<?php

namespace Drupal\block_visibility_groups;

use Drupal\block_visibility_groups\Entity\BlockVisibilityGroup;
use Drupal\Component\Plugin\Exception\ContextException;
use Drupal\Core\Condition\ConditionAccessResolverTrait;
use Drupal\Core\Condition\ConditionPluginCollection;
use Drupal\Core\Plugin\Context\ContextHandlerInterface;
use Drupal\Core\Plugin\Context\ContextRepositoryInterface;
use Drupal\Core\Plugin\ContextAwarePluginInterface;

/**
 * Evaluates block visibility group conditions.
 */
class GroupEvaluator implements GroupEvaluatorInterface {

  use ConditionAccessResolverTrait;

  /**
   * The plugin context handler.
   *
   * @var \Drupal\Core\Plugin\Context\ContextHandlerInterface
   */
  protected ContextHandlerInterface $contextHandler;

  /**
   * The context manager service.
   *
   * @var \Drupal\Core\Plugin\Context\ContextRepositoryInterface
   */
  protected ContextRepositoryInterface $contextRepository;

  /**
   * A list of group evaluations.
   *
   * @var array
   */
  protected array $groupEvaluations = [];

  /**
   * Constructs a new GroupEvaluator.
   *
   * @param \Drupal\Core\Plugin\Context\ContextHandlerInterface $context_handler
   *   The context handler.
   * @param \Drupal\Core\Plugin\Context\ContextRepositoryInterface $context_repository
   *   The context repository.
   */
  public function __construct(ContextHandlerInterface $context_handler, ContextRepositoryInterface $context_repository) {
    $this->contextRepository = $context_repository;
    $this->contextHandler = $context_handler;
  }

  /**
   * {@inheritdoc}
   */
  public function evaluateGroup(BlockVisibilityGroup $block_visibility_group): bool {
    $group_id = $block_visibility_group->id();
    if (!isset($this->groupEvaluations[$group_id])) {
      /** @var \Drupal\Core\Condition\ConditionPluginCollection $conditions */
      $conditions = $block_visibility_group->getConditions();
      if (empty($conditions)) {
        // If no conditions then always true.
        return TRUE;
      }
      $logic = $block_visibility_group->getLogic();
      if ($this->applyContexts($conditions, $logic)) {
        $this->groupEvaluations[$group_id] = $this->resolveConditions($conditions, $logic);
      }
      else {
        $this->groupEvaluations[$group_id] = FALSE;
      }
    }
    return $this->groupEvaluations[$group_id];
  }

  /**
   * Apply contexts to condition plugins.
   *
   * @param \Drupal\Core\Condition\ConditionPluginCollection $conditions
   *   A collection of condition plugins.
   * @param string $logic
   *   The logical operator ('and' or 'or').
   *
   * @return bool
   *   Whether the conditions have been applied successfully.
   */
  protected function applyContexts(ConditionPluginCollection &$conditions, string $logic): bool {
    $have_1_testable_condition = FALSE;
    foreach ($conditions as $id => $condition) {
      if ($condition instanceof ContextAwarePluginInterface) {
        try {
          $contexts = $this->contextRepository->getRuntimeContexts(array_values($condition->getContextMapping()));

          // Skip when any of the contexts is not set.
          $missingContextData = FALSE;
          foreach ($contexts as $context) {
            if ($context->getContextData()->getValue() === NULL) {
              if ($logic == 'and') {
                return FALSE;
              }
              else {
                $missingContextData = TRUE;
                break;
              }
            }
          }

          if ($missingContextData) {
            continue;
          }

          $this->contextHandler->applyContextMapping($condition, $contexts);
          $have_1_testable_condition = TRUE;
        }
        catch (ContextException $e) {
          // Log a message about the error.
          \Drupal::logger('block_visibility_groups')->error($e->getMessage());

          // If the condition is negated, shouldn't refuse so quickly.
          if ($logic == 'and' && !$condition->isNegated()) {
            // Logic is all and found condition with contextException.
            return FALSE;
          }
          $conditions->removeInstanceId($id);
        }
      }
      else {
        $have_1_testable_condition = TRUE;
      }
    }
    if ($logic == 'or' && !$have_1_testable_condition) {
      return FALSE;
    }
    return TRUE;
  }

}