<?php
/**
 * Which forms count as leads.
 *
 * @package Dealroot
 */

namespace Dealroot;

defined( 'ABSPATH' ) || exit;

/**
 * Forms of supported plugins are captured unless they were switched off on the Forms screen.
 * Other forms are captured when they were picked there, by a CSS selector found by the scan.
 */
class Form_Selection {

	const OPTION = 'dealroot_forms';

	/**
	 * Most forms that can be picked by selector.
	 */
	const MAX_CUSTOM = 50;

	/**
	 * Stored selection.
	 *
	 * @return array{excluded: string[], custom: array<int, array{selector: string, name: string}>, declined: string[]}
	 */
	public static function get() {
		$saved = get_option( self::OPTION, array() );
		$saved = is_array( $saved ) ? $saved : array();

		return array(
			'excluded' => array_values( array_filter( (array) ( $saved['excluded'] ?? array() ), 'is_string' ) ),
			'custom'   => array_values( array_filter( (array) ( $saved['custom'] ?? array() ), 'is_array' ) ),
			'declined' => array_values( array_filter( (array) ( $saved['declined'] ?? array() ), 'is_string' ) ),
		);
	}

	/**
	 * Saves the selection.
	 *
	 * @param string[] $excluded Keys such as "cf7:5" of forms that are not captured.
	 * @param array    $custom   Picked forms with selector and name.
	 * @param string[] $declined Selectors of found forms that were not picked, so a new scan
	 *                           leaves them unticked.
	 */
	public static function save( array $excluded, array $custom, array $declined = array() ) {
		$keys = array();
		foreach ( $excluded as $key ) {
			$key = self::sanitize_key( (string) $key );
			if ( '' !== $key ) {
				$keys[ $key ] = true;
			}
		}

		$forms = array();
		foreach ( $custom as $form ) {
			$selector = self::sanitize_selector( (string) ( $form['selector'] ?? '' ) );
			if ( '' === $selector || isset( $forms[ $selector ] ) ) {
				continue;
			}

			$forms[ $selector ] = array(
				'selector' => $selector,
				'name'     => mb_substr( sanitize_text_field( (string) ( $form['name'] ?? '' ) ), 0, 191 ),
			);
		}

		$skipped = array();
		foreach ( $declined as $selector ) {
			$selector = self::sanitize_selector( (string) $selector );
			if ( '' !== $selector && ! isset( $forms[ $selector ] ) ) {
				$skipped[ $selector ] = true;
			}
		}

		update_option(
			self::OPTION,
			array(
				'excluded' => array_slice( array_keys( $keys ), 0, 500 ),
				'custom'   => array_slice( array_values( $forms ), 0, self::MAX_CUSTOM ),
				'declined' => array_slice( array_keys( $skipped ), 0, 500 ),
			)
		);
	}

	/**
	 * Adds a form by its selector, or renames it when it is there already.
	 *
	 * @param string $selector Selector, see from_input().
	 * @param string $name     Name in the reports.
	 */
	public static function add( $selector, $name ) {
		$current = self::get();
		$custom  = array(
			array(
				'selector' => $selector,
				'name'     => $name,
			),
		);

		foreach ( $current['custom'] as $form ) {
			if ( ( $form['selector'] ?? '' ) !== $selector ) {
				$custom[] = $form;
			}
		}

		self::save( $current['excluded'], $custom, array_diff( $current['declined'], array( $selector ) ) );
	}

	/**
	 * Switches on the forms a scan found that the Forms screen shows as switched on: forms
	 * without a form plugin that are not a newsletter sign-up and were not switched off before.
	 * They count as leads from then on, without a click on Save.
	 *
	 * @param array $forms Forms of the scan.
	 */
	public static function pick_found( array $forms ) {
		$current = self::get();
		$custom  = $current['custom'];
		$picked  = wp_list_pluck( $custom, 'selector' );
		$added   = false;

		foreach ( $forms as $form ) {
			$selector = (string) ( $form['selector'] ?? '' );

			if ( 'custom' !== ( $form['kind'] ?? '' ) || '' !== (string) ( $form['tag'] ?? '' ) || '' === $selector
				|| in_array( $selector, $picked, true ) || in_array( $selector, $current['declined'], true ) || count( $custom ) >= self::MAX_CUSTOM ) {
				continue;
			}

			$custom[] = array(
				'selector' => $selector,
				'name'     => (string) ( $form['name'] ?? '' ),
			);
			$picked[] = $selector;
			$added    = true;
		}

		if ( $added ) {
			self::save( $current['excluded'], $custom, $current['declined'] );
		}
	}

	/**
	 * A form typed in by hand: its ID as written in the HTML, with or without "#", or a CSS
	 * selector of the form or of an element around it, such as a pop-up.
	 *
	 * @param string $input Raw input.
	 * @return string Selector, '' when invalid.
	 */
	public static function from_input( $input ) {
		$input = trim( wp_strip_all_tags( (string) $input ) );

		if ( preg_match( '/^#?([A-Za-z][\w-]{0,99})$/', $input, $match ) ) {
			return '#' . $match[1];
		}

		return self::sanitize_selector( $input );
	}

	/**
	 * Key of a plugin form, e.g. "cf7:5".
	 *
	 * @param string $plugin  Form plugin key.
	 * @param string $form_id Form ID.
	 * @return string
	 */
	public static function key( $plugin, $form_id ) {
		return self::sanitize_key( $plugin . ':' . $form_id );
	}

	/**
	 * Whether submissions of a form are ignored.
	 *
	 * @param string $plugin  Form plugin key.
	 * @param string $form_id Form ID.
	 * @return bool
	 */
	public static function is_excluded( $plugin, $form_id ) {
		if ( '' === (string) $form_id ) {
			return false;
		}

		return in_array( self::key( (string) $plugin, (string) $form_id ), self::get()['excluded'], true );
	}

	/**
	 * Selectors of the picked forms, separated by commas.
	 *
	 * @return string
	 */
	public static function selectors() {
		return implode( ', ', wp_list_pluck( self::get()['custom'], 'selector' ) );
	}

	/**
	 * Picked forms that have a name, as selector and name pairs for the tracker.
	 *
	 * @return array<int, string[]>
	 */
	public static function names() {
		$names = array();

		foreach ( self::get()['custom'] as $form ) {
			if ( '' !== (string) ( $form['name'] ?? '' ) ) {
				$names[] = array( (string) $form['selector'], (string) $form['name'] );
			}
		}

		return $names;
	}

	/**
	 * Plugin key and form ID, e.g. "cf7:5" or "elementor:3f2a1bc".
	 *
	 * @param string $key Raw key.
	 * @return string '' when invalid.
	 */
	public static function sanitize_key( $key ) {
		return preg_match( '/^[a-z0-9]{2,20}:[A-Za-z0-9_-]{1,64}$/', $key ) ? $key : '';
	}

	/**
	 * A CSS selector for one form. Anything that could end the selector list or a style
	 * rule is refused.
	 *
	 * @param string $selector Raw selector.
	 * @return string '' when invalid.
	 */
	public static function sanitize_selector( $selector ) {
		$selector = trim( wp_strip_all_tags( $selector ) );

		if ( '' === $selector || strlen( $selector ) > 300 || preg_match( '/[,{};<>\\\\]|\/\*/', $selector ) ) {
			return '';
		}

		return $selector;
	}
}