<?php
/**
 * Hints in the forms of the site.
 *
 * @package Dealroot
 */

namespace Dealroot;

defined( 'ABSPATH' ) || exit;

/**
 * While a visitor writes a message, a short hint below it names what the enquiries of this site
 * usually lack and the business then has to ask for: the date, the place or how many. Which ones
 * comes from what the AI assistant read in past enquiries; the check runs in the browser, so
 * nothing the visitor types is sent anywhere for it.
 *
 * phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
 */
class Form_Hints {

	const CACHE = 'dealroot_form_hints';

	/**
	 * Enquiries read before hints are shown.
	 */
	const MIN_LEADS = 20;

	/**
	 * Share of enquiries that must lack a detail before its hint is shown.
	 */
	const MIN_SHARE = 0.4;

	/**
	 * Hooks.
	 */
	public function register() {
		add_action( 'wp_enqueue_scripts', array( __CLASS__, 'enqueue' ) );
	}

	/**
	 * Details most enquiries lack, the most often missing first.
	 *
	 * @return array<string, float> Detail => share of enquiries without it.
	 */
	public static function missing() {
		$cached = get_transient( self::CACHE );

		if ( is_array( $cached ) ) {
			return $cached;
		}

		global $wpdb;

		$rows = (array) $wpdb->get_col(
			$wpdb->prepare(
				"SELECT ai_details FROM %i WHERE ai_state = 'done' AND ai_kind IN ('enquiry', 'order') AND form_plugin NOT IN ('manual', 'woocommerce') AND created_at >= %s ORDER BY id DESC LIMIT 400",
				Installer::table(),
				gmdate( 'Y-m-d H:i:s', time() - 180 * DAY_IN_SECONDS )
			)
		);

		$missing = array();

		if ( count( $rows ) >= self::MIN_LEADS ) {
			foreach ( array( 'when', 'place', 'quantity' ) as $detail ) {
				$without = 0;

				foreach ( $rows as $row ) {
					$details  = json_decode( (string) $row, true );
					$without += '' === trim( (string) ( $details[ $detail ] ?? '' ) ) ? 1 : 0;
				}

				$share = $without / count( $rows );

				if ( $share >= self::MIN_SHARE ) {
					$missing[ $detail ] = round( $share, 2 );
				}
			}

			arsort( $missing );
		}

		set_transient( self::CACHE, $missing, DAY_IN_SECONDS );

		return $missing;
	}

	/**
	 * Texts of the hints, for visitors, in the language of the site.
	 *
	 * @return array<string, string>
	 */
	public static function texts() {
		return array(
			'when'     => __( 'Tip: mention the date or by when you need it – you will get an offer faster.', 'dealroot' ),
			'place'    => __( 'Tip: mention the town or postcode – you will get an offer faster.', 'dealroot' ),
			'quantity' => __( 'Tip: mention how many or how large – you will get an offer faster.', 'dealroot' ),
		);
	}

	/**
	 * Loads the hints on the pages of the site.
	 */
	public static function enqueue() {
		if ( ! Settings::get( 'smart_form' ) ) {
			return;
		}

		$missing = self::missing();

		/**
		 * Filters the details hinted at in forms, e.g. to always ask for the date.
		 *
		 * @param array<string, float> $missing Detail => share of enquiries without it.
		 */
		$missing = (array) apply_filters( 'dealroot_form_hints', $missing );

		if ( ! $missing ) {
			return;
		}

		wp_enqueue_script(
			'dealroot-form-hints',
			DEALROOT_URL . 'assets/js/form-hints.js',
			array(),
			Plugin::asset_version( 'assets/js/form-hints.js' ),
			array(
				'strategy'  => 'defer',
				'in_footer' => true,
			)
		);
		wp_add_inline_script(
			'dealroot-form-hints',
			'window.dealrootHints = ' . wp_json_encode(
				array(
					'hints' => array_intersect_key( self::texts(), $missing ),
					'order' => array_keys( $missing ),
				)
			) . ';',
			'before'
		);
	}
}