<?php
/**
 * @package Polylang
 */

/**
 * A class to import languages and translations information form a WXR file
 *
 * @since 1.2
 */
class PLL_WP_Import extends WP_Import {
	/**
	 * Stores post_translations terms.
	 *
	 * @var array
	 */
	public $post_translations = array();

	/**
	 * Overrides WP_Import::process_terms to remap terms translations.
	 *
	 * @since 1.2
	 */
	public function process_terms() {
		$term_translations = array();
		$term_languages    = array();

		// Store this for future usage as parent function unsets $this->terms.
		foreach ( $this->terms as $term ) {
			if ( 'post_translations' == $term['term_taxonomy'] ) {
				$this->post_translations[] = $term;
			}
			if ( 'term_translations' == $term['term_taxonomy'] ) {
				$term_translations[] = $term;
			}

			if ( 'language' === $term['term_taxonomy'] ) {
				$term_languages[] = $term;
			}
		}

		parent::process_terms();

		// First reset the core terms cache as WordPress Importer calls wp_suspend_cache_invalidation( true );
		wp_cache_set_terms_last_changed();

		// Assign the default language in case the importer created the first language.
		if ( empty( PLL()->options['default_lang'] ) ) {
			$languages = get_terms( array( 'taxonomy' => 'language', 'hide_empty' => false, 'orderby' => 'term_id' ) );
			$default_lang = reset( $languages );
			PLL()->options['default_lang'] = $default_lang->slug;
		}

		/*
		 * Merge strings translations for an already existing language.
		 *
		 * Term metas are handled by the importer when creating a term,
		 * but not when updating an existing term.
		 */
		foreach ( $term_languages as $term ) {
			if ( empty( $this->processed_terms[ $term['term_id'] ] ) || empty( $term['termmeta'] ) ) {
				continue;
			}

			foreach ( $term['termmeta'] as $term_meta ) {
				if ( '_pll_strings_translations' !== $term_meta['key'] ) {
					continue;
				}

				$language = PLL()->model->languages->get( $term['term_id'] );
				if ( empty( $language ) ) {
					continue;
				}

				$strings = maybe_unserialize( $term_meta['value'] );
				$mo      = new PLL_MO();
				$mo->import_from_db( $language );
				foreach ( $strings as $msg ) {
					$mo->add_entry_or_merge( $mo->make_entry( $msg[0], $msg[1] ) );
				}
				$mo->export_to_db( $language );
			}
		}

		// Clean languages cache in case some of them were created during import.
		PLL()->model->languages->clean_cache();

		$this->remap_terms_relations( $term_translations );
		$this->remap_translations( $term_translations, $this->processed_terms );
	}

	/**
	 * Overrides WP_Import::process_post to remap posts translations
	 * Also merges strings translations from the WXR file to the existing ones
	 *
	 * @since 1.2
	 */
	public function process_posts() {
		$menu_items = array();

		// Store this for future usage as parent function unset $this->posts
		foreach ( $this->posts as $post ) {
			if ( 'nav_menu_item' == $post['post_type'] ) {
				$menu_items[] = $post;
			}
		}

		parent::process_posts();

		PLL()->model->languages->clean_cache(); // To update the posts count in (cached) languages list.

		$this->remap_translations( $this->post_translations, $this->processed_posts );
		unset( $this->post_translations );

		// Language switcher menu items
		foreach ( $menu_items as $item ) {
			foreach ( $item['postmeta'] as $meta ) {
				if ( '_pll_menu_item' == $meta['key'] ) {
					update_post_meta( $this->processed_menu_items[ $item['post_id'] ], '_pll_menu_item', maybe_unserialize( $meta['value'] ) );
				}
			}
		}
	}

	/**
	 * Remaps terms languages.
	 *
	 * @since 1.2
	 *
	 * @param array $terms array of terms in 'term_translations' taxonomy.
	 */
	protected function remap_terms_relations( &$terms ) {
		global $wpdb;

		$term_relationships = array();

		foreach ( $terms as $term ) {
			$translations = maybe_unserialize( $term['term_description'] );
			foreach ( $translations as $slug => $old_id ) {
				if ( $old_id && ! empty( $this->processed_terms[ $old_id ] ) && $lang = PLL()->model->get_language( $slug ) ) {
					// Language relationship.
					$term_relationships[] = array( $this->processed_terms[ $old_id ], $lang->get_tax_prop( 'term_language', 'term_taxonomy_id' ) );

					// Translation relationship.
					$term_relationships[] = array( $this->processed_terms[ $old_id ], get_term( $this->processed_terms[ $term['term_id'] ], 'term_translations' )->term_taxonomy_id );
				}
			}
		}

		// Insert term_relationships.
		if ( ! empty( $term_relationships ) ) {
			// Make sure we don't attempt to insert already existing term relationships.
			$existing_term_relationships = $wpdb->get_results(
				"SELECT tr.object_id, tr.term_taxonomy_id FROM {$wpdb->term_relationships} AS tr
				INNER JOIN {$wpdb->term_taxonomy} AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id
				WHERE tt.taxonomy IN ( 'term_language', 'term_translations' )"
			);

			foreach ( $existing_term_relationships as $key => $tr ) {
				$existing_term_relationships[ $key ] = array( $tr->object_id, $tr->term_taxonomy_id );
			}

			$term_relationships = array_udiff(
				$term_relationships,
				$existing_term_relationships,
				function ( $a, $b ) {
					return strcmp( implode( ',', $a ), implode( ',', $b ) ); // An easy way to compare arrays (ok if values are int or numeric strings).
				}
			);

			if ( ! empty( $term_relationships ) ) {
				$wpdb->query(
					$wpdb->prepare( // phpcs:ignore WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber
						sprintf(
							"INSERT INTO {$wpdb->term_relationships} ( object_id, term_taxonomy_id ) VALUES %s",
							implode( ',', array_fill( 0, count( $term_relationships ), '( %d, %d )' ) )
						),
						array_merge( ...$term_relationships )
					)
				);
			}
		}
	}

	/**
	 * Remaps translations for both posts and terms.
	 *
	 * @since 1.2
	 *
	 * @param array $terms             Array of terms in 'post_translations' or 'term_translations' taxonomies?
	 * @param array $processed_objects Array of posts or terms processed by WordPress Importer.
	 */
	protected function remap_translations( &$terms, &$processed_objects ) {
		global $wpdb;

		$languages = pll_languages_list();
		$to_update = array();

		foreach ( $terms as $term ) {
			$translations     = maybe_unserialize( $term['term_description'] );
			$new_translations = array();
			foreach ( $translations as $slug => $old_id ) {
				if ( in_array( $slug, $languages, true ) && $old_id && ! empty( $processed_objects[ $old_id ] ) ) {
					$new_translations[ $slug ] = $processed_objects[ $old_id ];
				} else {
					$new_translations[ $slug ] = $old_id; // Preserve values for all keys which are not our language slugs.
				}
			}

			if ( ! empty( $new_translations ) ) {
				$to_update['case'][] = array( $this->processed_terms[ $term['term_id'] ], maybe_serialize( $new_translations ) );
				$to_update['in'][]   = (int) $this->processed_terms[ $term['term_id'] ];
			}
		}

		if ( ! empty( $to_update ) ) {
			$wpdb->query(
				$wpdb->prepare(
					sprintf(
						"UPDATE {$wpdb->term_taxonomy}
						SET description = ( CASE term_id %s END )
						WHERE term_id IN (%s)",
						implode( ' ', array_fill( 0, count( $to_update['case'] ), 'WHEN %d THEN %s' ) ),
						implode( ',', array_fill( 0, count( $to_update['in'] ), '%d' ) )
					),
					array_merge( array_merge( ...$to_update['case'] ), $to_update['in'] )
				)
			);
		}
	}
}