import { h, mount, fmtTime, errorBox } from "../ui.js";
import { get } from "../api.js";
import { lineChart, chartCard, legend, timeTable, heatmap, heatmapTable, barList, compact, stepSeconds } from "../charts.js";

const ranges = [["1h", "1 hour"], ["6h", "6 hours"], ["24h", "24 hours"], ["7d", "7 days"], ["30d", "30 days"], ["90d", "90 days"]];
const rangeSecs = { "1h": 3600, "6h": 6 * 3600, "24h": 86400, "7d": 7 * 86400, "30d": 30 * 86400, "90d": 90 * 86400 };

// Failed answers keep the same color whatever the range: color follows
// the result code, never its rank.
const failures = [
  { key: "rcode:NXDOMAIN", label: "NXDOMAIN", slot: 1 },
  { key: "rcode:SERVFAIL", label: "SERVFAIL", slot: 2 },
  { key: "rcode:REFUSED", label: "REFUSED", slot: 3 },
];

const rttOrder = ["<10ms", "10-100ms", "100-500ms", "500-800ms", "800-1600ms", ">1600ms"];

let generation = 0;

export async function render(el, params, query) {
  const gen = ++generation;
  const want = query && query.get ? query.get("since") : null;
  const since = rangeSecs[want] ? want : "24h";
  const status = await get("/stats/status");
  const head = h("div", { class: "page-head" },
    h("div", { class: "grow" }, h("h1", null, "Statistics"),
      h("div", { class: "muted" }, status.enabled
        ? "From named's counters" + (status.query_log ? " and response log" : "") + " · data since " + (status.first_data ? fmtTime(status.first_data) : "–") +
          " · kept: minutes " + status.retention.minute + ", hours " + status.retention.hour + ", days " + status.retention.day
        : "Query statistics are off")));
  if (!status.enabled) {
    mount(el, head, disabledPanel());
    return;
  }
  const heatSince = rangeSecs[since] < 7 * 86400 ? "7d" : since;
  let data;
  try {
    data = await loadAll(since, heatSince, status.query_log);
  } catch (e) {
    mount(el, head, errorBox(e));
    return;
  }
  if (gen !== generation) return; // the user moved on
  const { summary: s, heat } = data;
  // The newest bucket is still filling up; drawing it would look like a
  // sudden drop in traffic.
  const timeline = complete(data.timeline), errors = complete(data.errors);
  const step = stepSeconds[timeline.step];
  const parts = [head, filterRow(since)];
  for (const w of status.warnings || []) parts.push(h("div", { class: "msg warn" }, w));

  // Headline numbers.
  const rangeLabel = "in the last " + ranges.find((r) => r[0] === since)[1];
  parts.push(h("div", { class: "cards" },
    tile("Queries", compact(s.queries), rangeLabel),
    tile("Per second", s.avg_qps < 10 ? s.avg_qps.toFixed(2) : Math.round(s.avg_qps).toLocaleString(), "on average"),
    s.peak ? tile("Busiest " + s.peak.per, compact(s.peak.queries), fmtTime(s.peak.time)) : null,
    s.nxdomain_ratio != null ? tile("NXDOMAIN", pct(s.nxdomain_ratio), "of queries named no existing name") : null,
    s.cache_hit_ratio != null ? tile("Cache hits", pct(s.cache_hit_ratio), "of recursive queries answered from cache") : null));

  // Volume over time: one series, so no legend box; the title names it.
  const q = timeline.series.find((x) => x.key === "queries") || { values: timeline.times.map(() => 0) };
  const qSeries = [{ label: "Queries", values: q.values, slot: 1 }];
  parts.push(chartCard("Queries", "per " + stepName(timeline.step) + ", " + rangeLabel,
    lineChart({ series: qSeries, times: timeline.times, step, area: true }), timeTable(qSeries, timeline.times, step), { wide: true }));

  // Failed answers: three fixed series, legend plus end labels.
  const fSeries = failures.map((f) => ({ ...f, values: (errors.series.find((x) => x.key === f.key) || { values: errors.times.map(() => 0) }).values }));
  const anyFailures = fSeries.some((f) => f.values.some((v) => v > 0));
  parts.push(chartCard("Failed answers", "NXDOMAIN: the name doesn't exist · SERVFAIL: resolution failed · REFUSED: not allowed",
    anyFailures ? lineChart({ series: fSeries, times: errors.times, step: stepSeconds[errors.step] }) : h("div", { class: "empty" }, "No failed answers " + rangeLabel + "."),
    anyFailures ? timeTable(fSeries, errors.times, stepSeconds[errors.step]) : null,
    { wide: true, legend: anyFailures ? legend(fSeries) : null }));

  // When is the server busy?
  parts.push(chartCard("Busiest times", "average queries per hour by weekday and hour of day (local time), last " + ranges.find((r) => r[0] === heatSince)[1],
    heatmap(heat, "queries"), heatmapTable(heat, "queries"), { wide: true }));

  // Who asks for what.
  if (status.query_log) {
    const t = data.tops;
    parts.push(h("div", { class: "chart-grid" },
      listCard("Most queried names", "", barList(t.name, { href: (k) => "#/search?q=" + encodeURIComponent(k) })),
      listCard("Busiest clients", "", barList(t.client)),
      listCard("Names that don't exist", "NXDOMAIN answers: typos, removed hosts, misconfigured clients, malware", barList(t.nxdomain, { empty: "None " + rangeLabel + "." })),
      listCard("Refused clients", "clients asking for something they may not have (often internet scanners)", barList(t.refused, { empty: "None " + rangeLabel + "." })),
      t.servfail.length ? listCard("Names that failed to resolve", "SERVFAIL answers", barList(t.servfail)) : null));
  } else {
    parts.push(h("div", { class: "msg info" }, "Top names and clients need the response log: set stats.query_log: true in /etc/jarl/jarl.yaml and restart jarl."));
  }

  // Breakdowns.
  const b = data.breakdowns;
  const rtt = rttOrder.map((k) => b.rtt.find((e) => e.key === k)).filter(Boolean);
  parts.push(h("div", { class: "chart-grid" },
    listCard("Record types", "", barList(b.qtype, { total: s.queries })),
    listCard("Result codes", "", barList(b.rcode, { total: s.queries })),
    b.view.length > 1 || (b.view.length === 1 && b.view[0].key !== "_default") ? listCard("Views", "", barList(b.view, { label: viewLabel })) : null,
    b.zone.length ? listCard("Zones", "queries per local zone; other = names in no local zone (recursion)", barList(b.zone, { label: (k) => (k === "-" ? "other" : k), href: (k) => (k === "-" ? null : "#/search?q=" + encodeURIComponent(k)) })) : null,
    b.answer.length ? listCard("Answers", "authoritative (your zones) or recursive (from the cache or the internet)", barList(b.answer)) : null,
    rtt.length ? listCard("Upstream response time", "how long other servers took to answer named's recursive queries", barList(rtt)) : null));
  el.classList.remove("refreshing");
  mount(el, parts);
  scheduleRefresh(el, params, query, gen);
}

async function loadAll(since, heatSince, queryLog) {
  const p = {
    summary: get("/stats/summary", { since, top: 0 }),
    timeline: get("/stats/timeline", { since, key: "queries" }),
    errors: get("/stats/timeline", { since, key: failures.map((f) => f.key).join(",") }),
    heat: get("/stats/heatmap", { since: heatSince }),
  };
  const groups = ["qtype", "rcode", "view", "zone", "answer", "rtt"];
  groups.forEach((g) => { p["b_" + g] = get("/stats/breakdown", { group: g, since }); });
  if (queryLog) {
    for (const k of ["name", "client", "nxdomain", "refused", "servfail"]) p["t_" + k] = get("/stats/top", { kind: k, since, limit: 15 });
  }
  const keys = Object.keys(p);
  const vals = await Promise.all(Object.values(p));
  const out = { breakdowns: {}, tops: {} };
  keys.forEach((k, i) => {
    if (k.startsWith("b_")) out.breakdowns[k.slice(2)] = vals[i];
    else if (k.startsWith("t_")) out.tops[k.slice(2)] = vals[i];
    else out[k] = vals[i];
  });
  return out;
}

// scheduleRefresh reloads the page's data every minute while it is shown,
// keeping the current render (dimmed) until the new one is ready.
function scheduleRefresh(el, params, query, gen) {
  setTimeout(() => {
    if (gen !== generation || !location.hash.startsWith("#/stats") || !el.isConnected) return;
    el.classList.add("refreshing");
    render(el, params, query).catch(() => el.classList.remove("refreshing"));
  }, 60_000);
}

// complete drops the last bucket of a timeline if it hasn't ended yet.
function complete(tl) {
  const step = stepSeconds[tl.step];
  const n = tl.times.length;
  if (n > 1 && tl.times[n - 1] + step > Date.now() / 1000) {
    return { ...tl, times: tl.times.slice(0, -1), series: tl.series.map((x) => ({ ...x, values: x.values.slice(0, -1) })) };
  }
  return tl;
}

function filterRow(since) {
  return h("div", { class: "filter-row", role: "group", "aria-label": "Time range" },
    h("span", { class: "muted" }, "Range"),
    h("div", { class: "segmented" }, ranges.map(([k, label]) =>
      h("a", { href: "#/stats?since=" + k, class: k === since ? "active" : "", "aria-current": k === since ? "true" : null, title: "last " + label }, k))));
}

function tile(label, value, sub) {
  return h("div", { class: "card stat" }, h("div", { class: "label" }, label), h("div", { class: "value big" }, value), h("div", { class: "sub" }, sub));
}

function listCard(title, subtitle, body) {
  return h("section", { class: "panel" }, h("h2", null, title), subtitle ? h("div", { class: "muted small list-sub" }, subtitle) : null, body);
}

function pct(r) {
  const p = r * 100;
  return (p < 10 ? p.toFixed(1) : Math.round(p)) + "%";
}

function stepName(step) {
  return { "1m": "minute", "5m": "5 minutes", "15m": "15 minutes", "1h": "hour", "6h": "6 hours", "1d": "day" }[step] || step;
}

function viewLabel(k) {
  return k === "_default" ? "(no view)" : k;
}

function disabledPanel() {
  return h("div", { class: "panel" },
    h("h2", null, "Turn on query statistics"),
    h("p", null, "Jarl can show how many queries named answers over time, the busiest hours, the most queried names and the clients asking most. " +
      "It is off by default. To turn it on, add this to /etc/jarl/jarl.yaml on the server and restart jarl (sudo systemctl restart jarl):"),
    h("pre", { class: "code" }, "stats:\n  enabled: true"),
    h("p", { class: "muted" }, "Jarl then makes named publish its counters on a local statistics channel and log responses to /var/log/named, and keeps aggregates " +
      "(never individual queries) in a separate database, by default for 7 days per minute, 90 days per hour and 2 years per day. See docs/stats.md."));
}