Bash pattern matching or regex inside while loop for extracting and enriching data (from json to cmd console)

I have data in .json like this

[
 "items": 
    [
         {
            "dateAdd": "2019-06-21 13:48:22",
            "status": "Disconnected",
            "name": "PLVM32",
            "lastKeepAlive": "2022-07-14 14:10:21",
            "id": "972"
         },
         {
            "dateAdd": "2019-06-21 13:48:23",
            "status": "Never connected",
            "name": "PLVN50",
            "id": "973"
         },
         {
            "dateAdd": "2019-03-05 09:24:04",
            "status": "Active",
            "name": "PWVEAC",
            "lastKeepAlive": "2022-09-12 04:21:09",
            "id": "009"
       }
    ]
]  

then I have a script like this, read line by line, when if[[ $line == $nameCheck ]] is true, pause for a while, then do a check one line below the matching line,

if the condition if[[ a == lastKeepCheck ]] is true, then the value of $lastKeepCheck is printed to the console directly, otherwise what is printed to the console is NULL

#!/bin/bash

file="/root/agentDisconnect.json"

nameCheck="name"
lastKeepCheck="lastKeepAlive"

while IFS= read -r line
do
   if [[ $line == nameCheck ]]; then
       a=$line+1
      if[[ a == lastKeepCheck ]]; then
          echo "$a";
   else
      echo "NULL"
done < "$file"

the result to be displayed in the console is as follows:

 [root@PLVWZHUTD201 ~]#./script.sh
     2022-07-14 14:10:21
     NULL
     2022-09-12 04:21:09

how should my script be correct to run properly?