import {Canonical} from './Canonical'

/**
 * Variant of the Canonical unit whose accessor allows accessing nested
 * properties on the resolved objects.
 *
 * @example
 * The Config unit is a CanonicalRecursive unit. So, once a config file is
 * resolved, a particular value in the config file can be retrieved as well:
 *
 * ```typescript
 * // app/config/my/config.config.ts
 * {
 *     foo: {
 *         bar: 123
 *     }
 * }
 * ```
 *
 * This can be accessed as:
 * ```typescript
 * config.get('my:config.foo.bar')  // => 123
 * ```
 */
export class CanonicalRecursive extends Canonical<any> {
    public get(key: string, fallback?: unknown): any | undefined {
        const parts = key.split('.')
        let currentValue = this.loadedItems
        for ( const part of parts ) {
            currentValue = currentValue?.[part]
        }
        return currentValue ?? fallback
    }
}