ianpaschal/aurora

// Aurora is distributed under the MIT license.

import Engine from "./Engine"; // Typing
import Entity from "./Entity"; // Typing

/**
 * @module core
 * @classdesc Class representing a state.
 */
export default class State {

    private _timestamp: number;
    private _entities:  any[];

    /**
     * @description Create a state instance from an engine.
     * @param {Engine} engine - Engine instance
     */
    constructor( engine: Engine, complete: boolean = false ) {
        this._timestamp = engine.lastTickTime;
        this._entities = [];
        engine.entities.forEach( ( entity ) => {

            // If not performing a full state capture and the entity is not dirty, skip it
            if ( !complete && !entity.dirty ) {
                return;
            }

            // Otherwise, flatten it to a JSON object and push it to the array
            this._entities.push( entity.flattened );
        });
        return this;
    }

    get flattened(): Object {
        return {
            timestamp: this._timestamp,
            entities: this._entities
        };
    }

    /**
     * @description Get the state's entities.
     * @readonly
     * @returns {Entity[]} - Array of entity instances
     */
    get entities(): Entity[] {
        return this._entities;
    }

    /**
     * @description Get the state's timestamp in milliseconds.
     * @readonly
     * @returns {number} - Timestamp in milliseconds
     */
    get timestamp(): number {
        return this._timestamp;
    }

    get json(): string {
        return JSON.stringify( this.flattened, null, 4 );
    }
}