<?php
/**
 * Rules for the pre-publish check (C-02).
 *
 * @package ForensixDigital
 */

declare(strict_types=1);

namespace ForensixDigital\Apps\PreCheck;

defined( 'ABSPATH' ) || exit;

use ForensixDigital\Apps\Business\ContactConsistency;
use ForensixDigital\Apps\Content\ContentRules;

/**
 * Looks at a draft before it is published and lists what is worth a second look. Pure: it gets
 * plain values and returns plain notes, so it is tested without WordPress. Nothing here blocks
 * publishing; every note is advice.
 */
final class PreCheckRules {

	/**
	 * Notes about a draft.
	 *
	 * @param array      $draft   Draft values.
	 * @param array|null $profile Business details, null when not used.
	 * @param string     $host    The site's host name.
	 * @param int        $now     Unix time.
	 * @phpstan-param array{title: string, content: string, type: string, featured: bool} $draft
	 * @phpstan-param array<string, mixed>|null $profile
	 * @return array<int, array{id: string, level: string, title: string, hint: string}>
	 */
	public static function notes( array $draft, ?array $profile, string $host, int $now ): array {
		$notes = array();
		$html  = $draft['content'];

		if ( '' === trim( $draft['title'] ) ) {
			$notes[] = self::note( 'no_title', 'warning', __( 'The title is empty', 'forensix-digital' ), __( 'Visitors and search engines see the title first. Give the page a clear title.', 'forensix-digital' ) );
		} elseif ( mb_strlen( trim( $draft['title'] ) ) > 70 ) {
			$notes[] = self::note( 'long_title', 'info', __( 'The title is long', 'forensix-digital' ), __( 'Search results usually cut a title after about 60 characters. Put the important words first.', 'forensix-digital' ) );
		}

		$placeholders = array_unique( array_merge( ContentRules::placeholders( $draft['title'] ), ContentRules::placeholders( $html ) ) );
		if ( array() !== $placeholders ) {
			$notes[] = self::note( 'placeholder', 'warning', __( 'Placeholder text is still in the page', 'forensix-digital' ), __( 'Lorem ipsum text or an address like info@example.com makes a page look unfinished. Replace it with the real text.', 'forensix-digital' ) );
		}

		$empty = ContentRules::empty_elements( $html );
		if ( $empty > 0 ) {
			$notes[] = self::note(
				'empty_elements',
				'info',
				/* translators: %d: number of empty elements. */
				sprintf( _n( '%d empty paragraph or heading', '%d empty paragraphs or headings', $empty, 'forensix-digital' ), $empty ),
				__( 'Empty elements add blank space, and screen readers announce empty headings. Remove them.', 'forensix-digital' )
			);
		}

		$images = self::images_without_alt( $html );
		if ( $images > 0 ) {
			$notes[] = self::note(
				'image_alt',
				'info',
				/* translators: %d: number of images. */
				sprintf( _n( '%d image has no description', '%d images have no description', $images, 'forensix-digital' ), $images ),
				__( 'People who cannot see an image rely on its alternative text. Describe what the image shows, or leave it empty on purpose only for pure decoration.', 'forensix-digital' )
			);
		}

		if ( self::skips_heading_level( $html ) ) {
			$notes[] = self::note( 'heading_order', 'info', __( 'Headings skip a level', 'forensix-digital' ), __( 'A heading level 2 followed by level 4, for example, confuses screen readers and the outline of the page. Use the next level down.', 'forensix-digital' ) );
		}

		if ( 1 === preg_match( '/<h1\b/i', $html ) ) {
			$notes[] = self::note( 'inner_h1', 'info', __( 'The text contains a main heading (H1)', 'forensix-digital' ), __( 'The page title is already the main heading. Use level 2 for headings inside the text.', 'forensix-digital' ) );
		}

		if ( 1 === preg_match( '/<a\b[^>]*\bhref\s*=\s*["\'](?:#|https?:\/\/|)["\']/i', $html ) ) {
			$notes[] = self::note( 'empty_link', 'warning', __( 'A link has no real address', 'forensix-digital' ), __( 'A link that points to "#" or to nothing leads nowhere. Add the address or remove the link.', 'forensix-digital' ) );
		}

		$dates = ContentRules::past_event_dates( $html, $now );
		if ( array() !== $dates ) {
			$notes[] = self::note(
				'past_date',
				'info',
				/* translators: %s: list of dates. */
				sprintf( __( 'The text mentions a date that has passed: %s', 'forensix-digital' ), implode( ', ', $dates ) ),
				__( 'Check that the date is still right, or update the text.', 'forensix-digital' )
			);
		}

		if ( null !== $profile ) {
			$wrong = ContactConsistency::mismatches( $html, $profile, $host );
			if ( array() !== array_merge( $wrong['phones'], $wrong['emails'] ) ) {
				$notes[] = self::note( 'contact', 'warning', __( 'A phone number or email address differs from your business details', 'forensix-digital' ), __( 'Check the contact details in this page against Business details.', 'forensix-digital' ) );
			}
		}

		if ( 'post' === $draft['type'] && ! $draft['featured'] ) {
			$notes[] = self::note( 'no_featured', 'info', __( 'There is no featured image', 'forensix-digital' ), __( 'Many themes and social networks show the featured image next to the post.', 'forensix-digital' ) );
		}

		return $notes;
	}

	/**
	 * Builds one note.
	 *
	 * @param string $id    Stable id.
	 * @param string $level "warning" or "info".
	 * @param string $title Short sentence.
	 * @param string $hint  What to do.
	 * @return array{id: string, level: string, title: string, hint: string}
	 */
	private static function note( string $id, string $level, string $title, string $hint ): array {
		return array(
			'id'    => $id,
			'level' => $level,
			'title' => $title,
			'hint'  => $hint,
		);
	}

	/**
	 * Number of images without alternative text. An empty alt attribute counts too, because the
	 * author should decide that on purpose.
	 *
	 * @param string $html Content.
	 */
	public static function images_without_alt( string $html ): int {
		$count = 0;
		if ( false !== preg_match_all( '/<img\b[^>]*>/i', $html, $tags ) ) {
			foreach ( $tags[0] as $tag ) {
				if ( 1 !== preg_match( '/\balt\s*=\s*"[^"]*\S[^"]*"|\balt\s*=\s*\'[^\']*\S[^\']*\'/i', $tag ) ) {
					++$count;
				}
			}
		}
		return $count;
	}

	/**
	 * Whether a heading is more than one level deeper than the one before it.
	 *
	 * @param string $html Content.
	 */
	public static function skips_heading_level( string $html ): bool {
		if ( false === preg_match_all( '/<h([1-6])\b/i', $html, $m ) ) {
			return false;
		}
		$previous = 0;
		foreach ( $m[1] as $level ) {
			$level = (int) $level;
			if ( $previous > 0 && $level > $previous + 1 ) {
				return true;
			}
			$previous = $level;
		}
		return false;
	}
}