Add a pager to the list command

src/Command/ListCommand.php

@@ -7,11 +7,15 @@
 namespace Platformsh\Cli\Command;
 
 use Platformsh\Cli\Console\CustomTextDescriptor;
+use Psy\Output\ProcOutputPager;
+use Psy\Output\ShellOutput;
 use Symfony\Component\Console\Command\ListCommand as ParentListCommand;
 use Symfony\Component\Console\Helper\DescriptorHelper;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\BufferedOutput;
 use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Output\StreamOutput;
 
 class ListCommand extends ParentListCommand
 {
@@ -20,12 +24,29 @@ protected function configure()
     {
         parent::configure();
         $this->addOption('all', null, InputOption::VALUE_NONE, 'Show all commands, including hidden ones');
+        $this->addOption('pager', null, InputOption::VALUE_REQUIRED, 'Set the pager command', 'less -R -F');
     }
 
     protected function execute(InputInterface $input, OutputInterface $output)
     {
         $helper = new DescriptorHelper();
         $helper->register('txt', new CustomTextDescriptor());
+
+        if ($output->isDecorated()
+            && $output instanceof StreamOutput
+            && getenv('PAGER') !== ''
+            && (!function_exists('posix_isatty') || posix_isatty($output->getStream()))) {
+
+            // Create a pager.
+            $pager = new ProcOutputPager($output, $input->getOption('pager'));
+
+            // Create an output object for the pager.
+            $pagerOutput = new ShellOutput($output->getVerbosity(), $output->isDecorated(), $output->getFormatter(), $pager);
+
+            // Replace the main output object with a buffer.
+            $output = new BufferedOutput($output->getVerbosity(), $output->isDecorated(), $output->getFormatter());
+        }
+
         $helper->describe(
             $output,
             $this->getApplication(),
@@ -36,5 +57,10 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 'all' => $input->getOption('all'),
             ]
         );
+
+        // If paging is enabled, send buffered output to the pager.
+        if (isset($pagerOutput) && $output instanceof BufferedOutput) {
+            $pagerOutput->page($output->fetch());
+        }
     }
 }