support stack in drawLine

packages/core/drawLine.mjs

@@ -1,26 +1,46 @@
 import { gcd } from './fraction.mjs';
 
-// TODO: make it work for stacked patterns + support silence
-
 function drawLine(pat, chars = 60) {
-  let s = '';
   let c = 0;
-  while (s.length < chars) {
+  let lines = [''];
+  const slots = [];
+  while (lines[0].length < chars) {
     const haps = pat.queryArc(c, c + 1);
-    const durations = haps.map((hap) => hap.duration);
+    const durations = haps.filter((hap) => hap.hasOnset()).map((hap) => hap.duration);
     const totalSlots = gcd(...durations).inverse();
-    s += '|';
-    haps.forEach((hap) => {
-      const duration = hap.whole.end.sub(hap.whole.begin);
-      const slots = totalSlots.mul(duration);
-      s += Array(slots.valueOf())
-        .fill()
-        .map((_, i) => (!i ? hap.value : '-'))
-        .join('');
-    });
-    ++c;
+    slots.push(totalSlots);
+    const minDuration = durations.reduce((a, b) => a.min(b), durations[0]);
+    lines = lines.map((line) => line + '|');
+
+    for (let i = 0; i < totalSlots; i++) {
+      const step = c * totalSlots + i;
+      const [begin, end] = [minDuration.mul(step), minDuration.mul(step + 1)];
+      const matches = haps.filter((hap) => hap.whole.begin.lte(begin) && hap.whole.end.gte(end));
+      const missingLines = matches.length - lines.length;
+      if (missingLines > 0) {
+        console.log(c, 'missingLines', missingLines);
+        const emptyCycles =
+          '|' +
+          new Array(c)
+            .fill()
+            .map((_, l) => Array(slots[l]).fill('.').join(''))
+            .join('|') +
+          Array(i).fill('.').join('');
+        lines = lines.concat(Array(missingLines).fill(emptyCycles));
+      }
+      lines = lines.map((line, i) => {
+        const hap = matches[i];
+        if (hap) {
+          const isOnset = hap.whole.begin.eq(begin);
+          const char = isOnset ? '' + hap.value : '-';
+          return line + char;
+        }
+        return line + '.';
+      });
+    }
+    c++;
   }
-  return s;
+  return lines.join('\n');
 }
 
 export default drawLine;