<?php

declare( strict_types=1 );

namespace AcezSeo\Analysis;

if ( ! defined( 'ABSPATH' ) )
{
	exit;
}

/**
 * "Lite" content analysis (M51) — the market-standard in-editor checks,
 * free like at every competitor. LITERAL, mechanical checks only; Polish
 * inflection (stemming), synonyms, readability and the AI review are the
 * Pro differentiators and live in the addon's ContentAnalyzer — this class
 * must never grow towards them.
 *
 * Statuses: 'good' | 'warn' | 'neutral'. No keyphrase = NEUTRAL (gray) for
 * keyphrase checks, never red — an empty field is not a mistake.
 */
final class LiteAnalyzer
{
	private const TITLE_MIN = 30;
	private const TITLE_MAX = 60;
	private const DESC_MIN  = 120;
	private const DESC_MAX  = 160;
	private const WORDS_MIN = 300;

	/**
	 * Lite renders only when the Pro addon is not active — no duplicate lights.
	 *
	 * NOT a licence gate on functionality (M69 Etap 7 acceptance criterion):
	 * it is the INVERSE of one. A licence never unlocks anything here — it
	 * makes this panel stand down so the addon's fuller analysis doesn't
	 * render a second keyphrase field next to it. Free users get MORE from
	 * this check, not less.
	 */
	public static function enabled(): bool
	{
		return ! ( defined( 'ACEZ_SEO_PRO_VERSION' ) && \AcezSeo\Support\ProGate::is_active() );
	}

	/**
	 * @param array{keyphrase?: string, seo_title?: string, description?: string, post_title?: string, content?: string, slug?: string} $input
	 *
	 * @return array<int, array{id: string, label: string, status: string, detail: string}>
	 */
	public static function analyze( array $input ): array
	{
		$keyphrase   = trim( (string) ( $input['keyphrase'] ?? '' ) );
		$seo_title   = trim( (string) ( $input['seo_title'] ?? '' ) );
		$description = trim( (string) ( $input['description'] ?? '' ) );
		$post_title  = trim( (string) ( $input['post_title'] ?? '' ) );
		$content     = (string) ( $input['content'] ?? '' );
		$slug        = trim( (string) ( $input['slug'] ?? '' ) );

		// The title shown in SERPs: the custom SEO title, else the post title.
		$effective_title = '' !== $seo_title ? $seo_title : $post_title;

		$checks = array();

		$checks[] = self::keyphrase_check(
			'keyphrase_in_title',
			__( 'Focus keyphrase in the SEO title', 'acez-seo' ),
			$keyphrase,
			$effective_title,
			__( 'Add the phrase to the title — it\'s the single strongest signal.', 'acez-seo' )
		);

		$checks[] = self::keyphrase_check(
			'keyphrase_in_description',
			__( 'Focus keyphrase in the meta description', 'acez-seo' ),
			$keyphrase,
			$description,
			__( 'A description containing the phrase gets bolded in results — it raises CTR.', 'acez-seo' )
		);

		$checks[] = self::keyphrase_check(
			'keyphrase_in_h1',
			__( 'Focus keyphrase in the heading (post title)', 'acez-seo' ),
			$keyphrase,
			$post_title,
			__( 'The post title is usually the page\'s H1 heading.', 'acez-seo' )
		);

		$checks[] = self::keyphrase_check(
			'keyphrase_in_first_paragraph',
			__( 'Focus keyphrase in the first paragraph', 'acez-seo' ),
			$keyphrase,
			self::first_paragraph( $content ),
			__( 'Confirm the topic right away — for both the reader and the search engine.', 'acez-seo' )
		);

		$checks[] = self::slug_check( $keyphrase, $slug );
		$checks[] = self::length_check( 'title_length', __( 'SEO title length', 'acez-seo' ), $effective_title, self::TITLE_MIN, self::TITLE_MAX );
		$checks[] = self::length_check( 'description_length', __( 'Meta description length', 'acez-seo' ), $description, self::DESC_MIN, self::DESC_MAX );
		$checks[] = self::word_count_check( $content );
		$checks[] = self::image_alt_check( $content );

		return $checks;
	}

	/**
	 * @return array{id: string, label: string, status: string, detail: string}
	 */
	private static function keyphrase_check( string $id, string $label, string $keyphrase, string $haystack, string $hint ): array
	{
		if ( '' === $keyphrase )
		{
			return self::check( $id, $label, 'neutral', __( 'Set a focus keyphrase to enable this check.', 'acez-seo' ) );
		}

		$found = '' !== $haystack && false !== mb_stripos( wp_strip_all_tags( $haystack ), $keyphrase );

		return self::check( $id, $label, $found ? 'good' : 'warn', $found ? __( 'The phrase is present (literal match).', 'acez-seo' ) : $hint );
	}

	/**
	 * @return array{id: string, label: string, status: string, detail: string}
	 */
	private static function slug_check( string $keyphrase, string $slug ): array
	{
		$label = __( 'Focus keyphrase in the URL (slug)', 'acez-seo' );

		if ( '' === $keyphrase )
		{
			return self::check( 'keyphrase_in_slug', $label, 'neutral', __( 'Set a focus keyphrase to enable this check.', 'acez-seo' ) );
		}

		if ( '' === $slug )
		{
			return self::check( 'keyphrase_in_slug', $label, 'neutral', __( 'The slug will be created when the post is saved.', 'acez-seo' ) );
		}

		$found = str_contains( $slug, sanitize_title( $keyphrase ) );

		return self::check(
			'keyphrase_in_slug',
			$label,
			$found ? 'good' : 'warn',
			$found ? __( 'The phrase is present (literal match).', 'acez-seo' ) : __( 'A short URL containing the phrase is more readable in results.', 'acez-seo' )
		);
	}

	/**
	 * @return array{id: string, label: string, status: string, detail: string}
	 */
	private static function length_check( string $id, string $label, string $text, int $min, int $max ): array
	{
		$length = mb_strlen( wp_strip_all_tags( $text ) );

		if ( 0 === $length )
		{
			return self::check( $id, $label, 'neutral', __( 'The field is empty — a template/fallback will be used.', 'acez-seo' ) );
		}

		if ( $length >= $min && $length <= $max )
		{
			return self::check(
				$id,
				$label,
				'good',
				sprintf(
					/* translators: 1: current length, 2: min, 3: max */
					__( '%1$d characters — within the recommended range of %2$d–%3$d.', 'acez-seo' ),
					$length,
					$min,
					$max
				)
			);
		}

		return self::check(
			$id,
			$label,
			'warn',
			sprintf(
				$length < $min
					/* translators: 1: current length, 2: min, 3: max */
					? __( '%1$d characters — too short (recommended %2$d–%3$d).', 'acez-seo' )
					/* translators: 1: current length, 2: min, 3: max */
					: __( '%1$d characters — too long, the result may get truncated (recommended %2$d–%3$d).', 'acez-seo' ),
				$length,
				$min,
				$max
			)
		);
	}

	/**
	 * @return array{id: string, label: string, status: string, detail: string}
	 */
	private static function word_count_check( string $content ): array
	{
		$label = __( 'Content length', 'acez-seo' );
		$words = self::word_count( $content );

		if ( 0 === $words )
		{
			return self::check( 'word_count', $label, 'neutral', __( 'No content to analyze.', 'acez-seo' ) );
		}

		if ( $words >= self::WORDS_MIN )
		{
			return self::check(
				'word_count',
				$label,
				'good',
				sprintf(
					/* translators: %d: word count */
					__( '%d words — enough to cover the topic thoroughly.', 'acez-seo' ),
					$words
				)
			);
		}

		return self::check(
			'word_count',
			$label,
			'warn',
			sprintf(
				/* translators: 1: word count, 2: recommended minimum */
				__( '%1$d words — short content rarely covers a topic thoroughly (recommended min. %2$d).', 'acez-seo' ),
				$words,
				self::WORDS_MIN
			)
		);
	}

	/**
	 * @return array{id: string, label: string, status: string, detail: string}
	 */
	private static function image_alt_check( string $content ): array
	{
		$label = __( 'Image alt texts', 'acez-seo' );

		preg_match_all( '/<img\b[^>]*>/i', $content, $matches );
		$images = $matches[0];

		if ( array() === $images )
		{
			return self::check( 'image_alts', $label, 'neutral', __( 'No images in the content.', 'acez-seo' ) );
		}

		$missing = 0;

		foreach ( $images as $tag )
		{
			if ( 1 !== preg_match( '/\balt\s*=\s*("[^"]+"|\'[^\']+\')/i', $tag ) )
			{
				$missing++;
			}
		}

		if ( 0 === $missing )
		{
			return self::check(
				'image_alts',
				$label,
				'good',
				sprintf(
					/* translators: %d: image count */
					__( 'All images (%d) have alt text.', 'acez-seo' ),
					count( $images )
				)
			);
		}

		return self::check(
			'image_alts',
			$label,
			'warn',
			sprintf(
				/* translators: 1: images without alt, 2: total images */
				__( '%1$d of %2$d images have no alt text.', 'acez-seo' ),
				$missing,
				count( $images )
			)
		);
	}

	private static function first_paragraph( string $content ): string
	{
		if ( 1 === preg_match( '/<p\b[^>]*>(.*?)<\/p>/is', $content, $m ) )
		{
			return (string) $m[1];
		}

		// No markup (plain text / classic textarea) — first 40 words.
		$words = preg_split( '/\s+/u', trim( wp_strip_all_tags( $content ) ), 41 ) ?: array();

		return implode( ' ', array_slice( $words, 0, 40 ) );
	}

	private static function word_count( string $content ): int
	{
		$text = trim( wp_strip_all_tags( $content ) );

		if ( '' === $text )
		{
			return 0;
		}

		return count( (array) preg_split( '/\s+/u', $text, -1, PREG_SPLIT_NO_EMPTY ) );
	}

	/**
	 * @return array{id: string, label: string, status: string, detail: string}
	 */
	private static function check( string $id, string $label, string $status, string $detail ): array
	{
		return array(
			'id'     => $id,
			'label'  => $label,
			'status' => $status,
			'detail' => $detail,
		);
	}
}