feature: support .spa files for Single Page Apps

handlers/html.ts

@@ -18,7 +18,7 @@ const replaceAsync = async (str: string, regex: RegExp, asyncFn: (match: any, ..
 };
 
 const SSI_REGEX: RegExp = /\<\!--\s+#include\s+(?<type>.*?)\s*=\s*["'](?<location>.*?)['"]\s+-->/mg;
-async function load_html_with_ssi(html_file: string): Promise<string> {
+export async function load_html_with_ssi(html_file: string): Promise<string> {
 	const html_file_content: string = await Deno.readTextFile(html_file);
 	const processed: string = await replaceAsync(
 		html_file_content,

handlers/index.ts

@@ -2,10 +2,12 @@ import * as html from './html.ts';
 import * as markdown from './markdown.ts';
 import * as static_files from './static.ts';
 import * as typescript from './typescript.ts';
+import * as spa from './spa.ts';
 
 export default {
 	html,
 	markdown,
 	typescript,
-	static: static_files
+	static: static_files,
+	spa
 };

handlers/spa.ts

@@ -0,0 +1,193 @@
+/**
+ * Handles requests for route beneath a directory with a .spa file dropped in it.
+ * @module
+ */
+
+import * as path from '@std/path';
+import { PRECHECK, SERVER } from '../server.ts';
+import { getCookies } from '@std/http/cookie';
+import { load_html_with_ssi } from './html.ts';
+
+async function find_spa_file_root(request_path: string): Promise<string | undefined> {
+	let current_path = Deno.cwd();
+	const relative_path = path.relative(current_path, request_path);
+	const path_elements = relative_path.split('/').slice(0, -1);
+
+	let element;
+
+	while ((element = path_elements.shift())) {
+		current_path = path.join(current_path, element);
+
+		try {
+			const spa_file_stat = await Deno.stat(path.join(current_path, '.spa'));
+
+			if (spa_file_stat.isFile) {
+				return current_path;
+			}
+		} catch (error) {
+			if (error instanceof Deno.errors.NotFound) {
+				continue;
+			}
+
+			throw error;
+		}
+	}
+
+	return undefined;
+}
+
+export type HTTP_METHOD = 'GET' | 'PUT' | 'POST' | 'DELETE' | 'HEAD' | 'OPTIONS';
+export type HANDLER_METHOD = (
+	request: Request,
+	normalized_path: string,
+	server: SERVER
+) => Promise<Response | undefined> | Response | undefined;
+export const PRECHECKS: Partial<Record<HTTP_METHOD, PRECHECK[]>> = {};
+export const HANDLERS: Partial<Record<HTTP_METHOD, HANDLER_METHOD>> = {
+	HEAD: async (_request: Request, normalized_path: string, _server: SERVER): Promise<Response | undefined> => {
+		const spa_root = await find_spa_file_root(normalized_path);
+		if (!spa_root) {
+			return;
+		}
+
+		for await (const index_filename of ['index.html', 'index.htm']) {
+			try {
+				const index_file_path = path.join(spa_root, index_filename);
+				const index_file_stat = await Deno.stat(index_file_path);
+
+				if (index_file_stat.isFile) {
+					return new Response('', {
+						headers: {
+							'Content-Type': 'text/html',
+							'Content-Length': `${index_file_stat.size}`,
+							'Last-Modified': `${index_file_stat.mtime ?? index_file_stat.ctime}`
+						}
+					});
+				}
+			} catch (error) {
+				if (error instanceof Deno.errors.NotFound) {
+					continue;
+				}
+
+				throw error;
+			}
+		}
+	},
+
+	GET: async (request: Request, normalized_path: string, _server: SERVER): Promise<Response | undefined> => {
+		const spa_root = await find_spa_file_root(normalized_path);
+		if (!spa_root) {
+			return;
+		}
+
+		for await (const index_filename of ['index.html', 'index.htm']) {
+			try {
+				const index_file_path = path.join(spa_root, index_filename);
+				const index_file_stat = await Deno.stat(index_file_path);
+
+				if (index_file_stat.isFile) {
+					const processed: string = await load_html_with_ssi(index_file_path);
+
+					const accepts = request.headers.get('accept') ?? 'text/html';
+					if (!['*/*', 'text/html', 'text/plain'].includes(accepts)) {
+						return new Response('unsupported accepts header for SPA: ' + accepts, {
+							status: 400
+						});
+					}
+
+					return new Response(processed, {
+						headers: {
+							'Content-Type': accepts === '*/*' ? 'text/html' : accepts
+						}
+					});
+				}
+			} catch (error) {
+				if (error instanceof Deno.errors.NotFound) {
+					continue;
+				}
+
+				throw error;
+			}
+		}
+	},
+
+	OPTIONS: async (request: Request, normalized_path: string): Promise<Response | undefined> => {
+		const spa_root = await find_spa_file_root(normalized_path);
+		if (!spa_root) {
+			return;
+		}
+
+		for await (const index_filename of ['index.html', 'index.htm']) {
+			try {
+				const index_file_path = path.join(spa_root, index_filename);
+				const index_file_stat = await Deno.stat(index_file_path);
+
+				if (index_file_stat.isFile) {
+					const accepts = request.headers.get('accept') ?? 'text/html';
+					if (!['*/*', 'text/html', 'text/plain'].includes(accepts)) {
+						return new Response('unsupported accepts header for SPA: ' + accepts, {
+							status: 400
+						});
+					}
+
+					const allowed = ['GET', 'HEAD', 'OPTIONS'];
+
+					return new Response('', {
+						headers: {
+							'Allow': allowed.sort().join(','),
+							'Access-Control-Allow-Origin': Deno.env.get('SERVERUS_ACCESS_CONTROL_ALLOW_ORIGIN') ?? '*'
+						}
+					});
+				}
+			} catch (error) {
+				if (error instanceof Deno.errors.NotFound) {
+					continue;
+				}
+
+				throw error;
+			}
+		}
+	}
+};
+
+/**
+ * Handles requests for static files.
+ *
+ * @param request The incoming HTTP request
+ * @returns Either a response (a static file was requested and returned properly) or undefined if unhandled.
+ */
+export default async function handle_spa_files_in_path(request: Request, server: SERVER): Promise<Response | undefined> {
+	const method: HTTP_METHOD = request.method.toUpperCase() as HTTP_METHOD;
+	const handler: HANDLER_METHOD | undefined = HANDLERS[method];
+
+	if (!handler) {
+		return;
+	}
+
+	const url = new URL(request.url);
+	const normalized_path = path.resolve(path.normalize(decodeURIComponent(url.pathname)).replace(/^\/+/, ''));
+
+	// if they're requesting something outside the working dir, just bail
+	if (!normalized_path.startsWith(Deno.cwd())) {
+		return;
+	}
+
+	const prechecks: PRECHECK[] = PRECHECKS[method] ?? [];
+
+	const cookies: Record<string, string> = getCookies(request.headers);
+	const query = Object.fromEntries(new URL(request.url).searchParams.entries());
+
+	const metadata = {
+		cookies,
+		query
+	};
+
+	for await (const precheck of prechecks) {
+		const error_response: Response | undefined = await precheck(request, metadata);
+		if (error_response) {
+			return error_response;
+		}
+	}
+
+	return await handler(request, normalized_path, server);
+}