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js/quiz.js

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+import { CHROMATIC, NATURAL, getNoteAt, getAnswerChoices } from './music.js';
+import { FRET_COUNT } from './fretboard.js';
+
+export function genMode1Question(numStrings, naturalOnly) {
+  let stringIdx, fret, note;
+  let attempts = 0;
+  do {
+    stringIdx = Math.floor(Math.random() * numStrings);
+    fret = Math.floor(Math.random() * (FRET_COUNT + 1));
+    note = getNoteAt(stringIdx, fret, numStrings);
+    attempts++;
+  } while (naturalOnly && !NATURAL.includes(note) && attempts < 100);
+
+  const choices = getAnswerChoices(note, naturalOnly);
+  return { stringIdx, fret, note, choices };
+}
+
+export function genMode2Question(numStrings, naturalOnly) {
+  const pool = naturalOnly ? NATURAL : CHROMATIC;
+  const targetNote = pool[Math.floor(Math.random() * pool.length)];
+
+  const rangeLen = Math.random() < 0.5 ? 4 : 5;
+  const fretStart = Math.floor(Math.random() * (FRET_COUNT - rangeLen + 1));
+  const fretEnd = fretStart + rangeLen;
+
+  const correctSet = new Set();
+  for (let s = 0; s < numStrings; s++) {
+    for (let f = fretStart; f <= fretEnd; f++) {
+      if (getNoteAt(s, f, numStrings) === targetNote) {
+        correctSet.add(`${s},${f}`);
+      }
+    }
+  }
+
+  return { targetNote, fretStart, fretEnd, correctSet };
+}
+
+export function evaluateMode2(selection, correctSet) {
+  const allCorrect = [...correctSet].every(k => selection.has(k)) &&
+                     [...selection].every(k => correctSet.has(k));
+  const missed = [...correctSet].filter(k => !selection.has(k)).length;
+  const extra  = [...selection].filter(k => !correctSet.has(k)).length;
+  return { allCorrect, missed, extra };
+}