Initial commit (by create-cloudflare CLI)

node_modules/wrangler/templates/pages-template-worker.ts

@@ -0,0 +1,198 @@
+import { match } from "path-to-regexp";
+
+//note: this explicitly does not include the * character, as pages requires this
+const escapeRegex = /[.+?^${}()|[\]\\]/g;
+
+type HTTPMethod =
+	| "HEAD"
+	| "OPTIONS"
+	| "GET"
+	| "POST"
+	| "PUT"
+	| "PATCH"
+	| "DELETE";
+
+/* TODO: Grab these from @cloudflare/workers-types instead */
+type Params<P extends string = string> = Record<P, string | string[]>;
+
+type EventContext<Env, P extends string, Data> = {
+	request: Request;
+	functionPath: string;
+	waitUntil: (promise: Promise<unknown>) => void;
+	passThroughOnException: () => void;
+	next: (input?: Request | string, init?: RequestInit) => Promise<Response>;
+	env: Env & { ASSETS: { fetch: typeof fetch } };
+	params: Params<P>;
+	data: Data;
+};
+
+declare type PagesFunction<
+	Env = unknown,
+	P extends string = string,
+	Data extends Record<string, unknown> = Record<string, unknown>
+> = (context: EventContext<Env, P, Data>) => Response | Promise<Response>;
+/* end @cloudflare/workers-types */
+
+type RouteHandler = {
+	routePath: string;
+	mountPath: string;
+	method?: HTTPMethod;
+	modules: PagesFunction[];
+	middlewares: PagesFunction[];
+};
+
+// inject `routes` via ESBuild
+declare const routes: RouteHandler[];
+// define `__FALLBACK_SERVICE__` via ESBuild
+declare const __FALLBACK_SERVICE__: string;
+
+// expect an ASSETS fetcher binding pointing to the asset-server stage
+type FetchEnv = {
+	[name: string]: { fetch: typeof fetch };
+	ASSETS: { fetch: typeof fetch };
+};
+
+type WorkerContext = {
+	waitUntil: (promise: Promise<unknown>) => void;
+	passThroughOnException: () => void;
+};
+
+function* executeRequest(request: Request) {
+	const requestPath = new URL(request.url).pathname;
+
+	// First, iterate through the routes (backwards) and execute "middlewares" on partial route matches
+	for (const route of [...routes].reverse()) {
+		if (route.method && route.method !== request.method) {
+			continue;
+		}
+
+		// replaces with "\\$&", this prepends a backslash to the matched string, e.g. "[" becomes "\["
+		const routeMatcher = match(route.routePath.replace(escapeRegex, "\\$&"), {
+			end: false,
+		});
+		const mountMatcher = match(route.mountPath.replace(escapeRegex, "\\$&"), {
+			end: false,
+		});
+		const matchResult = routeMatcher(requestPath);
+		const mountMatchResult = mountMatcher(requestPath);
+		if (matchResult && mountMatchResult) {
+			for (const handler of route.middlewares.flat()) {
+				yield {
+					handler,
+					params: matchResult.params as Params,
+					path: mountMatchResult.path,
+				};
+			}
+		}
+	}
+
+	// Then look for the first exact route match and execute its "modules"
+	for (const route of routes) {
+		if (route.method && route.method !== request.method) {
+			continue;
+		}
+		const routeMatcher = match(route.routePath.replace(escapeRegex, "\\$&"), {
+			end: true,
+		});
+		const mountMatcher = match(route.mountPath.replace(escapeRegex, "\\$&"), {
+			end: false,
+		});
+		const matchResult = routeMatcher(requestPath);
+		const mountMatchResult = mountMatcher(requestPath);
+		if (matchResult && mountMatchResult && route.modules.length) {
+			for (const handler of route.modules.flat()) {
+				yield {
+					handler,
+					params: matchResult.params as Params,
+					path: matchResult.path,
+				};
+			}
+			break;
+		}
+	}
+}
+
+export default {
+	async fetch(
+		originalRequest: Request,
+		env: FetchEnv,
+		workerContext: WorkerContext
+	) {
+		let request = originalRequest;
+		const handlerIterator = executeRequest(request);
+		let data = {}; // arbitrary data the user can set between functions
+		let isFailOpen = false;
+
+		const next = async (input?: RequestInfo, init?: RequestInit) => {
+			if (input !== undefined) {
+				let url = input;
+				if (typeof input === "string") {
+					url = new URL(input, request.url).toString();
+				}
+				request = new Request(url, init);
+			}
+
+			const result = handlerIterator.next();
+			// Note we can't use `!result.done` because this doesn't narrow to the correct type
+			if (result.done === false) {
+				const { handler, params, path } = result.value;
+				const context = {
+					request: new Request(request.clone()),
+					functionPath: path,
+					next,
+					params,
+					get data() {
+						return data;
+					},
+					set data(value) {
+						if (typeof value !== "object" || value === null) {
+							throw new Error("context.data must be an object");
+						}
+						// user has overriden context.data, so we need to merge it with the existing data
+						data = value;
+					},
+					env,
+					waitUntil: workerContext.waitUntil.bind(workerContext),
+					passThroughOnException: () => {
+						isFailOpen = true;
+					},
+				};
+
+				const response = await handler(context);
+
+				if (!(response instanceof Response)) {
+					throw new Error("Your Pages function should return a Response");
+				}
+
+				return cloneResponse(response);
+			} else if (__FALLBACK_SERVICE__) {
+				// There are no more handlers so finish with the fallback service (`env.ASSETS.fetch` in Pages' case)
+				const response = await env[__FALLBACK_SERVICE__].fetch(request);
+				return cloneResponse(response);
+			} else {
+				// There was not fallback service so actually make the request to the origin.
+				const response = await fetch(request);
+				return cloneResponse(response);
+			}
+		};
+
+		try {
+			return await next();
+		} catch (error) {
+			if (isFailOpen) {
+				const response = await env[__FALLBACK_SERVICE__].fetch(request);
+				return cloneResponse(response);
+			}
+
+			throw error;
+		}
+	},
+};
+
+// This makes a Response mutable
+const cloneResponse = (response: Response) =>
+	// https://fetch.spec.whatwg.org/#null-body-status
+	new Response(
+		[101, 204, 205, 304].includes(response.status) ? null : response.body,
+		response
+	);