<?php
/**
 * Plugin settings, stored in one non-autoloaded option. Settings that belong to one marketplace live under
 * "channels" => channel ID => values (see for_channel()); secrets are stored encrypted (SecretBox).
 *
 * @package Tidelist
 */

namespace Tidelist\Settings;

use Tidelist\Channel\ChannelSettings;
use Tidelist\Channel\SafetySwitches;
use Tidelist\Security\SecretBox;

/**
 * Plugin settings, stored in one non-autoloaded option.
 */
final class Settings implements SafetySwitches {

	const OPTION = 'tidelist_settings';

	/**
	 * Encryption.
	 *
	 * @var SecretBox
	 */
	private $box;

	/**
	 * Functions that move older settings into the current shape: callable( array $stored ): array. They must be
	 * safe to run again on settings that are already current.
	 *
	 * @var callable[]
	 */
	private $migrations;

	/**
	 * Cached values.
	 *
	 * @var array|null
	 */
	private $cache = null;

	/**
	 * Constructor.
	 *
	 * @param SecretBox  $box        Encryption.
	 * @param callable[] $migrations Settings migrations (one per channel that changed its keys).
	 */
	public function __construct( SecretBox $box, array $migrations = array() ) {
		$this->box        = $box;
		$this->migrations = $migrations;
	}

	/**
	 * Default values. Dry-run is ON and pause is OFF by default.
	 */
	public static function defaults(): array {
		return array(
			'dry_run'              => true,
			'paused'               => false,
			'image_base_url'       => '', // Empty = this site's own address.
			'delete_on_uninstall'  => false, // Remove all data when the plugin is deleted.
			'contact_name'         => '',
			'contact_phone'        => '',
			'title_template'       => '', // Empty = ListingBuilder::DEFAULT_TITLE.
			'description_template' => '', // Empty = ListingBuilder::DEFAULT_DESCRIPTION.
			'shop_footer'          => '', // Printed where {shop_footer} stands in the description.
			'category_overrides'   => array(), // Parent product ID => marketplace category ID.
			'category_map'         => array(), // Account ID => (WooCommerce category ID => marketplace category ID).
			'attribute_map'        => array(), // Account ID => (marketplace category ID => (attribute code => rule)).
			'photo_exclusions'     => array(), // Product ID => upload paths not to send.
			'channels'             => array(), // Channel ID => that channel's own settings.
		);
	}

	/**
	 * All settings with defaults applied.
	 */
	public function all(): array {
		if ( null === $this->cache ) {
			$this->cache = array_merge( self::defaults(), array_intersect_key( $this->migrated(), self::defaults() ) );
			if ( '' === trim( (string) $this->cache['image_base_url'] ) && function_exists( 'home_url' ) ) {
				$this->cache['image_base_url'] = untrailingslashit( home_url() );
			}
		}
		return $this->cache;
	}

	/**
	 * One setting.
	 *
	 * @param string $key Key.
	 * @return mixed
	 */
	public function get( string $key ) {
		$all = $this->all();
		return $all[ $key ] ?? null;
	}

	/**
	 * Saves changed values. Unknown keys are ignored. Values must already be sanitized.
	 *
	 * @param array $changes Key => value.
	 */
	public function update( array $changes ): void {
		$all = array_merge( $this->all(), array_intersect_key( $changes, self::defaults() ) );
		update_option( self::OPTION, $all, false );
		$this->cache = $all;
	}

	/**
	 * Writes the stored settings in their current shape when they were stored in an older one (the migration
	 * runs on every read; this makes it permanent). Does nothing when nothing changed.
	 */
	public function persist_migration(): void {
		$stored = get_option( self::OPTION, null );
		if ( ! is_array( $stored ) ) {
			return;
		}
		$migrated = $this->migrated();
		if ( $migrated !== $stored ) {
			update_option( self::OPTION, array_merge( self::defaults(), array_intersect_key( $migrated, self::defaults() ) ), false );
			$this->cache = null;
		}
	}

	/**
	 * Global pause switch.
	 */
	public function is_paused(): bool {
		return (bool) $this->get( 'paused' );
	}

	/**
	 * Dry-run switch.
	 */
	public function is_dry_run(): bool {
		return (bool) $this->get( 'dry_run' );
	}

	/**
	 * The settings of one channel.
	 *
	 * @param string $channel_id Channel ID.
	 * @param array  $defaults   Default values of the channel's fields.
	 */
	public function for_channel( string $channel_id, array $defaults ): ChannelSettings {
		return new ScopedSettings( $this, $this->box, $channel_id, $defaults );
	}

	/**
	 * The stored option with every migration applied.
	 */
	private function migrated(): array {
		$stored = get_option( self::OPTION, array() );
		$stored = is_array( $stored ) ? $stored : array();
		foreach ( $this->migrations as $migration ) {
			$stored = (array) call_user_func( $migration, $stored );
		}
		return $stored;
	}
}