<?php
/**
 * Works out who gets a site's scheduled email.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Email;

use TurtleReport\Access\AccessPolicy;
use TurtleReport\Profiles\Profile;

defined( 'ABSPATH' ) || exit;

/**
 * Resolves a schedule's audience to email addresses at send time:
 *
 * - "Everyone who can view this site": users granted the site directly or
 *   through a role, checked against the same access rules as the report
 *   (so the turtlereport_visible_site_ids filter applies). Administrators
 *   are only included if they were granted the site like anyone else.
 * - Specific WordPress users, chosen by the administrator.
 * - Other email addresses, typed in.
 *
 * Resolving late means a removed grant or a changed user email takes
 * effect on the next send without re-saving the site.
 */
final class Recipients {

	/** Most addresses one report goes to. */
	const MAX_TOTAL = 50;

	/**
	 * Access rules, or null when only typed addresses are needed.
	 *
	 * @var AccessPolicy|null
	 */
	private $access;

	/**
	 * Constructor.
	 *
	 * @param AccessPolicy|null $access Access rules.
	 */
	public function __construct( ?AccessPolicy $access = null ) {
		$this->access = $access;
	}

	/**
	 * Everyone who gets the email.
	 *
	 * @param Profile $site Site.
	 * @return array[] Items with email, name, user_id (0 for typed addresses) and source (viewer|user|address).
	 */
	public function resolve( Profile $site ) {
		$email = $site->email;
		$out   = array();
		$add   = static function ( $address, $name, $user_id, $source ) use ( &$out ) {
			$key = strtolower( (string) $address );
			if ( '' === $key || ! is_email( $address ) || isset( $out[ $key ] ) ) {
				return;
			}
			$out[ $key ] = array(
				'email'   => (string) $address,
				'name'    => (string) $name,
				'user_id' => (int) $user_id,
				'source'  => $source,
			);
		};

		if ( ! empty( $email['to_viewers'] ) ) {
			foreach ( $this->viewer_ids( $site ) as $user_id ) {
				$user = get_userdata( $user_id );
				if ( $user ) {
					$add( $user->user_email, $user->display_name, $user_id, 'viewer' );
				}
			}
		}
		foreach ( isset( $email['user_ids'] ) ? (array) $email['user_ids'] : array() as $user_id ) {
			$user = get_userdata( (int) $user_id );
			if ( $user ) {
				$add( $user->user_email, $user->display_name, (int) $user_id, 'user' );
			}
		}
		foreach ( isset( $email['recipients'] ) ? (array) $email['recipients'] : array() as $address ) {
			$add( $address, '', 0, 'address' );
		}

		return array_slice( array_values( $out ), 0, self::MAX_TOTAL );
	}

	/**
	 * Addresses only.
	 *
	 * @param Profile $site Site.
	 * @return string[]
	 */
	public function addresses( Profile $site ) {
		return array_column( $this->resolve( $site ), 'email' );
	}

	/**
	 * Users who can view the site through a direct or role grant.
	 *
	 * @param Profile $site Site.
	 * @return int[]
	 */
	public function viewer_ids( Profile $site ) {
		if ( ! $this->access || '' === $site->id ) {
			return array();
		}
		$ids = $this->access->users_for_site( $site->id );
		if ( $site->roles ) {
			$offset = 0;
			do {
				$page    = get_users(
					array(
						'role__in' => $site->roles,
						'fields'   => 'ID',
						'number'   => 500,
						'offset'   => $offset,
						'orderby'  => 'ID',
						'order'    => 'ASC',
					)
				);
				$ids     = array_merge( $ids, array_map( 'intval', $page ) );
				$offset += 500;
				$count   = count( $page );
			} while ( 500 === $count );
		}
		$ids = array_values( array_unique( array_map( 'intval', $ids ) ) );
		return array_values(
			array_filter(
				$ids,
				function ( $user_id ) use ( $site ) {
					return $this->access->can_view( $user_id, $site->id );
				}
			)
		);
	}
}