usage.js

const sumUsage = client => {
  const period = getPeriod(new Date())
  /** @type {Record<ProviderDID, Record<SpaceDID, number>>} */
  let totalBySpace = {}
  let total = 0
  for (const account of Object.values(client.accounts())) {
    const subscriptions = await client.capability.subscriptions.list(account.did())
    for (const { consumers } of subscriptions.results) {
      for (const space of consumers) {
        const report = await client.capability.usage.report(space)
        totalBySpace[report.provider] = totalBySpace[report.provider] ?? {}
        totalBySpace[report.provider][report.space] = report.size.final
        total += report.size.final
      }
    }
  }
  return { total, totalBySpace }
}

/** @param {Date} now */
const getPeriod = now => ({
  // we may not have done a snapshot for this month _yet_, so get report from last month -> now
  from: startOfLastMonth(now),
  to: now
})

/** @param {string|number|Date} now */
const startOfMonth = (now) => {
  const d = new Date(now)
  d.setUTCDate(1)
  d.setUTCHours(0)
  d.setUTCMinutes(0)
  d.setUTCSeconds(0)
  d.setUTCMilliseconds(0)
  return d
}

/** @param {string|number|Date} now */
const startOfLastMonth = (now) => {
  const d = startOfMonth(now)
  d.setUTCMonth(d.getUTCMonth() - 1)
  return d
}