<?php
function getFullHour($input) {
    $seconds = intval($input); //Converte para inteiro
 
    $negative = $seconds < 0; //Verifica se é um valor negativo
 
    if ($negative) {
        $seconds = -$seconds; //Converte o negativo para positivo para poder fazer os calculos
    }
 
    $hours = floor($seconds / 3600);
    $mins = floor(($seconds - ($hours * 3600)) / 60);
    $secs = floor($seconds % 60);
 
    $sign = $negative ? '-' : ''; //Adiciona o sinal de negativo se necessário
 
    return $sign . sprintf('%02d:%02d:%02d', $hours, $mins, $secs);
}
 
echo getFullHour(685), PHP_EOL; //00:11:25
 
echo getFullHour(140801), PHP_EOL; //39:06:41
echo getFullHour(100800), PHP_EOL; //28:00:00
 
echo getFullHour(-140801), PHP_EOL; //-39:06:41
echo getFullHour(-100800), PHP_EOL; //-28:00:00

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