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|
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
);
|
