第4回 タイピングWebアプリ制作｜サウンド・途中終了編

<!DOCTYPE html>
<html lang="ja">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>段別タイピング練習</title>
  <link rel="stylesheet" href="style.css">
</head>
<body>
  <main class="app">
    <header class="app__header">
      <div>
        <p class="app__eyebrow">のんびり研究所</p>
        <h1>段別タイピング練習</h1>
      </div>
      <dl class="status" aria-label="練習状況">
        <div class="status__item"><dt>残り時間</dt><dd><span id="time">60</span><small>秒</small></dd></div>
        <div class="status__item"><dt>スコア</dt><dd id="score">0</dd></div>
        <div class="status__item"><dt>ミス</dt><dd id="misses">0</dd></div>
      </dl>
    </header>

    <section id="play-area" class="play-area" aria-label="タイピング練習エリア">
      <div id="falling-key" class="falling-key" aria-live="off" hidden>A</div>
      <div id="effect-layer" class="effect-layer" aria-hidden="true"></div>

      <div id="start-panel" class="panel start-panel">
        <p class="panel__label">練習する段を選びましょう</p>
        <fieldset class="row-selector">
          <legend class="visually-hidden">練習する段</legend>
          <label class="row-option">
            <input type="radio" name="practice-row" value="top">
            <span>上段<small>Q W E R T Y U I O P</small></span>
          </label>
          <label class="row-option">
            <input type="radio" name="practice-row" value="home" checked>
            <span>ホームポジション段<small>A S D F G H J K L ;</small></span>
          </label>
          <label class="row-option">
            <input type="radio" name="practice-row" value="bottom">
            <span>下段<small>Z X C V B N M , . /</small></span>
          </label>
        </fieldset>
        <p class="panel__main"><kbd>Space</kbd> キーでスタート</p>
        <div class="sound-setting">
          <span>SE</span>
          <button id="sound-toggle" class="sound-toggle" type="button" aria-pressed="true">ON</button>
          <small>※音が出ます</small>
        </div>
        <p class="panel__sub">60秒間、表示された文字を入力しましょう</p>
      </div>
      <div id="countdown" class="countdown" aria-live="assertive" hidden></div>
      <div id="exit-panel" class="panel exit-panel" role="dialog" aria-modal="true" aria-labelledby="exit-title" hidden>
        <p class="panel__label">練習を一時停止しています</p>
        <h2 id="exit-title">練習を途中で終了しますか？</h2>
        <div class="exit-panel__buttons">
          <button id="exit-practice" class="dialog-button dialog-button--danger" type="button">終了する</button>
          <button id="continue-practice" class="dialog-button" type="button">続ける</button>
        </div>
      </div>
      <div id="result-panel" class="panel result" hidden>
        <p class="panel__label">練習終了！</p>
        <h2>今回の結果</h2>
        <div class="result__scores">
          <p>スコア<strong id="final-score">0</strong></p>
          <p>ミス<strong id="final-misses">0</strong></p>
        </div>
        <p class="panel__sub">もう一度練習するときは <kbd>Space</kbd> キー</p>
        <button id="change-row" class="change-row" type="button">練習する段を変更</button>
      </div>
    </section>
    <section class="guide" aria-label="画面キーボードと担当指ガイド">
      <div class="guide__header">
        <p class="guide__title">光っているキーを、光っている指で押しましょう</p>
        <p id="exit-hint" class="exit-hint" hidden><kbd>Esc</kbd>：途中終了</p>
      </div>
      <div class="keyboard-viewport">
        <div id="screen-keyboard" class="screen-keyboard" aria-label="4段の画面キーボード"></div>
      </div>
      <div id="hands" class="hands" aria-label="左右の担当指"></div>
    </section>
    <p id="message" class="message" aria-live="polite">練習する段を選び、Spaceキーを押してください</p>
  </main>
  <script src="script.js"></script>
</body>
</html>

:root {
  color-scheme: light;
  --ink: #253044;
  --muted: #68758b;
  --line: #dbe5ed;
  --accent: #1c92a9;
  --accent-dark: #126b7d;
  --glow: #40e6ff;
  --paper: #fff;
  --back: #eef7f8;
  font-family: "Yu Gothic UI", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
}
* { box-sizing: border-box; }
body { min-width: 320px; min-height: 100vh; margin: 0; color: var(--ink); background: radial-gradient(circle at 15% 10%, #dff4f6 0, transparent 34rem), linear-gradient(145deg, #f8fbfc, var(--back)); }
button, input { font: inherit; }
.app { width: min(1100px, calc(100% - 32px)); margin: 0 auto; padding: 26px 0 20px; }
.app__header { display: flex; align-items: flex-end; justify-content: space-between; gap: 24px; margin-bottom: 14px; }
.app__eyebrow { margin: 0 0 4px; color: var(--accent-dark); font-size: .82rem; font-weight: 700; letter-spacing: .12em; }
h1 { margin: 0; font-size: clamp(1.35rem, 3vw, 2rem); }
.status { display: flex; gap: 8px; margin: 0; }
.status__item { min-width: 92px; padding: 9px 14px; border: 1px solid var(--line); border-radius: 12px; background: rgba(255,255,255,.88); text-align: center; box-shadow: 0 5px 18px rgba(41,83,94,.06); }
.status dt { color: var(--muted); font-size: .75rem; font-weight: 700; }
.status dd { margin: 2px 0 0; color: var(--accent-dark); font-size: 1.55rem; font-weight: 800; line-height: 1; }
.status small { margin-left: 2px; font-size: .72rem; }
.play-area { position: relative; height: clamp(300px, 43vh, 420px); overflow: hidden; border: 3px solid #b9dbe0; border-radius: 22px; background: linear-gradient(rgba(255,255,255,.72), rgba(255,255,255,.92)), repeating-linear-gradient(90deg, transparent 0 79px, #d9eef0 80px); box-shadow: 0 18px 45px rgba(37,76,88,.12); }
.falling-key { position: absolute; z-index: 4; top: 0; left: 0; width: 1.25em; color: var(--accent-dark); font-family: Arial,sans-serif; font-size: clamp(4rem,10vw,6.5rem); font-weight: 900; line-height: 1; text-align: center; text-shadow: 0 5px 0 #d4edf0; will-change: transform, opacity; }
.falling-key.is-hit { animation: target-hit .18s ease-out forwards; }
.effect-layer { position: absolute; z-index: 5; inset: 0; pointer-events: none; overflow: hidden; }
.laser { position: fixed; z-index: 20; height: 9px; border-radius: 999px; background: linear-gradient(to bottom,#0877bd 0 20%,#69d8ff 20% 40%,#fff 40% 60%,#69d8ff 60% 80%,#0877bd 80%); box-shadow: 0 0 5px #0877bd,0 0 12px #39c8ff,0 0 24px rgba(30,157,226,.8); transform-origin: 0 50%; pointer-events: none; animation: laser-shot .2s ease-out forwards; }
.wrong-laser { position: fixed; z-index: 20; height: 5px; border-radius: 999px; background: linear-gradient(#665978,#93869e,#554b61); box-shadow: 0 0 5px rgba(92,76,109,.75); transform-origin: 0 50%; pointer-events: none; animation: wrong-laser-shot .11s ease-out forwards; }
.wrong-spark { position: fixed; z-index: 21; width: 5px; height: 5px; border-radius: 50%; background: #796b86; box-shadow: 0 0 6px #665978; pointer-events: none; animation: wrong-spark-burst .22s ease-out forwards; }
.spark { position: absolute; width: 8px; height: 8px; border-radius: 50%; background: #fff; box-shadow: 0 0 12px var(--glow); animation: spark-burst .28s ease-out forwards; }
.panel { position: absolute; z-index: 6; top: 50%; left: 50%; width: min(650px,calc(100% - 32px)); padding: clamp(20px,4vw,34px); border: 1px solid var(--line); border-radius: 20px; background: rgba(255,255,255,.96); text-align: center; box-shadow: 0 20px 50px rgba(37,76,88,.15); transform: translate(-50%,-50%); }
.panel__label,.panel__sub { margin: 0; color: var(--muted); }
.panel__main { margin: 16px 0 10px; font-size: clamp(1.15rem,3vw,1.5rem); font-weight: 800; }
.sound-setting { display: flex; align-items: center; justify-content: center; gap: 8px; margin: -1px 0 11px; color: var(--muted); font-weight: 700; }
.sound-setting small { font-weight: 500; }
.sound-toggle { min-width: 54px; padding: 4px 10px; border: 1px solid #75bdc9; border-radius: 999px; color: #07404c; background: #d8fbff; font-weight: 800; cursor: pointer; }
.sound-toggle[aria-pressed="false"] { color: #68758b; border-color: #becbd0; background: #edf1f2; }
kbd { display: inline-block; padding: .28em .65em; border: 1px solid #9eb8bf; border-bottom-width: 4px; border-radius: 8px; color: var(--accent-dark); background: #f8ffff; font: inherit; }
.row-selector { display: grid; grid-template-columns: repeat(3, 1fr); gap: 9px; margin: 15px 0 0; padding: 0; border: 0; }
.row-option { cursor: pointer; }
.row-option input { position: absolute; opacity: 0; pointer-events: none; }
.row-option span { display: grid; place-items: center; min-height: 68px; padding: 9px 6px; border: 2px solid #c7dade; border-radius: 12px; color: #40576a; background: #f7fbfc; font-weight: 800; transition: .15s; }
.row-option small { display: block; margin-top: 5px; color: var(--muted); font-family: Arial,sans-serif; font-size: .65rem; letter-spacing: .04em; }
.row-option input:checked + span { color: #07404c; border-color: #29c5db; background: #d8fbff; box-shadow: 0 0 0 3px rgba(64,230,255,.18), 0 7px 18px rgba(28,146,169,.12); }
.row-option input:focus-visible + span { outline: 3px solid #ef9f24; outline-offset: 2px; }
.row-option input:disabled + span { cursor: default; }
.countdown { position: absolute; z-index: 7; inset: 0; display: grid; place-items: center; color: var(--accent-dark); background: rgba(255,255,255,.84); font: 900 clamp(6rem,22vw,13rem)/1 Arial,sans-serif; text-shadow: 0 8px 0 #d4edf0; }
.result h2 { margin: 8px 0 20px; font-size: 1.8rem; }
.exit-panel h2 { margin: 8px 0 24px; font-size: clamp(1.25rem,3vw,1.65rem); }
.exit-panel__buttons { display: flex; justify-content: center; gap: 10px; }
.dialog-button { min-width: 120px; padding: 10px 18px; border: 1px solid #9eb8bf; border-radius: 999px; color: var(--accent-dark); background: #f6fcfd; font-weight: 800; cursor: pointer; }
.dialog-button--danger { color: #9b2833; border-color: #dfaab0; background: #fff1f2; }
.dialog-button:focus-visible { outline: 3px solid #ef9f24; outline-offset: 2px; }
.result__scores { display: flex; justify-content: center; gap: 12px; margin-bottom: 18px; }
.result__scores p { min-width: 130px; margin: 0; padding: 14px; border-radius: 12px; color: var(--muted); background: #edf8f9; font-size: .82rem; font-weight: 700; }
.result__scores strong { display: block; margin-top: 4px; color: var(--accent-dark); font-size: 2.2rem; }
.change-row { margin-top: 15px; padding: 9px 18px; border: 1px solid #9eb8bf; border-radius: 999px; color: var(--accent-dark); background: #f6fcfd; font-weight: 700; cursor: pointer; }
.change-row:hover { background: #e0f7fa; }
.guide { margin-top: 12px; padding: 12px 14px 9px; border: 1px solid #cfe2e6; border-radius: 18px; background: rgba(255,255,255,.88); box-shadow: 0 10px 30px rgba(37,76,88,.08); }
.guide__header { position: relative; display: flex; align-items: center; justify-content: center; min-height: 24px; margin-bottom: 9px; }
.guide__title { margin: 0; color: var(--muted); font-size: .78rem; font-weight: 700; text-align: center; }
.keyboard-viewport { overflow-x: auto; overflow-y: hidden; padding: 4px 3px 7px; scrollbar-width: thin; }
.screen-keyboard { --key-width: clamp(43px, 6.3vw, 68px); width: calc(var(--key-width) * 10 + 63px); min-width: 493px; margin: 0 auto; }
.keyboard-row { display: grid; grid-template-columns: repeat(10, var(--key-width)); gap: 7px; width: max-content; margin-bottom: 6px; transition: opacity .18s, filter .18s; }
.keyboard-row[data-row="number"] { margin-left: 0; }
.keyboard-row[data-row="top"] { margin-left: 15px; }
.keyboard-row[data-row="home"] { margin-left: 29px; }
.keyboard-row[data-row="bottom"] { margin-left: 43px; }
.keyboard-row.is-inactive-row { opacity: .48; filter: saturate(.65); }
.keyboard-row.is-active-row { opacity: 1; }
.keycap { position: relative; min-width: 0; min-height: 48px; padding: 0; border: 1px solid #a9c0c6; border-bottom: 5px solid #819ba2; border-radius: 9px; color: #33475b; background: linear-gradient(#fff,#eaf1f3); font: 800 clamp(.95rem,2vw,1.28rem)/1 Arial,sans-serif; box-shadow: 0 3px 6px rgba(37,76,88,.12); transition: color .08s, background .08s, box-shadow .08s, transform .08s, opacity .08s; }
.keycap::before { content: ""; position: absolute; inset: 3px; z-index: -1; border-radius: 7px; opacity: .28; }
.keycap[data-zone="left-little"]::before, .keycap[data-zone="right-little"]::before { background: #f6acc1; }
.keycap[data-zone="left-ring"]::before, .keycap[data-zone="right-ring"]::before { background: #efc57f; }
.keycap[data-zone="left-middle"]::before, .keycap[data-zone="right-middle"]::before { background: #d9dc75; }
.keycap[data-zone="left-index"]::before, .keycap[data-zone="right-index"]::before { background: #8edcc4; }
.keycap[data-bump="true"]::after { content: ""; position: absolute; left: 33%; right: 33%; bottom: 7px; height: 3px; border-radius: 2px; background: #718c94; box-shadow: 0 1px 0 #fff; }
.keycap.is-zone-target { opacity: 1; border-color: #68cbd8; background: #e5fbfd; box-shadow: 0 0 0 1px rgba(64,230,255,.35), 0 0 10px rgba(64,230,255,.3); }
.keycap.is-target { z-index: 2; color: #073e4b; background: #bdf8ff; box-shadow: 0 0 0 2px #5edbec, 0 0 18px rgba(64,230,255,.85); transform: translateY(-1px); }
.keycap.is-correct { color: #fff; background: #23cde6; transform: translateY(2px) scale(.98); box-shadow: 0 0 0 3px #fff, 0 0 30px var(--glow); }
.keycap.is-wrong { z-index: 3; color: #fff; background: #ef5360; border-color: #b32635; box-shadow: 0 0 18px rgba(239,50,67,.85); animation: wrong-shake .24s linear; }
.hands { display: flex; justify-content: center; gap: clamp(34px,11vw,130px); margin: 7px auto 0; }
.hand { display: flex; align-items: flex-end; gap: 4px; padding: 5px 13px 0; border-bottom: 7px solid #b8c9ce; border-radius: 0 0 24px 24px; }
.finger { display: grid; place-items: start center; width: clamp(22px,4vw,34px); height: var(--finger-height); padding-top: 6px; border: 2px solid #a9bcc2; border-radius: 15px 15px 8px 8px; color: #60727a; background: linear-gradient(#edf5f6,#dce9eb); font-size: clamp(.56rem,1.4vw,.68rem); font-weight: 800; transition: .1s; }
.finger.is-target { color: #07404c; border-color: #2bcbe2; background: #9cf3ff; box-shadow: 0 0 16px rgba(64,230,255,.9); transform: translateY(-4px); }
.message { min-height: 1.5em; margin: 10px 0 0; color: var(--muted); text-align: center; font-size: .92rem; }
.exit-hint { position: absolute; right: 0; margin: 0; color: var(--muted); font-size: .78rem; white-space: nowrap; }
.exit-hint kbd { padding: .12em .45em; border-bottom-width: 2px; }
.visually-hidden { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }
[hidden] { display: none !important; }
@keyframes wrong-shake { 0%,100%{transform:translateX(0)} 20%{transform:translateX(-5px)} 40%{transform:translateX(5px)} 60%{transform:translateX(-4px)} 80%{transform:translateX(3px)} }
@keyframes laser-shot { from{opacity:1;clip-path:inset(0 100% 0 0)} 45%{clip-path:inset(0 0 0 0)} to{opacity:0;clip-path:inset(0 0 0 0)} }
@keyframes wrong-laser-shot { from{opacity:.9;clip-path:inset(0 100% 0 0)} 70%{opacity:.8;clip-path:inset(0 0 0 0)} to{opacity:0;clip-path:inset(0 0 0 0)} }
@keyframes wrong-spark-burst { from{opacity:1;transform:translate(-50%,-50%) scale(1)} to{opacity:0;transform:translate(calc(-50% + var(--wrong-x)),calc(-50% + var(--wrong-y))) scale(.1)} }
@keyframes target-hit { to{opacity:0;filter:blur(5px);transform:translate(var(--key-x),var(--key-y)) scale(1.65) rotate(12deg)} }
@keyframes spark-burst { from{opacity:1;transform:translate(-50%,-50%) scale(.5)} to{opacity:0;transform:translate(calc(-50% + var(--spark-x)),calc(-50% + var(--spark-y))) scale(.1)} }
@media (max-width:720px) {
  .app { width:min(100% - 20px,1100px); padding-top:16px; }
  .app__header { align-items:stretch; flex-direction:column; gap:10px; }
  .status { width:100%; }
  .status__item { flex:1; min-width:0; padding:8px 4px; }
  .play-area { height:410px; border-radius:16px; }
  .panel { padding: 18px 14px; }
  .row-selector { grid-template-columns: 1fr; gap: 6px; }
  .row-option span { min-height: 49px; }
  .row-option small { margin-top: 3px; }
  .screen-keyboard { --key-width: 43px; margin-left: 0; }
  .keycap { min-height:43px; border-bottom-width:4px; }
  .hands { gap:18px; }
  .hand { gap:2px; padding-inline:4px; }
  .finger { width:clamp(18px,7vw,29px); }
  .guide__header { justify-content:space-between; gap:8px; }
  .guide__title { text-align:left; }
  .exit-hint { position:static; }
}
@media (prefers-reduced-motion:reduce) { *,*::before,*::after { animation-duration:.01ms !important; animation-iteration-count:1 !important; } }

"use strict";

const KEYBOARD_ROWS = [
  {
    id: "number",
    label: "数字段（今回は練習対象外）",
    keys: [
      ["1", "1"], ["2", "2"], ["3", "3"], ["4", "4"], ["5", "5"],
      ["6", "6"], ["7", "7"], ["8", "8"], ["9", "9"], ["0", "0"]
    ]
  },
  {
    id: "top",
    label: "上段",
    keys: [["q", "Q"], ["w", "W"], ["e", "E"], ["r", "R"], ["t", "T"], ["y", "Y"], ["u", "U"], ["i", "I"], ["o", "O"], ["p", "P"]]
  },
  {
    id: "home",
    label: "ホームポジション段",
    keys: [["a", "A"], ["s", "S"], ["d", "D"], ["f", "F"], ["g", "G"], ["h", "H"], ["j", "J"], ["k", "K"], ["l", "L"], [";", ";"]]
  },
  {
    id: "bottom",
    label: "下段",
    keys: [["z", "Z"], ["x", "X"], ["c", "C"], ["v", "V"], ["b", "B"], ["n", "N"], ["m", "M"], [",", ","], [".", "."], ["/", "/"]]
  }
];

const FINGER_COLUMNS = [
  { hand: "left", finger: "little", label: "小指" },
  { hand: "left", finger: "ring", label: "薬指" },
  { hand: "left", finger: "middle", label: "中指" },
  { hand: "left", finger: "index", label: "人差" },
  { hand: "left", finger: "index", label: "人差" },
  { hand: "right", finger: "index", label: "人差" },
  { hand: "right", finger: "index", label: "人差" },
  { hand: "right", finger: "middle", label: "中指" },
  { hand: "right", finger: "ring", label: "薬指" },
  { hand: "right", finger: "little", label: "小指" }
];

const KEY_GUIDE = KEYBOARD_ROWS.flatMap((row) => row.keys.map(([key, label], column) => ({
  key, label, row: row.id, ...FINGER_COLUMNS[column]
})));
const ROW_LABELS = { top: "上段", home: "ホームポジション段", bottom: "下段" };
const PRACTICE_TIME = 60;
const FALL_SPEED = 16;
const HIT_DELAY = 180;

const playArea = document.getElementById("play-area");
const fallingKey = document.getElementById("falling-key");
const effectLayer = document.getElementById("effect-layer");
const startPanel = document.getElementById("start-panel");
const countdown = document.getElementById("countdown");
const resultPanel = document.getElementById("result-panel");
const timeDisplay = document.getElementById("time");
const scoreDisplay = document.getElementById("score");
const missesDisplay = document.getElementById("misses");
const finalScore = document.getElementById("final-score");
const finalMisses = document.getElementById("final-misses");
const message = document.getElementById("message");
const screenKeyboard = document.getElementById("screen-keyboard");
const hands = document.getElementById("hands");
const changeRowButton = document.getElementById("change-row");
const soundToggle = document.getElementById("sound-toggle");
const exitPanel = document.getElementById("exit-panel");
const exitPracticeButton = document.getElementById("exit-practice");
const continuePracticeButton = document.getElementById("continue-practice");
const exitHint = document.getElementById("exit-hint");
const rowInputs = [...document.querySelectorAll('input[name="practice-row"]')];

let state = "waiting";
let selectedRow = "home";
let practiceKeys = [];
let currentKey = "";
let score = 0;
let misses = 0;
let keyX = 0;
let keyY = 0;
let previousFrameTime = 0;
let finishTime = 0;
let animationId = 0;
let countdownTimerId = 0;
let nextKeyTimerId = 0;
let soundEnabled = true;
let audioContext = null;
let pausedAt = 0;
let pausedState = "playing";

buildKeyboard();
buildHands();
selectPracticeRow(selectedRow);
document.addEventListener("keydown", handleKeydown);
rowInputs.forEach((input) => input.addEventListener("change", () => selectPracticeRow(input.value)));
changeRowButton.addEventListener("click", returnToSelection);
soundToggle.addEventListener("click", toggleSound);
exitPracticeButton.addEventListener("click", () => finishPractice(true));
continuePracticeButton.addEventListener("click", resumePractice);

function getAudioContext() {
  if (!audioContext) audioContext = new (window.AudioContext || window.webkitAudioContext)();
  if (audioContext.state === "suspended") audioContext.resume();
  return audioContext;
}

function tone({ frequency, endFrequency = frequency, duration = .05, volume = .035, type = "square", delay = 0 }) {
  if (!soundEnabled) return;
  const context = getAudioContext();
  const start = context.currentTime + delay;
  const oscillator = context.createOscillator();
  const gain = context.createGain();
  oscillator.type = type;
  oscillator.frequency.setValueAtTime(frequency, start);
  oscillator.frequency.exponentialRampToValueAtTime(Math.max(20, endFrequency), start + duration);
  gain.gain.setValueAtTime(.0001, start);
  gain.gain.exponentialRampToValueAtTime(volume, start + .004);
  gain.gain.exponentialRampToValueAtTime(.0001, start + duration);
  oscillator.connect(gain).connect(context.destination);
  oscillator.start(start);
  oscillator.stop(start + duration + .01);
}

function playSound(name) {
  if (!soundEnabled) return;
  if (name === "wrong") {
    tone({ frequency: 150, endFrequency: 75, duration: .105, volume: .055, type: "triangle" });
    tone({ frequency: 95, endFrequency: 55, duration: .09, volume: .025, delay: .012 });
  }
  if (name === "break") [1500, 2150, 2850].forEach((frequency, index) => tone({ frequency, endFrequency: frequency * .65, duration: .055 + index * .012, volume: .018, type: "triangle", delay: index * .009 }));
  if (name === "fizzle") tone({ frequency: 340, endFrequency: 85, duration: .075, volume: .03, type: "sawtooth" });
}

function toggleSound() {
  soundEnabled = !soundEnabled;
  soundToggle.textContent = soundEnabled ? "ON" : "OFF";
  soundToggle.setAttribute("aria-pressed", String(soundEnabled));
}

function buildKeyboard() {
  KEYBOARD_ROWS.forEach((rowData) => {
    const row = document.createElement("div");
    row.className = "keyboard-row";
    row.dataset.row = rowData.id;
    row.setAttribute("role", "group");
    row.setAttribute("aria-label", rowData.label);

    rowData.keys.forEach(([keyName, label], column) => {
      const guide = KEY_GUIDE.find((item) => item.key === keyName);
      const key = document.createElement("button");
      key.type = "button";
      key.className = "keycap";
      key.dataset.key = keyName;
      key.dataset.zone = `${guide.hand}-${guide.finger}`;
      key.dataset.bump = String(keyName === "f" || keyName === "j");
      key.style.setProperty("--column", column);
      key.textContent = label;
      key.tabIndex = -1;
      key.setAttribute("aria-label", `${label}キー ${guide.hand === "left" ? "左" : "右"}${guide.label}`);
      row.appendChild(key);
    });
    screenKeyboard.appendChild(row);
  });
}

function buildHands() {
  const fingerOrder = {
    left: ["little", "ring", "middle", "index"],
    right: ["index", "middle", "ring", "little"]
  };
  const labels = { little: "小指", ring: "薬指", middle: "中指", index: "人差" };
  const heights = { little: "43px", ring: "55px", middle: "62px", index: "57px" };

  ["left", "right"].forEach((side) => {
    const hand = document.createElement("div");
    hand.className = "hand";
    hand.setAttribute("aria-label", side === "left" ? "左手" : "右手");
    fingerOrder[side].forEach((fingerName) => {
      const finger = document.createElement("span");
      finger.className = "finger";
      finger.dataset.hand = side;
      finger.dataset.finger = fingerName;
      finger.style.setProperty("--finger-height", heights[fingerName]);
      finger.textContent = labels[fingerName];
      hand.appendChild(finger);
    });
    hands.appendChild(hand);
  });
}

function selectPracticeRow(rowName) {
  selectedRow = rowName;
  practiceKeys = KEY_GUIDE.filter((item) => item.row === selectedRow).map((item) => item.key);
  screenKeyboard.dataset.selectedRow = selectedRow;
  document.querySelectorAll(".keyboard-row").forEach((row) => {
    row.classList.toggle("is-active-row", row.dataset.row === selectedRow);
    row.classList.toggle("is-inactive-row", row.dataset.row !== selectedRow);
  });
  message.textContent = `${ROW_LABELS[selectedRow]}を練習します。Spaceキーを押してください`;
}

function handleKeydown(event) {
  if (event.code === "Escape" && (state === "playing" || state === "hit")) {
    event.preventDefault();
    pausePractice();
    return;
  }
  if (event.code === "Escape" && state === "paused") {
    event.preventDefault();
    resumePractice();
    return;
  }
  if (event.code === "Space" && (state === "waiting" || state === "finished")) {
    event.preventDefault();
    startCountdown();
    return;
  }
  if (state !== "playing" || event.repeat || event.ctrlKey || event.altKey || event.metaKey) return;

  const typedKey = event.key.toLowerCase();
  if (typedKey === currentKey) {
    event.preventDefault();
    handleCorrectInput();
  } else if (event.key.length === 1) {
    misses += 1;
    missesDisplay.textContent = misses;
    showWrongKey(typedKey);
    playSound("wrong");
    shootWrongLaser(getKeycap(typedKey) || getKeycap(currentKey));
  }
}

function startCountdown() {
  if (soundEnabled) getAudioContext();
  clearTimeout(countdownTimerId);
  clearTimeout(nextKeyTimerId);
  cancelAnimationFrame(animationId);
  state = "countdown";
  score = 0;
  misses = 0;
  timeDisplay.textContent = PRACTICE_TIME;
  scoreDisplay.textContent = score;
  missesDisplay.textContent = misses;
  startPanel.hidden = true;
  resultPanel.hidden = true;
  fallingKey.hidden = true;
  fallingKey.classList.remove("is-hit");
  effectLayer.replaceChildren();
  clearGuide();
  exitPanel.hidden = true;
  exitHint.hidden = true;
  countdown.hidden = false;
  message.textContent = `${ROW_LABELS[selectedRow]}のカウントダウン中です`;
  rowInputs.forEach((input) => { input.disabled = true; });
  const labels = ["3", "2", "1", "START"];
  let index = 0;
  const showCount = () => {
    countdown.textContent = labels[index++];
    countdownTimerId = window.setTimeout(index < labels.length ? showCount : beginPractice, index < labels.length ? 1000 : 700);
  };
  showCount();
}

function beginPractice() {
  state = "playing";
  countdown.hidden = true;
  message.textContent = "表示された文字を、光っている指で押してください";
  exitHint.hidden = false;
  finishTime = performance.now() + PRACTICE_TIME * 1000;
  previousFrameTime = performance.now();
  showNextKey();
  animationId = requestAnimationFrame(update);
}

function showNextKey() {
  if (state !== "playing") return;
  fallingKey.classList.remove("is-hit");
  currentKey = practiceKeys[Math.floor(Math.random() * practiceKeys.length)];
  fallingKey.textContent = currentKey;
  fallingKey.hidden = false;
  const sideMargin = 18;
  const maxX = Math.max(sideMargin, playArea.clientWidth - fallingKey.offsetWidth - sideMargin);
  keyX = sideMargin + Math.random() * (maxX - sideMargin);
  keyY = 54;
  drawKey();
  highlightGuide(currentKey);
}

function handleCorrectInput() {
  state = "hit";
  score += 1;
  scoreDisplay.textContent = score;
  const targetKey = getKeycap(currentKey);
  targetKey?.classList.add("is-correct");
  shootLaser(targetKey);
  fallingKey.style.setProperty("--key-x", `${keyX}px`);
  fallingKey.style.setProperty("--key-y", `${keyY}px`);
  fallingKey.classList.add("is-hit");
  createSparks();
  window.setTimeout(() => playSound("break"), 75);
  nextKeyTimerId = window.setTimeout(() => {
    targetKey?.classList.remove("is-correct");
    if (performance.now() >= finishTime) {
      finishPractice();
      return;
    }
    state = "playing";
    previousFrameTime = performance.now();
    showNextKey();
  }, HIT_DELAY);
}

function update(now) {
  if (state === "finished" || state === "waiting" || state === "countdown") return;
  const remainingMilliseconds = finishTime - now;
  if (remainingMilliseconds <= 0) {
    finishPractice();
    return;
  }
  timeDisplay.textContent = Math.ceil(remainingMilliseconds / 1000);
  if (state === "playing") {
    const elapsedSeconds = Math.min((now - previousFrameTime) / 1000, .1);
    const maxY = playArea.clientHeight - fallingKey.offsetHeight - 20;
    keyY = Math.min(keyY + FALL_SPEED * elapsedSeconds, maxY);
    previousFrameTime = now;
    drawKey();
  }
  animationId = requestAnimationFrame(update);
}

function drawKey() { fallingKey.style.transform = `translate(${keyX}px, ${keyY}px)`; }

function highlightGuide(keyName) {
  clearGuide();
  const guide = KEY_GUIDE.find((item) => item.key === keyName);
  getKeycap(keyName)?.classList.add("is-target");
  if (!guide) return;
  document.querySelector(`.finger[data-hand="${guide.hand}"][data-finger="${guide.finger}"]`)?.classList.add("is-target");
  document.querySelectorAll(`.keycap[data-zone="${guide.hand}-${guide.finger}"]`).forEach((key) => key.classList.add("is-zone-target"));
}

function clearGuide() {
  document.querySelectorAll(".keycap, .finger").forEach((element) => element.classList.remove("is-target", "is-zone-target", "is-correct", "is-wrong"));
}

function showWrongKey(keyName) {
  const wrongKey = getKeycap(keyName);
  if (!wrongKey) return;
  wrongKey.classList.remove("is-wrong");
  void wrongKey.offsetWidth;
  wrongKey.classList.add("is-wrong");
  window.setTimeout(() => wrongKey.classList.remove("is-wrong"), 260);
}

function getKeycap(keyName) {
  return document.querySelector(`.keycap[data-key="${CSS.escape(keyName)}"]`);
}

function shootLaser(sourceKey) {
  if (!sourceKey) return;
  const sourceRect = sourceKey.getBoundingClientRect();
  const targetRect = fallingKey.getBoundingClientRect();
  const startX = sourceRect.left + sourceRect.width / 2;
  const startY = sourceRect.top + 3;
  const endX = targetRect.left + targetRect.width / 2;
  const endY = targetRect.top + targetRect.height / 2;
  const distance = Math.hypot(endX - startX, endY - startY);
  const angle = Math.atan2(endY - startY, endX - startX) * 180 / Math.PI;
  const laser = document.createElement("span");
  laser.className = "laser";
  laser.style.cssText = `left:${startX}px;top:${startY}px;width:${distance}px;transform:rotate(${angle}deg)`;
  document.body.appendChild(laser);
  window.setTimeout(() => laser.remove(), 220);
}

function shootWrongLaser(sourceKey) {
  if (!sourceKey) return;
  const sourceRect = sourceKey.getBoundingClientRect();
  const startX = sourceRect.left + sourceRect.width / 2;
  const startY = sourceRect.top + 3;
  const angle = -155 + Math.random() * 130;
  const distance = 75 + Math.random() * 85;
  const radians = angle * Math.PI / 180;
  const endX = startX + Math.cos(radians) * distance;
  const endY = startY + Math.sin(radians) * distance;
  const laser = document.createElement("span");
  laser.className = "wrong-laser";
  laser.style.cssText = `left:${startX}px;top:${startY}px;width:${distance}px;transform:rotate(${angle}deg)`;
  document.body.appendChild(laser);
  window.setTimeout(() => {
    laser.remove();
    createWrongBurst(endX, endY);
    playSound("fizzle");
  }, 105);
}

function createWrongBurst(x, y) {
  for (let index = 0; index < 6; index += 1) {
    const particle = document.createElement("span");
    particle.className = "wrong-spark";
    particle.style.left = `${x}px`;
    particle.style.top = `${y}px`;
    particle.style.setProperty("--wrong-x", `${(Math.random() - .5) * 34}px`);
    particle.style.setProperty("--wrong-y", `${(Math.random() - .5) * 34}px`);
    document.body.appendChild(particle);
    window.setTimeout(() => particle.remove(), 230);
  }
}

function pausePractice() {
  pausedAt = performance.now();
  pausedState = state;
  state = "paused";
  cancelAnimationFrame(animationId);
  clearTimeout(nextKeyTimerId);
  exitPanel.hidden = false;
  continuePracticeButton.focus();
  message.textContent = "練習を一時停止しています";
}

function resumePractice() {
  if (state !== "paused") return;
  finishTime += performance.now() - pausedAt;
  exitPanel.hidden = true;
  state = pausedState;
  previousFrameTime = performance.now();
  message.textContent = "表示された文字を、光っている指で押してください";
  if (state === "hit") {
    state = "playing";
    showNextKey();
  }
  animationId = requestAnimationFrame(update);
}

function createSparks() {
  const areaRect = playArea.getBoundingClientRect();
  const targetRect = fallingKey.getBoundingClientRect();
  const x = targetRect.left + targetRect.width / 2 - areaRect.left;
  const y = targetRect.top + targetRect.height / 2 - areaRect.top;
  for (let index = 0; index < 8; index += 1) {
    const angle = Math.PI * 2 * index / 8;
    const spark = document.createElement("span");
    spark.className = "spark";
    spark.style.left = `${x}px`;
    spark.style.top = `${y}px`;
    spark.style.setProperty("--spark-x", `${Math.cos(angle) * 45}px`);
    spark.style.setProperty("--spark-y", `${Math.sin(angle) * 45}px`);
    effectLayer.appendChild(spark);
    window.setTimeout(() => spark.remove(), 330);
  }
}

function finishPractice(endedEarly = false) {
  state = "finished";
  clearTimeout(nextKeyTimerId);
  cancelAnimationFrame(animationId);
  timeDisplay.textContent = endedEarly ? Math.max(0, Math.ceil((finishTime - pausedAt) / 1000)) : "0";
  fallingKey.hidden = true;
  fallingKey.classList.remove("is-hit");
  effectLayer.replaceChildren();
  clearGuide();
  exitPanel.hidden = true;
  exitHint.hidden = true;
  finalScore.textContent = score;
  finalMisses.textContent = misses;
  resultPanel.hidden = false;
  message.textContent = `${endedEarly ? "途中終了しました。" : ""}${ROW_LABELS[selectedRow]}をもう一度練習するときはSpaceキーを押してください`;
}

function returnToSelection() {
  state = "waiting";
  resultPanel.hidden = true;
  startPanel.hidden = false;
  exitHint.hidden = true;
  rowInputs.forEach((input) => { input.disabled = false; });
  timeDisplay.textContent = PRACTICE_TIME;
  scoreDisplay.textContent = "0";
  missesDisplay.textContent = "0";
  selectPracticeRow(selectedRow);
}