<?php
/**
 * Elementor Form Lite markup injector.
 *
 * @package ZeroSpamForms
 */

namespace TwoOTwoCode\ZeroSpamForms\Integrations\ElementorFormLite;

defined( 'ABSPATH' ) || exit;

use TwoOTwoCode\ZeroSpamForms\Integrations\ProtectionFieldRenderer;

/**
 * Adds protection fields only to the supported Hello Plus form shape.
 */
final class ElementorFormLiteMarkupInjector {
	/**
	 * Field renderer.
	 *
	 * @var ProtectionFieldRenderer
	 */
	private $field_renderer;

	/**
	 * Constructor.
	 *
	 * @param ProtectionFieldRenderer $field_renderer Field renderer.
	 */
	public function __construct( ProtectionFieldRenderer $field_renderer ) {
		$this->field_renderer = $field_renderer;
	}

	/**
	 * Inject fields before the one expected Form Lite closing tag.
	 *
	 * @param string $content   Rendered widget content.
	 * @param string $widget_id Expected widget ID.
	 */
	public function inject( string $content, string $widget_id ): string {
		if ( ! ElementorFormLiteContextFactory::is_valid_widget_id( $widget_id ) ) {
			return $content;
		}

		$opening_tags = array();
		$closing_tags = array();

		if ( 1 !== preg_match_all( '/<form\b[^>]*>/i', $content, $opening_tags, PREG_OFFSET_CAPTURE )
			|| 1 !== preg_match_all( '/<\/form\s*>/i', $content, $closing_tags, PREG_OFFSET_CAPTURE ) ) {
			return $content;
		}

		$opening_tag    = (string) $opening_tags[0][0][0];
		$opening_offset = (int) $opening_tags[0][0][1];
		$closing_offset = (int) $closing_tags[0][0][1];

		if ( $closing_offset <= $opening_offset || ! $this->has_expected_form_class( $opening_tag ) ) {
			return $content;
		}

		$form_markup = substr( $content, $opening_offset, $closing_offset - $opening_offset );
		$input_data  = $this->extract_input_data( $form_markup );

		if ( $this->contains_protection_field( $input_data ) ) {
			return $content;
		}

		$post_id = isset( $input_data['post_id'] ) ? (int) $input_data['post_id'] : 0;
		$form_id = isset( $input_data['form_id'] ) ? (string) $input_data['form_id'] : '';

		if ( $post_id < 1 || $widget_id !== $form_id ) {
			return $content;
		}

		$fields = $this->field_renderer->render_fields(
			ElementorFormLiteContextFactory::create_form_id( $post_id, $widget_id )
		);

		return substr_replace( $content, $fields, $closing_offset, 0 );
	}

	/**
	 * Whether the opening form tag has the exact provider class token.
	 *
	 * @param string $opening_tag Opening form tag.
	 */
	private function has_expected_form_class( string $opening_tag ): bool {
		$class_value = $this->extract_attribute( $opening_tag, 'class' );

		if ( '' === $class_value ) {
			return false;
		}

		$class_tokens = preg_split( '/\s+/', trim( $class_value ) );

		return in_array( 'ehp-form', is_array( $class_tokens ) ? $class_tokens : array(), true );
	}

	/**
	 * Extract input names and values from the one bounded form.
	 *
	 * @param string $form_markup Form markup before its closing tag.
	 *
	 * @return array<string, string>
	 */
	private function extract_input_data( string $form_markup ): array {
		$input_tags = array();
		$input_data = array();

		if ( false === preg_match_all( '/<input\b[^>]*>/i', $form_markup, $input_tags ) ) {
			return $input_data;
		}

		foreach ( $input_tags[0] as $input_tag ) {
			$name = $this->extract_attribute( (string) $input_tag, 'name' );

			if ( '' === $name ) {
				continue;
			}

			$input_data[ $name ] = $this->extract_attribute( (string) $input_tag, 'value' );
		}

		return $input_data;
	}

	/**
	 * Extract a quoted or unquoted HTML attribute from a single tag.
	 *
	 * @param string $tag       HTML tag.
	 * @param string $attribute Attribute name.
	 */
	private function extract_attribute( string $tag, string $attribute ): string {
		$pattern = '/\b' . preg_quote( $attribute, '/' ) . '\s*=\s*(?:"([^"]*)"|\'([^\']*)\'|([^\s"\'=<>`]+))/i';

		if ( 1 !== preg_match( $pattern, $tag, $matches ) ) {
			return '';
		}

		$value = '';
		foreach ( array( 1, 2, 3 ) as $index ) {
			if ( isset( $matches[ $index ] ) && '' !== $matches[ $index ] ) {
				$value = (string) $matches[ $index ];
				break;
			}
		}

		return html_entity_decode( $value, ENT_QUOTES | ENT_HTML5, 'UTF-8' );
	}

	/**
	 * Whether ZSF already injected one of its root fields.
	 *
	 * @param array<string, string> $input_data Input data.
	 */
	private function contains_protection_field( array $input_data ): bool {
		return isset( $input_data[ ProtectionFieldRenderer::HONEYPOT_FIELD ] )
			|| isset( $input_data[ ProtectionFieldRenderer::TOKEN_FIELD ] )
			|| isset( $input_data[ ProtectionFieldRenderer::STARTED_AT_FIELD ] );
	}
}