import "../core/metadata.ts";
import { defineMemberMetadata, getMemberMetadata } from "../core/metadata.ts";

export const PARAM_METADATA_KEY = "muddle:params";

export type ParamKind =
	| "param"
	| "body"
	| "query"
	| "request"
	| "response"
	| "locals"
	| "form";

export interface ParamMetadata {
	index: number;
	kind: ParamKind;
	/** Name of the route parameter or query key. */
	name?: string;
}

/** `@Param('id')`, a route parameter. */
export function Param(name?: string): ParameterDecorator {
	return (target, _propertyKey, index) => {
		defineMemberMetadata(
			PARAM_METADATA_KEY,
			{ index, kind: "param", name } satisfies ParamMetadata,
			target as object,
			_propertyKey as string,
		);
	};
}

/** `@Body()`, the parsed request body. */
export function Body(): ParameterDecorator {
	return (target, _propertyKey, index) => {
		defineMemberMetadata(
			PARAM_METADATA_KEY,
			{ index, kind: "body" } satisfies ParamMetadata,
			target as object,
			_propertyKey as string,
		);
	};
}

/** `@Form()`, the submitted form fields. */
export function Form(): ParameterDecorator {
	return (target, _propertyKey, index) => {
		defineMemberMetadata(
			PARAM_METADATA_KEY,
			{ index, kind: "form" } satisfies ParamMetadata,
			target as object,
			_propertyKey as string,
		);
	};
}

/** `@Query('page')`, a query string entry. */
export function Query(name?: string): ParameterDecorator {
	return (target, _propertyKey, index) => {
		defineMemberMetadata(
			PARAM_METADATA_KEY,
			{ index, kind: "query", name } satisfies ParamMetadata,
			target as object,
			_propertyKey as string,
		);
	};
}

/** `@Req()`, the full request context. */
export function Req(): ParameterDecorator {
	return (target, _propertyKey, index) => {
		defineMemberMetadata(
			PARAM_METADATA_KEY,
			{ index, kind: "request" } satisfies ParamMetadata,
			target as object,
			_propertyKey as string,
		);
	};
}

/** `@Res()`, the response builder. */
export function Res(): ParameterDecorator {
	return (target, _propertyKey, index) => {
		defineMemberMetadata(
			PARAM_METADATA_KEY,
			{ index, kind: "response" } satisfies ParamMetadata,
			target as object,
			_propertyKey as string,
		);
	};
}

/** `@Locals()`, the mutable per request scratch space. */
export function Locals(): ParameterDecorator {
	return (target, _propertyKey, index) => {
		defineMemberMetadata(
			PARAM_METADATA_KEY,
			{ index, kind: "locals" } satisfies ParamMetadata,
			target as object,
			_propertyKey as string,
		);
	};
}

/**
 * Reads the parameter descriptors of a controller method.
 */
export function getParamMetadata(
	target: object,
	propertyKey?: string,
): Map<number, ParamMetadata> {
	const entries = propertyKey
		? (getMemberMetadata(
				PARAM_METADATA_KEY,
				target,
				propertyKey,
			) as ParamMetadata[])
		: [];
	const map = new Map<number, ParamMetadata>();
	for (const entry of entries) {
		map.set(entry.index, entry);
	}
	return map;
}