copy as part of immutability

packages/http-client/src/ImmutableRequest.ts

@@ -1,23 +1,42 @@
 import { ImmutableURL } from "~/src/ImmutableURL";
 import { Method } from "~/src/Method";
 import { ImmutableHeaders } from "~/src/ImmutableHeaders";
+import { HttpAbortSignal } from "~/src/HttpAbortSignal";
 
 export type Credentials = "omit" | "include" | "same-origin";
 
 export class ImmutableRequest {
   readonly #headers: ImmutableHeaders;
   readonly #url: ImmutableURL;
   readonly #method: Method;
-  readonly #abortSignal: AbortSignal | undefined;
+  readonly #abortSignal: HttpAbortSignal | undefined;
   readonly #credentials: Credentials | undefined;
   readonly #body: unknown;
 
+  copy(
+    request: Partial<
+      Pick<
+        ImmutableRequest,
+        "method" | "url" | "body" | "headers" | "abortSignal" | "credentials"
+      >
+    >,
+  ) {
+    return new ImmutableRequest(
+      request.method ?? this.method,
+      request.url?.copy() ?? this.url.copy(),
+      request.body ?? this.#body,
+      request.headers ?? this.headers,
+      request.abortSignal ?? this.abortSignal,
+      request.credentials ?? this.credentials,
+    );
+  }
+
   protected constructor(
     method: Method,
     url: ImmutableURL,
     body?: unknown | undefined,
     headers?: Record<string, string> | ImmutableHeaders,
-    abortSignal?: AbortSignal | undefined,
+    abortSignal?: HttpAbortSignal | undefined,
     credentials?: Credentials | undefined,
   ) {
     this.#headers = new ImmutableHeaders(headers);
@@ -31,7 +50,7 @@ export class ImmutableRequest {
   static get(
     url: ImmutableURL,
     headers?: Record<string, string> | ImmutableHeaders,
-    abortSignal?: AbortSignal | undefined,
+    abortSignal?: HttpAbortSignal | undefined,
     credentials?: Credentials | undefined,
   ) {
     return new ImmutableRequest(
@@ -47,7 +66,7 @@ export class ImmutableRequest {
   static delete(
     url: ImmutableURL,
     headers?: Record<string, string> | ImmutableHeaders,
-    abortSignal?: AbortSignal | undefined,
+    abortSignal?: HttpAbortSignal | undefined,
     credentials?: Credentials | undefined,
   ) {
     return new ImmutableRequest(
@@ -63,7 +82,7 @@ export class ImmutableRequest {
     url: ImmutableURL,
     body?: unknown | undefined,
     headers?: Record<string, string> | ImmutableHeaders,
-    abortSignal?: AbortSignal | undefined,
+    abortSignal?: HttpAbortSignal | undefined,
     credentials?: Credentials | undefined,
   ) {
     return new ImmutableRequest(
@@ -80,7 +99,7 @@ export class ImmutableRequest {
     url: ImmutableURL,
     body?: unknown | undefined,
     headers?: Record<string, string> | ImmutableHeaders,
-    abortSignal?: AbortSignal | undefined,
+    abortSignal?: HttpAbortSignal | undefined,
     credentials?: Credentials | undefined,
   ) {
     return new ImmutableRequest(
@@ -96,7 +115,7 @@ export class ImmutableRequest {
     url: ImmutableURL,
     body?: unknown | undefined,
     headers?: Record<string, string> | ImmutableHeaders,
-    abortSignal?: AbortSignal | undefined,
+    abortSignal?: HttpAbortSignal | undefined,
     credentials?: Credentials | undefined,
   ) {
     return new ImmutableRequest(
@@ -111,75 +130,19 @@ export class ImmutableRequest {
   get url() {
     return this.#url;
   }
-
   get headers() {
     return this.#headers;
   }
-
-  setHeaders(nextHeaders: ImmutableHeaders) {
-    return new ImmutableRequest(
-      this.#method,
-      this.#url,
-      this.#body,
-      nextHeaders,
-      this.#abortSignal,
-      this.#credentials,
-    );
+  get body() {
+    return this.#body;
   }
-
-  get abortSignal(): AbortSignal | undefined {
+  get abortSignal(): HttpAbortSignal | undefined {
     return this.#abortSignal;
   }
-
-  appendAbortSignal(signal: AbortSignal): ImmutableRequest {
-    return new ImmutableRequest(
-      this.#method,
-      this.#url,
-      this.#body,
-      this.#headers,
-      signal,
-      this.#credentials,
-    );
-  }
-
   get credentials(): Credentials | undefined {
     return this.#credentials;
   }
-
   get method(): Method {
     return this.#method;
   }
-
-  setCredentials(credentials: Credentials): ImmutableRequest {
-    return new ImmutableRequest(
-      this.#method,
-      this.#url,
-      this.#body,
-      this.#headers,
-      this.#abortSignal,
-      credentials,
-    );
-  }
-
-  setMethod(method: Method): ImmutableRequest {
-    return new ImmutableRequest(
-      method,
-      this.#url,
-      this.#body,
-      this.#headers,
-      this.#abortSignal,
-      this.#credentials,
-    );
-  }
-
-  setURL(url: ImmutableURL): ImmutableRequest {
-    return new ImmutableRequest(
-      this.#method,
-      url,
-      this.#body,
-      this.#headers,
-      this.#abortSignal,
-      this.#credentials,
-    );
-  }
 }

packages/http-client/src/ImmutableURL.ts

@@ -1,6 +1,22 @@
 import { URL } from "node:url";
 import { ImmutableURLSearchParams } from "~/src/ImmutableURLSearchParams";
 
+const mutableUrlField = [
+  "hash",
+  "host",
+  "hostname",
+  "href",
+  "password",
+  "pathname",
+  "port",
+  "protocol",
+  "search",
+  "username",
+] as const;
+type MutableURLFields = (typeof mutableUrlField)[number];
+const isMutableUrlField = (it: any): it is MutableURLFields =>
+  mutableUrlField.includes(it);
+
 export class ImmutableURL implements Readonly<URL> {
   readonly #searchParams: ImmutableURLSearchParams;
   readonly #url: URL;
@@ -12,6 +28,18 @@ export class ImmutableURL implements Readonly<URL> {
     this.#searchParams = new ImmutableURLSearchParams(this.#url.searchParams);
   }
 
+  copy(update?: Partial<Pick<ImmutableURL, MutableURLFields>>) {
+    const next = new URL(this.#url.toString());
+    if (update) {
+      Object.entries(update).forEach(([key, value]) => {
+        if (isMutableUrlField(key)) {
+          next[key] = value;
+        }
+      });
+    }
+    return new ImmutableURL(next);
+  }
+
   get searchParams() {
     return this.#searchParams;
   }

packages/http-client/test/ImmutableRequest.ts

@@ -10,11 +10,13 @@ it("constructs a request", () => {
   ImmutableRequest.patch(new ImmutableURL("http://example.com/api"));
 });
 
-it("can modify the headers a header", () => {
+it("can modify the headers", () => {
   const underTest = ImmutableRequest.get(
     new ImmutableURL("https://example.com/api"),
   );
-  const updated = underTest.setHeaders(underTest.headers.set("bingo", "bango"));
+  const updated = underTest.copy({
+    headers: underTest.headers.set("bingo", "bango"),
+  });
   expect(underTest.headers.get("bingo")).not.toEqual(
     updated.headers.get("bingo"),
   );

packages/http-client/test/ImmutableURL.ts

@@ -0,0 +1,11 @@
+import { expect, it } from "vitest";
+import { ImmutableRequest } from "~/src/ImmutableRequest";
+import { ImmutableURL } from "~/src/ImmutableURL";
+
+it("can copy the fields", () => {
+  const underTest = new ImmutableURL("https://example.com/api");
+  const changed = underTest.copy({ username: "user", password: "pass" });
+  expect(underTest.username).not.toEqual(changed.username);
+  expect(underTest.password).not.toEqual(changed.password);
+  expect(changed.toString()).toEqual("https://user:pass@example.com/api");
+});