orbitdb/src/db/GCounter.js

'use strict';

const isEqual = require('./utils').isEqual;

class GCounter {
  constructor(id, payload) {
    this.id = id;
    this._counters = payload ? payload : {};
    this._counters[this.id] = this._counters[this.id] ? this._counters[this.id] : 0;
  }

  increment(amount) {
    if(!amount) amount = 1;
    this._counters[this.id] = this._counters[this.id] + amount;
  }

  get value() {
    return Object.keys(this._counters)
      .map((f) => this._counters[f])
      .reduce((previousValue, currentValue) => previousValue + currentValue, 0);
  }

  get payload() {
    return { id: this.id, counters: this._counters };
  }

  compare(other) {
    if(other.id !== this.id)
      return false;

    return isEqual(other._counters, this._counters);
  }

  merge(other) {
    Object.keys(other._counters).forEach((f) => {
      this._counters[f] = Math.max(this._counters[f] ? this._counters[f] : 0, other._counters[f]);
    });
  }

  static from(payload) {
    return new GCounter(payload.id, payload.counters);
  }

}

module.exports = GCounter;