find users who can visit each other on same available time( time overlapping)

I want to write a function which must find the overlapping time that two or more people can visit each other at the available time. Let me explain:

Here's is my data:

$availability = [
    [
        ["8:30", "12:00"],
        ["17:00", "22:00"]
    ],
    [
        ["5:00", "11:15"],
        ["14:25", "20:05"]
    ]
];

and I want this result:

RESULT:
[
    ('8:30', '11:15'),
    ('17:00', '20:05')
]

My problem is that i can only get the latest result ('17:00', '20:05') not the first one. blank result:

$availability = [
    [
        ["8:30", "12:00"],
        ["17:00", "22:00"]
    ],
    [
        ["5:00", "11:15"],
        ["14:25", "20:05"]
    ]
];
$periods = [];
while (true) {
    $start = array_reduce($availability, function ($carry, $ranges) {
        $start = array_reduce($ranges, function ($carry, $range) {
            return !$carry ? $range[0] : min($range[0], $carry);
        });
        return !$carry ? $start : max($start, $carry);
    });
    $matching_ranges = array_filter(array_map(function ($ranges) use ($start) {
        return current(array_filter($ranges, function ($range) use ($start) {
            return $range[0] <= $start && $range[1] >= $start;
        }));
    }, $availability));
    if (count($matching_ranges) < count($availability)) {
        break;
    }
    $end = array_reduce($matching_ranges, function ($carry, $range) {
        return !$carry ? $range[1] : min($range[1], $carry);
    });
    $periods[] = [$start, $end];
    array_walk($availability, function (&$ranges) use ($end) {
        $ranges = array_filter($ranges, function ($range) use ($end) {
            return $range[1] > $end;
        });
    });
}

// Output the answer in the specified format.
foreach ($periods as $period) {
    echo "$period[0] -> $period[1]\n";
}

Thanks in advance.

source https://stackoverflow.com/questions/68103327/find-users-who-can-visit-each-other-on-same-available-time-time-overlapping