Find Resource Overlaps in an Array

Hello,

I have an array:

$lessons = Array
(
    [0] => Array
        (
            [res] => 45
            [start] => 2021-07-14 16:00:00
            [end] => 2021-07-14 16:45:00
            [start_int] => 1626292800
            [end_int] => 1626295500
            [tdur_slot] => 18
        )

    [1] => Array
        (
            [res] => 45
            [start] => 2021-07-14 16:45:00
            [end] => 2021-07-14 17:30:00
            [start_int] => 1626295500
            [end_int] => 1626298200
            [tdur_slot] => 18
        )

    [2] => Array
        (
            [res] => 45
            [start] => 2021-07-14 17:30:00
            [end] => 2021-07-14 18:30:00
            [start_int] => 1626298200
            [end_int] => 1626301800
            [tdur_slot] => 24
        )

    [3] => Array
        (
            [res] => 9
            [start] => 2021-07-14 10:00:00
            [end] => 2021-07-14 10:45:00
            [start_int] => 1626271200
            [end_int] => 1626273900
            [tdur_slot] => 18
        )

)

I am trying to compile two functions to help with scheduling lessons (conflicts and checking for valid availability).

function check_for_overlap($array, $resource, $sourceStart, $sourceEnd, $KeyResource, $tKeyStart, $tKeyEnd){

     I want check for a basic overlap in $array for that resource - 
     
     $resource = $KeyResource
     $sourceStart < $tKeyEnd && $sourceEnd > $tKeyStart

     if overlap return TRUE else FALSE

}

example using above array:

$result = function check_for_overlap($lessons, 9, 1626271200, 1626273900, ‘res’, 'start_int', 'end_int’)
$result would be TRUE

--------

function valid_availability($array, $resource, $sourceStart, $sourceEnd, $KeyResource, $tKeyStart, $tKeyEnd){

     loop every 5 minute interval between $sourceStart and $sourceEnd for that resource, check for an valid overlap
     each 5 minute interval
     $resource = $KeyResource
     $sourceStart < $tKeyEnd && $sourceEnd > $tKeyStart

     if any intervals test are FALSE exit and return FALSE else TRUE

}

example using above array:

$result = function valid_availability($lessons, 45, 1626273900, 1626292800, ‘res’, 'start_int', 'end_int’)
$result would be FALSE

I’d appreciate any assistance on this. Thanks ;-)

Don