<?php
/**
 * Transition engine — the single choke point. Applies validated workflow moves and
 * audits every managed status change (from any source), stamping time-in-status.
 *
 * @package OST\EditorialWorkflow
 */

namespace OST\EditorialWorkflow;

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

/**
 * Validates + applies transitions; audits status changes.
 */
class Transitions {

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

	/**
	 * Audit service.
	 *
	 * @var Audit
	 */
	private $audit;

	/**
	 * Config service.
	 *
	 * @var Config
	 */
	private $config;

	/**
	 * Note carried from an action into the transition hook.
	 *
	 * @var string
	 */
	private $pending_note = '';

	/**
	 * Action key carried from a user action into the transition hook.
	 *
	 * Empty when the status changed by some other route, which is exactly the
	 * distinction the audit trail needs to record.
	 *
	 * @var string
	 */
	private $pending_action = '';

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

	/**
	 * Register hooks.
	 *
	 * @return void
	 */
	public function register_hooks() {
		add_action( 'transition_post_status', array( $this, 'on_transition' ), 10, 3 );
		add_filter( 'wp_insert_post_data', array( $this, 'preserve_author' ), 10, 2 );
	}

	/**
	 * Integrity guard: a workflow save must never change a managed post's author.
	 * A reviewer editing/advancing someone else's post should not become its author.
	 * Administrators may still reassign deliberately.
	 *
	 * @param array $data    Sanitized post data about to be saved.
	 * @param array $postarr Raw post array (has ID for updates).
	 * @return array
	 */
	public function preserve_author( $data, $postarr ) {
		if ( empty( $postarr['ID'] ) ) {
			return $data; // new post — let author be set normally.
		}
		if ( empty( $data['post_type'] ) || ! $this->config->for_post_type( $data['post_type'] ) ) {
			return $data;
		}
		$existing = get_post( (int) $postarr['ID'] );
		if ( ! $existing ) {
			return $data;
		}
		if ( (int) $data['post_author'] === (int) $existing->post_author ) {
			return $data;
		}
		// Author is being changed. Allow it only for the original author or an admin.
		if ( (int) get_current_user_id() !== (int) $existing->post_author && ! current_user_can( 'manage_options' ) ) {
			$data['post_author'] = $existing->post_author;
		}
		return $data;
	}

	/**
	 * Perform a workflow action requested by a user.
	 *
	 * @param int               $post_id Post ID.
	 * @param string            $action  Action key (submit|approve|reject).
	 * @param string            $note    Optional editorial note.
	 * @param \WP_User|int|null $user    Acting user (defaults to current).
	 * @return string|\WP_Error New status on success, WP_Error otherwise.
	 */
	public function handle( $post_id, $action, $note = '', $user = null ) {
		$post = get_post( $post_id );
		if ( ! $post ) {
			return new \WP_Error( 'ostew_no_post', __( 'Item not found.', 'ost-editorial-workflow' ) );
		}

		$match = $this->workflow->find_action( $post, $action, $user );
		if ( ! $match ) {
			return new \WP_Error(
				'ostew_not_allowed',
				__( 'You are not allowed to perform that action on this item.', 'ost-editorial-workflow' ),
				array( 'status' => 403 )
			);
		}

		$this->pending_note   = ( 'reject' === $action ) ? sanitize_textarea_field( $note ) : '';
		$this->pending_action = (string) $action;

		$result = wp_update_post(
			array(
				'ID'          => $post->ID,
				'post_status' => $match['target'],
			),
			true
		);

		if ( is_wp_error( $result ) ) {
			$this->pending_note   = '';
			$this->pending_action = '';
			return $result;
		}

		$this->pending_action = '';

		return $match['target'];
	}

	/**
	 * Audit + stamp on every managed status change (choke point).
	 *
	 * @param string   $new_status New status.
	 * @param string   $old_status Old status.
	 * @param \WP_Post $post       Post.
	 * @return void
	 */
	public function on_transition( $new_status, $old_status, $post ) {
		if ( $new_status === $old_status ) {
			return;
		}
		if ( wp_is_post_revision( $post ) || ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) ) {
			return;
		}
		if ( in_array( $new_status, array( 'auto-draft', 'inherit' ), true ) || 'auto-draft' === $old_status ) {
			return;
		}
		if ( ! $this->config->for_post_type( $post->post_type ) ) {
			return;
		}

		$note    = $this->pending_note;
		$action  = $this->pending_action;
		$user_id = get_current_user_id();

		// Stamp time-in-status + reset escalation counters (the escalation scanner reads these).
		update_post_meta( $post->ID, '_ostew_status_since', current_time( 'mysql' ) );
		update_post_meta( $post->ID, '_ostew_escalation_count', 0 );
		delete_post_meta( $post->ID, '_ostew_last_escalated' );

		$this->audit->write( $post->ID, $old_status, $new_status, $user_id, $note, $action );

		/**
		 * Fires after a managed workflow transition. notifications hook here.
		 *
		 * @param int    $post_id    Post ID.
		 * @param string $old_status Old status.
		 * @param string $new_status New status.
		 * @param int    $user_id    Acting user ID.
		 * @param string $note       Editorial note (send-back).
		 */
		do_action( 'ostew/after_transition', $post->ID, $old_status, $new_status, $user_id, $note );

		$this->pending_note   = '';
		$this->pending_action = '';
	}
}