// The dashboard: reads /status/data.json every 30 seconds while the tab is visible and draws it.
// Every value goes in through textContent: the cells come from Word files, not from us.

const REFRESH_MS = 30_000;
const TZ = "Europe/Minsk";
const SVG = "http://www.w3.org/2000/svg";

const CODES = {
  weeks_partly: "Недели не целиком",
  weeks_unreadable: "Недели не прочитаны",
  weeks_like_date: "Опечатка в дате",
  weeks_out_of_range: "Неделя вне семестра",
  date_in_subject: "Дата в названии",
  time_in_subject: "Время в названии",
  dates_unread: "Даты не прочитаны",
  date_weekday: "Не тот день недели",
  date_out_of_year: "Дата вне года",
  subject_missing: "Нет названия",
  time_invalid: "Странное время",
  group_empty: "Группа без пар",
};
const EVENTS = {
  new: ["Новый документ", "ok"],
  republished: ["Перезалит", ""],
  failed: ["Не читается", "bad"],
  year: ["Новый учебный год", "ok"],
  year_late: ["Папка года задерживается", "warn"],
  source_down: ["Университет не отвечает", "bad"],
  source_up: ["Университет снова отвечает", "ok"],
};
const DAYS = ["", "пн", "вт", "ср", "чт", "пт", "сб", "вс"];

const $ = (id) => document.getElementById(id);

/** An element with a class and text or children. */
function el(tag, className, ...children) {
  const node = document.createElement(tag);
  if (className) node.className = className;
  for (const child of children)
    if (child != null && child !== false) node.append(child instanceof Node ? child : String(child));
  return node;
}

const plural = (n, one, few, many) => {
  const t = n % 100;
  return t >= 11 && t <= 14 ? many : n % 10 === 1 ? one : n % 10 >= 2 && n % 10 <= 4 ? few : many;
};
const time = (iso) =>
  iso ? new Date(iso).toLocaleTimeString("ru-RU", { timeZone: TZ, hour: "2-digit", minute: "2-digit" }) : "—";
const dateTime = (iso) =>
  iso ? new Date(iso).toLocaleString("ru-RU", { timeZone: TZ, day: "numeric", month: "long", hour: "2-digit", minute: "2-digit" }) : "—";
function ago(iso) {
  if (!iso) return "—";
  const minutes = Math.round((Date.now() - Date.parse(iso)) / 60000);
  if (minutes < 1) return "только что";
  if (minutes < 60) return `${minutes} мин назад`;
  const hours = Math.floor(minutes / 60);
  if (hours < 24) return `${hours} ч ${minutes % 60} мин назад`;
  return dateTime(iso);
}
const ms = (v) => (v == null ? "—" : typeof v === "number" ? `≤ ${v} мс` : `${v} мс`);

// Tiles

function tile(label, state, value, detail) {
  return el(
    "article",
    "tile",
    el("span", "label", el("i", `dot ${state}`), label),
    el("span", "value", value),
    detail ? el("span", "detail", detail) : null,
  );
}

function tiles(d) {
  const uptime = Math.round((Date.now() - Date.parse(d.server.startedAt)) / 60000);
  const up = uptime < 60 ? `${uptime} мин` : `${Math.floor(uptime / 60)} ч ${uptime % 60} мин`;
  const crawl = d.catalog?.lastCrawl;
  const failing = d.catalog?.failingSince;
  const dir = d.directory || {};
  const problems = d.diagnostics?.problems ?? dir.problems ?? 0;
  const tg = d.telegram;
  $("tiles").replaceChildren(
    tile(
      "Сервер",
      d.server.ready ? "ok" : "warn",
      d.server.ready ? "Готов" : "Загружается",
      d.server.ready
        ? `API ${d.server.apiVersion} · парсер ${d.server.parserVersion} · работает ${up}`
        : `Ждёт: ${d.server.waiting.join(", ")}`,
    ),
    tile(
      "Каталог",
      d.catalog?.stale ? "warn" : "ok",
      d.catalog ? `${d.catalog.files} ${plural(d.catalog.files, "документ", "документа", "документов")}` : "Нет",
      d.catalog
        ? `${d.catalog.year} · проверен ${ago(d.watch?.lastAt || d.catalog.updatedAt)}` +
            (crawl ? ` · ${crawl.requests} ${plural(crawl.requests, "запрос", "запроса", "запросов")}${crawl.full ? ", полный обход" : ""}` : "")
        : null,
    ),
    tile(
      "Университет",
      failing ? "bad" : "ok",
      failing ? "Не отвечает" : "Отвечает",
      failing ? `с ${dateTime(failing)}` : d.watch?.lastError || `таблица недель: ${d.calendar?.weeksFiles?.length ? "есть" : "нет"}`,
    ),
    tile(
      "Разбор",
      dir.failed ? "bad" : problems ? "warn" : "ok",
      `${problems} ${plural(problems, "ячейка", "ячейки", "ячеек")} под вопросом`,
      `прочитано ${dir.documents ?? 0} из ${dir.total ?? 0}` + (dir.failed ? ` · не читаются: ${dir.failed}` : ""),
    ),
    tile(
      "Telegram",
      !tg.enabled ? "" : tg.lastError ? "bad" : "ok",
      !tg.enabled ? "Выключен" : tg.lastError ? "Ошибка" : `Отправлено: ${tg.sent}`,
      !tg.enabled ? "задайте TELEGRAM_BOT_TOKEN и TELEGRAM_CHAT_ID" : tg.lastError || (tg.lastSentAt ? `последнее ${ago(tg.lastSentAt)}` : "с запуска ничего"),
    ),
  );
  const warnings = d.warnings || [];
  $("warnings").hidden = !warnings.length;
  $("warnings").replaceChildren(...warnings.map((w) => el("li", "", w)));
}

// Traffic

function kpi(label, value, state = "") {
  return el("div", `kpi ${state}`, el("b", "", value), el("span", "", label));
}

function traffic(t) {
  const h = t.lastHour;
  $("traffic-since").textContent = `с запуска ${t.total.requests} · считается с ${dateTime(t.since)}`;
  $("kpis").replaceChildren(
    kpi("запросов", h.requests),
    kpi("без изменений (304)", h.notModifiedShare == null ? "—" : `${Math.round(h.notModifiedShare * 100)}%`),
    kpi("медиана", ms(h.p50Ms)),
    kpi("95-й процентиль", ms(h.p95Ms), h.slow ? "warn" : ""),
    kpi("ошибок клиента", h.clientErrors),
    kpi("ошибок сервера", h.serverErrors, h.serverErrors ? "bad" : ""),
    kpi("лимит и таймаут", h.limited + h.timeouts, h.limited + h.timeouts ? "warn" : ""),
    kpi("сбоев университета", h.sourceFailures, h.sourceFailures ? "warn" : ""),
    kpi("клиентов", h.clients),
  );
  chart(t.series);
  const rows = Object.entries(h.endpoints).map(([path, e]) =>
    el("tr", "", el("td", "", path), el("td", "num", e.requests), el("td", "num", `${e.avgMs} мс`), el("td", "num", e.errors)),
  );
  $("endpoints").tBodies[0].replaceChildren(...(rows.length ? rows : [el("tr", "", el("td", "muted", "Запросов не было"))]));
  const clients = h.busiestClients.map((c) => el("tr", "", el("td", "", c.client), el("td", "num", c.requests)));
  $("clients").tBodies[0].replaceChildren(...(clients.length ? clients : [el("tr", "", el("td", "muted", "—"))]));
}

/** Bars per minute: answered requests, 304s under them and errors on top. */
function chart(series) {
  const svg = $("chart");
  const width = 600,
    height = 140,
    pad = 6;
  const max = Math.max(1, ...series.map((m) => m.requests));
  const step = width / series.length;
  const scale = (n) => (n / max) * (height - pad * 2);
  const nodes = [];
  series.forEach((m, i) => {
    const x = i * step + 1;
    const w = Math.max(1, step - 2);
    let y = height - pad;
    const part = (n, cls) => {
      if (!n) return;
      const h = Math.max(1.5, scale(n));
      y -= h;
      const r = document.createElementNS(SVG, "rect");
      r.setAttribute("x", x.toFixed(1));
      r.setAttribute("y", y.toFixed(1));
      r.setAttribute("width", w.toFixed(1));
      r.setAttribute("height", h.toFixed(1));
      r.setAttribute("rx", "1.5");
      r.setAttribute("class", cls);
      nodes.push(r);
    };
    part(m.notModified, "bar-cached");
    part(Math.max(0, m.requests - m.notModified - m.errors), "bar-fresh");
    part(m.errors, "bar-failed");
    // A hover target over the whole minute, with the numbers as its tooltip.
    const hit = document.createElementNS(SVG, "rect");
    hit.setAttribute("x", (i * step).toFixed(1));
    hit.setAttribute("y", "0");
    hit.setAttribute("width", step.toFixed(1));
    hit.setAttribute("height", String(height));
    hit.setAttribute("fill", "transparent");
    const title = document.createElementNS(SVG, "title");
    title.textContent = `${time(m.t)}: ${m.requests} ${plural(m.requests, "запрос", "запроса", "запросов")}, 304: ${m.notModified}, ошибок: ${m.errors}`;
    hit.append(title);
    nodes.push(hit);
  });
  svg.replaceChildren(...nodes);
  const total = series.reduce((n, m) => n + m.requests, 0);
  svg.setAttribute("aria-label", `Запросы по минутам за последний час: всего ${total}, максимум ${max} в минуту`);
}

// Events

function events(list) {
  if (!list.length) {
    $("events").replaceChildren(el("li", "empty", "Событий пока нет. Здесь появятся новые и перезалитые документы и сбои университета."));
    return;
  }
  $("events").replaceChildren(
    ...list.map((e) => {
      const [label, state] = EVENTS[e.kind] || [e.kind, ""];
      return el(
        "li",
        "",
        el("i", `dot ${state}`),
        el("span", "when", `${label} · ${dateTime(e.t)}`),
        el("span", "title", e.title),
        e.text ? el("span", "text", e.text) : null,
      );
    }),
  );
}

// Diagnostics

let diagnostics = null;
const selected = new Set();

function renderCodes() {
  const counts = diagnostics?.counts || {};
  $("codes").replaceChildren(
    ...Object.entries(counts)
      .sort((a, z) => z[1] - a[1])
      .map(([code, n]) => {
        const chip = el("button", "chip", CODES[code] || code, el("span", "n", n));
        chip.type = "button";
        chip.title = code;
        chip.setAttribute("aria-pressed", String(selected.has(code)));
        chip.addEventListener("click", () => {
          selected.has(code) ? selected.delete(code) : selected.add(code);
          renderCodes();
          renderProblems();
        });
        return chip;
      }),
  );
}

function renderProblems() {
  if (!diagnostics) {
    $("problems").replaceChildren(el("p", "empty", "Индекс каталога ещё собирается."));
    return;
  }
  const q = $("q").value.trim().toLowerCase();
  const matches = (doc, p) =>
    (!selected.size || selected.has(p.code)) &&
    (!q || [doc.name, doc.faculty, p.raw, ...(p.groups || [])].some((s) => s && s.toLowerCase().includes(q)));
  const docs = diagnostics.items
    .map((item) => ({ ...item, problems: item.problems.filter((p) => matches(item.doc, p)) }))
    .filter((item) => item.problems.length);
  const shown = docs.reduce((n, d) => n + d.problems.length, 0);
  $("diag-count").textContent = q || selected.size ? `${shown} из ${diagnostics.problems}` : `${diagnostics.problems} в ${diagnostics.items.length} ${plural(diagnostics.items.length, "документе", "документах", "документах")}`;

  $("failed").replaceChildren(
    ...(diagnostics.failed || []).map((f) => el("div", "failed-doc", el("b", "", `Не читается: ${f.name}`), el("div", "small", f.error))),
  );
  if (!docs.length) {
    $("problems").replaceChildren(el("p", "empty", diagnostics.problems ? "Ничего не найдено." : "Подозрительных ячеек нет."));
    return;
  }
  $("problems").replaceChildren(
    ...docs.map(({ doc, problems }) => {
      const original = el("a", "", "Оригинал");
      original.href = `/api/original/${encodeURIComponent(doc.id)}`;
      return el(
        "section",
        "doc",
        el("div", "doc-head", el("b", "", doc.name, doc.faculty ? el("span", "muted", ` · ${doc.faculty}`) : null), original),
        ...problems.map((p) =>
          el(
            "div",
            "problem",
            el(
              "div",
              "where",
              [CODES[p.code] || p.code, (p.groups || []).join(", "), p.day ? `${DAYS[p.day]} ${p.start || ""}` : ""].filter(Boolean).join(" · "),
            ),
            el("div", "", p.message),
            p.raw ? el("q", "", p.raw) : null,
          ),
        ),
      );
    }),
  );
}

// Loading

let timer = null;
async function load() {
  try {
    // From the origin, not the page's address: a page opened as user:password@host cannot fetch
    // relative URLs, which would carry the credentials.
    const response = await fetch(new URL("data.json", location.origin + location.pathname), { cache: "no-store" });
    if (response.status === 401) throw new Error("Сессия закончилась: обновите страницу и введите пароль.");
    if (!response.ok) throw new Error(`Сервер ответил ${response.status}.`);
    const d = await response.json();
    $("error").hidden = true;
    $("sub").textContent = `Статус сервера · каталог ${d.catalog?.year || "—"}`;
    tiles(d);
    traffic(d.traffic);
    events(d.events || []);
    diagnostics = d.diagnostics;
    for (const code of [...selected]) if (!diagnostics?.counts?.[code]) selected.delete(code);
    renderCodes();
    renderProblems();
    $("updated").textContent = `Обновлено в ${new Date().toLocaleTimeString("ru-RU", { timeZone: TZ })}`;
  } catch (error) {
    $("error").textContent = error.message || "Не удалось загрузить данные.";
    $("error").hidden = false;
  }
}

function schedule() {
  clearInterval(timer);
  if (!document.hidden) timer = setInterval(load, REFRESH_MS);
}

$("reload").addEventListener("click", load);
$("q").addEventListener("input", renderProblems);
document.addEventListener("visibilitychange", () => {
  if (!document.hidden) load();
  schedule();
});
load();
schedule();