import "../core/metadata.ts";
import { defineMetadata, getMetadata } from "../core/metadata.ts";
import { callerFile } from "../core/paths.ts";
import { dirname } from "node:path";

/**
 * `@Controller()` groups HTTP handlers under a path prefix.
 */
export const CONTROLLER_METADATA_KEY = "muddle:controller";

export interface ControllerOptions {
	/** Path prefix of every route of the controller, e.g. `/users`. */
	prefix?: string;
	/** Optional tag used by documentation adapters. */
	tag?: string;
	/** Directory of the file that declares the controller. */
	dir?: string;
}

/** Normalises a prefix to `/segment` shape (no trailing slash). */
export function normalizePrefix(prefix: string): string {
	if (!prefix || prefix === "/") return "";
	const withLeading = prefix.startsWith("/") ? prefix : `/${prefix}`;
	return withLeading.replace(/\/+$/, "");
}

/** Declares a controller. */
export function Controller(
	prefix?: string | ControllerOptions,
): ClassDecorator {
	return (target) => {
		const options: ControllerOptions =
			typeof prefix === "string" ? { prefix } : (prefix ?? {});
		const caller = callerFile();
		defineMetadata(
			CONTROLLER_METADATA_KEY,
			{
				...options,
				dir: options.dir ?? (caller ? dirname(caller) : undefined),
			},
			target as object,
		);
		return target;
	};
}

/** Reads the options of a `@Controller()` decorated class. */
export function getControllerOptions(target: object): ControllerOptions {
	return (
		(getMetadata(CONTROLLER_METADATA_KEY, target) as
			| ControllerOptions
			| undefined) ?? {}
	);
}

/** Reads the normalised path prefix of a controller. */
export function getControllerPrefix(target: object): string {
	return normalizePrefix(getControllerOptions(target).prefix ?? "");
}