/***********************************************************************************

    Abstractor | Cache module | MIT License | ©2016 Hexagon <github.com/hexagon>

    In memory key/value storage, great for storing the last payload
    of a specific topic.

    ----------------------------------------------------------------------------

    I/O

    -------------------------------+----------------------+---------------------
    Input                          |  Possible triggers   |  Sets property
    -------------------------------+----------------------+---------------------
                                   |  success             |  payload
    get: <key to get>              +----------------------+---------------------
                                   |  error               |  error
    -------------------------------+----------------------+---------------------
    topic: <key to store>          |  N/A                 |  N/A
    -------------------------------+----------------------+---------------------
                                   |  success             |  payload
    dump: true                     +----------------------+---------------------
                                   |  error               |  error
    -------------------------------+----------------------+---------------------


***********************************************************************************/

"use strict";

const   Node = require("../node.js");

class Cache extends Node {

    constructor(parameters) {
        super(parameters);

        this.memory = {};
        
    }

    invoke(msg) {
        
        // Sanity checks
        if ( !msg ) 
            return this.error(msg, "No message provided.");

        // User is requesting am entry
        if( msg.get ) {
            if ( this.memory[msg.get] ) {
                msg.topic = msg.get;
                this.success( msg, this.memory[msg.get] );
            } else {
                msg.topic = msg.get;
                this.success( msg, undefined );
            }

        // User want a dump of current cache
        } else if ( msg.dump === true ) {

            this.success( msg, this.memory );

        // User want to store an entry
        } else {
            if( msg.topic === undefined ) {
                return this.error(msg, "No topic provided.");
            }
            this.memory[msg.topic] = msg.payload;
        }

    }

}

module.exports = Cache;