<?php

/**
 * @file
 * Allow views to be used instead of default taxonomy term page behavior.
 */

use Drupal\taxonomy\Entity\Vocabulary;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Entity\EntityInterface;
use Drupal\views\Views;

/**
 * Implements hook_entity_extra_field_info().
 */
function tvi_entity_extra_field_info() {
  $extra = [];
  /** @var \Drupal\Core\Entity\EntityInterface $bundle */
  foreach (Vocabulary::loadMultiple() as $bundle) {
    $extra['taxonomy_term'][$bundle->id()]['form']['tvi'] = [
      'label' => t('TVI settings'),
      'description' => t('Show TVI settings'),
      'weight' => 100,
    ];
  }

  return $extra;
}

/**
 * Helper function to construct the forms for both term and vocab edit forms.
 *
 * @param array $form
 *   Settings form render array.
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 *   Submitted form state.
 */
function _tvi_settings_form(array &$form, FormStateInterface $form_state) {
  $entity = $form_state->getBuildInfo()['callback_object']->getEntity();
  $entity_type = $entity->getEntityType()->id();

  $config = Drupal::configFactory()->getEditable('tvi.' . $entity_type . '.' . $entity->id());

  $values = $form_state->getValues();
  $views = Views::getEnabledViews();
  $view_options = ['' => ' - Select a View -'];
  $display_options = ['' => ' - Select a View Display -'];
  $default_display = '';

  foreach ($views as $view) {
    $view_options[$view->id()] = $view->label();
  }

  if (isset($values['tvi_view'])) {
    $display_options += tvi_get_view_displays($values['tvi_view']);
  }
  elseif ($config !== NULL) {
    $view = $config->get('view');
    $view_display = $config->get('view_display');

    if (isset($view)) {
      $display_options += tvi_get_view_displays($view);
    }

    if (isset($view_display)) {
      $default_display = $view_display;
    }
  }

  $form['tvi'] = [
    '#type' => 'details',
    '#title' => t('Taxonomy Views Integrator Settings'),
    '#open' => TRUE,
  ];

  $form['tvi']['tvi_enable_override'] = [
    '#type' => 'checkbox',
    '#title' => t('Enable taxonomy views integrator to override presentation.'),
    '#default_value' => $config->get('enable_override'),
  ];

  $form['tvi']['tvi_view'] = [
    '#type' => 'select',
    '#title' => 'Using the view',
    '#default_value' => $config->get('view'),
    '#options' => $view_options,
    '#states' => [
      'visible' => [
        ':input[name="tvi_enable_override"]' => ['checked' => TRUE],
      ],
    ],
    '#ajax' => [
      'callback' => 'tvi_view_display_ajax_handler',
      'event' => 'change',
      'wrapper' => 'tvi-view-display',
      'progress' => [
        'type' => 'throbber',
      ],
    ],
  ];

  $form['tvi']['tvi_view_display'] = [
    '#type' => 'select',
    '#title' => 'With this view display',
    '#description' => t('The view display that you want to use from the selected view.'),
    '#default_value' => $default_display,
    '#options' => $display_options,
    '#states' => [
      'visible' => [
        ':input[name="tvi_enable_override"]' => ['checked' => TRUE],
      ],
    ],
    '#prefix' => '<div id="tvi-view-display">',
    '#suffix' => '</div>',
  ];

  $form['tvi']['tvi_inherit_settings'] = [
    '#id' => 'tvi-inherit-check',
    '#type' => 'checkbox',
    '#title' => t('Child terms will use these settings.'),
    '#default_value' => $config->get('inherit_settings'),
    '#description' => t('Checking this field will allow you to define a view used by the current term and display on all of its children, unless they have their own settings configured.'),
    '#states' => [
      'disabled' => [
        ':input[name="tvi_enable_override"]' => ['checked' => FALSE],
      ],
      'visible' => [
        ':input[name="tvi_enable_override"]' => ['checked' => TRUE],
      ],
    ],
  ];

  $form['tvi']['tvi_pass_arguments'] = [
    '#id' => 'tvi-pass-arguments',
    '#type' => 'checkbox',
    '#title' => t('Pass all arguments to views.'),
    '#description' => t('Enable this checkbox, and your views display will receive all arguments going after /taxonomy/term/ in the path. If disabled, your views display will only receive tid, and tid_depth.'),
    '#default_value' => $config->get('pass_arguments'),
    '#states' => [
      'disabled' => [
        ':input[name="tvi_enable_override"]' => ['checked' => FALSE],
      ],
      'visible' => [
        ':input[name="tvi_enable_override"]' => ['checked' => TRUE],
      ],
    ],
  ];

  if ($entity_type == 'taxonomy_term') {
    $form['tvi']['#description'] = t('Override the default presentation this term page.');
    $form['tvi']['tvi_view']['#description'] = t('The default view to use for this term page.');
  }

  if ($entity_type == 'taxonomy_vocabulary') {
    $form['tvi']['#description'] = t('Override the default presentation for terms in this vocabulary.');
    $form['tvi']['tvi_view']['#description'] = t('The default view to use for this term page.');
  }

  $form['#validate'][] = 'tvi_form_config_validate';
  $form['actions']['submit']['#submit'][] = 'tvi_submit_handler';
}

/**
 * Validate that if override is enable, that we have values for the view.
 *
 * Due to bugs in #states array, we can't have required fields that are hidden.
 *
 * @param array $form
 *   Settings form render array.
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 *   Submitted form state.
 */
function tvi_form_config_validate(array $form, FormStateInterface $form_state) {
  $values = $form_state->getValues();

  if ($values['tvi_enable_override']) {
    if (!mb_strlen($values['tvi_view'])) {
      $form_state->setError($form['tvi']['tvi_view'], t('To override the term presentation, you must specify a view.'));
    }

    if (!mb_strlen($values['tvi_view_display'])) {
      $form_state->setError($form['tvi']['tvi_view_display'], t('To override the term presentation, you must specify a view display.'));
    }
  }
}

/**
 * Implements hook_form_BASE_FORM_ID_alter().
 */
function tvi_form_taxonomy_term_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
  $entity = $form_state->getBuildInfo()['callback_object']->getEntity();

  if ($entity->id() !== NULL && Drupal::currentUser()->hasPermission('define view for terms in ' . $entity->bundle())) {
    _tvi_settings_form($form, $form_state, $entity);
  }
}

/**
 * Implements hook_form_BASE_FORM_ID_alter().
 */
function tvi_form_taxonomy_vocabulary_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
  $entity = $form_state->getBuildInfo()['callback_object']->getEntity();

  if ($entity->id() !== NULL && Drupal::currentUser()->hasPermission('define view for vocabulary ' . $entity->id())) {
    _tvi_settings_form($form, $form_state, $entity);
  }
}

/**
 * AJAX handler for vocabulary and term forms.
 *
 * @param array $form
 *   Settings form render array.
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 *   Submitted form state.
 *
 * @return mixed
 *   Local render array for ajax callback.
 */
function tvi_view_display_ajax_handler(array $form, FormStateInterface $form_state) {
  $form['tvi']['tvi_view_display']['#value'] = '';
  $form_state->setRebuild();
  return $form['tvi']['tvi_view_display'];
}

/**
 * Return an array of displays for a given view id.
 *
 * @param string $view_id
 *   The view id to get values from.
 *
 * @return array
 *   Option values with display name and id.
 */
function tvi_get_view_displays(string $view_id) {
  $display_options = [];
  $view = Drupal::entityTypeManager()->getStorage('view')->load($view_id);

  if ($view) {
    foreach ($view->get('display') as $display) {
      $display_options[$display['id']] = $display['display_title'] . ' (' . $display['display_plugin'] . ')';
    }
  }

  return $display_options;
}

/**
 * Submit handler attached to term and vocabulary forms.
 *
 * @param array $form
 *   Settings form render array.
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 *   Submitted form state.
 */
function tvi_submit_handler(array $form, FormStateInterface $form_state) {
  $entity = $form_state->getBuildInfo()['callback_object']->getEntity();
  $entity_type = $entity->getEntityType()->id();
  $form_values = $form_state->getValues();

  if ($form_values['tvi_enable_override']) {
    Drupal::configFactory()
      ->getEditable('tvi.' . $entity_type . '.' . $entity->id())
      ->set('enable_override', $form_values['tvi_enable_override'])
      ->set('view', $form_values['tvi_view'])
      ->set('view_display', $form_values['tvi_view_display'])
      ->set('inherit_settings', $form_values['tvi_inherit_settings'])
      ->set('pass_arguments', $form_values['tvi_pass_arguments'])
      ->save();
  }
  else {
    Drupal::configFactory()
      ->getEditable('tvi.' . $entity_type . '.' . $entity->id())
      ->delete();
  }
}

/**
 * Implements hook_ENTITY_TYPE_delete().
 *
 * Remove TVI settings when vocabularies are deleted.
 */
function tvi_taxonomy_vocabulary_delete(EntityInterface $entity) {
  Drupal::configFactory()->getEditable('tvi.taxonomy_vocabulary.' . $entity->id())->delete();
}

/**
 * Implements hook_taxonomy_term_delete().
 *
 * Remove TVI settings when terms are deleted.
 */
function tvi_taxonomy_term_delete(EntityInterface $entity) {
  Drupal::configFactory()->getEditable('tvi.taxonomy_term.' . $entity->id())->delete();
}