<?php

/**
 * @file
 * Primary module hooks for Site Structure module.
 */

declare(strict_types=1);

use Drupal\Core\Entity\EntityInterface;
use Drupal\node\NodeInterface;
use Drupal\taxonomy\TermInterface;
use Drupal\user\UserInterface;

/**
 * Implements hook_entity_presave().
 *
 * Inherits field_site_section from parent to content_page.
 * Validates circular reference in field_parent_page.
 */
function site_structure_entity_presave(EntityInterface $entity): void {
  if (!$entity instanceof NodeInterface || $entity->bundle() !== 'content_page') {
    return;
  }

  // Check if has parent page.
  if (!$entity->hasField('field_parent_page') || $entity->get('field_parent_page')->isEmpty()) {
    return;
  }

  $parent_field = $entity->get('field_parent_page')->first();
  if (!$parent_field) {
    return;
  }

  $parent_entity_type = $parent_field->target_type ?? NULL;
  $parent_id = $parent_field->target_id ?? NULL;

  if (!$parent_entity_type || !$parent_id) {
    return;
  }

  // Circular reference validation (only for node parents).
  if ($parent_entity_type === 'node' && !$entity->isNew() && $parent_id) {
    if (_site_structure_creates_circular_reference($entity->id(), $parent_id)) {
      \Drupal::messenger()->addError(t('Circular reference detected. A page cannot be a parent of itself or its ancestors.'));
      // Remove invalid reference.
      $entity->set('field_parent_page', NULL);
      return;
    }
  }

  // Handle site section based on parent type.
  // Some entity types (like user and group) act as context containers themselves.
  /** @var \Drupal\site_structure\ParentEntityHandler\ParentEntityHandlerManagerInterface $handler_manager */
  $handler_manager = \Drupal::service('plugin.manager.parent_entity_handler');
  if ($handler_manager->clearsSiteSection($parent_entity_type)) {
    // Clear field_site_section as the context is the parent entity, not a site section.
    $entity->set('field_site_section', NULL);
    return;
  }

  // Inherit field_site_section based on parent type (node or taxonomy_term).
  $site_section_id = _site_structure_get_section_from_parent($parent_entity_type, $parent_id);
  if ($site_section_id) {
    $entity->set('field_site_section', $site_section_id);
  }
}

/**
 * Gets the site section ID from a parent entity.
 *
 * @param string $parent_entity_type
 *   The parent entity type (node or taxonomy_term).
 * @param int|string $parent_id
 *   The parent entity ID.
 *
 * @return int|string|null
 *   The site section term ID, or NULL if not found.
 */
function _site_structure_get_section_from_parent(string $parent_entity_type, int|string $parent_id): int|string|null {
  $entity_type_manager = \Drupal::entityTypeManager();

  if ($parent_entity_type === 'taxonomy_term') {
    // If parent is a taxonomy term, verify it's from site_section vocabulary.
    $term = $entity_type_manager->getStorage('taxonomy_term')->load($parent_id);
    if ($term instanceof TermInterface && $term->bundle() === 'site_section') {
      return $term->id();
    }
    return NULL;
  }

  if ($parent_entity_type === 'node') {
    $parent_node = $entity_type_manager->getStorage('node')->load($parent_id);
    if (!$parent_node instanceof NodeInterface) {
      return NULL;
    }

    // If parent has field_site_section, use it.
    if ($parent_node->hasField('field_site_section') && !$parent_node->get('field_site_section')->isEmpty()) {
      return $parent_node->get('field_site_section')->target_id;
    }
  }

  return NULL;
}

/**
 * Gets the parent context information for a content_page.
 *
 * @param \Drupal\node\NodeInterface $node
 *   The content_page node.
 *
 * @return array|null
 *   An array with 'type' and 'entity' keys, or NULL if no parent.
 */
function _site_structure_get_parent_context(NodeInterface $node): ?array {
  if (!$node->hasField('field_parent_page') || $node->get('field_parent_page')->isEmpty()) {
    return NULL;
  }

  $parent_field = $node->get('field_parent_page')->first();
  if (!$parent_field) {
    return NULL;
  }

  $parent_entity_type = $parent_field->target_type ?? NULL;
  $parent_id = $parent_field->target_id ?? NULL;

  if (!$parent_entity_type || !$parent_id) {
    return NULL;
  }

  $parent = \Drupal::entityTypeManager()
    ->getStorage($parent_entity_type)
    ->load($parent_id);

  if (!$parent) {
    return NULL;
  }

  return [
    'type' => $parent_entity_type,
    'entity' => $parent,
  ];
}

/**
 * Checks if setting parent_id as parent of node_id would create circular reference.
 *
 * @param int|string $node_id
 *   The ID of the node being edited.
 * @param int|string $parent_id
 *   The ID of the potential parent.
 *
 * @return bool
 *   TRUE if it would create circular reference, FALSE otherwise.
 */
function _site_structure_creates_circular_reference(int|string $node_id, int|string $parent_id): bool {
  $visited = [];
  $current_id = $parent_id;
  $node_storage = \Drupal::entityTypeManager()->getStorage('node');

  while ($current_id) {
    // If we find the original node in the parent chain, it's circular.
    if ($current_id == $node_id) {
      return TRUE;
    }

    // Avoid infinite loops in case of corrupted data.
    if (isset($visited[$current_id])) {
      return TRUE;
    }
    $visited[$current_id] = TRUE;

    // Load the current node and get its parent.
    $current_node = $node_storage->load($current_id);
    if (!$current_node instanceof NodeInterface ||
        !$current_node->hasField('field_parent_page') ||
        $current_node->get('field_parent_page')->isEmpty()) {
      break;
    }

    $parent_field = $current_node->get('field_parent_page')->first();
    // Only continue checking if parent is also a node.
    if (!$parent_field || ($parent_field->target_type ?? NULL) !== 'node') {
      break;
    }

    $current_id = $parent_field->target_id;
  }

  return FALSE;
}

/**
 * Implements hook_theme().
 */
function site_structure_theme(): array {
  return [
    'site_structure_menu' => [
      'variables' => [
        'ancestor' => NULL,
        'tree' => [],
        'active_trail' => [],
        'show_ancestor_title' => TRUE,
      ],
    ],
    'site_structure_menu_tree' => [
      'variables' => [
        'items' => [],
        'active_trail' => [],
        'depth' => 0,
      ],
    ],
  ];
}

/**
 * Implements hook_token_info().
 */
function site_structure_token_info(): array {
  $info = [];

  $info['tokens']['node']['site-section-path'] = [
    'name' => t('Site Section Path'),
    'description' => t('The hierarchical path of the site_section taxonomy (e.g., undergraduate/courses).'),
  ];

  $info['tokens']['term']['hierarchy-path'] = [
    'name' => t('Hierarchy Path'),
    'description' => t('The hierarchical path of the term including ancestors (e.g., institutional/news).'),
  ];

  return $info;
}

/**
 * Implements hook_tokens().
 */
function site_structure_tokens(string $type, array $tokens, array $data, array $options, $bubbleable_metadata): array {
  $replacements = [];

  if ($type === 'node' && !empty($data['node'])) {
    $node = $data['node'];
    foreach ($tokens as $name => $original) {
      if ($name === 'site-section-path') {
        $replacements[$original] = _site_structure_get_section_path($node);
      }
    }
  }

  if ($type === 'term' && !empty($data['term'])) {
    $term = $data['term'];
    foreach ($tokens as $name => $original) {
      if ($name === 'hierarchy-path') {
        $replacements[$original] = _site_structure_get_term_hierarchy_path($term);
      }
    }
  }

  return $replacements;
}

/**
 * Gets the hierarchical path of the site section for a node.
 *
 * @param \Drupal\node\NodeInterface $node
 *   The node.
 *
 * @return string
 *   The section path (e.g., "undergraduate/courses") or empty string.
 */
function _site_structure_get_section_path(NodeInterface $node): string {
  if (!$node->hasField('field_site_section') || $node->get('field_site_section')->isEmpty()) {
    return '';
  }

  $term_id = $node->get('field_site_section')->target_id;
  $term_storage = \Drupal::entityTypeManager()->getStorage('taxonomy_term');
  $term = $term_storage->load($term_id);

  if (!$term) {
    return '';
  }

  // Get all ancestors of the term.
  $ancestors = $term_storage->loadAllParents($term_id);
  $ancestors = array_reverse($ancestors);

  // Build the path using the term names converted to URL.
  $path_parts = [];
  foreach ($ancestors as $ancestor) {
    $path_parts[] = \Drupal::service('pathauto.alias_cleaner')->cleanString($ancestor->getName());
  }

  return implode('/', $path_parts);
}

/**
 * Gets the hierarchical path of a taxonomy term.
 *
 * @param \Drupal\taxonomy\TermInterface $term
 *   The taxonomy term.
 *
 * @return string
 *   The hierarchical path (e.g., "institutional/news") or empty string.
 */
function _site_structure_get_term_hierarchy_path(TermInterface $term): string {
  $term_storage = \Drupal::entityTypeManager()->getStorage('taxonomy_term');

  // Get all ancestors of the term (including itself).
  $ancestors = $term_storage->loadAllParents($term->id());
  $ancestors = array_reverse($ancestors);

  // Build the path using the term names converted to URL.
  $path_parts = [];
  foreach ($ancestors as $ancestor) {
    $path_parts[] = \Drupal::service('pathauto.alias_cleaner')->cleanString($ancestor->getName());
  }

  return implode('/', $path_parts);
}