<?php

/**
 * @file
 * Primary module hooks for Structural Pages 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 structural_pages_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() && $parent_id) {
    if (_structural_pages_creates_circular_reference($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\structural_pages\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).
  $site_section_id = _structural_pages_get_section_from_parent($parent_entity_type, $parent_id);
  if ($site_section_id) {
    $entity->set('field_site_section', $site_section_id);
  }
}

/**
 * Returns the configured site section vocabulary machine name.
 *
 * @return string
 *   The vocabulary ID (e.g., 'site_sections').
 */
function _structural_pages_get_vocabulary(): string {
  return \Drupal::config('structural_pages.settings')
    ->get('site_section_vocabulary') ?? 'site_sections';
}

/**
 * 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 _structural_pages_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 the configured vocabulary.
    $term = $entity_type_manager->getStorage('taxonomy_term')->load($parent_id);
    if ($term instanceof TermInterface && $term->bundle() === _structural_pages_get_vocabulary()) {
      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 _structural_pages_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 _structural_pages_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 structural_pages_theme(): array {
  return [
    'structural_pages_menu' => [
      'variables' => [
        'ancestor' => NULL,
        'ancestor_url' => '',
        'tree' => [],
        'active_trail' => [],
        'show_ancestor_title' => TRUE,
      ],
    ],
    'structural_pages_menu_tree' => [
      'variables' => [
        'items' => [],
        'active_trail' => [],
        'depth' => 0,
      ],
    ],
  ];
}

/**
 * Implements hook_token_info().
 */
function structural_pages_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 structural_pages_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] = _structural_pages_get_section_path($node);
      }
    }
  }

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

/**
 * Implements hook_form_FORM_ID_alter() for node_content_page_form.
 */
function structural_pages_form_node_content_page_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  _structural_pages_alter_parent_page_form($form, $form_state);
}

/**
 * Implements hook_form_FORM_ID_alter() for node_content_page_edit_form.
 */
function structural_pages_form_node_content_page_edit_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  _structural_pages_alter_parent_page_form($form, $form_state);
}

/**
 * Helper to alter the content_page forms for parent page filtering.
 */
function _structural_pages_alter_parent_page_form(&$form, \Drupal\Core\Form\FormStateInterface $form_state) {
  // Hide the native Drupal menu settings tab, since this module generates
  // the structural pages menu automatically.
  if (isset($form['menu'])) {
    $form['menu']['#access'] = FALSE;
  }

  if (isset($form['field_site_section']) && isset($form['field_parent_page'])) {
    
    // 1. Add AJAX behavior to update parent page options when section changes.
    if (isset($form['field_site_section']['widget'])) {
      $form['field_site_section']['widget']['#ajax'] = [
        'callback' => 'structural_pages_parent_page_ajax_callback',
        'wrapper' => 'parent-page-wrapper',
      ];
    }

    // Wrap the container where our custom select will go.
    $form['structural_pages_wrapper'] = [
      '#type' => 'container',
      '#attributes' => ['id' => 'parent-page-wrapper'],
      '#weight' => $form['field_parent_page']['#weight'] ?? 1,
      '#attached' => [
        'library' => [
          'structural_pages/select2',
        ],
      ],
    ];

    // 3. Retrieve the currently selected site_section ID.
    $site_section_id = NULL;

    // From AJAX state (user just changed it).
    $site_section_value = $form_state->getValue('field_site_section');
    if (!empty($site_section_value[0]['target_id'])) {
      $site_section_id = $site_section_value[0]['target_id'];
    }
    // From initial form load.
    elseif (isset($form['field_site_section']['widget']['#default_value'])) {
      $default = $form['field_site_section']['widget']['#default_value'];
      if (is_array($default) && !empty($default[0])) {
        $site_section_id = $default[0];
      }
      elseif (is_scalar($default)) {
        $site_section_id = $default;
      }
    }

    $current_entity = $form_state->getFormObject()->getEntity();
    $current_nid = $current_entity ? $current_entity->id() : NULL;

    if ($site_section_id) {
      $options = _structural_pages_build_parent_tree_options($site_section_id, $current_nid);
      
      $default_parent = '';
      if ($current_entity && !$current_entity->isNew() && !$current_entity->get('field_parent_page')->isEmpty()) {
         $default_parent = $current_entity->get('field_parent_page')->target_type . ':' . $current_entity->get('field_parent_page')->target_id;
      }

      // Add the Root (Taxonomy term) as the default option at the top of the tree.
      $term = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->load($site_section_id);
      $term_label = $term ? $term->label() : t('Taxonomia');
      $root_key = 'taxonomy_term:' . $site_section_id;
      
      $options = [$root_key => '< ' . t('Raiz (@term)', ['@term' => $term_label]) . ' >'] + $options;
      
      if (empty($default_parent)) {
        $default_parent = $root_key;
      }

      // Hide the original field.
      $form['field_parent_page']['#access'] = FALSE;

      // Create a new visual field.
      $form['structural_pages_wrapper']['custom_parent_page'] = [
        '#type' => 'select',
        '#title' => t('Parent Page'),
        '#options' => $options,
        '#default_value' => $default_parent,
        '#empty_option' => t('- Selecione a Página Pai -'),
        '#description' => t('Select the parent page within this site section. Select Root if this is a top-level page.'),
        // Attach a select2/chosen class if available in standard themes
        '#attributes' => [
          'class' => ['select2-widget', 'chosen-enable'],
          'data-placeholder' => t('Search for a parent page...'),
        ],
      ];
      
      // We must add a custom submit/validate handler to map our select back to field_parent_page.
      array_unshift($form['#validate'], 'structural_pages_custom_parent_validate');
    } else {
      // If no section chosen yet, hide parent page completely so they pick a section first.
      $form['field_parent_page']['#access'] = FALSE;
      $form['structural_pages_wrapper']['custom_parent_page'] = [
        '#type' => 'markup',
        '#markup' => '<p><em>' . t('Por favor, selecione uma Site Section primeiro.') . '</em></p>',
      ];
    }
  }
}

/**
 * Validation callback to map the select list back into dynamic_entity_reference.
 */
function structural_pages_custom_parent_validate(&$form, \Drupal\Core\Form\FormStateInterface $form_state) {
  $custom_val = $form_state->getValue('custom_parent_page');
  if (!empty($custom_val)) {
    list($type, $id) = explode(':', $custom_val);
    $form_state->setValue('field_parent_page', [
      ['target_id' => $id, 'target_type' => $type]
    ]);
  } else {
    $form_state->setValue('field_parent_page', []);
  }
}

/**
 * AJAX callback to replace the parent page wrapper.
 */
function structural_pages_parent_page_ajax_callback(array &$form, \Drupal\Core\Form\FormStateInterface $form_state) {
  return $form['structural_pages_wrapper'];
}

/**
 * Builds a hierarchical tree array of content_pages for a given section.
 */
function _structural_pages_build_parent_tree_options($site_section_id, $current_node_id = NULL) {
  $options = [];

  $query = \Drupal::entityQuery('node')
    ->condition('type', 'content_page')
    ->condition('field_site_section', $site_section_id)
    ->accessCheck(TRUE)
    ->sort('title', 'ASC');
  $nids = $query->execute();
  
  if (empty($nids)) {
    return $options;
  }
  
  $nodes = \Drupal::entityTypeManager()->getStorage('node')->loadMultiple($nids);
  
  $children = [];
  $roots = [];
  
  foreach ($nodes as $nid => $node) {
    if ($nid == $current_node_id) {
      continue; // Skip self
    }
    
    $parent_id = NULL;
    $parent_type = NULL;
    if (!$node->get('field_parent_page')->isEmpty()) {
       $parent_id = $node->get('field_parent_page')->target_id;
       $parent_type = $node->get('field_parent_page')->target_type;
    }
    
    // If the parent is another content_page in our list, it's a child.
    if ($parent_type === 'node' && isset($nodes[$parent_id])) {
      $children[$parent_id][] = $nid;
    } else {
      // It's a root (parent is a taxonomy term, a section_page, or empty)
      $roots[] = $nid;
    }
  }
  
  // Try to sort roots alphabetically
  usort($roots, function($a, $b) use ($nodes) {
    return strcmp($nodes[$a]->getTitle(), $nodes[$b]->getTitle());
  });
  
  $build_options = function($nids, $depth) use (&$build_options, &$options, $nodes, $children) {
    // We use non-breaking spaces and hyphens for a tree view look
    $prefix = str_repeat('— ', $depth);
    foreach ($nids as $nid) {
      $options['node:' . $nid] = $prefix . $nodes[$nid]->getTitle();
      if (isset($children[$nid])) {
        // Sort children alphabetically too
        $child_nids = $children[$nid];
        usort($child_nids, function($a, $b) use ($nodes) {
          return strcmp($nodes[$a]->getTitle(), $nodes[$b]->getTitle());
        });
        $build_options($child_nids, $depth + 1);
      }
    }
  };
  
  $build_options($roots, 0);
  
  return $options;
}

/**
 * Implements hook_preprocess_node().
 */
function structural_pages_preprocess_node(array &$variables): void {
  // Forcefully remove the "submitted by" author and date information 
  // for content pages, regardless of theme settings.
  if (isset($variables['node']) && $variables['node']->bundle() === 'content_page') {
    $variables['display_submitted'] = FALSE;
  }
}

/**
 * Implements hook_views_post_execute().
 */
function structural_pages_views_post_execute(\Drupal\views\ViewExecutable $view) {
  // Fallback for child_pages view: if empty, show sibling pages instead.
  if ($view->id() === 'child_pages' && empty($view->result)) {
    $args = $view->args;
    if (!empty($args[0]) && is_numeric($args[0])) {
      $node_storage = \Drupal::entityTypeManager()->getStorage('node');
      $current_node = $node_storage->load($args[0]);
      
      if ($current_node instanceof \Drupal\node\NodeInterface && $current_node->bundle() === 'content_page') {
        $query = \Drupal::entityQuery('node')
          ->condition('type', 'content_page')
          ->condition('status', 1)
          ->accessCheck(TRUE)
          ->sort('title', 'ASC');
          
        $parent_id = NULL;
        if (!$current_node->get('field_parent_page')->isEmpty()) {
          $parent_field = $current_node->get('field_parent_page')->first();
          if (($parent_field->target_type ?? '') === 'node') {
            $parent_id = $parent_field->target_id;
          }
        }
        
        if ($parent_id) {
          // Has a node parent. Siblings are nodes with the same parent.
          $query->condition('field_parent_page.target_id', $parent_id);
          $query->condition('field_parent_page.target_type', 'node');
        } else {
          // Root page. Siblings are other root pages in the same site section.
          $orGroup = $query->orConditionGroup()
            ->notExists('field_parent_page')
            ->condition('field_parent_page.target_type', 'taxonomy_term');
          $query->condition($orGroup);
          
          if (!$current_node->get('field_site_section')->isEmpty()) {
            $query->condition('field_site_section.target_id', $current_node->get('field_site_section')->target_id);
          }
        }
        
        $nids = $query->execute();
        
        if (!empty($nids)) {
          // Load the sibling nodes
          $siblings = $node_storage->loadMultiple($nids);
          $index = 0;
          $view->result = [];
          
          foreach ($siblings as $nid => $sibling) {
            $row = new \Drupal\views\ResultRow();
            $row->_entity = $sibling;
            $row->nid = $nid;
            $row->index = $index++;
            $view->result[] = $row;
          }
          
          $view->total_rows = count($view->result);
          
          // Optionally alter the title to indicate these are siblings
          $view->setTitle(t('Páginas do mesmo nível'));

          // Remove empty text since we now have results
          $view->empty = [];
        }
      }
    }
  }
}