kaction.ts

type LiteralString<T> = string extends T ? never : T

export type Kaction = {
	name: string
	schema: ZodType
	actions: Record<string, Action>
	action_name: string
	_types: {
		input: unknown
		output: Record<string, unknown>
	}
}

export function kaction<
	N extends string,
	I,
	O,
	R extends string | null,
	P extends Partial<Record<string, string>> = Partial<Record<string, string>>,
>(options: {
	/** This has to be specified as a constant, for example `'login' as const` */
	name: LiteralString<N>
	schema: ZodType<I>
	handler: (event: RequestEvent<P, R> & { input: I }, input: I) => O | Promise<O>
}): Record<
	N,
	((event: RequestEvent<P, R>) => Promise<O>) & {
		action_name: LiteralString<N>
		_types: { input: I; output: Awaited<O> }
	}
> {
	const action_fn = async function (event: RequestEvent<P, R>) {
		const json = await event.request.json()
		const result = options.schema.safeParse(json)
		if (!result.success) sk_error(400, prettifyError(result.error))

		const action_event = Object.assign(event, {
			input: result.data,
		})

		return options.handler(action_event, result.data)
	}

	const action = Object.assign(action_fn, {
		action_name: options.name,
		_types: {
			input: undefined as unknown as I,
			output: undefined as unknown as Awaited<O>,
		},
	})

	const actions = {} as Record<N, typeof action>
	actions[options.name] = action
	return actions
}