using System;
using System.Collections.Generic;
using System.Linq;

namespace Sunless.Architecture;

// Every host of a given type standing in the plan - ONE walk for Unfile, derived from the walks the manifests
// carried by hand.
public static class ArchPlanHosts
{
	public static IEnumerable<object> Of( ArchPlan plan, IEnumerable<Type> types )
	{
		if ( plan is null || types is null )
		{
			yield break;
		}

		foreach ( var type in types )
		{
			foreach ( var host in HostsOf( plan, type ) )
			{
				yield return host;
			}
		}
	}

	static IEnumerable<object> HostsOf( ArchPlan plan, Type type )
	{
		if ( type == typeof( ArchBuilding ) )
		{
			return plan.Buildings;
		}

		if ( type == typeof( ArchRoom ) )
		{
			return plan.AllRooms();
		}

		if ( type == typeof( ArchRoofPart ) )
		{
			return plan.AllRoofs();
		}

		if ( type == typeof( ArchWall ) )
		{
			return plan.AllWalls();
		}

		if ( type == typeof( ArchPorchPart ) )
		{
			return plan.AllRooms().SelectMany( room => room.Porches );
		}

		if ( type == typeof( ArchRoadPart ) )
		{
			return plan.Roads();
		}

		return Array.Empty<object>();
	}
}