<?php
/**
 * Mapping of Kordiam task fields onto WordPress post fields.
 *
 * @package Kordiam
 */

declare( strict_types=1 );

namespace Kordiam\Import;

use Kordiam\Support\Config;
use Kordiam\Support\MetaValue;
use Kordiam\Support\Options;

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

/**
 * Writes a task's value into the post field the site has mapped it to.
 *
 * Each task format maps either onto the post author or onto a custom field.
 */
final class TaskFieldSync {

	/**
	 * Result meaning the story must not be imported at all.
	 *
	 * @var null
	 */
	public const SKIP_STORY = null;

	/**
	 * Blocking instantiation: this class is a namespaced function group.
	 */
	private function __construct() {
	}

	/**
	 * Applying one task to the post data being assembled.
	 *
	 * @param array<string, mixed> $post_data Post data being assembled.
	 * @param array<string, mixed> $task      Task data from Kordiam.
	 *
	 * @return array<string, mixed>|null Updated post data, or null to skip the story.
	 */
	public static function apply( array $post_data, array $task ): ?array {
		$format_id = self::format_id( $task );

		if ( 0 === $format_id ) {
			return $post_data;
		}

		$option_key = self::option_key( $format_id );

		if ( Options::is_do_not_import( $option_key ) ) {
			return self::SKIP_STORY;
		}

		$target = Options::get_string( $option_key );

		if ( '' === $target || Options::is_no_sync( $option_key ) ) {
			return $post_data;
		}

		if ( 'post_author' === $target ) {
			return self::apply_author( $post_data, $task );
		}

		$value = self::value_for( $task, $format_id );

		if ( null === $value ) {
			return $post_data;
		}

		if ( ! isset( $post_data['meta_input'] ) || ! is_array( $post_data['meta_input'] ) ) {
			$post_data['meta_input'] = array();
		}

		// Meta is not covered by the kses filters wp_insert_post() applies.
		$post_data['meta_input'][ $target ] = MetaValue::sanitise( $value );

		return $post_data;
	}

	/**
	 * Reading a task's format ID.
	 *
	 * @param array<string, mixed> $task Task data.
	 *
	 * @return int Format ID, or 0 when the task carries none.
	 */
	public static function format_id( array $task ): int {
		$format_id = $task['format']['id'] ?? null;

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

	/**
	 * Building the option key holding a format's mapping.
	 *
	 * @param int $format_id Kordiam format ID.
	 *
	 * @return string Unprefixed option key.
	 */
	public static function option_key( int $format_id ): string {
		return 'task_import_' . $format_id;
	}

	/**
	 * Deciding what value a task contributes: text content, or the assignee's email address.
	 *
	 * @param array<string, mixed> $task      Task data.
	 * @param int                  $format_id Task format ID.
	 *
	 * @return string|null The value, or null when the task has nothing to contribute.
	 */
	private static function value_for( array $task, int $format_id ): ?string {
		if ( Config::TEXT_TASK_FORMAT_ID === $format_id ) {
			$content = $task['content'] ?? null;

			if ( is_scalar( $content ) && '' !== trim( (string) $content ) ) {
				return (string) $content;
			}

			return null;
		}

		$name = $task['assignee']['name'] ?? null;

		if ( is_scalar( $name ) && '' !== trim( (string) $name ) ) {
			return (string) $name;
		}

		return null;
	}

	/**
	 * Setting the post author from a task's assignee.
	 *
	 * @param array<string, mixed> $post_data Post data being assembled.
	 * @param array<string, mixed> $task      Task data.
	 *
	 * @return array<string, mixed> Post data, with the author set when the assignee is known here.
	 */
	private static function apply_author( array $post_data, array $task ): array {
		$user_id = AuthorResolver::user_id_for_task( $task );

		if ( 0 === $user_id ) {
			return $post_data;
		}

		return AuthorResolver::assign( $post_data, $user_id, AuthorResolver::assignee_id( $task ) );
	}
}