// Circle Suite — Network Intelligence (Corona, L8).
//
// Every member running ads is generating an answer to the same question: which
// wording actually makes a stranger click. Until now each of them only saw
// their own slice, which on display inventory is far too small to learn from —
// a member with 5,000 impressions and 4 clicks knows nothing.
//
// Pooled across the whole team it becomes a real asset, and one that cannot be
// bought or copied: it is the team's own accumulated result. It also gets
// better every month without anyone building anything, which is exactly what
// the top of a ladder should feel like.
//
// Two rules it holds to:
//  1. NOTHING identifies a member. No ids, no names, no per-person numbers.
//     This is a picture of what works, not a leaderboard of who is working.
//  2. It refuses to report anything that has not earned the right to be
//     reported. Display click rates are tiny, so a row with 300 impressions
//     behind it is noise. Under-evidenced rows are counted and disclosed, not
//     quietly dropped, so the reader knows what was left out.
'use strict';
const fs = require('fs');
const path = require('path');
const suiteTraffic = require('./suite-traffic');

let DATA_DIR = null;
function init(opts) { DATA_DIR = opts.dataDir; }

const MIN_LEVEL = 8;
const MIN_SERVED = 2000;    // per row, before we will report a rate
const MIN_ROWS = 2;         // before we will compare rows at all

function readJson(f) { try { return JSON.parse(fs.readFileSync(path.join(DATA_DIR, f), 'utf8')); } catch (e) { return {}; } }

// Pull every campaign the team has run, from every month we still hold.
function allCampaigns() {
  const led = readJson('traffic-grants.json');
  const out = [];
  Object.keys(led).forEach(function (mk) {
    const byMember = led[mk] || {};
    Object.keys(byMember).forEach(function (mid) {
      (byMember[mid] || []).forEach(function (c) {
        out.push({
          adId: Number(c.adId), kind: c.kind || 'banner', size: c.size || '',
          creative: c.creative || '', subject: c.subject || '',
          target: c.target || '', month: mk
        });
      });
    });
  });
  return out;
}

// The angle is encoded in the destination (?v=pocket etc). Personal pages carry
// no angle, so they group separately rather than being lumped into "general".
function angleOf(target) {
  const m = String(target || '').match(/[?&]v=([a-z]+)/i);
  if (m) return m[1].toLowerCase();
  if (String(target).indexOf('/p/') !== -1) return 'personal page';
  return 'general';
}

function blankRow(label) {
  return { label: label, served: 0, clicks: 0, ads: 0 };
}

function finish(map) {
  const rows = Object.keys(map).map(function (k) {
    const r = map[k];
    r.rate = r.served > 0 ? r.clicks / r.served : 0;
    r.enough = r.served >= MIN_SERVED;
    return r;
  });
  const solid = rows.filter(function (r) { return r.enough; }).sort(function (a, b) { return b.rate - a.rate; });
  const thin = rows.filter(function (r) { return !r.enough; });
  return {
    rows: solid,
    thin: thin.length,
    thinServed: thin.reduce(function (s, r) { return s + r.served; }, 0),
    comparable: solid.length >= MIN_ROWS
  };
}

async function report() {
  const camps = allCampaigns();
  if (!camps.length) return { ready: false, reason: 'No campaigns have run yet — this fills in as the team advertises.' };

  // NAS caps a stats call, so batch.
  const ids = camps.map(function (c) { return c.adId; }).filter(Boolean);
  const stats = {};
  for (let i = 0; i < ids.length; i += 150) {
    try {
      const chunk = await suiteTraffic.stats(ids.slice(i, i + 150));
      chunk.forEach(function (s) { stats[s.ad_id] = s; });
    } catch (e) { /* partial data still beats none */ }
  }
  if (!Object.keys(stats).length) {
    return { ready: false, reason: 'The ad network did not return counters just now — try again shortly.' };
  }

  const byFormat = {}, bySize = {}, byAngle = {}, byCreative = {}, byHeadline = {};
  let totalServed = 0, totalClicks = 0, counted = 0;

  camps.forEach(function (c) {
    const s = stats[c.adId];
    if (!s) return;
    const served = Math.max(0, Number(s.served) || 0);
    const clicks = Math.max(0, Number(s.hits) || 0);
    if (served <= 0) return;
    counted++;
    totalServed += served; totalClicks += clicks;

    const add = function (map, key, label) {
      if (!key) return;
      if (!map[key]) map[key] = blankRow(label || key);
      map[key].served += served; map[key].clicks += clicks; map[key].ads++;
    };

    add(byFormat, c.kind === 'text' ? 'text' : 'banner', c.kind === 'text' ? 'Text ads' : 'Banner ads');
    add(byAngle, angleOf(c.target));
    if (c.kind === 'text') {
      if (c.subject) add(byHeadline, c.subject.toLowerCase(), c.subject);
    } else {
      if (c.size) add(bySize, c.size);
      if (c.creative) add(byCreative, c.creative);
    }
  });

  return {
    ready: true,
    totals: {
      ads: counted, served: totalServed, clicks: totalClicks,
      rate: totalServed > 0 ? totalClicks / totalServed : 0,
      months: Object.keys(readJson('traffic-grants.json')).length
    },
    format: finish(byFormat),
    angle: finish(byAngle),
    size: finish(bySize),
    creative: finish(byCreative),
    headline: finish(byHeadline),
    minServed: MIN_SERVED
  };
}

// One plain-English read of the numbers. Deliberately written here rather than
// generated: these are conclusions about money, and a model paraphrasing a
// table is exactly where an invented number would slip in.
function readout(rep) {
  if (!rep || !rep.ready) return [];
  const out = [];
  const pct = function (r) { return (r * 100).toFixed(3) + '%'; };

  out.push('Across ' + rep.totals.ads.toLocaleString() + ' team ads: ' +
    rep.totals.served.toLocaleString() + ' impressions served, ' +
    rep.totals.clicks.toLocaleString() + ' clicks — ' + pct(rep.totals.rate) + ' overall.');

  if (rep.format.comparable) {
    const top = rep.format.rows[0], next = rep.format.rows[1];
    const edge = next.rate > 0 ? ((top.rate - next.rate) / next.rate) * 100 : 0;
    out.push(top.label + ' are pulling ' + pct(top.rate) + ' against ' + pct(next.rate) + ' for ' +
      next.label.toLowerCase() + (edge >= 20 ? ' — a ' + Math.round(edge) + '% edge worth acting on.' : ' — close enough to call it a tie.'));
  }
  if (rep.angle.comparable) {
    const a = rep.angle.rows[0];
    out.push('The "' + a.label + '" angle is the strongest performer at ' + pct(a.rate) +
      ' across ' + a.served.toLocaleString() + ' impressions.');
  }
  if (rep.creative.comparable) {
    const c = rep.creative.rows[0];
    out.push('Best banner: ' + c.label + ' at ' + pct(c.rate) + '.');
  }
  const thinTotal = rep.format.thin + rep.angle.thin + rep.size.thin + rep.creative.thin + rep.headline.thin;
  if (thinTotal) {
    out.push(thinTotal + ' grouping(s) are held back for now — under ' + rep.minServed.toLocaleString() +
      ' impressions each, which is not enough to read anything into.');
  }
  return out;
}

module.exports = { init, report, readout, MIN_LEVEL, MIN_SERVED };