<?php
/**
 * Story import endpoints.
 *
 * @package Kordiam
 */

declare( strict_types=1 );

namespace Kordiam\Rest;

use Kordiam\Auth\RequestAuthenticator;
use Kordiam\Export\ApiClient;
use Kordiam\Import\ImportOutcome;
use Kordiam\Import\ImportResult;
use Kordiam\Import\StoryImporter;
use Kordiam\Import\StoryMetaWriter;
use Kordiam\Import\StoryPayload;
use Kordiam\Media\FormatRegistry;
use Kordiam\Media\StoryContentBuilder;
use WP_REST_Request;
use WP_REST_Response;

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Receives stories from Kordiam and answers with what became of them.
 *
 * /publication serves an ordinary sync, /element a global export.
 */
final class PublicationController extends AbstractController {

	/**
	 * Importer doing the work.
	 *
	 * @var StoryImporter
	 */
	private StoryImporter $importer;

	/**
	 * Constructing the controller.
	 *
	 * @param RequestAuthenticator|null $authenticator Authenticator to use, or null for a default one.
	 * @param StoryImporter|null        $importer      Importer to use, or null for a default one.
	 */
	public function __construct( ?RequestAuthenticator $authenticator = null, ?StoryImporter $importer = null ) {
		parent::__construct( $authenticator );

		$this->importer = $importer ?? new StoryImporter(
			new StoryContentBuilder( new FormatRegistry( new ApiClient() ) )
		);
	}

	/**
	 * Registering the story routes.
	 */
	protected function routes(): array {
		$routes = array();

		foreach ( array( 'publication', 'element' ) as $name ) {
			$routes[ '/' . $name ] = array(
				'methods'             => 'POST',
				'callback'            => 'element' === $name
					? array( $this, 'create_from_global_export' )
					: array( $this, 'create' ),
				'permission_callback' => array( $this, 'require_token' ),
			);

			$routes[ '/' . $name . '/(?P<post_id>\d+)' ] = array(
				array(
					'methods'             => 'PUT',
					'callback'            => 'element' === $name
						? array( $this, 'update_from_global_export' )
						: array( $this, 'update' ),
					'permission_callback' => array( $this, 'require_token' ),
					'args'                => $this->post_id_arg(),
				),
				array(
					'methods'             => 'DELETE',
					'callback'            => array( $this, 'delete' ),
					'permission_callback' => array( $this, 'require_token' ),
					'args'                => $this->post_id_arg(),
				),
			);
		}

		return $routes;
	}

	/**
	 * Importing a story as a new post.
	 *
	 * @param WP_REST_Request<array<string, mixed>>|WP_REST_Request $request Incoming request.
	 *
	 * @return WP_REST_Response What became of the story.
	 */
	public function create( $request ): WP_REST_Response {
		return $this->import( $request, false, false );
	}

	/**
	 * Importing a story as a new post, from a global export.
	 *
	 * @param WP_REST_Request<array<string, mixed>>|WP_REST_Request $request Incoming request.
	 *
	 * @return WP_REST_Response What became of the story.
	 */
	public function create_from_global_export( $request ): WP_REST_Response {
		return $this->import( $request, false, true );
	}

	/**
	 * Importing a story onto an existing post.
	 *
	 * @param WP_REST_Request<array<string, mixed>>|WP_REST_Request $request Incoming request.
	 *
	 * @return WP_REST_Response What became of the story.
	 */
	public function update( $request ): WP_REST_Response {
		return $this->import( $request, true, false );
	}

	/**
	 * Importing a story onto an existing post, from a global export.
	 *
	 * @param WP_REST_Request<array<string, mixed>>|WP_REST_Request $request Incoming request.
	 *
	 * @return WP_REST_Response What became of the story.
	 */
	public function update_from_global_export( $request ): WP_REST_Response {
		return $this->import( $request, true, true );
	}

	/**
	 * Retiring the post of a story deleted in Kordiam.
	 *
	 * @param WP_REST_Request<array<string, mixed>>|WP_REST_Request $request Incoming request.
	 *
	 * @return WP_REST_Response The result.
	 */
	public function delete( $request ): WP_REST_Response {
		$post_id  = (int) $request->get_param( 'post_id' );
		$rejected = $this->reject_unusable_post( $post_id, false );

		if ( null !== $rejected ) {
			return $rejected;
		}

		$this->importer->retire( $post_id );

		return Response::accepted_no_action();
	}

	/**
	 * Running an import and turning its outcome into a response.
	 *
	 * @param WP_REST_Request<array<string, mixed>>|WP_REST_Request $request       Incoming request.
	 * @param bool                                                  $updating      Whether an existing post is the target.
	 * @param bool                                                  $global_export Whether this is a global export route.
	 *
	 * @return WP_REST_Response What became of the story.
	 */
	private function import( $request, bool $updating, bool $global_export ): WP_REST_Response {
		$payload = StoryPayload::from( $request->get_json_params() );

		if ( $payload->is_empty() ) {
			return Response::text( 'Error: Empty JSON request data', 400 );
		}

		if ( ! $updating ) {
			return $this->respond( $this->importer->create( $payload, $global_export ), $global_export );
		}

		$post_id  = (int) $request->get_param( 'post_id' );
		$rejected = $this->reject_unusable_post( $post_id, $global_export );

		if ( null !== $rejected ) {
			return $rejected;
		}

		$payload = $payload->with_post_id( $post_id );

		// A public post keeps its slug so inbound links do not break.
		if ( $this->is_public( $post_id ) ) {
			$payload = $payload->without_slug();
		}

		return $this->respond( $this->importer->update( $payload, $global_export ), $global_export );
	}

	/**
	 * Turning an outcome into the response Kordiam expects.
	 *
	 * @param ImportOutcome $outcome       What happened.
	 * @param bool          $global_export Whether this is a global export route.
	 *
	 * @return WP_REST_Response The response.
	 */
	private function respond( ImportOutcome $outcome, bool $global_export ): WP_REST_Response {
		switch ( $outcome->result ) {
			case ImportResult::SKIPPED:
				return Response::accepted_no_action();

			case ImportResult::REJECTED:
				return Response::text( $outcome->message, 428 );

			case ImportResult::FAILED:
				return Response::text( $outcome->message, 500 );

			case ImportResult::REMOVED:
			case ImportResult::SUCCEEDED:
				return $this->created_payload( $outcome->post_id, $global_export );
		}
	}

	/**
	 * Building the payload Kordiam records against a story.
	 *
	 * @param int  $post_id       Post ID.
	 * @param bool $global_export Whether this is a global export route.
	 *
	 * @return WP_REST_Response The response.
	 */
	private function created_payload( int $post_id, bool $global_export ): WP_REST_Response {
		if ( $global_export ) {
			return Response::created( array( 'id' => $post_id ) );
		}

		$edit_link = get_edit_post_link( $post_id, 'raw' );

		if ( ! is_string( $edit_link ) || '' === $edit_link ) {
			$edit_link = admin_url( 'post.php?post=' . $post_id . '&action=edit' );
		}

		$permalink = get_permalink( $post_id );

		return Response::created(
			array(
				'id'          => $post_id,
				'cmsEditLink' => $edit_link,
				'cmsOpenLink' => is_string( $permalink ) ? $permalink : '',
			)
		);
	}

	/**
	 * Refusing a request whose target post cannot be used.
	 *
	 * A story already removed in Kordiam deliberately answers 200, not an error.
	 *
	 * @param int  $post_id       Post ID from the route.
	 * @param bool $global_export Whether this is a global export route.
	 *
	 * @return WP_REST_Response|null A refusal, or null to carry on.
	 */
	private function reject_unusable_post( int $post_id, bool $global_export ): ?WP_REST_Response {
		if ( $post_id <= 0 ) {
			return Response::text( '', 406 );
		}

		if ( null === get_post( $post_id ) ) {
			return Response::text( '', 404 );
		}

		if ( ! $global_export && StoryMetaWriter::is_removed( $post_id ) ) {
			return Response::text(
				'Post was removed by Kordiam in previous user actions on the Kordiam side',
				200
			);
		}

		return null;
	}

	/**
	 * Checking whether a post is already visible to readers.
	 *
	 * @param int $post_id Post ID.
	 *
	 * @return bool Whether the post is published or scheduled.
	 */
	private function is_public( int $post_id ): bool {
		$status = get_post_status( $post_id );

		return 'publish' === $status || 'future' === $status;
	}

	/**
	 * Describing the post_id route parameter.
	 *
	 * @return array<string, array<string, mixed>> Argument definition.
	 */
	private function post_id_arg(): array {
		return array(
			'post_id' => array(
				'type'              => 'integer',
				'required'          => true,
				'sanitize_callback' => 'absint',
			),
		);
	}
}