<?php

declare(strict_types=1);

namespace Sarcio\WordPress\Assistant;

/**
 * Pages built with a page builder keep their text outside post_content.
 * Elementor stores the page as a tree of elements in the `_elementor_data`
 * meta, each widget's text in its settings; this reads that tree as lines of
 * text, replaces an exact piece of text in it, and writes it back the way
 * Elementor does, clearing its cache so the page renders the new text.
 */
final class Builders
{
    public const DIVI = 'divi';
    public const DIVI_MODE = '_et_pb_use_builder';
    public const ELEMENTOR = 'elementor';
    public const ELEMENTOR_CACHE = '_elementor_element_cache';
    public const ELEMENTOR_DATA = '_elementor_data';
    public const ELEMENTOR_MODE = '_elementor_edit_mode';

    /**
     * Which builder owns a post's content, or null for the block editor.
     * Elementor keeps its page in meta; Divi keeps it as shortcodes in the
     * content itself, so a Divi page is changed through the content, only
     * read and cached differently.
     */
    public static function of(int $postId, ?Overlay $overlay = null): ?string
    {
        if ((string) self::meta($postId, self::ELEMENTOR_MODE, $overlay) === 'builder' && self::data($postId, $overlay) !== null) {
            return self::ELEMENTOR;
        }
        if ((string) self::meta($postId, self::DIVI_MODE, $overlay) === 'on') {
            return self::DIVI;
        }
        return null;
    }

    /** A Divi page's words, with the shortcode scaffolding stripped. */
    public static function diviText(string $content): string
    {
        $text = preg_replace('~\[/?et_pb_[a-z0-9_]+[^\]]*\]~i', "\n", $content) ?? $content;
        return ContentAbilities::readable($text);
    }

    /** Divi caches each page's CSS; a changed page must not render the old one. */
    public static function clearDiviCache(int $postId): void
    {
        if (function_exists('et_core_page_resource_remove_all')) {
            et_core_page_resource_remove_all($postId);
        } elseif (class_exists('\ET_Core_PageResource') && method_exists('\ET_Core_PageResource', 'remove_static_resources')) {
            \ET_Core_PageResource::remove_static_resources('all', 'all');
        }
        delete_post_meta($postId, '_et_pb_static_css_file');
    }

    /** The page's text as the owner reads it, one widget text per line. */
    public static function text(int $postId, ?Overlay $overlay = null): string
    {
        $data = self::data($postId, $overlay);
        return $data === null ? '' : self::textOf($data);
    }

    /** @param array<int,mixed> $data */
    public static function textOf(array $data): string
    {
        $lines = [];
        self::walk($data, static function (string &$value) use (&$lines): void {
            $line = ContentAbilities::readable($value);
            if ($line !== '') {
                $lines[] = $line;
            }
        });
        return mb_substr(implode("\n", $lines), 0, 20000);
    }

    /**
     * Replaces an exact piece of text across every text setting of the page.
     *
     * @return array{data?:array<int,mixed>,count:int,error?:string}
     */
    public static function replace(int $postId, string $search, string $replace, bool $all, ?Overlay $overlay = null): array
    {
        $replace = wp_kses_post($replace);
        $data = self::data($postId, $overlay);
        if ($data === null) {
            return ['count' => 0, 'error' => __('That page is not built with a page builder the assistant can change.', 'sarcio')];
        }
        $count = 0;
        self::walk($data, static function (string &$value) use ($search, &$count): void {
            $count += $search === '' ? 0 : substr_count($value, $search);
        });
        if ($count === 0) {
            return ['count' => 0, 'error' => __('That text was not found on the page. Read the page and copy the text exactly.', 'sarcio')];
        }
        if ($count > 1 && !$all) {
            return ['count' => $count, 'error' => sprintf(
                /* translators: %d: how many times the text appears. */
                __('That text appears %d times on the page. Say which one, or ask to change all of them.', 'sarcio'),
                $count,
            )];
        }
        self::walk($data, static function (string &$value) use ($search, $replace): void {
            $value = str_replace($search, $replace, $value);
        });
        return ['count' => $count, 'data' => $data];
    }

    /** Elementor's own encoding of the tree, as a value for the meta. */
    public static function encode(array $data): string
    {
        return (string) wp_json_encode($data);
    }

    /** Writes the tree back and clears what Elementor cached for the page. */
    public static function write(int $postId, array $data): bool
    {
        $stored = update_post_meta($postId, self::ELEMENTOR_DATA, wp_slash(self::encode($data)));
        if ($stored === false) {
            return (string) get_post_meta($postId, self::ELEMENTOR_DATA, true) === self::encode($data);
        }
        delete_post_meta($postId, '_elementor_css');
        delete_post_meta($postId, self::ELEMENTOR_CACHE);
        if (class_exists('\Elementor\Plugin') && isset(\Elementor\Plugin::$instance->files_manager)) {
            \Elementor\Plugin::$instance->files_manager->clear_cache();
        }
        return true;
    }

    /** @return array<int,mixed>|null */
    public static function data(int $postId, ?Overlay $overlay = null): ?array
    {
        $raw = self::meta($postId, self::ELEMENTOR_DATA, $overlay);
        if (!is_string($raw) || $raw === '') {
            return null;
        }
        $decoded = json_decode($raw, true);
        return is_array($decoded) ? $decoded : null;
    }

    /** Every text-bearing setting of every element, in page order. */
    private static function walk(array &$elements, callable $visit): void
    {
        foreach ($elements as &$element) {
            if (!is_array($element)) {
                continue;
            }
            if (($element['elType'] ?? '') === 'widget' && is_array($element['settings'] ?? null)) {
                foreach ($element['settings'] as $key => &$value) {
                    if (is_string($value) && self::isText($key, $value)) {
                        $visit($value);
                    }
                }
                unset($value);
            }
            if (is_array($element['elements'] ?? null)) {
                self::walk($element['elements'], $visit);
            }
        }
        unset($element);
    }

    /** A setting that holds words rather than a size, a colour, a url or an id. */
    private static function isText(string $key, string $value): bool
    {
        if (trim($value) === '' || preg_match('~^(#[0-9a-f]{3,8}|-?\d+(\.\d+)?(px|em|rem|%|vh|vw)?|https?://\S+|/\S*|[a-z0-9_-]+)$~i', $value)) {
            return false;
        }
        return !preg_match('~(^_|_id$|_size$|_color$|_url$|_class|_icon|_align|_position|_tag$|_type$|^css_|^html_tag$|^link$)~', $key);
    }

    private static function meta(int $postId, string $key, ?Overlay $overlay): mixed
    {
        if ($overlay !== null && array_key_exists($key, $overlay->meta[$postId] ?? [])) {
            return $overlay->meta[$postId][$key];
        }
        return get_post_meta($postId, $key, true);
    }
}