Compare a property value to an aggregated value in Gremlin - graph-databases

Question

I'm trying to implement a sort of "window function" in a Gremlin query: I want to select all the edges leaving a vertex, which have a timestamp within 24 hours of the last update (local to the vertex).
For example if User A accessed the following resources:
Resource 1 at 2019/04/02 23:00
Resource 2 at 2019/04/02 01:00
Resource 3 at 2019/04/01 22:00
.. then I'd want the query to return resources 1 & 2, and omit resource 3 because it was accessed 25 hours before User A's latest access (outside the 24-hour window).
I've tried a few different approaches, for example using local and aggregate:
g.V()
.hasLabel(VertexLabel.User)
.local(__.outE(EdgeLabel.Accesses) // I also tried "sideEffect" here
.values(EdgeProperties.UpdateTime).max().math("_ - 24*60*60*1000")
.aggregate("windowStart"))
.where(
__.outE(EdgeLabel.Accesses)
.has(EdgeProperties.UpdateTime, P.gt("windowStart"))
)
This particular example gives me the error ClassCastException: java.lang.Double cannot be cast to org.apache.tinkerpop.gremlin.structure.Element.
And also using a sack:
g.V()
.hasLabel(VertexLabel.User)
.sack(Operator.assign).by(
__.outE(EdgeLabel.Accesses).values(EdgeProperties.UpdateTime).max())
.sack(Operator.minus).by(__.constant(24*60*60*1000)
.where(
__.outE(EdgeLabel.Accesses)
.not(__.sack().is(P.gt(__.values(EdgeProperties.UpdateTime))))
)
This gives me the error ClassCastException: org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.DefaultGraphTraversal cannot be cast to java.lang.Long.
I feel like I'm just getting hung up on Gremlin semantics--I'm trying to compare the values in the wrong form. What do I need to do to access the "windowStart" value for the current vertex in the traversal, in a gt/lt predicate?

Answer 1

I've made a few assumptions on what the answers to my comments could be. The following query will give you every user and his respective accessed resources within the last 24 hours (with the reference time being the times of the last resource access time):
g.V().hasLabel(VertexLabel.User).
match(__.as("user").map(outE(EdgeLabel.Accesses).
values(EdgeProperties.UpdateTime).max()).
math("_-24*60*60*1000").as("m"),
__.as("user").outE(EdgeLabel.Accesses).
where(gt("m")).
by(EdgeProperties.UpdateTime).
by().
inV().fold().as("resources")).
select("user","resources")