import { decode } from "/vendor/msgpack/index.mjs";

const target = document.querySelector("#target");
const day = document.querySelector("#day");
const detail = document.querySelector("#detail");
const observed = document.querySelector("#observed");

const percent = (value) =>
  value === null ? "Unknown" : `${(value * 100).toFixed(2)}% healthy`;

function state(value) {
  switch (value) {
    case null:
      return "unknown";
    case 1:
      return "good";
    case 0:
      return "down";
    default:
      return "mixed";
  }
}

async function load() {
  const response = await fetch(
    document.querySelector("script[data-api]").dataset.api,
  );

  return response.ok ? decode(await response.arrayBuffer()) : null;
}

function renderRow(record, recordIndex, dates, select) {
  const row = document.createElement("article");
  row.className = "health-row";

  const title = document.createElement("h3");
  title.textContent = record.name;

  const bars = document.createElement("div");
  bars.className = "bars";
  bars.setAttribute("role", "group");
  bars.setAttribute("aria-label", `${record.name}, daily history`);

  for (const [dayIndex, value] of record.values.entries()) {
    const button = document.createElement("button");
    button.type = "button";
    button.className = `bar ${state(value)}`;
    button.title = `${dates[dayIndex]}: ${percent(value)}`;
    button.setAttribute("aria-label", `${record.name} · ${button.title}`);
    button.setAttribute("aria-pressed", "false");
    button.dataset.target = String(recordIndex);
    button.dataset.day = String(dayIndex);

    button.addEventListener("click", () => {
      target.value = String(recordIndex);
      day.value = String(dayIndex);
      select();
    });

    bars.append(button);
  }

  row.append(title, bars);
  return row;
}

function renderGroup(group, groupIndex, records, dates, select) {
  const [header, labels, values] = group;
  const section = document.createElement("section");
  section.className = "health-group";

  const heading = document.createElement("h2");
  heading.id = `group-${groupIndex}`;
  heading.textContent = `${String(groupIndex + 1).padStart(2, "0")}  ${header}`;
  section.setAttribute("aria-labelledby", heading.id);
  section.append(heading);

  for (const [seriesIndex, metric] of labels.entries()) {
    const name =
      Object.entries(metric)
        .map(([key, value]) => `${key}=${value}`)
        .join(", ") || "{}";
    const record = { name, values: values[seriesIndex] };
    const recordIndex = records.length;

    records.push(record);
    target.add(new Option(`${header} · ${name}`, String(recordIndex)));
    section.append(renderRow(record, recordIndex, dates, select));
  }

  return section;
}

function render([start, groups]) {
  const dates = Array.from({ length: 30 }, (_, index) =>
    new Date((start + index * 86400) * 1000).toISOString().slice(0, 10),
  );
  observed.textContent = `${dates[0]} – ${dates.at(-1)} · UTC`;

  const records = [];
  const select = () => {
    const record = records[Number(target.value)];
    const dayIndex = Number(day.value);
    detail.textContent = `${record.name} · ${dates[dayIndex]}: ${percent(record.values[dayIndex])}.`;

    for (const bar of document.querySelectorAll(".bar")) {
      const selected =
        bar.dataset.target === target.value && bar.dataset.day === day.value;
      bar.setAttribute("aria-pressed", String(selected));
    }
  };

  for (const [index, date] of dates.entries()) {
    day.add(new Option(date, String(index)));
  }
  day.value = "29";

  groups.sort((left, right) => left[1].length - right[1].length);
  const container = document.querySelector("#groups");

  for (const [groupIndex, group] of groups.entries()) {
    container.append(renderGroup(group, groupIndex, records, dates, select));
  }

  if (records.length) {
    document.querySelector(".controls").hidden = false;
    target.addEventListener("change", select);
    day.addEventListener("change", select);
    select();
  } else {
    observed.textContent = "No data";
  }
}

let snapshot;

try {
  snapshot = await load();
} catch {
  snapshot = null;
}

if (snapshot === null) {
  observed.textContent = "No data";
} else {
  render(snapshot);
}

document.documentElement.dataset.ready = "true";