index.astro

---
import { sidebar } from 'virtual:docs-template/site-meta';
import { readFileSync, existsSync } from 'node:fs';
import path from 'node:path';

type SidebarEntry = { label: string; slug: string } | { label: string; items: SidebarEntry[] };
type TocItem = { name?: string; href?: string; default?: boolean; header?: boolean; items?: TocItem[] };

// DOCS_SOURCE_PATH is set by createDocsSite() to the absolute components docsDir.
// This is the same path used by the sidebar and content collection — single source of truth.
const docsDir = process.env.DOCS_SOURCE_PATH ?? path.join(process.cwd(), 'src', 'content', (process.env.DOCS_LANG ?? 'en'), 'components');
const tocPath = path.join(docsDir, 'toc.json');
const toc: TocItem[] = existsSync(tocPath)
    ? (JSON.parse(readFileSync(tocPath, 'utf8')) as TocItem[])
    : [];

function hrefToSlug(href: string): string {
    if (!href) return '';
    let slug = href
        .replace(/\\/g, '/')
        .replace(/\.(md|mdx)$/i, '')
        .toLowerCase();
    slug = slug.replace(/\/index$/, '');
    return slug === 'index' ? '' : slug;
}


function joinSlugPrefix(slugPrefix: string, slug: string): string {
    if (!slugPrefix) return slug;
    return slug ? `${slugPrefix}/${slug}` : slugPrefix;
}

function findDefaultSlug(items: TocItem[]): string | null {
    for (const item of items) {
        if (item.default && item.href) {
            return hrefToSlug(item.href);
        }
        if (item.items) {
            const found = findDefaultSlug(item.items);
            if (found) return found;
        }
    }
    return null;
}

function firstSlug(items: SidebarEntry[]): string | null {
    for (const item of items) {
        if ('slug' in item) return item.slug;
        if ('items' in item) {
            const found = firstSlug(item.items);
            if (found) return found;
        }
    }
    return null;
}

function slugExistsInSidebar(items: SidebarEntry[], target: string): boolean {
    for (const item of items) {
        if ('slug' in item && item.slug === target) return true;
        if ('items' in item && slugExistsInSidebar(item.items, target)) return true;
    }
    return false;
}

const typedSidebar = sidebar as SidebarEntry[];
const defaultSlug = findDefaultSlug(toc);
const slugPrefix = process.env.DOCS_SLUG_PREFIX ?? '';
const prefixedDefault = defaultSlug !== null ? joinSlugPrefix(slugPrefix, defaultSlug) : null;
const slug = (prefixedDefault && slugExistsInSidebar(typedSidebar, prefixedDefault))
    ? prefixedDefault
    : firstSlug(typedSidebar);
const base = import.meta.env.BASE_URL.replace(/\/$/, '');
const redirectTo = slug ? `${base}/${slug}` : `${base}/404`;
return Astro.redirect(redirectTo, 301);
---