Extract buildDisplaySeries from rCpnlChart into 05b-pnl.js

docs/architecture.md

@@ -63,6 +63,7 @@ flowchart TD
 
     subgraph PnL ["P&L — 05b-pnl.js"]
         CP["computePnl(trades, assetFilter, livePrices)\n→ { realised, unrealised, total,\n   missingSpotAssets,\n   realisedSeries, realisedByMonth }"]
+        BDS["buildDisplaySeries(series, period, today)\n→ [{date, val}]"]
     end
 
     subgraph Stats ["Stats — 05d-calc-stats.js"]

src/js/05b-pnl.js

@@ -80,6 +80,39 @@ function computePnl(trades, assetFilter, livePrices) {
   return { realised, unrealised, total, missingSpotAssets, realisedSeries, realisedByMonth };
 }
 
+function buildDisplaySeries(series, period, today) {
+  if (!series.length) return [];
+
+  const allSeries = [{ date: series[0].date, val: 0 }, ...series];
+
+  let dispSeries;
+  if (period === 'ALL') {
+    dispSeries = allSeries;
+  } else {
+    const days = period === '1M' ? 30 : 90;
+    const cutDate = new Date(today + 'T12:00:00');
+    cutDate.setDate(cutDate.getDate() - days);
+    const cutStr = cutDate.toISOString().slice(0, 10);
+
+    const lastBefore = allSeries.filter(p => p.date < cutStr);
+    const baseline = lastBefore.length ? lastBefore[lastBefore.length - 1].val : 0;
+    const inPeriod = allSeries.filter(p => p.date >= cutStr);
+
+    if (!inPeriod.length) {
+      dispSeries = [{ date: cutStr, val: baseline }, { date: today, val: baseline }];
+    } else {
+      dispSeries = [{ date: cutStr, val: baseline }, ...inPeriod];
+    }
+  }
+
+  const last = dispSeries[dispSeries.length - 1];
+  if (last.date < today) {
+    dispSeries = [...dispSeries, { date: today, val: last.val }];
+  }
+
+  return dispSeries;
+}
+
 if (typeof module !== 'undefined' && module.exports) {
-  module.exports = { computePnl };
+  module.exports = { computePnl, buildDisplaySeries };
 }

src/js/07-render-charts.js

@@ -65,42 +65,9 @@ function rCpnlChart() {
     return;
   }
 
-  // Period filter cutoff
-  const today = new Date();
-  let cutoff = null;
-  if (sCpnlPeriod === '1M') {
-    cutoff = new Date(today); cutoff.setDate(cutoff.getDate() - 30);
-  } else if (sCpnlPeriod === '3M') {
-    cutoff = new Date(today); cutoff.setDate(cutoff.getDate() - 90);
-  }
-
-  // Cumulative series: prepend a zero-baseline so the first point starts at 0.
-  const allSeries = [{ date: realisedSeries[0].date, val: 0 }, ...realisedSeries];
+  const todayStr = today();
   const totalPnl = realisedSeries[realisedSeries.length - 1].val;
-
-  // Filter series for display period
-  let dispSeries;
-  if (!cutoff) {
-    dispSeries = allSeries;
-  } else {
-    const cutStr = cutoff.toISOString().slice(0, 10);
-    let baseline = 0;
-    let lastBefore = allSeries.filter(p => p.date < cutStr);
-    if (lastBefore.length) baseline = lastBefore[lastBefore.length - 1].val;
-    const inPeriod = allSeries.filter(p => p.date >= cutStr);
-    if (!inPeriod.length) {
-      dispSeries = [{ date: cutStr, val: totalPnl }, { date: today.toISOString().slice(0, 10), val: totalPnl }];
-    } else {
-      dispSeries = [{ date: cutStr, val: baseline }, ...inPeriod];
-    }
-  }
-
-  // Add today as the final point (carries last value forward)
-  const todayStr = today.toISOString().slice(0, 10);
-  const last = dispSeries[dispSeries.length - 1];
-  if (last.date < todayStr) {
-    dispSeries = [...dispSeries, { date: todayStr, val: last.val }];
-  }
+  const dispSeries = buildDisplaySeries(realisedSeries, sCpnlPeriod, todayStr);
 
   // Period change
   const periodStart = dispSeries[0].val;

test/unit/pnl.test.js

@@ -242,3 +242,54 @@ test('realisedSeries: CALLED event contributes premium AND capital gain at expir
   assert.strictEqual(last.date, '2026-02-15');
   assert.strictEqual(last.val, 550);
 });
+
+// buildDisplaySeries tests
+const { buildDisplaySeries } = require('../../src/js/05b-pnl.js');
+
+test('buildDisplaySeries: empty input returns empty', () => {
+  assert.deepStrictEqual(buildDisplaySeries([], 'ALL', '2026-05-16'), []);
+});
+
+test("buildDisplaySeries: ALL prepends zero-baseline and appends today", () => {
+  const series = [
+    { date: '2026-01-15', val: 100 },
+    { date: '2026-03-01', val: 250 },
+  ];
+  const result = buildDisplaySeries(series, 'ALL', '2026-05-16');
+  assert.deepStrictEqual(result, [
+    { date: '2026-01-15', val: 0 },
+    { date: '2026-01-15', val: 100 },
+    { date: '2026-03-01', val: 250 },
+    { date: '2026-05-16', val: 250 },
+  ]);
+});
+
+test("buildDisplaySeries: 1M with no in-range points returns flat [{cutoff,lastVal},{today,lastVal}]", () => {
+  // All trades before the 30-day window
+  const series = [{ date: '2026-01-15', val: 100 }];
+  // today=2026-05-16 → cutoff=2026-04-16; series point is before cutoff
+  const result = buildDisplaySeries(series, '1M', '2026-05-16');
+  assert.strictEqual(result.length, 2);
+  assert.strictEqual(result[0].date, '2026-04-16');
+  assert.strictEqual(result[0].val, 100);
+  assert.strictEqual(result[1].date, '2026-05-16');
+  assert.strictEqual(result[1].val, 100);
+});
+
+test("buildDisplaySeries: baseline carry-forward is last point before the cutoff", () => {
+  // today=2026-05-16 → 1M cutoff=2026-04-16
+  // Two points before cutoff; baseline should be 250 (the later one)
+  // One point after cutoff at 300
+  const series = [
+    { date: '2026-01-15', val: 100 },
+    { date: '2026-03-01', val: 250 },
+    { date: '2026-04-20', val: 300 },
+  ];
+  const result = buildDisplaySeries(series, '1M', '2026-05-16');
+  // dispSeries: [{cutoff, 250}, {2026-04-20, 300}], then today appended
+  assert.deepStrictEqual(result, [
+    { date: '2026-04-16', val: 250 },
+    { date: '2026-04-20', val: 300 },
+    { date: '2026-05-16', val: 300 },
+  ]);
+});