feat: add createMutation function

.changeset/strong-bugs-allow.md

@@ -0,0 +1,5 @@
+---
+"@epicenterhq/result": minor
+---
+
+Add createMutation function

src/index.ts

@@ -1,2 +1,3 @@
-export { Result, Ok, Err, trySync, tryAsync } from "./result";
-export { createServiceErrorFns, MutationFn, QueryFn } from "./services";
+export { Err, Ok, Result, tryAsync, trySync } from "./result";
+export { createMutation, QueryFn } from "./query";
+export { createServiceErrorFns } from "./services";

src/query.ts

@@ -0,0 +1,54 @@
+import type { Result } from "./result";
+import { Ok } from "./result";
+
+export type QueryFn<I, O, ServiceErrorProperties> = (
+	input: I,
+) => Promise<Result<O, ServiceErrorProperties>>;
+
+export function createMutation<I, O, ServiceError, TContext>({
+	mutationFn,
+	onMutate = () => Ok({} as TContext),
+	onSuccess = () => undefined,
+	onError = () => undefined,
+	onSettled = () => undefined,
+}: {
+	mutationFn: (args: { input: I; context: TContext }) =>
+		| Promise<Result<O, ServiceError>>
+		| Result<O, ServiceError>;
+	onMutate?: (
+		input: I,
+	) => Promise<Result<TContext, ServiceError>> | Result<TContext, ServiceError>;
+	onSuccess?: (args: { output: O; input: I; context: TContext }) => void;
+	onError?: (args: {
+		error: ServiceError;
+		input: I;
+		contextResult: Result<TContext, ServiceError>;
+	}) => void;
+	onSettled?: (args: {
+		result: Result<O, ServiceError>;
+		input: I;
+		contextResult: Result<TContext, ServiceError>;
+	}) => void;
+}) {
+	const mutate = async (input: I): Promise<void> => {
+		const contextResult = await onMutate(input);
+		if (!contextResult.ok) {
+			const error = contextResult.error;
+			onError({ error, input, contextResult });
+			onSettled({ result: contextResult, input, contextResult });
+			return;
+		}
+		const context = contextResult.data;
+		const result = await mutationFn({ input, context });
+		if (!result.ok) {
+			const error = result.error;
+			onError({ error, input, contextResult });
+			onSettled({ result, input, contextResult });
+			return;
+		}
+		const output = result.data;
+		onSuccess({ output, input, context });
+		onSettled({ result, input, contextResult });
+	};
+	return { mutate };
+}

src/services.ts

@@ -20,21 +20,3 @@ export const createServiceErrorFns = <
 	trySync,
 	tryAsync,
 });
-
-export type QueryFn<I, O, ServiceErrorProperties> = (
-	input: I,
-) => Promise<Result<O, ServiceErrorProperties>>;
-
-export type MutationFn<I, O, ServiceErrorProperties> = (
-	input: I,
-	callbacks?: {
-		onMutate?: (input: I) => Promise<void> | void;
-		onSuccess?: (output: O, input: I) => Promise<void> | void;
-		onError?: (error: ServiceErrorProperties, input: I) => Promise<void> | void;
-		onSettled?: (
-			output: O | undefined,
-			error: ServiceErrorProperties | null,
-			input: I,
-		) => Promise<void> | void;
-	},
-) => Promise<void>;