<?php
/**
 * Post and comment permissions.
 *
 * @package SpaceBay
 */

namespace SpaceBay\Feed;

use SpaceBay\Spaces\Membership;
use SpaceBay\Spaces\SpaceAccess;
use SpaceBay\Spaces\SpaceRepository;

defined( 'ABSPATH' ) || exit;

/**
 * Decides who can post, comment, edit, delete and pin.
 */
final class PostAccess {

	/**
	 * Request cache of readable space IDs per user.
	 *
	 * @var array<string, int[]>
	 */
	private static $readable = array();

	/**
	 * IDs of every space the user may read.
	 *
	 * @param int $user_id User ID, 0 for a visitor.
	 * @return int[]
	 */
	public static function readable_space_ids( $user_id ) {
		// Key on the cache generations so new spaces and memberships are seen at once.
		$user_id = absint( $user_id );
		$key     = $user_id . ':' . wp_cache_get_last_changed( 'spacebay_spaces' ) . ':' . wp_cache_get_last_changed( 'spacebay_space_members' ) . ':' . wp_cache_get_last_changed( 'spacebay_profiles' );

		if ( ! isset( self::$readable[ $key ] ) ) {
			$ids = array();

			foreach ( SpaceRepository::all( 'space' ) as $space ) {
				if ( SpaceAccess::can_read( $space, $user_id ) ) {
					$ids[] = $space['id'];
				}
			}

			self::$readable[ $key ] = $ids;
		}

		return self::$readable[ $key ];
	}

	/**
	 * Clears the request cache after memberships change.
	 *
	 * @return void
	 */
	public static function flush() {
		self::$readable = array();
	}

	/**
	 * Whether the user is an active member of the space or a community manager.
	 *
	 * @param array $space   Space row.
	 * @param int   $user_id User ID.
	 * @return bool
	 */
	public static function is_participant( array $space, $user_id ) {
		$user_id = SpaceAccess::effective_id( $user_id );

		if ( ! $user_id ) {
			return false;
		}

		if ( SpaceAccess::is_manager( $user_id ) ) {
			return true;
		}

		$membership = Membership::get( $space['id'], $user_id );

		return $membership && 'active' === $membership['status'];
	}

	/**
	 * Whether the user may start a post in the space.
	 *
	 * @param array $space   Space row.
	 * @param int   $user_id User ID.
	 * @return bool
	 */
	public static function can_post( array $space, $user_id ) {
		if ( 'published' !== $space['status'] || ! self::is_participant( $space, $user_id ) ) {
			return false;
		}

		$who = $space['settings']['who_can_post'] ?? 'members';

		return 'admins' === $who ? SpaceAccess::can_moderate( $space, $user_id ) : true;
	}

	/**
	 * Whether the user may comment on posts in the space.
	 *
	 * @param array $space   Space row.
	 * @param int   $user_id User ID.
	 * @return bool
	 */
	public static function can_comment( array $space, $user_id ) {
		return 'published' === $space['status'] && self::is_participant( $space, $user_id );
	}

	/**
	 * Whether the user may edit or delete content written by someone.
	 *
	 * @param array $space     Space row.
	 * @param int   $author_id Author of the content.
	 * @param int   $user_id   User ID.
	 * @return bool
	 */
	public static function can_change( array $space, $author_id, $user_id ) {
		$user_id = SpaceAccess::effective_id( $user_id );

		if ( ! $user_id ) {
			return false;
		}

		if ( SpaceAccess::can_moderate( $space, $user_id ) ) {
			return true;
		}

		return (int) $author_id === (int) $user_id && SpaceAccess::can_read( $space, $user_id );
	}
}