'use strict';

const activityIngestQueue = require('./activityIngestQueue');

let epoch = null;

async function beginGlobalActivityScan(db) {
  if (!epoch || !epoch.active) {
    const created = {
      active: true,
      baselineDone: 0,
      enumerationsInProgress: 0,
      initPromise: null,
    };

    epoch = created;
    created.initPromise = activityIngestQueue
      .getActivityIngestQueueCounts(db)
      .then(counts => {
        created.baselineDone = Number(counts.done || 0);
      })
      .catch(err => {
        if (epoch === created) created.active = false;
        throw err;
      });
  }

  const current = epoch;
  current.enumerationsInProgress++;

  try {
    await current.initPromise;
  } catch (err) {
    current.enumerationsInProgress = Math.max(
      0, current.enumerationsInProgress - 1
    );
    throw err;
  }
}

function finishGlobalActivityScan() {
  if (epoch) {
    epoch.enumerationsInProgress = Math.max(
      0, epoch.enumerationsInProgress - 1
    );
  }
}

async function getGlobalActivityScanStatus(db) {
  const counts = await activityIngestQueue.getActivityIngestQueueCounts(db);
  const pending = Number(counts.pending || 0);
  const processing = Number(counts.processing || 0);
  const done = Number(counts.done || 0);
  const errors = Number(counts.error || 0);
  const remaining = pending + processing;
  const totalCurrent = pending + processing + done + errors;

  let current;
  let total;
  let percent;
  let baselineDone = done;

  if (epoch && epoch.active) {
    baselineDone = epoch.baselineDone;
    total = Math.max(0, totalCurrent - baselineDone);
    current = Math.max(0, (done - baselineDone) + errors);
    percent = total <= 0
      ? 100
      : Math.max(0, Math.min(100, Math.round(current / total * 100)));

    // Chiude il ciclo quando tutte le scansioni hanno terminato
    // l'accodamento e non restano job pending o processing.
    if (epoch.enumerationsInProgress === 0 && remaining === 0) {
      epoch.active = false;
    }
  } else {
    total = totalCurrent;
    current = totalCurrent;
    percent = 100;
  }

  return {
    pending, processing, done, errors, remaining,
    current, total, percent, baselineDone,
  };
}

module.exports = {
  beginGlobalActivityScan,
  finishGlobalActivityScan,
  getGlobalActivityScanStatus,
};