// Copyright (c) Cratis. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

import 'reflect-metadata';
import { FromEventMetadata } from './FromEventMetadata.js';
import { FromEventOptions } from './FromEventOptions.js';
import { DecoratorType, TypeDiscoverer } from '../../types/index.js';
import type { Constructor } from '@cratis/fundamentals';

const METADATA_KEY = 'chronicle:projection:fromEvent';

/**
 * Class decorator that declares which event type populates instances of this read model.
 * @param eventType - The event constructor.
 * @param options - Optional key configuration.
 * @returns A class decorator.
 */
export function fromEvent(eventType: Function, options?: FromEventOptions): ClassDecorator {
    return (target: object) => {
        const existing: FromEventMetadata[] = Reflect.getMetadata(METADATA_KEY, target) ?? [];
        const metadata: FromEventMetadata = { eventType, ...options };
        Reflect.defineMetadata(METADATA_KEY, [...existing, metadata], target);
        TypeDiscoverer.default.register(DecoratorType.ReadModel, target as Constructor);
    };
}

/**
 * Retrieves all fromEvent metadata stored on the given class constructor.
 * @param target - The class constructor.
 * @returns An array of fromEvent metadata entries.
 */
export function getFromEventMetadata(target: Function): FromEventMetadata[] {
    return Reflect.getMetadata(METADATA_KEY, target) ?? [];
}

/**
 * Checks whether the given class has any fromEvent metadata.
 * @param target - The class constructor.
 * @returns True if the class has fromEvent metadata; false otherwise.
 */
export function hasFromEventMetadata(target: Function): boolean {
    return Reflect.hasMetadata(METADATA_KEY, target);
}