import {Model} from '../Model.ts'

/**
 * Decorator for model relations. This caches the relation value, so lookups are only done once.
 * @constructor
 */
export function Relation(): MethodDecorator {
    return (target: any, propertyKey, descriptor) => {
        // @ts-ignore
        const original = descriptor.value

        // @ts-ignore
        descriptor.value = function(...args) {
            const model = this as Model<any>
            const cache = model.relation_cache

            const existing_relation = cache.firstWhere('accessor_name', '=', propertyKey)
            if ( existing_relation ) return existing_relation.relation

            // @ts-ignore
            const value = original.apply(this, args)

            cache.push({
                accessor_name: propertyKey,
                relation: value,
            })

            return value
        }
    }
}