Calculating the total time in an online meeting - bash

Question

Suppose there was a meeting and the meeting record is saved in a CSV file. How to write a bash script/awk script to find out the total amount of time for which an employee stayed online. One employee may leave and rejoin the meeting, all his/her online time should be calculated.
What I did is as follows, but got stuck on how to compare one record with all other record, and add the total time of each joined and left pairs of a person.
#!/bin/bash
inputFile=$1
startTime=$(date -u -d $2 +"%s")
endTime=$(date -u -d $3 +"%s")
awk 'BEGIN{ FS=","; totalTime=0; }
{
for (rows=1; rows <= NR; rows++) {
#I am stuck here on how to compare a record with each and every record
if (($1==?? && $2=="Joined") && ($1==?? && $2=="Left")) {
totalTime=$($(date -u -d $3 +"%s")-$(date -u -d $3 +"%s"))
print $1 "," $totalTime +"%H:%M:%S"
}' $inputFile
The start_time and end_time of the meeting are given at command line such as:
$ ./script.sh input.csv 10:00:00 13:00:00
The output look like this: (Can be stored in an output file)
Bob, 00:30:00
John, 01:02:00
The contents of the CSV file is as follows:
Employee_name, Joined/Left, Time
John, joined, 10:00:00
Bob, joined, 10:01:00
James, joined, 10:00:30
Bob, left, 10:20:00
Bob, joined, 10:35:00
Bob, left, 11:40:00
James, left, 11:40:00
John, left, 10:41:00
Bob, joined, 11:45:00

Answer 1

$ cat tst.awk
BEGIN { FS=" *, *"; OFS=", " }
NR==1 { next }
$1 in joined {
jt = time2secs(joined[$1])
lt = time2secs($3)
totSecs[$1] += (lt - jt)
delete joined[$1]
next
}
{ joined[$1] = $3 }
END {
for (name in totSecs) {
print name, secs2time(totSecs[name])
}
}
function time2secs(time, t) {
split(time,t,/:/)
return (t[1]*60 + t[2])*60 + t[3]
}
function secs2time(secs, h,m,s) {
h = int(secs / (60*60))
m = int((secs - (h*60*60)) / 60)
s = int(secs % 60)
return sprintf("%02d:%02d:%02d", h, m, s)
}
.
$ awk -f tst.awk file
James, 01:39:30
Bob, 01:24:00
John, 00:41:00
If you need to consider DST transitions, leap-seconds, meetings going overnight (or for multiple days), people still being in the meeting when it ends, or anything else you haven't shown in your question - that is left as an exercise :-).