Files
ihasmail-inbuxa/scripts/basePath.mjs
T

71 lines
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JavaScript

/**
* The subpath ihasmail is mounted at, from `BASE_PATH`.
*
* Plain JS, and here rather than in either package, because both halves of the
* app have to agree on the answer: `web/vite.config.ts` bakes it into the built
* asset URLs and `server/src/config.ts` reads it again to decide where the
* routes live. Two implementations of "what does /mail/ mean" is exactly the
* bug where the server serves an app whose own script tags point somewhere
* else, and the page comes up blank with no clue why.
*
* The canonical form is a leading slash and no trailing one -- `/mail` -- with
* the empty string for the root. Empty is the ordinary case and it is chosen
* so that the concatenation `${base}/api/health` is right without a branch:
* anything with a trailing slash would need one, and every caller that forgot
* would produce `//api/health`, which browsers read as a *protocol-relative
* URL* and send to a host called `api`. Getting that wrong once, quietly, in
* one call site is worse than the small awkwardness of an empty string.
*/
/**
* Reduce whatever the operator wrote to the canonical form.
*
* Accepts `/mail`, `mail`, `/mail/`, `mail/`, `//mail//`, an empty string and
* undefined, because the variable is typed by a human into a compose file or a
* `docker run` line and every one of those is a reasonable thing to write.
* Being strict here would mean an instance that refuses to start over a
* trailing slash, which teaches nobody anything.
*
* A value of `/` means the root and is returned as empty, since `/` and `""`
* describe the same mount and only one of them can be the canonical one.
*/
export function normalizeBasePath(value) {
if (typeof value !== "string") return "";
// Collapse repeated separators before trimming: `//mail//` is a typo, not a
// path with empty segments in it, and `path.posix.normalize` is not
// available to the browser bundle that also uses this.
const trimmed = value.trim().replace(/\/+/g, "/").replace(/^\/|\/$/g, "");
if (!trimmed) return "";
return `/${trimmed}`;
}
/**
* The same value as a directory URL -- `/` or `/mail/`.
*
* This is the form Vite's `base` and the PWA scope want, both of which are
* about "the directory the app lives in" rather than a path to join onto.
*/
export function baseUrlOf(basePath) {
return `${normalizeBasePath(basePath)}/`;
}
/**
* Whether `pathname` falls inside the mount, and what is left of it if so.
*
* Returns null for anything outside, so a caller can 404 rather than guess.
* The bare mount with no trailing slash -- a request for `/mail` -- yields
* `/`, because that is the app's own index and typing the prefix without the
* slash is how people reach it.
*
* The comparison is deliberately not `startsWith(base)`: that would let
* `/mailbox` in under a `/mail` mount and serve it the app shell, which is
* both wrong and a small open door for a neighboring site on the same host.
*/
export function stripBasePath(basePath, pathname) {
const base = normalizeBasePath(basePath);
if (!base) return pathname;
if (pathname === base) return "/";
if (pathname.startsWith(`${base}/`)) return pathname.slice(base.length);
return null;
}