<?php

namespace Drupal\{{ machine_name }}\Plugin\Validation\Constraint;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

/**
 * Validates the {{ plugin_label }} constraint.
 */
class {{ class }}Validator extends ConstraintValidator {

  /**
   * {@inheritdoc}
   */
{% if input_type == 'entity' %}
  public function validate($entity, Constraint $constraint) {

    // @DCG Validate the entity here.
    if ($entity->label() == 'foo') {
      $this->context->buildViolation($constraint->errorMessage)
        // @DCG The path depends on entity type. It can be title, name, etc.
        ->atPath('title')
        ->addViolation();
    }

  }
{% elseif input_type == 'item_list' %}
  public function validate($items, Constraint $constraint) {

    foreach ($items as $delta => $item) {
      // @DCG Validate the item here.
      if ($item->value == 'foo') {
        $this->context->buildViolation($constraint->errorMessage)
          ->atPath($delta)
          ->addViolation();
      }
    }

  }
{% elseif input_type == 'item' %}
  public function validate($item, Constraint $constraint) {

    $value = $item->getValue()['value'];
    // @DCG Validate the value here.
    if ($value == 'foo') {
      $this->context->addViolation($constraint->errorMessage);
    }

  }
{% else %}
  public function validate($value, Constraint $constraint) {

    // @DCG Validate the value here.
    if ($value == 'foo') {
      $this->context->addViolation($constraint->errorMessage);
    }

  }
{% endif %}

}