gaemstone.ECS/src/gaemstone.ECS/World.cs

using System;
using gaemstone.ECS.Internal;
using static flecs_hub.flecs;

namespace gaemstone.ECS;

public unsafe struct World<TContext>
	: IEquatable<World<TContext>>
	, IDisposable
{
	public readonly World Value;

	public bool IsDeferred      => Value.IsDeferred;
	public bool IsQuitRequested => Value.IsQuitRequested;

	public World(World value)
		=> Value = value;

	/// <summary> Initializes a new Flecs world. </summary>
	/// <param name="minimal"> If true, doesn't automatically import built-in modules. </param>
	public World(bool minimal = false)
		: this(new World(minimal)) {  }

	public bool Progress(TimeSpan delta) => Value.Progress(delta);
	public void Quit()    => Value.Quit();
	public void Dispose() => Value.Dispose();


	public EntityBuilder<TContext> New(EntityPath? path = null, Entity parent = default)
		=> new(this, parent, path);


	public Entity<TContext>? LookupAliveOrNull(Entity value)
		=> ECS.Entity<TContext>.GetOrNull(this, Value.LookupAlive(value));
	public Entity<TContext> LookupAliveOrThrow(Entity value)
		=> LookupAliveOrNull(value) ?? throw new EntityNotFoundException(
			$"Entity '{value}' could not be found");

	public Entity<TContext>? LookupPathOrNull(EntityPath path, Entity parent = default)
		=> ECS.Entity<TContext>.GetOrNull(this, Value.LookupPath(path, parent, false));
	public Entity<TContext> LookupPathOrThrow(EntityPath path, Entity parent = default)
		=> ECS.Entity<TContext>.GetOrInvalid(this, Value.LookupPath(path, parent, true));

	public Entity<TContext>? LookupSymbolOrNull(string symbol)
		=> ECS.Entity<TContext>.GetOrNull(this, Value.LookupSymbol(symbol));
	public Entity<TContext> LookupSymbolOrThrow(string symbol)
		=> LookupSymbolOrNull(symbol) ?? throw new EntityNotFoundException(
			$"Entity with symbol '{symbol}' could not be found");


	public Entity<TContext> Entity<T>()
		=> ECS.Entity<TContext>.GetOrThrow(this,
			Lookup<TContext>.Entity<T>.Value);

	public Id<TContext> Pair(Entity relation, Entity target)
		=> Id<TContext>.GetOrThrow(this, Id.Pair(relation, target));
	public Id<TContext> Pair<TRelation>(Entity target)
		=> Pair(Entity<TRelation>(), target);
	public Id<TContext> Pair<TRelation, TTarget>()
		=> Pair(Entity<TRelation>(), Entity<TTarget>());


	public Iterator<TContext> Term(Term term) => Iterator<TContext>.FromTerm(this, term);
	public Filter<TContext> Filter(FilterDesc desc) => new(this, desc);
	public Query<TContext> Query(QueryDesc desc) => new(this, desc);
	public Rule<TContext> Rule(FilterDesc desc) => new(this, desc);


	public bool Equals(World<TContext> other) => Value == other.Value;
	public override bool Equals(object? obj) => (obj is World<TContext> other) && Equals(other);
	public override int GetHashCode() => Value.GetHashCode();

	public static bool operator ==(World<TContext> left, World<TContext> right) =>  left.Equals(right);
	public static bool operator !=(World<TContext> left, World<TContext> right) => !left.Equals(right);

	public static implicit operator World       (World<TContext> world) => world.Value;
	public static implicit operator ecs_world_t*(World<TContext> world) => world.Value.Handle;
}