<?php
namespace Relay\Files;

use Relay\Support\RelayError;

/**
 * Which files a pull or push copies (spec §5.1): a choice per group, the user's exclude rules, mirror and
 * low-disk mode. normalize() checks input from this site's UI and from another site alike; every group is
 * present in the result.
 */
final class FileParts
{
    public const MODES = [
        'themes' => ['none', 'all', 'active', 'selected', 'except'],
        'plugins' => ['none', 'all', 'active', 'selected', 'except'],
        'mu-plugins' => ['none', 'all', 'selected', 'except'],
        'uploads' => ['none', 'all', 'changed', 'since'],
        'other' => ['none', 'all', 'selected', 'except'],
    ];
    private const MAX_ITEMS = 500;
    private const MAX_RULES = 100;

    /** @param mixed $input */
    public static function normalize($input): array
    {
        $in = is_array($input) ? $input : [];
        $out = [];
        foreach (self::MODES as $group => $modes) {
            $g = is_array($in[$group] ?? null) ? $in[$group] : [];
            $mode = is_string($g['mode'] ?? null) ? $g['mode'] : 'none';
            if (!in_array($mode, $modes, true)) {
                /* translators: 1: choice, 2: file group, e.g. "plugins" */
                throw self::invalid(esc_html(sprintf(__('Unknown choice "%1$s" for %2$s.', 'siterelay'), substr($mode, 0, 40), $group)));
            }
            if ($group === 'uploads') {
                $since = null;
                if ($mode === 'since') {
                    $since = is_string($g['since'] ?? null) ? $g['since'] : '';
                    if (!preg_match('/^\d{4}-\d{2}-\d{2}$/', $since) || !checkdate((int) substr($since, 5, 2), (int) substr($since, 8, 2), (int) substr($since, 0, 4))) {
                        throw self::invalid(esc_html__('Choose the date from which uploads are copied.', 'siterelay'));
                    }
                }
                $out[$group] = ['mode' => $mode, 'since' => $since];
                continue;
            }
            $items = [];
            if ($mode === 'selected' || $mode === 'except') {
                foreach ((array) ($g['items'] ?? []) as $item) {
                    if (!is_string($item) || !RelPath::valid($item) || strpos($item, '/') !== false) {
                        /* translators: %s: name of a theme, plugin or folder */
                        throw self::invalid(esc_html(sprintf(__('"%s" is not a valid name.', 'siterelay'), is_string($item) ? substr($item, 0, 80) : '?')));
                    }
                    $items[] = $item;
                }
                $items = array_values(array_unique($items));
                if (count($items) > self::MAX_ITEMS) {
                    throw self::invalid(esc_html__('Too many items were chosen.', 'siterelay'));
                }
                if ($mode === 'selected' && $items === []) {
                    /* translators: %s: file group, e.g. "plugins" */
                    throw self::invalid(esc_html(sprintf(__('Choose at least one item for %s, or copy none.', 'siterelay'), $group)));
                }
            }
            $out[$group] = ['mode' => $mode, 'items' => $items];
        }
        $rules = $in['excludes'] ?? [];
        if (is_string($rules)) {
            $rules = preg_split('/\r\n|\r|\n/', $rules) ?: [];
        }
        $out['excludes'] = [];
        foreach (is_array($rules) ? $rules : [] as $rule) {
            $rule = is_string($rule) ? trim($rule) : '';
            if ($rule === '') {
                continue;
            }
            if (strlen($rule) > 255 || strpos($rule, "\0") !== false) {
                /* translators: %s: an exclude rule */
                throw self::invalid(esc_html(sprintf(__('This exclude rule is not valid: %s', 'siterelay'), substr($rule, 0, 80))));
            }
            $out['excludes'][] = $rule;
        }
        if (count($out['excludes']) > self::MAX_RULES) {
            throw self::invalid(esc_html__('Too many exclude rules.', 'siterelay'));
        }
        // Low-disk mode only concerns uploads; mirror needs the restore point low-disk mode skips (spec §5.1, §5.4).
        $out['low_disk'] = !empty($in['low_disk']) && $out['uploads']['mode'] !== 'none';
        $out['mirror'] = !empty($in['mirror']) && !$out['low_disk'];
        return $out;
    }

    public static function any(array $parts): bool
    {
        return self::groups($parts) !== [];
    }

    /** @return string[] the groups that are copied, in a fixed order */
    public static function groups(array $parts): array
    {
        $out = [];
        foreach (array_keys(self::MODES) as $group) {
            if (($parts[$group]['mode'] ?? 'none') !== 'none') {
                $out[] = $group;
            }
        }
        return $out;
    }

    /**
     * Which of a site's top-level items in $group are copied.
     *
     * @param string[] $available the site's top-level items in the group
     * @param string[] $active the active ones (themes: current theme and its parent; plugins: active plugins)
     * @return string[]
     */
    public static function items(array $parts, string $group, array $available, array $active): array
    {
        $part = $parts[$group] ?? ['mode' => 'none'];
        switch ($part['mode']) {
            case 'none':
                return [];
            case 'active':
                return array_values(array_intersect($available, $active));
            case 'selected':
                return array_values(array_intersect($available, $part['items']));
            case 'except':
                return array_values(array_diff($available, $part['items']));
            default:
                return array_values($available);
        }
    }

    /** May a file list entry of $group/$rel belong to these parts? (Checks what can be checked from the other side.) */
    public static function allows(array $parts, string $group, string $rel): bool
    {
        $part = $parts[$group] ?? ['mode' => 'none'];
        $top = RelPath::top($rel);
        switch ($part['mode']) {
            case 'none':
                return false;
            case 'selected':
                return in_array($top, $part['items'], true);
            case 'except':
                return !in_array($top, $part['items'], true);
            default:
                return true;
        }
    }

    private static function invalid(string $message): RelayError
    {
        return new RelayError('files.invalid', esc_html($message));
    }
}