<?php
namespace Relay\Restore;

/** The replacements needed when data made on one site goes to another (URLs and file paths). */
final class AutoPairs
{
    /**
     * Each side: site_url, home_url, path; optionally uploads_url, uploads_dir, content_url (where a subsite's
     * files live) and alt_uploads_url, alt_content_url (a subsite's same folders as the main site writes them).
     * Pairs apply in one pass, longest match first, so an uploads address wins over the site address it contains.
     *
     * @param array<string, mixed> $from the site the data comes from (other keys, such as "network", are ignored)
     * @param array<string, mixed> $to   the site it goes to
     * @return array<string, string> find => replace, longest first; empty when nothing differs
     */
    public static function map(array $from, array $to): array
    {
        $map = [];
        // [from key, to key]; home_url last: it wins where two keys map the same text.
        $urls = [['content_url', 'content_url'], ['alt_content_url', 'content_url'], ['uploads_url', 'uploads_url'], ['alt_uploads_url', 'uploads_url'], ['site_url', 'site_url'], ['home_url', 'home_url']];
        foreach ($urls as [$from_key, $to_key]) {
            $old = self::split_url((string) ($from[$from_key] ?? ''));
            $new = self::split_url((string) ($to[$to_key] ?? ''));
            if ($old === null || $new === null || $old === $new) {
                continue;
            }
            $map['https://' . $old[1]] = $new[0] . '://' . $new[1];
            $map['http://' . $old[1]] = $new[0] . '://' . $new[1];
            $map['//' . $old[1]] = '//' . $new[1];
            // URL-encoded too, as Elementor keeps a dynamic tag's settings (encodeURIComponent: "https%3A%2F%2F…").
            foreach (['https://', 'http://'] as $scheme) {
                $map[rawurlencode($scheme . $old[1])] = rawurlencode($new[0] . '://' . $new[1]);
            }
        }
        foreach (['uploads_dir', 'path'] as $key) {
            $old_path = rtrim((string) ($from[$key] ?? ''), '/');
            $new_path = rtrim((string) ($to[$key] ?? ''), '/');
            // A one-segment path such as "/app" could also appear inside URLs, so only real paths are mapped.
            if (substr_count($old_path, '/') >= 2 && $new_path !== '') {
                $map[$old_path] = $new_path;
            }
        }
        foreach ($map as $find => $replace) {
            $map[str_replace('/', '\\/', $find)] = str_replace('/', '\\/', $replace);
        }
        $map = array_filter($map, static fn ($replace, $find) => $find !== $replace, ARRAY_FILTER_USE_BOTH);
        uksort($map, static fn ($a, $b) => strlen($b) <=> strlen($a) ?: strcmp($a, $b));
        return $map;
    }

    /** @return array{0: string, 1: string}|null scheme and "host[:port][/path]" without a trailing slash */
    private static function split_url(string $url): ?array
    {
        if (!preg_match('#^(https?)://([^/?\#]+)(/[^?\#]*)?#i', trim($url), $m)) {
            return null;
        }
        return [strtolower($m[1]), strtolower($m[2]) . rtrim($m[3] ?? '', '/')];
    }
}