private async Task<bool> MoveCoreAsync(Point sourcePosition, Point targetPosition, ITransactionWithMoveSupport transaction)
{
var source = await GetAsync(sourcePosition);
var target = await GetAsync(targetPosition);
var oldSource = source;
var oldTarget = target;
source.Tile.EnsureNotNull();
target.Tile.EnsureNotNull();
if (source.Tile.Entity == Entity.None)
{
// Cancel if there's no entity to move
transaction.IsSealed = true;
return false;
}
var move = new EntityMoveInfo(source.Tile.Entity, sourcePosition, targetPosition);
transaction.Moves.Push(move);
IBeginMoveArgs beginMoveArgs = new GameplayArgs(transaction, this);
IDetachArgs detachArgs = new GameplayArgs(transaction, this);
IAttachArgs attachArgs = new GameplayArgs(transaction, this);
// OnBeginMove: Notify entity that a move has been initiated
await source.Tile.Entity.BeginMoveAsync(beginMoveArgs);
beginMoveArgs.ValidateResult();
if (transaction.IsSealed) return false;
var newSource = source.WithTile(Tile.Compose(source.Tile, beginMoveArgs.ResultingEntity));
if (transaction.Set(sourcePosition, source, newSource))
source = newSource;
move.Entity = beginMoveArgs.ResultingEntity;
// Detach: Remove the entity from the source tile
await source.Tile.DetachEntityAsync(detachArgs);
detachArgs.ValidateResult();
if (transaction.IsSealed) return false;
// Attach: Add the entity to the target tile
await target.Tile.AttachEntityAsync(attachArgs);
attachArgs.ValidateResult();
if (transaction.IsSealed) return false;
// Detach from old tile, attach to new tile have succeeded
// => Apply changes to transaction
var newSource2 = source.WithTile(detachArgs.Result);
if (transaction.Set(sourcePosition, source, newSource2))
source = newSource2;
var newTarget = target.WithTile(attachArgs.Result);
if (transaction.Set(targetPosition, target, newTarget))
target = newTarget;
// Emit events
var moveEvent = new EntityMoveEvent(sourcePosition, targetPosition, oldSource.Tile, target.Tile);
transaction.Emit(moveEvent);
if (source.Tile.Entity != Entity.None)
{
// A new entity has been created at source position
var spawnEvent = new EntitySpawnEvent(sourcePosition, source.Tile.Entity);
transaction.Emit(spawnEvent);
}
if (oldTarget.Tile.Entity != Entity.None)
{
// The entity at target position has either been replaced
// or it has been moved/collected/... during a nested move
var oldTargetEntityOverwritten =
!(transaction.Events.OfType<EntityDespawnEvent>().Any(ev => ev.Position == targetPosition) ||
transaction.Events.OfType<EntityMoveEvent>().Any(ev => ev.SourcePosition == targetPosition));
if (oldTargetEntityOverwritten)
{
// If replaced, emit despawn event
var despawnEvent = new EntityDespawnEvent(targetPosition, oldTarget.Tile.Entity);
transaction.Emit(despawnEvent);
}
}
transaction.Moves.Pop();
return true;
}
public async Task<IReadOnlyCollection<FollowUpEvent>> UpdateTilesAsync(IEnumerable<Point> positions, ITransactionWithMoveSupport transaction)
{
var initialPoints = new HashSet<Point>(positions);
var followUpEvents = new List<FollowUpEvent>();
var now = DateTimeOffset.Now;
// Notify the initial tiles and tiles that are directly or indirectly
// (transitively) dependent on them in topological order
await Dependencies.DoAsyncWorkFollowingDependenciesAsync(initialPoints, async p =>
{
// Try to get from transaction first; if that fails get from map
var tileInfo = transaction.Changes.TryGetValue(p);
if (tileInfo == TileInfo.Empty) tileInfo = await GetAsync(p);
followUpEvents.Add(new FollowUpEvent(p, transaction.Initiator, now + tileInfo.Tile.FollowUpDelay));
var completionArgs = new GameplayArgs(transaction, this);
await tileInfo.Tile.OnEntityMoveTransactionCompletedAsync(completionArgs);
completionArgs.ValidateResult();
if (transaction.IsSealed)
return null; // Null terminates the loop
var newTileInfo = tileInfo.WithTile(completionArgs.Result);
if (transaction.Set(p, tileInfo, newTileInfo))
{
// TODO: Test and check whether this is sufficient
// (Initial idea:
// Somehow modify events that have been emitted during the move.
// E.g. when a balloon is moved onto an InkTile the move event's target
// still contains the balloon with its old color.
// Here, after the InkTile has changed the balloons color, we have to
// change that event to reflect the changes of InkTile and balloon.
// We probably have to emit spawn/despawn events as well.)
if (tileInfo.Tile.Entity != Entity.None)
{
if (newTileInfo.Tile.Entity == Entity.None)
transaction.Emit(new EntityDespawnEvent(p, tileInfo.Tile.Entity));
else
transaction.Emit(new EntityChangeEvent(p, newTileInfo.Tile.Entity));
}
else
{
if (newTileInfo.Tile.Entity != Entity.None)
transaction.Emit(new EntitySpawnEvent(p, newTileInfo.Tile.Entity));
}
return true;
}
return initialPoints.Contains(p);
});
return followUpEvents;
}
/// <inheritdoc/>
public async Task<MoveResult> DespawnAsync(Point position, ITransactionWithMoveSupport transaction)
{
var tileInfo = await GetAsync(position);
tileInfo.Tile.EnsureNotNull();
// No entity => nothing to despawn
if (tileInfo.Tile.Entity == Entity.None)
return new MoveResult(transaction, true, Enumerable.Empty<FollowUpEvent>());
transaction.Moves.Push(new EntityMoveInfo(tileInfo.Tile.Entity, position, position));
// Try to detach entity
var detachArgs = new GameplayArgs(transaction, this);
await tileInfo.Tile.DetachEntityAsync(detachArgs);
detachArgs.ValidateResult();
if (transaction.IsSealed)
return new MoveResult(transaction, false, Enumerable.Empty<FollowUpEvent>());
var newTileInfo = tileInfo.WithTile(detachArgs.Result);
transaction.Set(position, tileInfo, newTileInfo);
transaction.Emit(new EntityDespawnEvent(position, tileInfo.Tile.Entity));
// Update tile
var followUpEvents = await UpdateTilesAsync(new[] { position }, transaction);
return new MoveResult(transaction, true, followUpEvents);
}