class Date

class Date extends FieldPluginBase {
    
    /**
     * The date formatter service.
     *
     * @var \Drupal\Core\Datetime\DateFormatterInterface
     */
    protected $dateFormatter;
    
    /**
     * The date format storage.
     *
     * @var \Drupal\Core\Entity\EntityStorageInterface
     */
    protected $dateFormatStorage;
    
    /**
     * Constructs a new Date object.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin ID for the plugin instance.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\Core\Datetime\DateFormatterInterface $date_formatter
     *   The date formatter service.
     * @param \Drupal\Core\Entity\EntityStorageInterface $date_format_storage
     *   The date format storage.
     * @param \Drupal\Component\Datetime\TimeInterface $time
     *   The time service.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, DateFormatterInterface $date_formatter, EntityStorageInterface $date_format_storage, TimeInterface $time) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->dateFormatter = $date_formatter;
        $this->dateFormatStorage = $date_format_storage;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('date.formatter'), $container->get('entity_type.manager')
            ->getStorage('date_format'), $container->get('datetime.time'));
    }
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['date_format'] = [
            'default' => 'small',
        ];
        $options['custom_date_format'] = [
            'default' => '',
        ];
        $options['timezone'] = [
            'default' => '',
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        $date_formats = [];
        foreach ($this->dateFormatStorage
            ->loadMultiple() as $machine_name => $value) {
            $date_formats[$machine_name] = $this->t('@name format: @date', [
                '@name' => $value->label(),
                '@date' => $this->dateFormatter
                    ->format($this->time
                    ->getRequestTime(), $machine_name),
            ]);
        }
        $form['date_format'] = [
            '#type' => 'select',
            '#title' => $this->t('Date format'),
            '#options' => $date_formats + [
                'custom' => $this->t('Custom'),
                'raw time ago' => $this->t('Time ago'),
                'time ago' => $this->t('Time ago (with "ago" appended)'),
                'raw time hence' => $this->t('Time hence'),
                'time hence' => $this->t('Time hence (with "hence" appended)'),
                'raw time span' => $this->t('Time span (future dates have "-" prepended)'),
                'inverse time span' => $this->t('Time span (past dates have "-" prepended)'),
                'time span' => $this->t('Time span (with "ago/hence" appended)'),
            ],
            '#default_value' => $this->options['date_format'] ?? 'small',
        ];
        $form['custom_date_format'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Custom date format'),
            '#description' => $this->t('If "Custom", see <a href="https://www.php.net/manual/datetime.format.php#refsect1-datetime.format-parameters" target="_blank">the PHP docs</a> for date formats. Otherwise, enter the number of different time units to display, which defaults to 2.'),
            '#default_value' => $this->options['custom_date_format'] ?? '',
        ];
        // Setup #states for all possible date_formats on the custom_date_format form element.
        foreach ([
            'custom',
            'raw time ago',
            'time ago',
            'raw time hence',
            'time hence',
            'raw time span',
            'time span',
            'raw time span',
            'inverse time span',
            'time span',
        ] as $custom_date_possible) {
            $form['custom_date_format']['#states']['visible'][] = [
                ':input[name="options[date_format]"]' => [
                    'value' => $custom_date_possible,
                ],
            ];
        }
        $form['timezone'] = [
            '#type' => 'select',
            '#title' => $this->t('Timezone'),
            '#description' => $this->t('Timezone to be used for date output.'),
            '#options' => [
                '' => $this->t('- Default site/user timezone -'),
            ] + TimeZoneFormHelper::getOptionsListByRegion(),
            '#default_value' => $this->options['timezone'],
        ];
        foreach (array_merge([
            'custom',
        ], array_keys($date_formats)) as $timezone_date_formats) {
            $form['timezone']['#states']['visible'][] = [
                ':input[name="options[date_format]"]' => [
                    'value' => $timezone_date_formats,
                ],
            ];
        }
        parent::buildOptionsForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function render(ResultRow $values) {
        $value = $this->getValue($values);
        $format = $this->options['date_format'];
        if (in_array($format, [
            'custom',
            'raw time ago',
            'time ago',
            'raw time hence',
            'time hence',
            'raw time span',
            'time span',
            'raw time span',
            'inverse time span',
            'time span',
        ])) {
            $custom_format = $this->options['custom_date_format'];
        }
        if ($value) {
            $timezone = !empty($this->options['timezone']) ? $this->options['timezone'] : NULL;
            // Will be positive for a datetime in the past (ago), and negative for a
            // datetime in the future (hence).
            $time_diff = $this->time
                ->getRequestTime() - $value;
            switch ($format) {
                case 'raw time ago':
                    return $this->dateFormatter
                        ->formatTimeDiffSince($value, [
                        'granularity' => is_numeric($custom_format) ? $custom_format : 2,
                    ]);
                case 'time ago':
                    return $this->t('%time ago', [
                        '%time' => $this->dateFormatter
                            ->formatTimeDiffSince($value, [
                            'granularity' => is_numeric($custom_format) ? $custom_format : 2,
                        ]),
                    ]);
                case 'raw time hence':
                    return $this->dateFormatter
                        ->formatTimeDiffUntil($value, [
                        'granularity' => is_numeric($custom_format) ? $custom_format : 2,
                    ]);
                case 'time hence':
                    return $this->t('%time hence', [
                        '%time' => $this->dateFormatter
                            ->formatTimeDiffUntil($value, [
                            'granularity' => is_numeric($custom_format) ? $custom_format : 2,
                        ]),
                    ]);
                case 'raw time span':
                    return ($time_diff < 0 ? '-' : '') . $this->dateFormatter
                        ->formatTimeDiffSince($value, [
                        'strict' => FALSE,
                        'granularity' => is_numeric($custom_format) ? $custom_format : 2,
                    ]);
                case 'inverse time span':
                    return ($time_diff > 0 ? '-' : '') . $this->dateFormatter
                        ->formatTimeDiffSince($value, [
                        'strict' => FALSE,
                        'granularity' => is_numeric($custom_format) ? $custom_format : 2,
                    ]);
                case 'time span':
                    $time = $this->dateFormatter
                        ->formatTimeDiffSince($value, [
                        'strict' => FALSE,
                        'granularity' => is_numeric($custom_format) ? $custom_format : 2,
                    ]);
                    return $time_diff < 0 ? $this->t('%time hence', [
                        '%time' => $time,
                    ]) : $this->t('%time ago', [
                        '%time' => $time,
                    ]);
                case 'custom':
                    if ($custom_format == 'r') {
                        return $this->dateFormatter
                            ->format($value, $format, $custom_format, $timezone, 'en');
                    }
                    return $this->dateFormatter
                        ->format($value, $format, $custom_format, $timezone);
                default:
                    return $this->dateFormatter
                        ->format($value, $format, '', $timezone);
            }
        }
    }

}