<?php
/**
 * Recipient resolver — turns a notification rule's `notify` target into a deduped
 * list of WP_User objects, minus the person who triggered the transition.
 *
 * @package OST\EditorialWorkflow
 */

namespace OST\EditorialWorkflow\Notifications;

use OST\EditorialWorkflow\Workflow;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Resolves notification recipients.
 */
class Recipients {

	/**
	 * Workflow service.
	 *
	 * @var Workflow
	 */
	private $workflow;

	/**
	 * Constructor.
	 *
	 * @param Workflow $workflow Workflow service.
	 */
	public function __construct( Workflow $workflow ) {
		$this->workflow = $workflow;
	}

	/**
	 * Resolve recipients.
	 *
	 * @param string   $notify     Target: approver_roles|author|role:slug|user:email.
	 * @param \WP_Post $post       Post.
	 * @param array    $workflow   Workflow definition.
	 * @param string   $new_status Status just entered.
	 * @param int      $actor_id   User who triggered the transition.
	 * @return \WP_User[]
	 */
	public function resolve( $notify, $post, array $workflow, $new_status, $actor_id ) {
		$users = array();

		if ( 'approver_roles' === $notify ) {
			$step  = $this->workflow->step( $workflow, $new_status );
			$roles = ( $step && isset( $step['approver_roles'] ) ) ? $step['approver_roles'] : array();
			$users = $this->users_with_roles( $roles );

			// Anyone who approves on every step is an approver here too, otherwise a
			// site whose only approver is an administrator is never told anything.
			if ( $step ) {
				$users = array_merge( $users, $this->workflow->global_approver_users() );
			}
		} elseif ( 'author' === $notify ) {
			$u = get_user_by( 'id', (int) $post->post_author );
			if ( $u ) {
				$users = array( $u );
			}
		} elseif ( 0 === strpos( $notify, 'role:' ) ) {
			$users = $this->users_with_roles( array( substr( $notify, 5 ) ) );
		} elseif ( 0 === strpos( $notify, 'user:' ) ) {
			$u = get_user_by( 'email', substr( $notify, 5 ) );
			if ( $u ) {
				$users = array( $u );
			}
		}

		// Dedupe by ID and drop the actor (don't notify yourself).
		$out = array();
		foreach ( $users as $u ) {
			if ( (int) $u->ID === (int) $actor_id ) {
				continue;
			}
			$out[ (int) $u->ID ] = $u;
		}

		return array_values( $out );
	}

	/**
	 * All users holding any of the given roles.
	 *
	 * @param array $roles Role slugs.
	 * @return \WP_User[]
	 */
	private function users_with_roles( array $roles ) {
		$roles = array_filter( $roles );
		if ( empty( $roles ) ) {
			return array();
		}
		return get_users( array( 'role__in' => $roles ) );
	}
}