import "../core/metadata.ts";
import { defineMemberMetadata, getLatestMetadata } from "../core/metadata.ts";
import type { Token } from "../core/container.ts";
import {
	INJECT_TOKENS_METADATA,
	OPTIONAL_PARAMS_METADATA,
} from "../core/container.ts";

/**
 * `@Inject()` overrides the injection token of a constructor parameter.
 */
export function Inject(token: Token): ParameterDecorator {
	return (target, _propertyKey, index) => {
		const entries =
			(getLatestMetadata(INJECT_TOKENS_METADATA, target) as
				| { index: number; token: Token }[]
				| undefined) ?? [];
		entries.push({ index, token });
		defineMemberMetadata(INJECT_TOKENS_METADATA, entries, target as object);
	};
}

/**
 * `@Optional()` allows a dependency to be missing.
 */
export function Optional(): ParameterDecorator {
	return (target, _propertyKey, index) => {
		const entries =
			(getLatestMetadata(OPTIONAL_PARAMS_METADATA, target) as
				| number[]
				| undefined) ?? [];
		entries.push(index);
		defineMemberMetadata(OPTIONAL_PARAMS_METADATA, entries, target as object);
	};
}