fully-react/src/redirects.ts

React Server for Vite

import type { AstroConfig, RouteData, RoutePart } from 'astro';

// https://vercel.com/docs/project-configuration#legacy/routes
interface VercelRoute {
	src: string;
	methods?: string[];
	dest?: string;
	headers?: Record<string, string>;
	status?: number;
	continue?: boolean;
}

// Copied from /home/juanm04/dev/misc/astro/packages/astro/src/core/routing/manifest/create.ts
// 2022-04-26
function getMatchPattern(segments: RoutePart[][]) {
	return segments
		.map((segment) => {
			return segment[0].spread
				? '(?:\\/(.*?))?'
				: '\\/' +
						segment
							.map((part) => {
								if (part)
									return part.dynamic
										? '([^/]+?)'
										: part.content
												.normalize()
												.replace(/\?/g, '%3F')
												.replace(/#/g, '%23')
												.replace(/%5B/g, '[')
												.replace(/%5D/g, ']')
												.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
							})
							.join('');
		})
		.join('');
}

function getReplacePattern(segments: RoutePart[][]) {
	let n = 0;
	let result = '';

	for (const segment of segments) {
		for (const part of segment) {
			if (part.dynamic) result += '$' + ++n;
			else result += part.content;
		}
		result += '/';
	}

	// Remove trailing slash
	result = result.slice(0, -1);

	return result;
}

export function getRedirects(routes: RouteData[], config: AstroConfig): VercelRoute[] {
	let redirects: VercelRoute[] = [];

	if (config.trailingSlash === 'always') {
		for (const route of routes) {
			if (route.type !== 'page' || route.segments.length === 0) continue;

			redirects.push({
				src: config.base + getMatchPattern(route.segments),
				headers: { Location: config.base + getReplacePattern(route.segments) + '/' },
				status: 308,
			});
		}
	} else if (config.trailingSlash === 'never') {
		for (const route of routes) {
			if (route.type !== 'page' || route.segments.length === 0) continue;

			redirects.push({
				src: config.base + getMatchPattern(route.segments) + '/',
				headers: { Location: config.base + getReplacePattern(route.segments) },
				status: 308,
			});
		}
	}

	return redirects;
}