Improve emitted type declarations for TS 5.5+ (#116)

.changeset/flat-bugs-relate.md

@@ -0,0 +1,127 @@
+---
+"astro-integration-kit": minor
+---
+
+Improve emitted inferred types for libraries
+
+For the following code:
+
+```ts
+export const utility = defineUtility('astro:config:setup')((
+	params: HookParameters<'astro:config:setup'>,
+	options: { name: string }
+) => {
+	// do something
+});
+
+export const integration defineIntegration({
+	name: 'some-integration',
+	setup: () => ({
+		hooks: {
+			'astro:config:setup': (params) => {
+				// do something
+			},
+		},
+		something: (it: string): string => it,
+	}),
+});
+```
+
+Previously, the emitted declarations would be:
+
+```ts
+import * as astro from "astro";
+import { AstroIntegrationLogger } from "astro";
+
+type Prettify<T> = {
+  [K in keyof T]: T[K];
+} & {};
+
+type DeepPartial<T> = {
+  [P in keyof T]?: T[P] extends (infer U)[]
+    ? DeepPartial<U>[]
+    : T[P] extends object | undefined
+    ? DeepPartial<T[P]>
+    : T[P];
+};
+
+export const utility: (
+  params: {
+    config: astro.AstroConfig;
+    command: "dev" | "build" | "preview";
+    isRestart: boolean;
+    updateConfig: (
+      newConfig: DeepPartial<astro.AstroConfig>
+    ) => astro.AstroConfig;
+    addRenderer: (renderer: astro.AstroRenderer) => void;
+    addWatchFile: (path: URL | string) => void;
+    injectScript: (stage: astro.InjectedScriptStage, content: string) => void;
+    injectRoute: (injectRoute: astro.InjectedRoute) => void;
+    addClientDirective: (directive: astro.ClientDirectiveConfig) => void;
+    addDevOverlayPlugin: (entrypoint: string) => void;
+    addDevToolbarApp: (entrypoint: astro.DevToolbarAppEntry | string) => void;
+    addMiddleware: (mid: astro.AstroIntegrationMiddleware) => void;
+    logger: AstroIntegrationLogger;
+  },
+  options: {
+    name: string;
+  }
+) => void;
+export const integration: () => astro.AstroIntegration &
+  Prettify<
+    Omit<
+      ReturnType<
+        () => {
+          hooks: {
+            "astro:config:setup": (params: {
+              config: astro.AstroConfig;
+              command: "dev" | "build" | "preview";
+              isRestart: boolean;
+              updateConfig: (
+                newConfig: DeepPartial<astro.AstroConfig>
+              ) => astro.AstroConfig;
+              addRenderer: (renderer: astro.AstroRenderer) => void;
+              addWatchFile: (path: URL | string) => void;
+              injectScript: (
+                stage: astro.InjectedScriptStage,
+                content: string
+              ) => void;
+              injectRoute: (injectRoute: astro.InjectedRoute) => void;
+              addClientDirective: (
+                directive: astro.ClientDirectiveConfig
+              ) => void;
+              addDevOverlayPlugin: (entrypoint: string) => void;
+              addDevToolbarApp: (
+                entrypoint: astro.DevToolbarAppEntry | string
+              ) => void;
+              addMiddleware: (mid: astro.AstroIntegrationMiddleware) => void;
+              logger: AstroIntegrationLogger;
+            }) => void;
+          };
+          something: (it: string) => string;
+        }
+      >,
+      keyof astro.AstroIntegration
+    >
+  >;
+```
+
+Now the emitted declarations would be:
+
+```ts
+import * as astro from "astro";
+import * as astro_integration_kit from "astro-integration-kit";
+
+export const utility: astro_integration_kit.HookUtility<
+  "astro:config:setup",
+  [
+    options: {
+      name: string;
+    }
+  ],
+  void
+>;
+export const integration: () => astro.AstroIntegration & {
+  something: (it: string) => string;
+};
+```