quiz/public/buzzer.js

"use strict"

/* global document, window */
const crypto = window.crypto
const location = document.location
const performance = window.performance
const storage = window.sessionStorage

// TODOs
// - measure/report latency
// - use server reported time to find winner

import {
  clear,
  Connection,
  isEmpty,
  isString,
  ms_ns,
  node,
  off,
  on,
  q,
  s_ns,
  session_id,
  session_id_from_url,
  session_url,
} from "./shared.js"

const buzzer_key = {
  code: 0x20,
  name: "space bar",
}

let socket,
  conn,
  clients = [],
  me,
  session_key

function hide(e) {
  e = isString(e) ? q(`#${e}`) : e
  e.style.display = "none"
}

function show(e) {
  e = isString(e) ? q(`#${e}`) : e
  e.style.display = "block"
}

function find_client(client_id) {
  return clients.find((c) => c.id === client_id)
}

function new_session_id() {
  if (!crypto) {
    return Math.random().toString(36).substr(2)
  }
  const data = new Uint8Array(10)
  crypto.getRandomValues(data)
  return Array.from(data, (v) => v.toString(36)).join("")
}

function setup_url() {
  const sid = session_id() || new_session_id()
  location.hash = sid
}

const player_list = q("#info ul")
function redraw_clients(me, clients) {
  if (!me) {
    return
  }
  clear(player_list)
  const player_tpl = q("template#player").content.firstElementChild
  for (const c of clients) {
    const player_el = node(player_tpl.cloneNode(true), {
      data: { cid: c.id },
      appendTo: player_list,
      cls: {
        me: c.id === me.id,
        inactive: !c.active,
      },
    })
    q(".name", player_el).textContent = c.name
    q(".points", player_el).textContent = c.points
    q(".tokens", player_el).textContent = c.tokens
  }
}

const highlights = {}
function highlight(client_id, until_ns) {
  if (highlights[client_id]) {
    return
  }
  const timeout_ms = (until_ns - conn.servertime_now_ns()) / ms_ns
  if (timeout_ms <= 10) {
    console.warn("That highlight timeout was ridiculously low:", client_id, timeout_ms)
    return
  }
  for (const li of player_list.children) {
    if (li.dataset.cid === client_id) {
      li.classList.add("buzzing")
      if (!isEmpty(highlights)) {
        li.classList.add("too-late")
      } else {
        li.classList.add("first")
      }
      highlights[client_id] = setTimeout(() => {
        delete highlights[client_id]
        li.classList.remove("buzzing")
        li.classList.remove("too-late")
        li.classList.remove("first")
      }, timeout_ms)
      return
    }
  }
}

function setup_ui() {
  on("focus", (event) => {
    hide("active")
    hide("inactive")
    show("ready")
  })
  on("blur", (event) => {
    hide("active")
    show("inactive")
    hide("ready")
  })
  if (document.hasFocus()) {
    hide("inactive")
  } else {
    hide("ready")
  }

  q("#bkey").textContent = buzzer_key.name
  let buzzing = false
  on("keydown", (event) => {
    if (!buzzing && event.keyCode === buzzer_key.code) {
      buzzing = true
      conn.send("buzz", conn.servertime_now_ns())
      show("active")
      hide("ready")
    }
  })
  on("keyup", (event) => {
    if (event.keyCode === buzzer_key.code) {
      buzzing = false
      hide("active")
      show("ready")
    }
  })

  const username_el = q("#username")
  if (storage["my_name"]) {
    username_el.value = storage["my_name"]
  }
  on(
    "change",
    (event) => {
      set_name(event.target.value)
    },
    { target: username_el },
  )
}

function disable_player_ui() {
  off("focus")
  off("blur")
  off("keydown")
  off("keyup")
  node(q("body"), { cls: { player: 0 } })
}

function enable_admin_ui() {
  const body = q("body")
  if (body.classList.contains("admin")) {
    return
  }
  body.classList.add("admin")

  const named = Object.fromEntries(
    Array.from(document.querySelectorAll("[name]")).map((el) => [el.name, el]),
  )
  on(
    "click",
    ({ target }) => {
      if (!target.dataset.eval) {
        return
      }
      eval(target.dataset.eval)
    },
    { target: q("#points-admin") },
  )
  on(
    "click",
    ({ target }) => {
      let node = target
      while (!node.dataset.cid && node.parentElement) {
        node = node.parentElement
      }
      if (!target.dataset.eval) {
        return
      }
      const client = find_client(node.dataset.cid)
      if (!client) {
        return
      }
      eval(target.dataset.eval)
    },
    { target: q("#info .players") },
  )
}

function set_name(name) {
  storage["my_name"] = name
  conn.send("name", name)
}

function setup_ws() {
  const sid = session_id()
  const credentials = { id: storage["my_uid"], key: storage["my_key"] }
  conn = new Connection()
  conn.on("helo", () => {
    if (sid === storage["my_sid"]) {
      conn.send("login", credentials)
    }
    set_name(q("#username").value)
  })
  conn.on("id", ({ value }) => {
    me = value
    storage["my_uid"] = me.id
    storage["my_key"] = me.key
    storage["my_sid"] = session_id_from_url(me.path)
    redraw_clients(me, clients)
  })
  conn.on("buzz", ({ value }) => {
    const { time: buzztime_ns, client: client_id } = value
    const duration_ns = 3 * s_ns
    const until_ns = buzztime_ns + duration_ns
    highlight(client_id, until_ns)
  })
  conn.on("clients", ({ value }) => {
    clients = value.clients
    redraw_clients(me, clients)
  })
  conn.on("client", ({ value: { client } }) => {
    const idx = clients.findIndex((c) => c.id === client.id)
    if (idx >= 0) {
      clients[idx] = client
    } else {
      clients.push(client)
    }
    redraw_clients(me, clients)
  })
  conn.on("session_key", ({ value }) => {
    session_key = value
    storage["session_path"] = session_key.path
    storage["session_key"] = session_key.key
    disable_player_ui()
    enable_admin_ui()
  })
  conn.on("control", ({ value }) => {
    // ignore
  })
  conn.on("error", (msg) => {
    console.error(`Error: ${msg.value.reason}`)
    const errorbox = q("#error")
    q("code", errorbox).textContent = JSON.stringify(msg, null, 2)
    q("body").classList.add("error")
  })
  conn.connect(session_url(sid))
}

setup_url()
setup_ui()
setup_ws()