SpacetimeDB/crates/bindings-csharp/Runtime/Runtime.cs

namespace SpacetimeDB;

using System.Runtime.CompilerServices;
using SpacetimeDB.BSATN;
using SpacetimeDB.Internal;
using static System.Text.Encoding;

public class ReducerContext
{
    public readonly Identity Sender;
    public readonly DateTimeOffset Time;
    public readonly Address? Address;

    internal ReducerContext(
        Identity senderIdentity,
        Address? senderAddress,
        DateTimeOffset timestamp
    )
    {
        Sender = senderIdentity;
        Address = senderAddress;
        Time = timestamp;
    }
}

// [SpacetimeDB.Type] - we have custom representation of time in microseconds, so implementing BSATN manually
public abstract partial record ScheduleAt
    : SpacetimeDB.TaggedEnum<(DateTimeOffset Time, TimeSpan Interval)>
{
    public static implicit operator ScheduleAt(DateTimeOffset time) => new Time(time);

    public static implicit operator ScheduleAt(TimeSpan interval) => new Interval(interval);

    // Manual expansion of what would be otherwise generated by the [SpacetimeDB.Type] codegen,
    // except we forward to/from a `ScheduleAtRepr` that has the actual generated implementation.

    private ScheduleAt() { }

    [SpacetimeDB.Type]
    private partial record ScheduleAtRepr
        : SpacetimeDB.TaggedEnum<(DateTimeOffsetRepr Time, TimeSpanRepr Interval)>;

    public sealed record Time(DateTimeOffset Time_) : ScheduleAt
    {
        public override void WriteFields(BinaryWriter writer) =>
            new ScheduleAtRepr.Time(new(Time_)).WriteFields(writer);
    }

    public sealed record Interval(TimeSpan Interval_) : ScheduleAt
    {
        public override void WriteFields(BinaryWriter writer) =>
            new ScheduleAtRepr.Interval(new(Interval_)).WriteFields(writer);
    }

    public readonly partial struct BSATN : IReadWrite<ScheduleAt>
    {
        private static readonly ScheduleAtRepr.BSATN ReprBSATN = new();

        public ScheduleAt Read(BinaryReader reader) =>
            ReprBSATN.Read(reader) switch
            {
                ScheduleAtRepr.Time(var timeRepr) => new Time(timeRepr.ToStd()),
                ScheduleAtRepr.Interval(var intervalRepr) => new Interval(intervalRepr.ToStd()),
                _ => throw new SwitchExpressionException(),
            };

        public void Write(BinaryWriter writer, ScheduleAt value) => value.WriteFields(writer);

        public AlgebraicType GetAlgebraicType(ITypeRegistrar registrar) =>
            // Constructing a custom one instead of ScheduleAtRepr.GetAlgebraicType()
            // to avoid leaking the internal *Repr wrappers in generated SATS.
            new AlgebraicType.Sum(
                [
                    new(nameof(Time), new AlgebraicType.U64(default)),
                    new(nameof(Interval), new AlgebraicType.U64(default)),
                ]
            );
    }
}

public static class Runtime
{
    public enum LogLevel : byte
    {
        Error,
        Warn,
        Info,
        Debug,
        Trace,
        Panic,
    }

    public static void Log(
        string text,
        LogLevel level = LogLevel.Info,
        [CallerMemberName] string target = "",
        [CallerFilePath] string filename = "",
        [CallerLineNumber] uint lineNumber = 0
    )
    {
        var target_bytes = UTF8.GetBytes(target);
        var filename_bytes = UTF8.GetBytes(filename);
        var text_bytes = UTF8.GetBytes(text);

        FFI._console_log(
            (byte)level,
            target_bytes,
            (uint)target_bytes.Length,
            filename_bytes,
            (uint)filename_bytes.Length,
            lineNumber,
            text_bytes,
            (uint)text_bytes.Length
        );
    }

    // An instance of `System.Random` that is reseeded by each reducer's timestamp.
    public static Random Random { get; internal set; } = new();
}