/*!
 * V4Fire Core
 * https://github.com/V4Fire/Core
 *
 * Released under the MIT license
 * https://github.com/V4Fire/Core/blob/master/LICENSE
 */

import Assembler, { AssemblerOptions } from 'core/json/stream/assembler';
import type { Token, TokenProcessor } from 'core/json/stream/parser';

export interface StreamedArray<T = unknown> {
	index: number;
	value: T;
}

export interface StreamedObject<T = unknown> {
	key: string;
	value: T;
}

export default abstract class Streamer<T = unknown> implements TokenProcessor<T> {
	/**
	 * Actual depth of the streamed structure
	 */
	protected level: number = 1;

	/**
	 * Instance of a token assembler
	 */
	protected assembler: Assembler;

	/**
	 * True if the streamed structure is already checked
	 */
	protected isChecked: boolean = false;

	/**
	 * Checks that specified token is matched for the streamer type
	 * @param token
	 */
	protected abstract checkToken(token: Token): boolean;

	/**
	 * Method to yield assembled tokens
	 */
	protected abstract push(): Generator<T>;

	/**
	 * @param [opts] - assembler options
	 */
	protected constructor(opts?: AssemblerOptions) {
		this.assembler = new Assembler(opts);
	}

	/**
	 * Processes the passed JSON token and yields the assembled value
	 */
	*processToken(chunk: Token): Generator<T> {
		if (!this.isChecked && this.checkToken(chunk)) {
			this.isChecked = true;
		}

		if (!this.isChecked) {
			return;
		}

		if (Object.isFunction(this.assembler[chunk.name])) {
			this.assembler[chunk.name](chunk.value);

			if (this.assembler.depth === this.level) {
				yield* this.push();
			}
		}
	}
}