<?php

declare(strict_types=1);

namespace LinkCheckup\Features\Scanning;

use LinkCheckup\Shared\Extraction\PostLinkSync;
use LinkCheckup\Shared\Scan\ScanState;
use LinkCheckup\Shared\Scan\ScanStateStore;
use LinkCheckup\Shared\Settings\SettingsStore;

final class PostReader {

	private const NO_POSTS_READ = 0;

	public function __construct(
		private CheckedPosts $checked_posts,
		private PostLinkSync $post_link_sync,
		private SettingsStore $settings_store,
		private ScanStateStore $scan_state_store,
		private ScanTransitions $transitions
	) {
	}

	public function read_next_posts( ScanState $state ): int {
		$post_ids = $this->checked_posts->ids_after(
			$state->last_read_post_id,
			$this->settings_store->load()
		);

		if ( array() === $post_ids ) {
			$checking_state = $this->transitions->checking( $state );

			$this->scan_state_store->save( $checking_state );

			return self::NO_POSTS_READ;
		}

		foreach ( $post_ids as $post_id ) {
			$this->post_link_sync->sync( $post_id );
		}

		$advanced_state = $this->transitions->advanced(
			$state,
			max( $post_ids ),
			count( $post_ids )
		);

		$this->scan_state_store->save( $advanced_state );

		return count( $post_ids );
	}
}