<?php
/**
 * Front-end loader for the hosted CauseWise tracker.
 *
 * @package CauseWise_Analytics
 */

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

/**
 * Enqueues https://causewise.io/causewise.js once on public pages.
 *
 * That script sends the initial page view itself. This plugin does not emit another one.
 */
class Causewise_Tracker {
	const SCRIPT_HANDLE = 'causewise-analytics';
	const SCRIPT_URL    = 'https://causewise.io/causewise.js';
	const COLLECT_BASE  = 'https://causewise.io';

	/**
	 * True after this request has enqueued the tracker once.
	 *
	 * @var bool
	 */
	private static $enqueued = false;

	/**
	 * Register hooks.
	 */
	public static function init() {
		add_action( 'wp_enqueue_scripts', array( __CLASS__, 'enqueue' ) );
		add_filter( 'script_loader_tag', array( __CLASS__, 'script_tag' ), 10, 2 );
	}

	/**
	 * Whether the hosted tracker should be printed.
	 *
	 * @param array{site_key?: string, enabled?: bool} $settings Saved settings.
	 * @param bool                                     $is_admin True on wp-admin requests.
	 * @return bool
	 */
	public static function should_load( $settings, $is_admin ) {
		if ( $is_admin ) {
			return false;
		}
		if ( empty( $settings['enabled'] ) ) {
			return false;
		}
		return Causewise_Settings::is_valid_public_key( isset( $settings['site_key'] ) ? $settings['site_key'] : '' );
	}

	/**
	 * Enqueue the production tracker in the document head.
	 */
	public static function enqueue() {
		if ( self::$enqueued ) {
			return;
		}
		if ( ! self::should_load( Causewise_Settings::get_settings(), is_admin() ) ) {
			return;
		}

		self::$enqueued = true;
		wp_enqueue_script(
			self::SCRIPT_HANDLE,
			self::SCRIPT_URL,
			array(),
			null, // phpcs:ignore WordPress.WP.EnqueuedResourceParameters.MissingVersion -- The hosted tracker must load without a WordPress version query.
			false
		);
	}

	/**
	 * Add the data attributes from the production embed snippet.
	 *
	 * @param string $tag    Script tag.
	 * @param string $handle Enqueued handle.
	 * @return string
	 */
	public static function script_tag( $tag, $handle ) {
		if ( self::SCRIPT_HANDLE !== $handle ) {
			return $tag;
		}

		$settings = Causewise_Settings::get_settings();
		if ( ! self::should_load( $settings, is_admin() ) ) {
			return '';
		}

		return self::inject_attributes( $tag, $settings['site_key'] );
	}

	/**
	 * Insert async, data-site, and data-collect-base on the script tag once.
	 *
	 * @param string $tag      Existing script tag.
	 * @param string $site_key Valid public tracking key.
	 * @return string
	 */
	public static function inject_attributes( $tag, $site_key ) {
		if ( false !== strpos( $tag, 'data-site=' ) ) {
			return $tag;
		}

		$extra = sprintf(
			' data-site="%s" data-collect-base="%s"',
			esc_attr( Causewise_Settings::normalize_site_key( $site_key ) ),
			esc_url( self::COLLECT_BASE )
		);

		if ( ! preg_match( '/\sasync(?:[\s=>]|$)/', $tag ) ) {
			$extra = ' async' . $extra;
		}

		$updated = preg_replace( '/<script\b/', '<script' . $extra, $tag, 1 );
		if ( ! is_string( $updated ) ) {
			return $tag;
		}

		return $updated;
	}
}