Create chartjs-plugin-tick-duplicate.ts

web/src/components/ui/charts/BusterChartJS/core/plugins/chartjs-plugin-tick-duplicate.ts

@@ -0,0 +1,51 @@
+import { ChartType, Chart, Plugin } from 'chart.js';
+
+declare module 'chart.js' {
+  interface PluginOptionsByType<TType extends ChartType> {}
+}
+
+export const ChartJSTickDuplicatePlugin: Plugin<ChartType> = {
+  id: 'chartjs-plugin-tick-duplicate',
+  afterBuildTicks(chart) {
+    const scale = chart.scales['x'];
+    if (!scale || scale.type !== 'time') return;
+
+    const adapter = scale._adapter;
+    const format = (v) => adapter.format(v, scale.options.time.displayFormats?.month || 'MMM');
+
+    const allTicks = scale._generate(); // Chart.js's default generated ticks (raw values)
+    const seenLabels = new Set();
+    const unique = [];
+
+    for (const tick of allTicks) {
+      const label = format(tick.value ?? tick);
+      if (!seenLabels.has(label)) {
+        seenLabels.add(label);
+        unique.push({ value: tick.value ?? tick, label });
+      }
+    }
+
+    if (unique.length < 2) return;
+
+    const min = scale.min ?? Math.min(...allTicks.map((t) => t.value ?? t));
+    const max = scale.max ?? Math.max(...allTicks.map((t) => t.value ?? t));
+    const spacing = (max - min) / (unique.length - 1);
+
+    const evenlySpaced = unique.map((tick, i) => ({
+      value: min + i * spacing,
+      label: tick.label
+    }));
+
+    scale.ticks = evenlySpaced;
+  },
+  beforeDraw(chart) {
+    // Prevent Chart.js from auto-reformatting tick labels
+    const scale = chart.scales['x'];
+    if (!scale || !scale.ticks) return;
+    scale.ticks.forEach((tick) => {
+      tick.label = tick.label;
+    });
+  }
+};
+
+export default ChartJSTickDuplicatePlugin;