Creating trigger to compare timestamp

[maxxer]

hi.
I'm trying to create a trigger to check last backup freshness.
This script return the timestamp of the last successful backup.

I also created a discovery rule which returns the enabled backups and the max age of it. Returned data is something like this (of course I can change maxage to whatever needed):

{"data":[                                                               
        { "{#TYPE}":"hourly", "{#MAXAGE}":"1d" },                       
        { "{#TYPE}":"daily", "{#MAXAGE}":"1d" },                        
        { "{#TYPE}":"weekly", "{#MAXAGE}":"7d" },                       
        { "{#TYPE}":"monthly", "{#MAXAGE}":"1m" }                       
]}

I managed to create the item, but how do I create the trigger? I had a look through the available expressions but didn't find one that could fit.
The function should be

last()

but how do I generate the NOW()-#MAXAGE value? I tried

{Template App rsnapshot:rsnapshot.check[{#TYPE}].last()}<now()

but it's not accepted (also it's missing the time span...).

Help appreciated.
thanks!

[maxxer]

solved with this trigger expression:

{Template App rsnapshot:rsnapshot.check[{#TYPE}].now()}-{Template App rsnapshot:rsnapshot.check[{#TYPE}].last()}>{#MAXAGE}

and changing MAXAGE to be in seconds