<?php
/**
 * Settings persistence backed by the options table.
 *
 * @package AdPix\Analytics
 */

declare( strict_types = 1 );

namespace AdPix\Analytics\Model\Repository;

use AdPix\Analytics\Contracts\SettingsRepositoryInterface;
use AdPix\Analytics\Model\Settings;

defined( 'ABSPATH' ) || exit;

/**
 * Stores the configuration in a single autoloaded option.
 *
 * One option rather than one per field: the settings are read together on every request that prints
 * the tag, and a single autoloaded row costs one cache entry instead of fourteen. It also makes the
 * whole configuration atomic, so a half-saved form cannot leave the site pointing at one property
 * with another property's key.
 */
final class OptionSettingsRepository implements SettingsRepositoryInterface {

	/**
	 * Resolved settings for this request.
	 *
	 * @var Settings|null
	 */
	private $cache;

	/**
	 * Read the configuration.
	 *
	 * @return Settings
	 */
	public function load(): Settings {
		if ( null === $this->cache ) {
			$stored      = get_option( Settings::OPTION, array() );
			$this->cache = Settings::from_array( is_array( $stored ) ? $stored : array() );
		}

		return $this->cache;
	}

	/**
	 * Write the configuration.
	 *
	 * @param Settings $settings Settings to persist.
	 * @return bool True when the stored value changed or already matched.
	 */
	public function save( Settings $settings ): bool {
		$values = $settings->to_array();

		// A value fixed by a wp-config constant is not ours to store. Writing it back would put the
		// server key into the database that the constant exists to keep it out of, and would leave a
		// stale copy behind on the day the constant changes.
		foreach ( array_keys( Settings::defaults() ) as $key ) {
			if ( $settings->is_locked( $key ) ) {
				$values[ $key ] = '';
			}
		}

		$this->cache = null;

		// update_option() returns false when the value is unchanged, which is not a failure; the caller
		// only wants to know that the stored state now matches what it asked for.
		$saved = update_option( Settings::OPTION, $values, true );

		return $saved || get_option( Settings::OPTION ) === $values;
	}

	/**
	 * Forget the per-request copy.
	 *
	 * @return void
	 */
	public function flush(): void {
		$this->cache = null;
	}
}