<?php
/**
 * Selection of the publication a story should be imported from.
 *
 * @package Kordiam
 */

declare( strict_types=1 );

namespace Kordiam\Import;

use Kordiam\Support\MetaKeys;
use Kordiam\Support\Options;

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

/**
 * Picks which of a story's publications this site is the target of.
 *
 * Preference: the globalExportPublication on a global export; otherwise, among this
 * platform's publications, isMainPublication, then the previously imported one, then the
 * last match.
 */
final class PublicationResolver {

	/**
	 * Option holding the Kordiam platform this site corresponds to.
	 *
	 * @var string
	 */
	public const PLATFORM_OPTION = 'platform_id';

	/**
	 * Resolving the publication that applies to this site.
	 *
	 * @param StoryPayload $payload       Story payload.
	 * @param bool         $global_export Whether the request came through a global export route.
	 *
	 * @return array<string, mixed>|null The publication, or null when the story has none for this site.
	 */
	public function resolve( StoryPayload $payload, bool $global_export = false ): ?array {
		$found = $global_export
			? $this->find_global_export_publication( $payload )
			: $this->find_platform_publication( $payload );

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

		return $payload->inline_publication();
	}

	/**
	 * Finding the publication a global export targets.
	 *
	 * Also stores its platform ID: this is how an unpaired site learns its platform.
	 *
	 * @param StoryPayload $payload Story payload.
	 *
	 * @return array<string, mixed>|null The publication, or null when none is flagged.
	 */
	private function find_global_export_publication( StoryPayload $payload ): ?array {
		foreach ( $payload->publications() as $publication ) {
			if ( empty( $publication['globalExportPublication'] ) ) {
				continue;
			}

			if ( isset( $publication['platform'] ) && is_numeric( $publication['platform'] ) ) {
				Options::set( self::PLATFORM_OPTION, (int) $publication['platform'] );
			}

			return $publication;
		}

		return null;
	}

	/**
	 * Finding the publication for this site's platform.
	 *
	 * @param StoryPayload $payload Story payload.
	 *
	 * @return array<string, mixed>|null The publication, or null when the story targets other platforms only.
	 */
	private function find_platform_publication( StoryPayload $payload ): ?array {
		$platform_id = Options::get_int( self::PLATFORM_OPTION );

		if ( 0 === $platform_id ) {
			return null;
		}

		$previous_publication_id = $this->previously_imported_publication_id( $payload->post_id() );
		$found                   = null;

		foreach ( $payload->publications() as $publication ) {
			if ( ! isset( $publication['platform'] ) || ! is_numeric( $publication['platform'] ) ) {
				continue;
			}

			if ( (int) $publication['platform'] !== $platform_id ) {
				continue;
			}

			$found = $publication;

			if ( ! empty( $publication['isMainPublication'] ) ) {
				break;
			}

			if ( $previous_publication_id > 0 && $this->publication_id( $publication ) === $previous_publication_id ) {
				break;
			}
		}

		return $found;
	}

	/**
	 * Reading the publication a post was imported from last time.
	 *
	 * @param int $post_id Post ID, or 0 on a create.
	 *
	 * @return int Publication ID, or 0 when unknown.
	 */
	private function previously_imported_publication_id( int $post_id ): int {
		if ( $post_id <= 0 ) {
			return 0;
		}

		$stored = get_post_meta( $post_id, MetaKeys::PUBLICATION_ID, true );

		if ( is_numeric( $stored ) ) {
			return (int) $stored;
		}

		$legacy = get_post_meta( $post_id, MetaKeys::legacy_post_meta()[ MetaKeys::PUBLICATION_ID ], true );

		return is_numeric( $legacy ) ? (int) $legacy : 0;
	}

	/**
	 * Reading a publication's own ID.
	 *
	 * @param array<string, mixed> $publication Publication data.
	 *
	 * @return int Publication ID, or 0 when absent.
	 */
	private function publication_id( array $publication ): int {
		return isset( $publication['id'] ) && is_numeric( $publication['id'] ) ? (int) $publication['id'] : 0;
	}

	/**
	 * Finding where a publication sits in a story's list.
	 *
	 * @param array<string, mixed> $story          Story as Kordiam holds it.
	 * @param int                  $publication_id Publication ID to locate.
	 *
	 * @return int|null The index, or null when the story does not contain it.
	 */
	public static function position_of( array $story, int $publication_id ): ?int {
		$publications = $story['publications'] ?? null;

		if ( ! is_array( $publications ) || $publication_id <= 0 ) {
			return null;
		}

		foreach ( $publications as $index => $publication ) {
			if ( ! is_array( $publication ) || ! isset( $publication['id'] ) || ! is_numeric( $publication['id'] ) ) {
				continue;
			}

			if ( (int) $publication['id'] === $publication_id && is_int( $index ) ) {
				return $index;
			}
		}

		return null;
	}

	/**
	 * Reading the Kordiam status ID off a publication.
	 *
	 * @param array<string, mixed>|null $publication Publication data.
	 *
	 * @return int Status ID, or 0 when absent.
	 */
	public static function status_id( ?array $publication ): int {
		$status_id = $publication['status']['id'] ?? null;

		return is_numeric( $status_id ) ? (int) $status_id : 0;
	}

	/**
	 * Reading the Kordiam status name off a publication.
	 *
	 * @param array<string, mixed>|null $publication Publication data.
	 *
	 * @return string Status name, or an empty string when absent.
	 */
	public static function status_name( ?array $publication ): string {
		$name = $publication['status']['name'] ?? null;

		return is_scalar( $name ) ? (string) $name : '';
	}

	/**
	 * Reading the Kordiam category ID off a publication.
	 *
	 * @param array<string, mixed>|null $publication Publication data.
	 *
	 * @return int Category ID, or 0 when the publication has no category.
	 */
	public static function category_id( ?array $publication ): int {
		$category_id = $publication['category']['id'] ?? null;

		return is_numeric( $category_id ) ? (int) $category_id : 0;
	}

	/**
	 * Reading a publication's custom fields.
	 *
	 * @param array<string, mixed>|null $publication Publication data.
	 *
	 * @return array<int, array<string, mixed>> Custom fields.
	 */
	public static function custom_fields( ?array $publication ): array {
		$fields = $publication['customFields'] ?? null;

		if ( ! is_array( $fields ) ) {
			return array();
		}

		$valid = array();

		foreach ( $fields as $field ) {
			if ( is_array( $field ) ) {
				$valid[] = $field;
			}
		}

		return $valid;
	}

	/**
	 * Reading the scheduled start date of a publication.
	 *
	 * @param array<string, mixed>|null $publication Publication data.
	 *
	 * @return array{date: string, time: string}|null The schedule, or null when unscheduled.
	 */
	public static function schedule( ?array $publication ): ?array {
		$start = $publication['single']['start'] ?? null;

		if ( ! is_array( $start ) || ! isset( $start['date'] ) || ! is_scalar( $start['date'] ) ) {
			return null;
		}

		$date = trim( (string) $start['date'] );

		if ( '' === $date ) {
			return null;
		}

		$time = isset( $start['time'] ) && is_scalar( $start['time'] ) ? trim( (string) $start['time'] ) : '';

		return array(
			'date' => $date,
			'time' => $time,
		);
	}
}