import "../core/metadata.ts";
import { defineMetadata, getMetadata } from "../core/metadata.ts";

export const COMPONENT_METADATA_KEY = "muddle:component";

export interface ComponentOptions {
	/** Name used inside the templates, defaults to the class name. */
	name?: string;
	/**
	 * Renders the component after the page, the response is streamed.
	 */
	deferred?: boolean;
	description?: string;
	params?: Record<string, string>;
}

/** Runtime description of a server component. */
export interface ComponentMetadata {
	name: string;
	deferred: boolean;
	description?: string;
	params?: Record<string, string>;
}

/** Declares a server component. */
export function Component(options: ComponentOptions = {}): ClassDecorator {
	return (target) => {
		const metadata: ComponentMetadata = {
			name: options.name ?? target.name,
			deferred: options.deferred === true,
			description: options.description,
			params: options.params,
		};
		defineMetadata(COMPONENT_METADATA_KEY, metadata, target as object);
		return target;
	};
}

/** Reads the metadata of a server component. */
export function getComponentMetadata(
	target: object,
): ComponentMetadata | undefined {
	return getMetadata(COMPONENT_METADATA_KEY, target) as
		| ComponentMetadata
		| undefined;
}

/** `true` when the class is a server component. */
export function isComponent(target: object): boolean {
	return getComponentMetadata(target) !== undefined;
}