Random time selection logic is not working and loops forever - powershell

Question

My input is a text file with license plate and date for tire repair. I am then prompted to write a time e.g like 12:30. Then the script checks if the time is good or not. It's good if there is 30 minutes after and before not being used.
Using the example won't work since the 12:00-13:00 block contains an entry. Then the time isn't good, so the script has to search a good date for me. I tried to check line by line minute per minute. After, if the $help variable didn't change then it's good, but if it did, then make a random time, to check. Any ideas why that logic is not working?
Edit: Since I edited, the only thing I saw that isn't working, is that my script generates a random time, but it didn't check if that time is right, just accept that time and goodbye. Somehow I should make it to check it more times, and don't stop at the first generated time, check it, and if its still wrong, then randomize it again.
Sample data
ABC-145 8:30
BDE-540 9:45
EDS-598 10:30
SDF-478 11:30
HUT-434 12:15
JEC-238 13:15
ASD-325 14:00
VRA-123 16:15
HGV-456 18:00
$file = Get-Content Desktop/database.txt
[datetime]$time = Read-Host "Time for date?"
$start = $time
$check = $time
$help = 0
echo $time
foreach ($line in $file) {
#here I check if the date is free
$out = $line.Split()
while ($true) {
#until I found a good time
for ($i=0; $i -lt 30; $i++) {
#check the next half hour if good
if ($time -eq $out[1]) {
$help = 1
}
$time = $time.AddMinutes(1)
}
for ($i=0; $i -lt 60; $i++) {
#back check the half hour
if ($time -eq $out[1]) {
$help = 1
}
$time = $time.AddMinutes(-1)
}
$time = $time.AddMinutes(30)
if ($help -eq 0) {
break
} else {
$hour = Get-Random -Minimum 8 -Maximum 20
$minute = Get-Random -Minimum 0 -Maximum 59
$start = "$ora`:$perc"
$time = $start
$help = 0
#echo $time
}
}
}
if ($start-ne $check) {
echo "There wasnt a free date, but there is a free spot at " + $start
} else {
echo "This is free date"
}

Answer 1

I would recommend a different approach. First extract the times from your input file and convert them to DateTime values:
$times = Get-Content 'Desktop/database.txt' |
ForEach-Object { $_.Split("`t")[1] | Get-Date }
From that list determine the intervals that are actually wide enough to fit another appointment (at least 30 min after the previous and before the next appointment respectively, hence a minimum time window of 60 minutes):
$available = 0..($times.Count-1) |
Where-Object { ($times[$_+1]-$times[$_]).TotalMinutes -ge 60 }
Pick a random index from that list and add 30 minutes to the corresponding time:
$index = $available[(Get-Random -Maximum $available.Count)]
$start = $times[$index].AddMinutes(30)
'{0:HH:mm}' -f $start
Or, if you want some more variation, calculate a new starting time from the timeframe 30 minutes after the previous appointment to 30 minutes before the next appointment like this:
$index = $available[(Get-Random -Maxmimum $available.Count)]
$delta = ($times[$index+1]-$times[$index]).TotalMinutes - 60
$offset = 30 + [int](Get-Random -Maximum ($delta + 1))
$start = $times[$index].AddMinutes($offset)
'{0:HH:mm}' -f $start
This approach ensures that you don't run into an infinite loop when there are no available timeslots left.