<?php
namespace Relay\Files;

use Relay\Install\CompatPlugin;
use Relay\Multisite\Scope;
use Relay\Support\Paths;

/** The five file groups of a backup, their folders on this site, and what each leaves out. */
final class Groups
{
    /** Groups whose live items that are missing from the backup are moved into the restore point. */
    public const MIRRORED = ['themes', 'plugins', 'uploads'];

    /** wp-content items that never belong to the "other" group. */
    private const NOT_OTHER = [
        'upgrade', 'upgrade-temp-backup', 'cache', 'siterelay-staging', 'siterelay-backups', 'relay-staging', 'relay-backups',
        'advanced-cache.php', 'object-cache.php', 'db.php', 'db-error.php', 'sunrise.php', 'maintenance.php', 'fatal-error-handler.php',
    ];

    /**
     * $scope: a subsite's uploads live in its own folder (uploads/sites/N); everything else is the network's.
     *
     * @return array<string, string> group => absolute folder without a trailing slash
     */
    public static function roots(?Scope $scope = null): array
    {
        $uploads = wp_upload_dir(null, false);
        $roots = [
            'themes' => get_theme_root(),
            'plugins' => WP_PLUGIN_DIR,
            'mu-plugins' => WPMU_PLUGIN_DIR,
            'uploads' => $scope !== null && $scope->is_subsite() ? $scope->uploads_dir : $uploads['basedir'],
            'other' => WP_CONTENT_DIR,
        ];
        /** Lets tests (and unusual hosts) point the groups at other folders. */
        $roots = (array) apply_filters('relay_backup_roots', $roots);
        return array_map(static fn ($path) => rtrim(wp_normalize_path((string) $path), '/'), $roots);
    }

    /**
     * Relay's own plugin folder name, never backed up, copied or overwritten. Taken from plugin_basename(),
     * which knows the name under wp-content/plugins even when that folder is a symlink (PHP's __FILE__ is
     * the resolved path there).
     */
    public static function relay_dir(): string
    {
        $basename = plugin_basename(RELAY_FILE);
        return substr_count($basename, '/') === 1 ? dirname($basename) : basename(dirname(RELAY_FILE));
    }

    /**
     * What each group leaves out: Relay's own items (always), the built-in rules, the user's rules and, per
     * group, top-level items that were not chosen.
     *
     * @param string[] $user user rules (spec §5.1), "!rule" re-includes
     * @param array<string, string[]> $unchosen group => top-level names to leave out
     * @return array<string, Excludes>
     */
    public static function excludes(array $roots, array $user = [], array $unchosen = []): array
    {
        $own = [
            'themes' => [],
            'plugins' => [self::relay_dir()],
            'mu-plugins' => [CompatPlugin::FILE],
            'uploads' => Paths::NAMES,
            'other' => self::other_top_level($roots),
        ];
        $out = [];
        foreach ($own as $group => $names) {
            $out[$group] = new Excludes(in_array($group, ['uploads', 'other'], true), array_merge($names, $unchosen[$group] ?? []), $user, $group === 'other' ? '' : $group . '/');
        }
        return $out;
    }

    /** "group/top-level" items a backup archive or another site may never write (see EntryName::parse(), FileList::import()). */
    public static function protected_items(array $roots): array
    {
        $items = ['plugins/' . self::relay_dir(), 'mu-plugins/' . CompatPlugin::FILE, 'uploads/siterelay', 'uploads/relay'];
        foreach (self::other_top_level($roots) as $name) {
            $items[] = 'other/' . $name;
        }
        foreach (RootFiles::never($roots) as $name) {
            $items[] = 'root/' . $name;
        }
        return $items;
    }

    /** @return string[] top-level wp-content names excluded from "other": the other four roots, caches, drop-ins */
    public static function other_top_level(array $roots): array
    {
        $names = self::NOT_OTHER;
        foreach (['themes', 'plugins', 'mu-plugins', 'uploads'] as $group) {
            // The wp-content folder that holds the group, also when the group lives deeper (a subsite's uploads/sites/N).
            if (strpos($roots[$group], $roots['other'] . '/') === 0) {
                $names[] = explode('/', substr($roots[$group], strlen($roots['other']) + 1))[0];
            }
        }
        return array_values(array_unique($names));
    }
}