0) : LandblockStreamResult(LandblockId, Generation);

    /// <summary>
    /// The worker loop itself crashed with an unhandled exception. Not tied
    /// to a specific landblock — distinguished from <see cref="Failed"/>
    /// because consumers typically route this to a fatal-log path rather
    /// than retrying a single landblock later. LandblockId is 0 by
    /// convention; readers should pattern-match on the type, not the id.
    /// </summary>
    public sealed record WorkerCrashed(string Error) : LandblockStreamResult(0, 0);
}