<?php
/**
 * Mapping of a Kordiam story onto WordPress post data.
 *
 * @package Kordiam
 */

declare( strict_types=1 );

namespace Kordiam\Import;

use Kordiam\Support\Config;
use Kordiam\Support\Dates;
use Kordiam\Support\MetaKeys;
use Kordiam\Support\Str;

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

/**
 * Turns a story payload and its publication into fields for wp_insert_post().
 *
 * Writes nothing itself; the caller stores the returned mapping.
 */
final class PayloadMapper {

	/**
	 * Mapping a story for a new post.
	 *
	 * @param StoryPayload              $payload       Story payload.
	 * @param array<string, mixed>|null $publication   Publication the import selected.
	 * @param bool                      $global_export Whether the request came through a global export route.
	 *
	 * @return MappedStory|null The mapping, or null when the story cannot be imported.
	 */
	public function map_for_create( StoryPayload $payload, ?array $publication, bool $global_export = false ): ?MappedStory {
		$title = $this->title_for_create( $payload, $global_export );

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

		$post_data = array( 'post_title' => $title );

		if ( $payload->has_slug() ) {
			$post_data = SlugMapper::apply( $post_data, $payload->slug() );
		}

		$status = $this->status_for_create( $publication );

		if ( '' !== $status ) {
			$post_data['post_status'] = $status;
		}

		$dates = $this->dates_for( $publication );

		if ( false === $dates ) {
			return null;
		}

		return new MappedStory(
			array_merge( $post_data, $dates ),
			$payload->description( $global_export )
		);
	}

	/**
	 * Mapping a story onto an existing post.
	 *
	 * @param StoryPayload              $payload       Story payload.
	 * @param array<string, mixed>|null $publication   Publication the import selected.
	 * @param bool                      $global_export Whether the request came through a global export route.
	 *
	 * @return MappedStory|null The mapping, or null when the story cannot be imported.
	 */
	public function map_for_update( StoryPayload $payload, ?array $publication, bool $global_export = false ): ?MappedStory {
		$post_id     = $payload->post_id();
		$description = $payload->description( $global_export );

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

		$post_data = array();

		if ( $post_id > 0 ) {
			$post_data['ID'] = $post_id;
		}

		$title = $this->title_for_update( $payload, $post_id );

		if ( '' !== $title ) {
			$post_data['post_title'] = $title;
		}

		if ( $payload->has_slug() && FieldSyncPolicy::may_sync_slug( $post_id ) ) {
			$post_data = SlugMapper::apply( $post_data, $payload->slug() );
		}

		$status = $this->status_for_update( $publication, $post_id );

		if ( '' !== $status ) {
			$post_data['post_status'] = $status;
		}

		$dates = $this->dates_for( $publication );

		if ( false === $dates ) {
			return null;
		}

		return new MappedStory( array_merge( $post_data, $dates ), $description );
	}

	/**
	 * Deciding a new post's title.
	 *
	 * Preference: first task headline, slug (when mapped to title), then description.
	 *
	 * @param StoryPayload $payload       Story payload.
	 * @param bool         $global_export Whether the request came through a global export route.
	 *
	 * @return string The title, or an empty string when the story carries none.
	 */
	private function title_for_create( StoryPayload $payload, bool $global_export ): string {
		$headline = $payload->headline();

		if ( '' !== $headline ) {
			return $headline;
		}

		if ( $payload->has_slug() && SlugMapper::targets_title() ) {
			return $payload->slug();
		}

		return Str::truncate( $payload->description( $global_export ), Config::MAX_DESCRIPTION_TITLE_LENGTH );
	}

	/**
	 * Deciding whether an existing post's title should change.
	 *
	 * No description fallback: it would overwrite a title the editors rewrote.
	 *
	 * @param StoryPayload $payload Story payload.
	 * @param int          $post_id Post ID.
	 *
	 * @return string The new title, or an empty string to leave it alone.
	 */
	private function title_for_update( StoryPayload $payload, int $post_id ): string {
		$headline = $payload->headline();

		if ( '' !== $headline ) {
			return $headline;
		}

		if ( $payload->has_slug() && SlugMapper::targets_title() && FieldSyncPolicy::may_sync_slug( $post_id ) ) {
			return $payload->slug();
		}

		return '';
	}

	/**
	 * Deciding a new post's status.
	 *
	 * @param array<string, mixed>|null $publication Publication the import selected.
	 *
	 * @return string The status, or an empty string to let WordPress decide.
	 */
	private function status_for_create( ?array $publication ): string {
		$status_id = PublicationResolver::status_id( $publication );

		if ( 0 === $status_id || StatusMapper::is_status_sync_disabled( $status_id ) ) {
			return '';
		}

		return StatusMapper::wp_status_for( $status_id );
	}

	/**
	 * Deciding whether an existing post's status should change.
	 *
	 * Only when the Kordiam status moved, so an editor's change between syncs survives.
	 *
	 * @param array<string, mixed>|null $publication Publication the import selected.
	 * @param int                       $post_id     Post ID.
	 *
	 * @return string The new status, or an empty string to leave it alone.
	 */
	private function status_for_update( ?array $publication, int $post_id ): string {
		$status_id = PublicationResolver::status_id( $publication );

		if ( 0 === $status_id || StatusMapper::is_status_sync_disabled( $status_id ) ) {
			return '';
		}

		if ( ! FieldSyncPolicy::may_sync_status( $post_id ) ) {
			return '';
		}

		if ( $this->recorded_status_id( $post_id ) === $status_id ) {
			return '';
		}

		return StatusMapper::wp_status_for( $status_id );
	}

	/**
	 * Reading the Kordiam status recorded against a post at its last sync.
	 *
	 * @param int $post_id Post ID.
	 *
	 * @return int Status ID, or 0 when none is recorded.
	 */
	private function recorded_status_id( int $post_id ): int {
		if ( $post_id <= 0 ) {
			return 0;
		}

		$recorded = get_post_meta( $post_id, MetaKeys::STATUS_ID, true );

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

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

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

	/**
	 * Building the date fields from a publication's schedule.
	 *
	 * No schedule means no dates. An invalid schedule abandons the import rather than
	 * risk publishing at the wrong time.
	 *
	 * @param array<string, mixed>|null $publication Publication the import selected.
	 *
	 * @return array<string, string>|false Date fields, or false when the schedule is unusable.
	 */
	private function dates_for( ?array $publication ) {
		$schedule = PublicationResolver::schedule( $publication );

		if ( null === $schedule ) {
			return array();
		}

		$scheduled_utc = Dates::from_kordiam( $schedule['date'], $schedule['time'] );

		if ( null === $scheduled_utc ) {
			return false;
		}

		return array(
			'post_date_gmt'     => $scheduled_utc,
			'post_date'         => Dates::utc_to_local( $scheduled_utc ),
			'post_modified'     => Dates::now_local(),
			'post_modified_gmt' => Dates::now_utc(),
		);
	}
}