<?php

namespace Drupal\simple_sitemap;

use Drupal\Core\Database\Connection;
use Drupal\Core\Entity\EntityTypeManagerInterface;
use Drupal\Core\Path\PathValidator;
use Drupal\Core\Config\ConfigFactory;
use Drupal\Core\Datetime\DateFormatter;
use Drupal\Component\Datetime\Time;
use Drupal\simple_sitemap\Plugin\simple_sitemap\UrlGenerator\UrlGeneratorManager;

/**
 * Class Simplesitemap
 * @package Drupal\simple_sitemap
 */
class Simplesitemap {

  /**
   * @var \Drupal\simple_sitemap\SitemapGenerator
   */
  protected $sitemapGenerator;

  /**
   * @var \Drupal\simple_sitemap\EntityHelper
   */
  protected $entityHelper;

  /**
   * @var \Drupal\Core\Config\ConfigFactory
   */
  protected $configFactory;

  /**
   * @var \Drupal\Core\Database\Connection
   */
  protected $db;

  /**
   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
   */
  protected $entityTypeManager;

  /**
   * @var \Drupal\Core\Path\PathValidator
   */
  protected $pathValidator;

  /**
   * @var \Drupal\Core\Datetime\DateFormatter
   */
  protected $dateFormatter;

  /**
   * @var \Drupal\Component\Datetime\Time
   */
  protected $time;

  /**
   * @var \Drupal\simple_sitemap\Batch
   */
  protected $batch;

  /**
   * @var \Drupal\Core\Extension\ModuleHandler
   */
  protected $moduleHandler;

  /**
   * @var \Drupal\simple_sitemap\Plugin\simple_sitemap\UrlGenerator\UrlGeneratorManager
   */
  protected $urlGeneratorManager;

  /**
   * @var array
   */
  protected static $allowedLinkSettings = [
    'entity' => ['index', 'priority', 'changefreq', 'include_images'],
    'custom' => ['priority', 'changefreq'],
  ];

  /**
   * @var array
   */
  protected static $linkSettingDefaults = [
    'index' => 1,
    'priority' => 0.5,
    'changefreq' => '',
    'include_images' => 0,
  ];

  /**
   * Simplesitemap constructor.
   * @param \Drupal\simple_sitemap\SitemapGenerator $sitemapGenerator
   * @param \Drupal\simple_sitemap\EntityHelper $entityHelper
   * @param \Drupal\Core\Config\ConfigFactory $configFactory
   * @param \Drupal\Core\Database\Connection $database
   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entityTypeManager
   * @param \Drupal\Core\Path\PathValidator $pathValidator
   * @param \Drupal\Core\Datetime\DateFormatter $dateFormatter
   * @param \Drupal\Component\Datetime\Time $time
   * @param \Drupal\simple_sitemap\Batch $batch
   * @param \Drupal\simple_sitemap\Plugin\simple_sitemap\UrlGenerator\UrlGeneratorManager $urlGeneratorManager
   */
  public function __construct(
    SitemapGenerator $sitemapGenerator,
    EntityHelper $entityHelper,
    ConfigFactory $configFactory,
    Connection $database,
    EntityTypeManagerInterface $entityTypeManager,
    PathValidator $pathValidator,
    DateFormatter $dateFormatter,
    Time $time,
    Batch $batch,
    UrlGeneratorManager $urlGeneratorManager
  ) {
    $this->sitemapGenerator = $sitemapGenerator;
    $this->entityHelper = $entityHelper;
    $this->configFactory = $configFactory;
    $this->db = $database;
    $this->entityTypeManager = $entityTypeManager;
    $this->pathValidator = $pathValidator;
    $this->dateFormatter = $dateFormatter;
    $this->time = $time;
    $this->batch = $batch;
    $this->urlGeneratorManager = $urlGeneratorManager;
  }

  /**
   * Returns a specific sitemap setting or a default value if setting does not
   * exist.
   *
   * @param string $name
   *   Name of the setting, like 'max_links'.
   *
   * @param mixed $default
   *   Value to be returned if the setting does not exist in the configuration.
   *
   * @return mixed
   *   The current setting from configuration or a default value.
   */
  public function getSetting($name, $default = FALSE) {
    $setting = $this->configFactory
      ->get('simple_sitemap.settings')
      ->get($name);
    return NULL !== $setting ? $setting : $default;
  }

  /**
   * Stores a specific sitemap setting in configuration.
   *
   * @param string $name
   *   Setting name, like 'max_links'.
   * @param mixed $setting
   *   The setting to be saved.
   *
   * @return $this
   */
  public function saveSetting($name, $setting) {
    $this->configFactory->getEditable('simple_sitemap.settings')
      ->set($name, $setting)->save();
    return $this;
  }

  /**
   * Returns the whole sitemap, a requested sitemap chunk,
   * or the sitemap index file.
   *
   * @param int $chunk_id
   *
   * @return string|false
   *   If no sitemap id provided, either a sitemap index is returned, or the
   *   whole sitemap, if the amount of links does not exceed the max links
   *   setting. If a sitemap id is provided, a sitemap chunk is returned. False
   *   if sitemap is not retrievable from the database.
   */
  public function getSitemap($chunk_id = NULL) {
    $chunk_info = $this->fetchSitemapChunkInfo();

    if (NULL === $chunk_id || !isset($chunk_info[$chunk_id])) {

      if (count($chunk_info) > 1) {
        // Return sitemap index, if there are multiple sitemap chunks.
        return $this->getSitemapIndex($chunk_info);
      }
      else {
        // Return sitemap if there is only one chunk.
        return count($chunk_info) === 1
        && isset($chunk_info[SitemapGenerator::FIRST_CHUNK_INDEX])
          ? $this->fetchSitemapChunk(SitemapGenerator::FIRST_CHUNK_INDEX)
            ->sitemap_string
          : FALSE;
      }
    }
    else {
      // Return specific sitemap chunk.
      return $this->fetchSitemapChunk($chunk_id)->sitemap_string;
    }
  }

  /**
   * Fetches all sitemap chunk timestamps keyed by chunk ID.
   *
   * @return array
   *   An array containing chunk creation timestamps keyed by chunk ID.
   */
  protected function fetchSitemapChunkInfo() {
    return $this->db
      ->query('SELECT id, sitemap_created FROM {simple_sitemap}')
      ->fetchAllAssoc('id');
  }

  /**
   * Fetches a single sitemap chunk by ID.
   *
   * @param int $id
   *   The chunk ID.
   *
   * @return object
   *   A sitemap chunk object.
   */
  protected function fetchSitemapChunk($id) {
    return $this->db->query('SELECT * FROM {simple_sitemap} WHERE id = :id',
      [':id' => $id])->fetchObject();
  }

  /**
   * Generates the XML sitemap and saves it to the db.
   *
   * @param string $from
   *   Can be 'form', 'backend', 'drush' or 'nobatch'.
   *   This decides how the batch process is to be run.
   *
   * @return bool|\Drupal\simple_sitemap\Simplesitemap
   */
  public function generateSitemap($from = 'form') {

    $this->batch->setBatchSettings([
      'base_url' => $this->getSetting('base_url', ''),
      'batch_process_limit' => $this->getSetting('batch_process_limit', NULL),
      'max_links' => $this->getSetting('max_links', 2000),
      'skip_untranslated' => $this->getSetting('skip_untranslated', FALSE),
      'remove_duplicates' => $this->getSetting('remove_duplicates', TRUE),
      'excluded_languages' => $this->getSetting('excluded_languages', []),
      'from' => $from,
    ]);

    $plugins = $this->urlGeneratorManager->getDefinitions();

    usort($plugins, function($a, $b) {
      return $a['weight'] - $b['weight'];
    });

    foreach ($plugins as $plugin) {
      if ($plugin['enabled']) {
        if (!empty($plugin['settings']['instantiate_for_each_data_set'])) {
          foreach ($this->urlGeneratorManager->createInstance($plugin['id'])->getDataSets() as $data_sets) {
            $this->batch->addOperation($plugin['id'], $data_sets);
          }
        }
        else {
          $this->batch->addOperation($plugin['id']);
        }
      }
    }

    $success = $this->batch->start();
    return $from === 'nobatch' ? $this : $success;
  }

  /**
   * Generates and returns the sitemap index as string.
   *
   * @param array $chunk_info
   *   Array containing chunk creation timestamps keyed by chunk ID.
   *
   * @return string
   *   The sitemap index.
   *
   * @todo Need to make sure response is cached.
   */
  protected function getSitemapIndex($chunk_info) {
    return $this->sitemapGenerator
      ->setSettings(['base_url' => $this->getSetting('base_url', '')])
      ->generateSitemapIndex($chunk_info);
  }

  /**
   * Returns a 'time ago' string of last timestamp generation.
   *
   * @return string|false
   *   Formatted timestamp of last sitemap generation, otherwise FALSE.
   */
  public function getGeneratedAgo() {
    $chunks = $this->fetchSitemapChunkInfo();
    if (isset($chunks[SitemapGenerator::FIRST_CHUNK_INDEX]->sitemap_created)) {
      return $this->dateFormatter
        ->formatInterval($this->time->getRequestTime() - $chunks[SitemapGenerator::FIRST_CHUNK_INDEX]
            ->sitemap_created);
    }
    return FALSE;
  }

  /**
   * Enables sitemap support for an entity type. Enabled entity types show
   * sitemap settings on their bundle setting forms. If an enabled entity type
   * features bundles (e.g. 'node'), it needs to be set up with
   * setBundleSettings() as well.
   *
   * @param string $entity_type_id
   *  Entity type id like 'node'.
   *
   * @return $this
   */
  public function enableEntityType($entity_type_id) {
    $enabled_entity_types = $this->getSetting('enabled_entity_types');
    if (!in_array($entity_type_id, $enabled_entity_types)) {
      $enabled_entity_types[] = $entity_type_id;
      $this->saveSetting('enabled_entity_types', $enabled_entity_types);
    }
    return $this;
  }

  /**
   * Disables sitemap support for an entity type. Disabling support for an
   * entity type deletes its sitemap settings permanently and removes sitemap
   * settings from entity forms.
   *
   * @param string $entity_type_id
   *  Entity type id like 'node'.
   *
   * @return $this
   */
  public function disableEntityType($entity_type_id) {

    // Updating settings.
    $enabled_entity_types = $this->getSetting('enabled_entity_types');
    if (FALSE !== ($key = array_search($entity_type_id, $enabled_entity_types))) {
      unset ($enabled_entity_types[$key]);
      $this->saveSetting('enabled_entity_types', array_values($enabled_entity_types));
    }

    // Deleting inclusion settings.
    $config_names = $this->configFactory->listAll("simple_sitemap.bundle_settings.$entity_type_id.");
    foreach ($config_names as $config_name) {
      $this->configFactory->getEditable($config_name)->delete();
    }

    // Deleting entity overrides.
    $this->removeEntityInstanceSettings($entity_type_id);
    return $this;
  }

  /**
   * Sets sitemap settings for a non-bundle entity type (e.g. user) or a bundle
   * of an entity type (e.g. page).
   *
   * @param string $entity_type_id
   *  Entity type id like 'node' the bundle belongs to.
   * @param string $bundle_name
   *  Name of the bundle. NULL if entity type has no bundles.
   * @param array $settings
   *  An array of sitemap settings for this bundle/entity type.
   *  Example: ['index' => TRUE, 'priority' => 0.5, 'changefreq' => 'never', 'include_images' => FALSE].
   *
   * @return $this
   *
   * @todo: enableEntityType automatically
   */
  public function setBundleSettings($entity_type_id, $bundle_name = NULL, $settings = []) {
    $bundle_name = empty($bundle_name) ? $entity_type_id : $bundle_name;

    if (!empty($old_settings = $this->getBundleSettings($entity_type_id, $bundle_name))) {
      $settings = array_merge($old_settings, $settings);
    }
    else {
      self::supplementDefaultSettings('entity', $settings);
    }

    $bundle_settings = $this->configFactory
      ->getEditable("simple_sitemap.bundle_settings.$entity_type_id.$bundle_name");
    foreach ($settings as $setting_key => $setting) {
      if ($setting_key === 'index') {
        $setting = intval($setting);
      }
      $bundle_settings->set($setting_key, $setting);
    }
    $bundle_settings->save();

    // Delete entity overrides which are identical to new bundle setting.
    $sitemap_entity_types = $this->entityHelper->getSupportedEntityTypes();
    if (isset($sitemap_entity_types[$entity_type_id])) {
      $entity_type = $sitemap_entity_types[$entity_type_id];
      $keys = $entity_type->getKeys();

      // Menu fix.
      $keys['bundle'] = $entity_type_id === 'menu_link_content' ? 'menu_name' : $keys['bundle'];

      $query = $this->entityTypeManager->getStorage($entity_type_id)->getQuery();
      if (!$this->entityHelper->entityTypeIsAtomic($entity_type_id)) {
        $query->condition($keys['bundle'], $bundle_name);
      }
      $entity_ids = $query->execute();

      $query = $this->db->select('simple_sitemap_entity_overrides', 'o')
        ->fields('o', ['id', 'inclusion_settings'])
        ->condition('o.entity_type', $entity_type_id);
      if (!empty($entity_ids)) {
        $query->condition('o.entity_id', $entity_ids, 'IN');
      }

      $delete_instances = [];
      foreach ($query->execute()->fetchAll() as $result) {
        $delete = TRUE;
        $instance_settings = unserialize($result->inclusion_settings);
        foreach ($instance_settings as $setting_key => $instance_setting) {
          if ($instance_setting != $settings[$setting_key]) {
            $delete = FALSE;
            break;
          }
        }
        if ($delete) {
          $delete_instances[] = $result->id;
        }
      }
      if (!empty($delete_instances)) {
        $this->db->delete('simple_sitemap_entity_overrides')
          ->condition('id', $delete_instances, 'IN')
          ->execute();
      }
    }
    else {
      //todo: log error
    }
    return $this;
  }

  /**
   * Gets sitemap settings for an entity bundle, a non-bundle entity type or for
   * all entity types and their bundles.
   *
   * @param string|null $entity_type_id
   *  If set to null, sitemap settings for all entity types and their bundles
   *  are fetched.
   * @param string|null $bundle_name
   *
   * @return array|false
   *  Array of sitemap settings for an entity bundle, a non-bundle entity type
   *  or for all entity types and their bundles.
   *  False if entity type does not exist.
   */
  public function getBundleSettings($entity_type_id = NULL, $bundle_name = NULL) {
    if (NULL !== $entity_type_id) {
      $bundle_name = empty($bundle_name) ? $entity_type_id : $bundle_name;
      $bundle_settings = $this->configFactory
        ->get("simple_sitemap.bundle_settings.$entity_type_id.$bundle_name")
        ->get();
      return !empty($bundle_settings) ? $bundle_settings : FALSE;
    }
    else {
      $config_names = $this->configFactory->listAll('simple_sitemap.bundle_settings.');
      $all_settings = [];
      foreach ($config_names as $config_name) {
        $config_name_parts = explode('.', $config_name);
        $all_settings[$config_name_parts[2]][$config_name_parts[3]] = $this->configFactory->get($config_name)->get();
      }
      return $all_settings;
    }
  }

  /**
   * Supplements all missing link setting with default values.
   *
   * @param string $type
   *  'entity'|'custom'
   * @param array &$settings
   * @param array $overrides
   */
  public static function supplementDefaultSettings($type, &$settings, $overrides = []) {
    foreach (self::$allowedLinkSettings[$type] as $allowed_link_setting) {
      if (!isset($settings[$allowed_link_setting])
        && isset(self::$linkSettingDefaults[$allowed_link_setting])) {
        $settings[$allowed_link_setting] = isset($overrides[$allowed_link_setting])
          ? $overrides[$allowed_link_setting]
          : self::$linkSettingDefaults[$allowed_link_setting];
      }
    }
  }

  /**
   * Overrides entity bundle/entity type sitemap settings for a single entity.
   *
   * @param string $entity_type_id
   * @param int $id
   * @param array $settings
   *
   * @return $this
   */
  public function setEntityInstanceSettings($entity_type_id, $id, $settings) {
    $entity = $this->entityTypeManager->getStorage($entity_type_id)->load($id);
    $bundle_settings = $this->getBundleSettings(
      $entity_type_id, $this->entityHelper->getEntityInstanceBundleName($entity)
    );
    if (!empty($bundle_settings)) {

      // Check if overrides are different from bundle setting before saving.
      $override = FALSE;
      foreach ($settings as $key => $setting) {
        if (!isset($bundle_settings[$key]) || $setting != $bundle_settings[$key]) {
          $override = TRUE;
          break;
        }
      }
      // Save overrides for this entity if something is different.
      if ($override) {
        $this->db->merge('simple_sitemap_entity_overrides')
          ->key([
            'entity_type' => $entity_type_id,
            'entity_id' => $id])
          ->fields([
            'entity_type' => $entity_type_id,
            'entity_id' => $id,
            'inclusion_settings' => serialize(array_merge($bundle_settings, $settings)),])
          ->execute();
      }
      // Else unset override.
      else {
        $this->removeEntityInstanceSettings($entity_type_id, $id);
      }
    }
    else {
      //todo: log error
    }
    return $this;
  }

  /**
   * Gets sitemap settings for an entity instance which overrides the sitemap
   * settings of its bundle, or bundle settings, if they are not overridden.
   *
   * @param string $entity_type_id
   * @param int $id
   *
   * @return array|false
   */
  public function getEntityInstanceSettings($entity_type_id, $id) {
    $results = $this->db->select('simple_sitemap_entity_overrides', 'o')
      ->fields('o', ['inclusion_settings'])
      ->condition('o.entity_type', $entity_type_id)
      ->condition('o.entity_id', $id)
      ->execute()
      ->fetchField();

    if (!empty($results)) {
      return unserialize($results);
    }
    else {
      $entity = $this->entityTypeManager->getStorage($entity_type_id)
        ->load($id);
      return $this->getBundleSettings(
        $entity_type_id,
        $this->entityHelper->getEntityInstanceBundleName($entity)
      );
    }
  }

  /**
   * Removes sitemap settings for an entity that overrides the sitemap settings
   * of its bundle.
   *
   * @param string $entity_type_id
   * @param string|null $entity_ids
   *
   * @return $this
   */
  public function removeEntityInstanceSettings($entity_type_id, $entity_ids = NULL) {
    $query = $this->db->delete('simple_sitemap_entity_overrides')
      ->condition('entity_type', $entity_type_id);
    if (NULL !== $entity_ids) {
      $entity_ids = !is_array($entity_ids) ? [$entity_ids] : $entity_ids;
      $query->condition('entity_id', $entity_ids, 'IN');
    }
    $query->execute();
    return $this;
  }

  /**
   * Checks if an entity bundle (or a non-bundle entity type) is set to be
   * indexed in the sitemap settings.
   *
   * @param string $entity_type_id
   * @param string|null $bundle_name
   *
   * @return bool
   */
  public function bundleIsIndexed($entity_type_id, $bundle_name = NULL) {
    $settings = $this->getBundleSettings($entity_type_id, $bundle_name);
    return !empty($settings['index']);
  }

  /**
   * Checks if an entity type is enabled in the sitemap settings.
   *
   * @param string $entity_type_id
   *
   * @return bool
   */
  public function entityTypeIsEnabled($entity_type_id) {
    return in_array($entity_type_id, $this->getSetting('enabled_entity_types', []));
  }

  /**
   * Stores a custom path along with its sitemap settings to configuration.
   *
   * @param string $path
   * @param array $settings
   *
   * @return $this
   *
   * @todo Validate $settings and throw exceptions
   */
  public function addCustomLink($path, $settings = []) {
    if (!$this->pathValidator->isValid($path)) {
      // todo: log error.
      return $this;
    }
    if ($path[0] !== '/') {
      // todo: log error.
      return $this;
    }

    $custom_links = $this->getCustomLinks(FALSE);
    foreach ($custom_links as $key => $link) {
      if ($link['path'] === $path) {
        $link_key = $key;
        break;
      }
    }
    $link_key = isset($link_key) ? $link_key : count($custom_links);
    $custom_links[$link_key] = ['path' => $path] + $settings;
    $this->configFactory->getEditable('simple_sitemap.custom')
      ->set('links', $custom_links)->save();
    return $this;
  }

  /**
   * Returns an array of custom paths and their sitemap settings.
   *
   * @param bool $supplement_default_settings
   * @return array
   */
  public function getCustomLinks($supplement_default_settings = TRUE) {
    $custom_links = $this->configFactory
      ->get('simple_sitemap.custom')
      ->get('links');

    if ($supplement_default_settings) {
      foreach ($custom_links as $i => $link_settings) {
        self::supplementDefaultSettings('custom', $link_settings);
        $custom_links[$i] = $link_settings;
      }
    }

    return $custom_links !== NULL ? $custom_links : [];
  }

  /**
   * Returns settings for a custom path added to the sitemap settings.
   *
   * @param string $path
   *
   * @return array|false
   */
  public function getCustomLink($path) {
    foreach ($this->getCustomLinks() as $key => $link) {
      if ($link['path'] === $path) {
        return $link;
      }
    }
    return FALSE;
  }

  /**
   * Removes a custom path from the sitemap settings.
   *
   * @param string $path
   *
   * @return $this
   */
  public function removeCustomLink($path) {
    $custom_links = $this->getCustomLinks(FALSE);
    foreach ($custom_links as $key => $link) {
      if ($link['path'] === $path) {
        unset($custom_links[$key]);
        $custom_links = array_values($custom_links);
        $this->configFactory->getEditable('simple_sitemap.custom')
          ->set('links', $custom_links)->save();
        break;
      }
    }
    return $this;
  }

  /**
   * Removes all custom paths from the sitemap settings.
   *
   * @return $this
   */
  public function removeCustomLinks() {
    $this->configFactory->getEditable('simple_sitemap.custom')
      ->set('links', [])->save();
    return $this;
  }
}