convert csv to json (powershell / bash /perl)

This can be done in powershell or bash or perl (listed in order of preference) I have a log file in CSV (with headers), I need to select a subset of it, transform a date and time field to epoch then give an output in JSON. Only select rows from csv where context = patient Change date_time to epoch (integer) populate json where the calculated epoch $CE is entered as a point [$CE,1] in the json.