/*!
 * lib/bitcoind-rpc/fees.js
 * Copyright © 2019 – Katana Cryptographic Ltd. All Rights Reserved.
 */
'use strict'

const errors = require('../errors')
const Logger = require('../logger')
const network = require('../bitcoin/network')
const keys = require('../../keys')[network.key]
const { createRpcClient, waitForBitcoindRpcApi } = require('./rpc-client')
const latestBlock = require('./latest-block')


/**
 * A singleton providing information about network fees
 */
class Fees {

  /**
   * Constructor
   */
  constructor() {
    this.block = -1
    this.targets = [2, 4, 6, 12, 24]
    this.fees = {
      2: 0,
      4: 0,
      6: 0,
      12: 0,
      24: 0
    }
    this.feeType = keys.bitcoind.feeType

    this.rpcClient = createRpcClient()

    waitForBitcoindRpcApi().then(() => {
      this.refresh()
    })
  }

  /**
   * Refresh and return the current fees
   * @returns {Promise<object>}
   */
  async getFees() {
    try {
      if (latestBlock.height > this.block)
        await this.refresh()

      return this.fees

    } catch(err) {
      return Promise.reject(errors.generic.GEN)
    }
  }

  /**
   * Refresh the current fees
   * @returns {Promise<void>}
   */
  async refresh() {
    try {
      const requests = this.targets.map((target) => {
        return { method: 'estimatesmartfee', params: { conf_target: target, estimate_mode: this.feeType }, id: target }
      })
      const responses = await this.rpcClient.batch(requests)

      responses.forEach((fee) => {
        this.fees[fee.id] = (fee.result.errors && fee.result.errors.length > 0) ? 0 : Math.round(fee.result.feerate * 1e5)
      })
    } catch(e) {
      Logger.error(e, 'Bitcoind RPC : Fees.refresh()')
    }
    this.block = latestBlock.height
  }

}

module.exports = new Fees()