1 files changed, 66 insertions, 0 deletions
diff --git a/web/src/stats.js b/web/src/stats.js
new file mode 100644
index 0000000..00d4db6
--- /dev/null
+++ b/web/src/stats.js
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+export function emptyStats() {
+    return {
+        wpm: 0,
+        rawWpm: 0,
+        keystrokes: 0,
+        accuracy: 100,
+        time: 0,
+        correctChars: 0,
+        incorrectChars: 0,
+        totalChars: 0,
+        currentStreak: 0,
+        bestStreak: 0,
+    };
+}
+
+// `totalKeystrokes` is a persistent, never-decremented count of every forward
+// keystroke made during the test, including ones later backspaced away. It
+// must be tracked externally (see typingGame.js) because a backspaced
+// mistake is no longer present in `input` by the time this runs - without
+// it, raw WPM would silently collapse to equal WPM whenever the final input
+// happens to be fully correct, hiding every corrected mistake. Falls back to
+// `input.length` (final-state only) when the caller doesn't track it.
+export function calculateStats(input, text, elapsedTime, totalKeystrokes) {
+    let correct = 0;
+    let totalErrors = 0;
+    let currentStreak = 0;
+    let bestStreak = 0;
+    const hasStartedTyping = input.length > 0;
+
+    for (let i = 0; i < input.length; i++) {
+        if (i < text.length && input[i] === text[i]) {
+            correct++;
+            currentStreak++;
+            bestStreak = Math.max(bestStreak, currentStreak);
+        } else {
+            totalErrors++;
+            currentStreak = 0;
+        }
+    }
+
+    const totalTyped = input.length;
+    const accuracy = !hasStartedTyping ? 100 : Math.max(0, Math.min(100, (correct / totalTyped) * 100));
+    const wpm = elapsedTime === 0 ? 0 : (correct / 5) / (elapsedTime / 60);
+    // Raw WPM: same formula as WPM, but counting every keystroke ever made
+    // (right, wrong, or later corrected) instead of only correct ones --
+    // this is how MonkeyType/TypeRacer define it: raw speed ignores accuracy
+    // entirely, including keystrokes you fixed with backspace.
+    const rawCount = totalKeystrokes ?? totalTyped;
+    const rawWpm = elapsedTime === 0 ? 0 : (rawCount / 5) / (elapsedTime / 60);
+
+    return {
+        wpm,
+        rawWpm,
+        accuracy,
+        time: elapsedTime,
+        correctChars: correct,
+        incorrectChars: totalErrors,
+        totalChars: text.length,
+        // Every forward keystroke of the test, corrected-away ones included --
+        // the same figure rawWpm is derived from. Reported on the end screen
+        // in its own right, the way 10FastFingers does.
+        keystrokes: rawCount,
+        currentStreak,
+        bestStreak,
+    };
+}