<?php
/**
 * Google reCAPTCHA v3.
 *
 * @package FormPilot
 * @since   1.0.0
 */

declare( strict_types = 1 );

namespace FormPilot\Security\Captcha;

use FormPilot\Settings\Settings;
use WP_Error;

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

/**
 * The invisible, score based challenge.
 *
 * Nothing is shown to the visitor; the answer is a number between 0 and 1 that
 * the site compares against a threshold it chooses. That threshold is a
 * judgement call, not a fact, which is why a failure here feeds the spam score
 * rather than deciding the outcome on its own.
 *
 * @since 1.0.0
 */
final class RecaptchaV3 extends CaptchaProvider {

	/**
	 * Name of the hidden input the token is written into.
	 */
	public const FIELD = 'formpilot_recaptcha_token';

	/**
	 * Action the frontend mints its tokens for.
	 *
	 * Must match `grecaptcha.execute(key, { action: ... })` in
	 * `assets/frontend/js/frontend.js`; the verification compares the two.
	 */
	public const ACTION = 'formpilot_submit';

	/**
	 * Returns the slug stored in the settings.
	 */
	public function id(): string {
		return 'recaptcha_v3';
	}

	/**
	 * Returns the name shown on the settings screen.
	 */
	public function label(): string {
		return __( 'Google reCAPTCHA v3 (invisible)', 'devplugins-custom-form-builder' );
	}

	/**
	 * Returns the public key the widget is rendered with.
	 */
	public function site_key(): string {
		return Settings::text( 'recaptcha_site_key' );
	}

	/**
	 * Returns the URL of the script the page must load.
	 */
	public function script_url(): string {
		return 'https://www.google.com/recaptcha/api.js?render=' . rawurlencode( $this->site_key() );
	}

	/**
	 * Returns the class the provider's own script looks for.
	 *
	 * v3 draws nothing, so there is no widget to mark.
	 *
	 * @return string An empty string.
	 */
	public function widget_class(): string {
		return '';
	}

	/**
	 * Returns the request field the answer arrives in.
	 */
	public function response_field(): string {
		return self::FIELD;
	}

	/**
	 * Returns the score a submission must reach.
	 *
	 * @return float The threshold, between 0 and 1.
	 */
	public function threshold(): float {
		return min( 1.0, max( 0.0, (float) Settings::get( 'recaptcha_threshold', 0.5 ) ) );
	}

	/**
	 * Refuses a token whose score is below the threshold.
	 *
	 * @param array<string, mixed> $body Decoded response.
	 *
	 * @return WP_Error|null The reason it failed, or null when it passed.
	 */
	protected function inspect( array $body ): ?WP_Error {
		/*
		 * The action names what the token was minted for. Without checking it, a
		 * token solved on any other v3 widget on the same site — a login form, a
		 * comment box, a third-party plugin's — is accepted here, because they all
		 * verify against the same secret. Absent means the site key is a v2 one, so
		 * there is nothing to compare.
		 */
		$action = strtolower( trim( (string) ( $body['action'] ?? '' ) ) );

		if ( '' !== $action && self::ACTION !== $action ) {
			return new WP_Error(
				'formpilot_captcha_action',
				__( 'The spam check rejected this submission.', 'devplugins-custom-form-builder' )
			);
		}

		// A response without a score is a v2 key answering a v3 request. Treating
		// that as a pass is right: the checkbox was solved.
		$score = isset( $body['score'] ) ? (float) $body['score'] : 1.0;

		if ( $score >= $this->threshold() ) {
			return null;
		}

		return new WP_Error(
			'formpilot_captcha_score',
			__( 'The spam check rejected this submission.', 'devplugins-custom-form-builder' ),
			array( 'score' => $score )
		);
	}

	/**
	 * Returns the endpoint the answer is checked against.
	 */
	protected function verify_url(): string {
		return 'https://www.google.com/recaptcha/api/siteverify';
	}

	/**
	 * Returns the private key.
	 */
	protected function secret(): string {
		return Settings::text( 'recaptcha_secret' );
	}
}