<?php
/**
 * SureForms - AI Auth.
 *
 * @package sureforms
 * @since 0.0.8
 */

namespace SRFM\Inc\AI_Form_Builder;

use SRFM\Inc\Helper;
use SRFM\Inc\Traits\Get_Instance;

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * SureForms AI Form Builder Class.
 */
class AI_Auth {
	use Get_Instance;

	/**
	 * The key for encryption and decryption.
	 *
	 * @since 0.0.8
	 * @var string
	 */
	private $key = '';

	/**
	 * Initiates the auth process.
	 *
	 * @param \WP_REST_Request $request The request object.
	 * @since 0.0.8
	 * @return void
	 */
	public function get_auth_url( $request ) {

		$nonce = Helper::get_string_value( $request->get_header( 'X-WP-Nonce' ) );

		if ( ! wp_verify_nonce( sanitize_text_field( $nonce ), 'wp_rest' ) ) {
			wp_send_json_error( __( 'Nonce verification failed.', 'sureforms' ) );
		}

		// Generate a random key of 16 characters.
		$this->key = wp_generate_password( 16, false );
		// Persist key for decryption in handle_access_key (10 min TTL).
		set_transient( 'srfm_ai_auth_key_' . get_current_user_id(), $this->key, 10 * MINUTE_IN_SECONDS );

		// Get the source parameter from the query.
		$source = sanitize_text_field( Helper::get_string_value( $request->get_param( 'source' ) ?? '' ) );
		switch ( $source ) {
			case 'onboarding':
				$redirect_back = site_url() . '/wp-admin/admin.php?page=sureforms_menu#/onboarding/email-delivery';
				break;
			default:
				$redirect_back = site_url() . '/wp-admin/admin.php?page=add-new-form';
		}

		// Prepare the token data.
		$token_data = [
			'redirect-back' => $redirect_back,
			'key'           => $this->key,
			'site-url'      => site_url(),
			'nonce'         => wp_create_nonce( 'ai_auth_nonce' ),
		];

		$encoded_token_data = wp_json_encode( $token_data );

		if ( empty( $encoded_token_data ) ) {
			wp_send_json_error( [ 'message' => __( 'Failed to encode the token data.', 'sureforms' ) ] );
		}

		// Send the token data to the frontend for redirection.
		wp_send_json_success( SRFM_BILLING_PORTAL . 'auth/?token=' . base64_encode( $encoded_token_data ) );  // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode
	}

	/**
	 * Handles the access key.
	 *
	 * @param \WP_REST_Request $request The request object.
	 * @since 0.0.8
	 * @return void
	 */
	public function handle_access_key( $request ) {

		$nonce = Helper::get_string_value( $request->get_header( 'X-WP-Nonce' ) );

		if ( ! wp_verify_nonce( sanitize_text_field( $nonce ), 'wp_rest' ) ) {
			wp_send_json_error( __( 'Nonce verification failed.', 'sureforms' ) );
		}

		// get body data.
		$body = json_decode( $request->get_body(), true );

		if ( empty( $body ) ) {
			wp_send_json_error( [ 'message' => __( 'Error processing Access Key.', 'sureforms' ) ] );
		}

		// get access key.
		$access_key = is_array( $body ) && ! empty(
			$body['accessKey']
		) ? Helper::get_string_value( $body['accessKey'] ) : '';

		$stored_key = Helper::get_string_value( get_transient( 'srfm_ai_auth_key_' . get_current_user_id() ) );

		if ( empty( $stored_key ) ) {
			wp_send_json_error( [ 'message' => __( 'Authentication session expired. Please try again.', 'sureforms' ) ] );
		}

		// decrypt the access key.
		if ( ! empty( $access_key ) ) {
			$this->decrypt_access_key( $access_key, $stored_key );
		} else {
			wp_send_json_error( [ 'message' => __( 'No access key provided.', 'sureforms' ) ] );
		}
	}

	/**
	 * Decrypts a string using OpenSSL decryption.
	 *
	 * @param string $data The data to decrypt.
	 * @param string $key The encryption key.
	 * @param string $method The encryption method (e.g., AES-256-CBC).
	 * @since 0.0.8
	 * @return string|false The decrypted string or false on failure.
	 */
	public function decrypt_access_key( $data, $key, $method = 'AES-256-CBC' ) {
		// Decode the data and split IV and encrypted data.
		$decoded_data = base64_decode( $data ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_decode

		// if the data is not base64 encoded then return false.
		if ( empty( $decoded_data ) ) {
			return false;
		}

		// Extract the IV and encrypted data (billing portal sends IV::ENCRYPTED_DATA format).
		$parts = explode( '::', $decoded_data, 2 );

		if ( ! isset( $parts[1] ) ) {
			wp_send_json_error( [ 'message' => __( 'Invalid access key format.', 'sureforms' ) ] );
		}

		$iv        = $parts[0];
		$encrypted = $parts[1];

		// Decrypt the data using the server-stored key and the billing-portal-supplied IV.
		$decrypted = openssl_decrypt( $encrypted, $method, $key, 0, $iv );

		// if the decryption returns false then send error.
		if ( empty( $decrypted ) ) {
			wp_send_json_error( [ 'message' => __( 'Failed to decrypt the access key.', 'sureforms' ) ] );
		}

		// json decode the decrypted data.
		$decrypted_data_array = json_decode( $decrypted, true );

		if ( ! is_array( $decrypted_data_array ) || empty( $decrypted_data_array ) ) {
			wp_send_json_error( [ 'message' => __( 'Failed to json decode the decrypted data.', 'sureforms' ) ] );
		}

		// verify the nonce that comes in $encrypted_email_array.
		if ( empty( $decrypted_data_array['nonce'] ) || ! wp_verify_nonce( $decrypted_data_array['nonce'], 'ai_auth_nonce' ) ) {
			wp_send_json_error( [ 'message' => __( 'Nonce verification failed.', 'sureforms' ) ] );
		}

		// check if the user email is present in the decrypted data.
		if ( empty( $decrypted_data_array['user_email'] ) ) {
			wp_send_json_error( [ 'message' => __( 'No user email found in the decrypted data.', 'sureforms' ) ] );
		}

		// Extract is_subscribed value if present.
		$is_subscribed = false;
		if ( isset( $decrypted_data_array['is_subscribed'] ) ) {
			// Convert string 'true'/'false' to boolean if needed.
			if ( is_string( $decrypted_data_array['is_subscribed'] ) ) {
				$is_subscribed = 'true' === $decrypted_data_array['is_subscribed'];
			} else {
				$is_subscribed = (bool) $decrypted_data_array['is_subscribed'];
			}

			// Update the analytics option based on the preference.
			// Set 'yes' if opted in, empty string if not.
			$enable_contribution = $is_subscribed ? 'yes' : '';
			update_option( 'sureforms_usage_optin', $enable_contribution );

			// Remove is_subscribed from the decrypted data.
			unset( $decrypted_data_array['is_subscribed'] );
		}

		// remove the nonce from the decrypted data before saving it to the options.
		unset( $decrypted_data_array['nonce'] );

		// Clean up the auth key transient.
		delete_transient( 'srfm_ai_auth_key_' . get_current_user_id() );

		// save the user email to the options.
		update_option( 'srfm_ai_auth_user_email', $decrypted_data_array );

		wp_send_json_success();
	}
}
