Extract substring with mutiple [ in a string

[rreddy]

I have a String is in the pattern:

[substring1][substring2][substring3] Spark App State changed to FAILED. Total time taken is 10 minutes

I want to extract it into 4 fileds:

Field1 = substring1

Field2 = substring2

Field3 = substring3

Field4 = 10 

Please help.

[ITWhisperer]

| rex "\[(?<field1>[^\[]+)\]\[(?<field2>[^\[]+)\]\[(?<field3>[^\[]+)\].*Total time taken is (?<field4>\d+)"