<?php

namespace Glovario\Repository;

use Glovario\Database\Transaction;
defined( 'ABSPATH' ) || exit;

final class RuleRepository {
	const CACHE_GROUP = 'glovario_rules';
	/** Cache key, in CACHE_GROUP, of the locales that rules use. */
	const USED_LOCALES_KEY = 'used_locales';

	private function table() {
		global $wpdb;
		return $wpdb->prefix . 'glovario_rules';
	}

	public function register() {
		add_action( 'glovario_variable_deleted', array( $this, 'delete_for_variable' ) );
	}

	public function find( $id ) {
		global $wpdb;
		$row = $wpdb->get_row( $wpdb->prepare( 'SELECT * FROM %i WHERE id = %d', $this->table(), absint( $id ) ), ARRAY_A ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Glovario's own table (no WordPress API for custom tables); admin lookup by ID before edits (resolution reads the cached for_variable()).
		return $this->hydrate( $row );
	}

	/**
	 * Return a variable's rules in evaluation order.
	 *
	 * Enabled rules are read on every resolution, so they are cached per
	 * variable in the object cache (shared by every repository instance and
	 * persistent when a persistent object cache is installed). The cache also
	 * stores empty results, which is the common case for variables without rules.
	 *
	 * @param int  $variable_id  Variable ID.
	 * @param bool $enabled_only Whether to return only enabled rules.
	 * @return array[]
	 */
	public function for_variable( $variable_id, $enabled_only = false ) {
		global $wpdb;
		$variable_id = absint( $variable_id );
		if ( $enabled_only ) {
			$cached = wp_cache_get( $variable_id, self::CACHE_GROUP, false, $found );
			if ( $found && is_array( $cached ) ) {
				return $cached;
			}
		}
		if ( $enabled_only ) {
			$rows = $wpdb->get_results( $wpdb->prepare( 'SELECT * FROM %i WHERE variable_id = %d AND enabled = 1 ORDER BY priority DESC, id ASC', $this->table(), $variable_id ), ARRAY_A ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- Glovario's own table (no WordPress API for custom tables); cached above and below.
		} else {
			$rows = $wpdb->get_results( $wpdb->prepare( 'SELECT * FROM %i WHERE variable_id = %d ORDER BY priority DESC, id ASC', $this->table(), $variable_id ), ARRAY_A ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Glovario's own table (no WordPress API for custom tables); every rule of one variable, for its edit screen and exports.
		}
		$rules = array_map( array( $this, 'hydrate' ), $rows );
		if ( $enabled_only ) {
			wp_cache_set( $variable_id, $rules, self::CACHE_GROUP );
		}
		return $rules;
	}

	public function invalidate( $variable_id ) {
		wp_cache_delete( absint( $variable_id ), self::CACHE_GROUP );
		wp_cache_delete( self::USED_LOCALES_KEY, self::CACHE_GROUP );

		/**
		 * Fires after a variable's rules were added, changed, or removed.
		 *
		 * @param int $variable_id Variable ID.
		 */
		do_action( 'glovario_rules_changed', absint( $variable_id ) );
	}

	public function all( $enabled_only = false ) {
		global $wpdb;
		if ( $enabled_only ) {
			$rows = $wpdb->get_results( $wpdb->prepare( 'SELECT * FROM %i WHERE enabled = 1 ORDER BY variable_id ASC, priority DESC, id ASC', $this->table() ), ARRAY_A ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Glovario's own table (no WordPress API for custom tables); read when a rule change reschedules the boundary event.
		} else {
			$rows = $wpdb->get_results( $wpdb->prepare( 'SELECT * FROM %i ORDER BY variable_id ASC, priority DESC, id ASC', $this->table() ), ARRAY_A ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Glovario's own table (no WordPress API for custom tables); read by the Usage Inspector scan an administrator starts.
		}
		return array_map( array( $this, 'hydrate' ), $rows );
	}

	/**
	 * Locales named by any rule.
	 *
	 * Read whenever a multilingual plugin's locale is normalized (every
	 * resolution in Automatic mode) and for the admin toolbar's preview list,
	 * so the result is cached; invalidate() clears it on every rule write.
	 *
	 * @return string[]
	 */
	public function used_locales() {
		global $wpdb;
		$cached = wp_cache_get( self::USED_LOCALES_KEY, self::CACHE_GROUP, false, $found );
		if ( $found && is_array( $cached ) ) {
			return $cached;
		}
		$rows    = $wpdb->get_col( $wpdb->prepare( 'SELECT conditions FROM %i', $this->table() ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- Glovario's own table (no WordPress API for custom tables); cached above.
		$locales = array();
		foreach ( $rows as $conditions_json ) {
			$conditions = json_decode( $conditions_json, true );
			foreach ( (array) ( $conditions['locales'] ?? array() ) as $locale ) {
				$locale = sanitize_locale_name( $locale );
				if ( $locale ) {
					$locales[ $locale ] = true;
				}
			}
		}
		$locales = array_keys( $locales );
		wp_cache_set( self::USED_LOCALES_KEY, $locales, self::CACHE_GROUP );
		return $locales;
	}

	public function save( $data, $id = 0 ) {
		global $wpdb;
		$now     = current_time( 'mysql', true );
		$row     = array(
			'variable_id'       => absint( $data['variable_id'] ),
			'name'              => sanitize_text_field( $data['name'] ),
			'alternative_value' => (string) $data['alternative_value'],
			'enabled'           => empty( $data['enabled'] ) ? 0 : 1,
			'priority'          => (int) $data['priority'],
			'conditions'        => wp_json_encode( $data['conditions'] ),
			'updated_at'        => $now,
		);
		$formats = array( '%d', '%s', '%s', '%d', '%d', '%s', '%s' );
		if ( $id ) {
			$previous = $this->find( $id );
			if ( $previous ) {
				$this->invalidate( $previous['variable_id'] );
			}
			$ok = $wpdb->update( $this->table(), $row, array( 'id' => absint( $id ) ), $formats, array( '%d' ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Glovario's own table (no WordPress API for custom tables); invalidate() clears the rule caches after the write.
		} else {
			$row['created_at'] = $now;
			$formats[]         = '%s';
			$ok                = $wpdb->insert( $this->table(), $row, $formats ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- Glovario's own table (no WordPress API for custom tables); invalidate() clears the rule caches after the write.
			$id                = $wpdb->insert_id;
		}
		$this->invalidate( $row['variable_id'] );
		return false === $ok ? new \WP_Error( 'rule_database_error', __( 'The rule could not be saved.', 'glovario' ) ) : $this->find( $id );
	}

	public function delete( $id ) {
		global $wpdb;
		$rule    = $this->find( $id );
		$deleted = (bool) $wpdb->delete( $this->table(), array( 'id' => absint( $id ) ), array( '%d' ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Glovario's own table (no WordPress API for custom tables); invalidate() clears the rule caches after the write.
		if ( $rule ) {
			$this->invalidate( $rule['variable_id'] );
		}
		return $deleted;
	}

	public function delete_for_variable( $variable ) {
		if ( is_array( $variable ) && isset( $variable['id'] ) ) {
			global $wpdb;
			$wpdb->delete( $this->table(), array( 'variable_id' => absint( $variable['id'] ) ), array( '%d' ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Glovario's own table (no WordPress API for custom tables); invalidate() clears the rule caches after the write.
			$this->invalidate( $variable['id'] );
		}
	}

	public function replace_for_variable( $variable_id, $rules ) {
		return Transaction::run(
			function () use ( $variable_id, $rules ) {
				global $wpdb;
				$deleted = $wpdb->delete( $this->table(), array( 'variable_id' => absint( $variable_id ) ), array( '%d' ) ); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Glovario's own table (no WordPress API for custom tables); invalidate() clears the rule caches after the write.
				$this->invalidate( $variable_id );
				if ( false === $deleted ) {
					return new \WP_Error( 'rule_database_error', __( 'The existing rules could not be prepared for replacement.', 'glovario' ) );
				}
				foreach ( $rules as $rule ) {
					$rule['variable_id'] = absint( $variable_id );
					$result              = $this->save( $rule );
					if ( is_wp_error( $result ) ) {
						return $result;
					}
				}
				return true;
			}
		);
	}

	private function hydrate( $row ) {
		if ( ! $row ) {
			return null;
		}
		$row['conditions'] = json_decode( $row['conditions'], true );
		$row['conditions'] = is_array( $row['conditions'] ) ? $row['conditions'] : array( 'version' => 1 );
		return $row;
	}
}