From 8caf775fe71e86ce5fd86800d0237bae1c33d3fe Mon Sep 17 00:00:00 2001
From: Jens Mohrmann <mail@jensmohrmann.de>
Date: Sun, 21 Dec 2025 17:53:26 +0100
Subject: [PATCH] key signatures working

---
 src/App.tsx                   |   4 +-
 src/components/Controls.tsx   |  30 +++++++++
 src/components/SheetMusic.tsx |  28 ++++-----
 src/music/NoteUtils.ts        | 112 ++++++++++++++++++++++++++++++++--
 4 files changed, 155 insertions(+), 19 deletions(-)

diff --git a/src/App.tsx b/src/App.tsx
index 9dca115..c9c9e63 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -26,7 +26,8 @@ function App() {
   const [settings, setSettings] = useState<AppSettings>({
     difficulty: 'first_pos',
     showHint: false,
-    tuningId: 'standard'
+    tuningId: 'standard',
+    keySignature: 'C'
   });
 
   const [streak, setStreak] = useState(0);
@@ -122,6 +123,7 @@ function App() {
           <SheetMusic
             targetMidi={targetMidi}
             playedMidi={pitchData?.midi}
+            keySignature={settings.keySignature}
             width={Math.min(window.innerWidth - 40, 500)}
             height={250}
           />
diff --git a/src/components/Controls.tsx b/src/components/Controls.tsx
index a6e8336..05f72a2 100644
--- a/src/components/Controls.tsx
+++ b/src/components/Controls.tsx
@@ -8,6 +8,7 @@ export interface AppSettings {
     difficulty: Difficulty;
     showHint: boolean;
     tuningId: string;
+    keySignature: string;
 }
 
 interface ControlsProps {
@@ -63,6 +64,34 @@ export const Controls: React.FC<ControlsProps> = ({ settings, onUpdateSettings }
                 </select>
             </div>
 
+
+            <div className="control-group">
+                <label className="control-label">
+                    <span>Key Signature</span>
+                </label>
+                <select
+                    value={settings.keySignature}
+                    onChange={(e) => onUpdateSettings({ ...settings, keySignature: e.target.value })}
+                    className="control-select"
+                >
+                    <optgroup label="Major Keys">
+                        <option value="C">C Major</option>
+                        <option value="G">G Major</option>
+                        <option value="D">D Major</option>
+                        <option value="A">A Major</option>
+                        <option value="E">E Major</option>
+                        <option value="F">F Major</option>
+                        <option value="Bb">Bb Major</option>
+                        <option value="Eb">Eb Major</option>
+                    </optgroup>
+                    <optgroup label="Minor Keys">
+                        <option value="Am">A Minor</option>
+                        <option value="Em">E Minor</option>
+                        <option value="Dm">D Minor</option>
+                    </optgroup>
+                </select>
+            </div>
+
             <button
                 className={`control-button ${settings.showHint ? 'active' : ''}`}
                 onClick={toggleHint}
@@ -73,3 +102,4 @@ export const Controls: React.FC<ControlsProps> = ({ settings, onUpdateSettings }
         </div>
     );
 };
+
diff --git a/src/components/SheetMusic.tsx b/src/components/SheetMusic.tsx
index 8dbe26e..e722081 100644
--- a/src/components/SheetMusic.tsx
+++ b/src/components/SheetMusic.tsx
@@ -1,6 +1,7 @@
 import React, { useEffect, useRef } from 'react';
 import { Renderer, Stave, StaveNote, Accidental, Voice, Formatter } from 'vexflow';
-import { getNoteDetails } from '../music/NoteUtils';
+import { getNoteInKey } from '../music/NoteUtils';
+
 
 interface SheetMusicProps {
     targetMidi: number;
@@ -9,6 +10,7 @@ interface SheetMusicProps {
     width?: number;
     height?: number;
     transpose?: number; // Transposition in semitones for visualization (e.g., +12 for guitar)
+    keySignature?: string;
 }
 
 export const SheetMusic: React.FC<SheetMusicProps> = ({
@@ -17,7 +19,8 @@ export const SheetMusic: React.FC<SheetMusicProps> = ({
     clef = 'treble',
     width = 300,
     height = 200,
-    transpose = 12 // Default to +1 octave (Guitar Notation)
+    transpose = 12, // Default to +1 octave (Guitar Notation)
+    keySignature = 'C'
 }) => {
     const containerRef = useRef<HTMLDivElement>(null);
 
@@ -35,16 +38,13 @@ export const SheetMusic: React.FC<SheetMusicProps> = ({
         // Create Stave
         const stave = new Stave(10, 40, width - 20);
         stave.addClef(clef);
+        stave.addKeySignature(keySignature);
         stave.setContext(context).draw();
 
-        // Helper to create keys for VexFlow
+        // Helper to create keys for VexFlow using key signature logic
         const getVexFlowKey = (midi: number) => {
             const visualMidi = midi + transpose;
-            const details = getNoteDetails(visualMidi);
-            return {
-                keys: [`${details.name.toLowerCase()}/${details.octave}`],
-                hasAccidental: details.name.includes("#")
-            };
+            return getNoteInKey(visualMidi, keySignature);
         };
 
         // Create Target Note
@@ -56,8 +56,8 @@ export const SheetMusic: React.FC<SheetMusicProps> = ({
             clef: clef
         });
 
-        if (targetData.hasAccidental) {
-            targetStaveNote.addModifier(new Accidental("#"));
+        if (targetData.accidental) {
+            targetStaveNote.addModifier(new Accidental(targetData.accidental));
         }
 
         if (playedMidi) {
@@ -75,7 +75,7 @@ export const SheetMusic: React.FC<SheetMusicProps> = ({
                 duration: "h",
                 clef: clef
             });
-            if (targetData.hasAccidental) targetNoteHalf.addModifier(new Accidental("#"));
+            if (targetData.accidental) targetNoteHalf.addModifier(new Accidental(targetData.accidental));
 
 
             if (playedMidi === targetMidi) {
@@ -84,8 +84,8 @@ export const SheetMusic: React.FC<SheetMusicProps> = ({
                 playedStaveNote.setStyle({ fillStyle: "var(--color-error)", strokeStyle: "var(--color-error)" });
             }
 
-            if (playedData.hasAccidental) {
-                playedStaveNote.addModifier(new Accidental("#"));
+            if (playedData.accidental) {
+                playedStaveNote.addModifier(new Accidental(playedData.accidental));
             }
 
             // Use camelCase properties as fixed previously
@@ -102,7 +102,7 @@ export const SheetMusic: React.FC<SheetMusicProps> = ({
             voice.draw(context, stave);
         }
 
-    }, [targetMidi, playedMidi, clef, width, height, transpose]);
+    }, [targetMidi, playedMidi, clef, width, height, transpose, keySignature]);
 
     return <div ref={containerRef} className="sheet-music-container" />;
 };
diff --git a/src/music/NoteUtils.ts b/src/music/NoteUtils.ts
index 08d3eb9..becd93e 100644
--- a/src/music/NoteUtils.ts
+++ b/src/music/NoteUtils.ts
@@ -50,7 +50,111 @@ export function getRandomNote(min: number, max: number, validNotes?: number[]):
     return Math.floor(Math.random() * (max - min + 1)) + min;
 }
 
-// Helper to convert Written note to Sounding note for guitar
-// e.g. Input: "C4" (Written) -> Returns C3 (Sounding) MIDI
-// But usually we work with MIDI.
-// This is just a note for logic: Guitar Sounding = Written - 12.
+
+export const KEY_SIGNATURES: { [key: string]: { name: string, accidentals: string[] } } = {
+    'C': { name: 'C Major', accidentals: [] },
+    'G': { name: 'G Major', accidentals: ['F#'] },
+    'D': { name: 'D Major', accidentals: ['F#', 'C#'] },
+    'A': { name: 'A Major', accidentals: ['F#', 'C#', 'G#'] },
+    'E': { name: 'E Major', accidentals: ['F#', 'C#', 'G#', 'D#'] },
+    'F': { name: 'F Major', accidentals: ['Bb'] },
+    'Bb': { name: 'Bb Major', accidentals: ['Bb', 'Eb'] },
+    'Eb': { name: 'Eb Major', accidentals: ['Bb', 'Eb', 'Ab'] },
+    'Am': { name: 'A Minor', accidentals: [] },
+    'Em': { name: 'E Minor', accidentals: ['F#'] },
+    'Dm': { name: 'D Minor', accidentals: ['Bb'] },
+};
+
+// Map of midi values to their "natural" note names (0=C, 1=C#/Db, etc.)
+// We use this to decide if we need a sharp, flat, or natural based on the key.
+
+// 0=C, 1=C#, 2=D, 3=D#, 4=E, 5=F, 6=F#, 7=G, 8=G#, 9=A, 10=A#, 11=B
+// But wait, VexFlow needs specific spelling.
+// Let's rely on standard theory:
+// Key of G (F#): If we have F# (midi 6), it's consistent. If we have F (midi 5), it's a natural.
+
+/**
+ * Specs for a note to be rendered by VexFlow
+ */
+export interface VexFlowNoteSpec {
+    keys: string[]; // e.g., ["c/4"]
+    accidental?: string; // "#", "b", "n" (natural), etc.
+}
+
+export function getNoteInKey(midi: number, keySignature: string): VexFlowNoteSpec {
+    // 1. Get fundamental details
+    // We default to Sharps for sharp keys, Flats for flat keys?
+    // Simplified logic:
+    // C Major: Sharps for chromatics? Usually yes.
+
+    // Let's determine the step and accidental.
+    // 60 = C4.
+
+    const keySpec = KEY_SIGNATURES[keySignature] || KEY_SIGNATURES['C'];
+    const accList = keySpec.accidentals;
+
+    // Determine if key is "sharp-y" or "flat-y"
+    const isFlatKey = accList.some(a => a.includes('b')) || keySignature === 'F' || keySignature.includes('b');
+
+    // Basic chromatic map preference
+    const NOTE_NAMES_SHARP = ["C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"];
+    const NOTE_NAMES_FLAT = ["C", "Db", "D", "Eb", "E", "F", "Gb", "G", "Ab", "A", "Bb", "B"];
+
+    const preferredNames = isFlatKey ? NOTE_NAMES_FLAT : NOTE_NAMES_SHARP;
+
+    const semitone = midi % 12;
+    const octave = Math.floor(midi / 12) - 1;
+    const rawName = preferredNames[semitone]; // e.g., "F#" or "Gb" or "C"
+
+    // Check if this note is in the key signature
+    // In G Major: F# is in key. F is NOT.
+    // In start keys (C, Am), no accidentals in key.
+
+    // Parse the rawName: "F#" -> step "F", mod "#"
+    let step = rawName.charAt(0);
+    let mod = rawName.length > 1 ? rawName.charAt(1) : "";
+
+    // VexFlow Key Format: "c/4", "f/4", "fb/4"
+    // We need to return the accidental to *display*.
+    // Rule:
+    // If note is in key signature (e.g. F# in G Major) -> Show nothing (implied).
+    // If note is NOT in key signature:
+    //    - If it's natural but key has accidental (e.g. F natural in G Major) -> Show Natural.
+    //    - If it has accidental and matches key (e.g. F# in G Major) -> Show nothing.
+    //    - If it has accidental and doesn't match key (e.g. C# in G Major) -> Show #.
+    //    - If it's natural and key is natural (e.g. C in C Major) -> Show nothing.
+
+    // Let's find what the key signature expects for this step.
+    // Iterate accidentals in key to find if this step is modified in key.
+    // e.g. G Major has F#. So for step 'F', expected is '#'. For 'C', expected is ''.
+
+    let expectedMod = "";
+    for (const acc of accList) {
+        if (acc.startsWith(step)) {
+            expectedMod = acc.substring(1); // "#" or "b"
+            break;
+        }
+    }
+
+    let displayAccidental = undefined;
+
+    if (mod === expectedMod) {
+        // Matches key signature -> No symbol needed
+        displayAccidental = undefined;
+    } else {
+        // Diverges from key signature
+        if (mod === "") {
+            // Note is natural, but key expects accidental (e.g. F in G Major)
+            displayAccidental = "n";
+        } else {
+            // Note has accidental (e.g. F# in C Major, or F# in F Major)
+            displayAccidental = mod;
+        }
+    }
+
+    return {
+        keys: [`${step.toLowerCase()}${mod}/${octave}`], // Vexflow key: "c/4", "c#/4", "db/4"
+        accidental: displayAccidental
+    };
+}
+