<?php
/**
 * A/B Testing Handler
 *
 * Manages A/B test CRUD operations via AJAX.
 *
 * @since      1.0.0
 * @package    Acumenpopup
 * @subpackage Acumenpopup/includes/Dashboard
 */

namespace Acumenpopup\Dashboard;

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Class AB_Testing
 *
 * Handles A/B test creation, retrieval, update, and deletion (Singleton).
 *
 * @since   1.0.0
 * @package Acumenpopup
 */
class AB_Testing {

	/**
	 * The single instance of the class.
	 *
	 * @since  1.0.0
	 * @access private
	 * @var    AB_Testing|null
	 */
	private static $instance = null;

	/**
	 * WordPress option key for storing A/B tests.
	 *
	 * @since  1.0.0
	 * @access private
	 * @var    string
	 */
	private $option_key = 'acumenpopup_ab_tests';

	/**
	 * Allowed winner parameter values.
	 *
	 * @since  1.0.0
	 * @access private
	 * @var    array
	 */
	private $allowed_params = array( 'total_conversions', 'conversion_rate', 'total_impressions', 'revenue' );

	/**
	 * Private constructor.
	 *
	 * @since  1.0.0
	 * @access private
	 */
	private function __construct() {
		$this->init_hooks();
	}

	/**
	 * Get the single instance.
	 *
	 * @since  1.0.0
	 * @access public
	 *
	 * @return AB_Testing
	 */
	public static function get_instance() {
		if ( is_null( self::$instance ) ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Register AJAX action hooks.
	 *
	 * @since  1.0.0
	 * @access private
	 *
	 * @return void
	 */
	private function init_hooks() {
		add_action( 'wp_ajax_acumenpopup_get_ab_tests',    array( $this, 'get_tests' ) );
		add_action( 'wp_ajax_acumenpopup_create_ab_test',  array( $this, 'create_test' ) );
		add_action( 'wp_ajax_acumenpopup_delete_ab_test',  array( $this, 'delete_test' ) );
		add_action( 'wp_ajax_acumenpopup_toggle_ab_test',  array( $this, 'toggle_test' ) );
	}

	/**
	 * Verify nonce and capability for every request.
	 *
	 * @since  1.0.0
	 * @access private
	 *
	 * @return void Sends JSON error and exits on failure.
	 */
	private function verify_request() {
		check_ajax_referer( 'acumenpopup-nonce', 'nonce' );
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_send_json_error( array( 'message' => 'Unauthorized' ), 403 );
		}
	}

	/**
	 * Load all A/B tests from the database.
	 *
	 * @since  1.0.0
	 * @access private
	 *
	 * @return array
	 */
	private function load_tests() {
		$tests = get_option( $this->option_key, array() );
		return is_array( $tests ) ? $tests : array();
	}

	/**
	 * AJAX: Return all A/B tests.
	 *
	 * @since  1.0.0
	 * @access public
	 *
	 * @return void
	 */
	public function get_tests() {
		$this->verify_request();
		wp_send_json_success( array_values( $this->load_tests() ) );
	}

	/**
	 * AJAX: Create a new A/B test.
	 *
	 * @since  1.0.0
	 * @access public
	 *
	 * @return void
	 */
	public function create_test() {
		$this->verify_request();

		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
		$raw   = isset( $_POST['test'] ) ? wp_unslash( $_POST['test'] ) : '{}';
		$input = json_decode( $raw, true );

		if ( ! is_array( $input ) ) {
			wp_send_json_error( array( 'message' => __( 'Invalid data.', 'acumen-popup' ) ) );
		}

		$name = sanitize_text_field( $input['name'] ?? '' );
		if ( empty( $name ) ) {
			wp_send_json_error( array( 'message' => __( 'Test name is required.', 'acumen-popup' ) ) );
		}

		$variants = array_filter( array_map( 'absint', (array) ( $input['variants'] ?? array() ) ) );
		if ( count( $variants ) < 2 ) {
			wp_send_json_error( array( 'message' => __( 'At least 2 variants with campaigns are required.', 'acumen-popup' ) ) );
		}

		$winner_mode = in_array( $input['winner_mode'] ?? '', array( 'manual', 'automatic' ), true )
			? $input['winner_mode']
			: 'manual';

		$winner_param = in_array( $input['winner_param'] ?? '', $this->allowed_params, true )
			? $input['winner_param']
			: 'total_conversions';

		$duration = max( 1, min( 365, absint( $input['duration'] ?? 7 ) ) );

		$test = array(
			'id'          => wp_generate_uuid4(),
			'name'        => $name,
			'enabled'     => ! empty( $input['enabled'] ),
			'variants'    => array_values( $variants ),
			'winner_mode' => $winner_mode,
			'winner_param'=> $winner_param,
			'duration'    => $duration,
			'status'      => ! empty( $input['enabled'] ) ? 'active' : 'inactive',
			'created'     => time(),
		);

		$tests              = $this->load_tests();
		$tests[ $test['id'] ] = $test;
		update_option( $this->option_key, $tests );

		wp_send_json_success( $test );
	}

	/**
	 * AJAX: Delete an A/B test by ID.
	 *
	 * @since  1.0.0
	 * @access public
	 *
	 * @return void
	 */
	public function delete_test() {
		$this->verify_request();

		$id    = sanitize_text_field( wp_unslash( $_POST['id'] ?? '' ) );
		$tests = $this->load_tests();

		if ( ! isset( $tests[ $id ] ) ) {
			wp_send_json_error( array( 'message' => __( 'Test not found.', 'acumen-popup' ) ) );
		}

		unset( $tests[ $id ] );
		update_option( $this->option_key, $tests );
		wp_send_json_success();
	}

	/**
	 * AJAX: Toggle the enabled state of an A/B test.
	 *
	 * @since  1.0.0
	 * @access public
	 *
	 * @return void
	 */
	public function toggle_test() {
		$this->verify_request();

		$id      = sanitize_text_field( wp_unslash( $_POST['id'] ?? '' ) );
		$enabled = ! empty( $_POST['enabled'] ) && 'true' === $_POST['enabled'];
		$tests   = $this->load_tests();

		if ( ! isset( $tests[ $id ] ) ) {
			wp_send_json_error( array( 'message' => __( 'Test not found.', 'acumen-popup' ) ) );
		}

		$tests[ $id ]['enabled'] = $enabled;
		$tests[ $id ]['status']  = $enabled ? 'active' : 'inactive';
		update_option( $this->option_key, $tests );

		wp_send_json_success( $tests[ $id ] );
	}

	/**
	 * Prevent cloning of the instance.
	 *
	 * @since  1.0.0
	 * @access public
	 *
	 * @return void
	 */
	public function __clone() {
		_doing_it_wrong(
			__FUNCTION__,
			esc_html__( 'Cloning is forbidden.', 'acumen-popup' ),
			'1.0.0'
		);
	}

	/**
	 * Prevent unserializing of the instance.
	 *
	 * @since  1.0.0
	 * @access public
	 *
	 * @return void
	 */
	public function __wakeup() {
		_doing_it_wrong(
			__FUNCTION__,
			esc_html__( 'Unserializing is forbidden.', 'acumen-popup' ),
			'1.0.0'
		);
	}
}