Fix x-axis labels for statistics graph month/year periods (#51295)

src/components/chart/axis-label.ts

@@ -5,12 +5,41 @@ import {
   formatDateMonthYear,
   formatDateVeryShort,
   formatDateWeekdayShort,
+  formatDateYear,
 } from "../../common/datetime/format_date";
 import {
   formatTime,
   formatTimeWithSeconds,
 } from "../../common/datetime/format_time";
 
+export function getPeriodicAxisLabelConfig(
+  period: string,
+  locale: FrontendLocaleData,
+  config: HassConfig
+):
+  | {
+      formatter: (value: number) => string;
+    }
+  | undefined {
+  if (period === "month") {
+    return {
+      formatter: (value: number) => {
+        const date = new Date(value);
+        return date.getMonth() === 0
+          ? `{bold|${formatDateMonthYear(date, locale, config)}}`
+          : formatDateMonth(date, locale, config);
+      },
+    };
+  }
+  if (period === "year") {
+    return {
+      formatter: (value: number) =>
+        formatDateYear(new Date(value), locale, config),
+    };
+  }
+  return undefined;
+}
+
 export function formatTimeLabel(
   value: number | Date,
   locale: FrontendLocaleData,

src/components/chart/ha-chart-base.ts

@@ -651,7 +651,7 @@ export class HaChartBase extends LitElement {
             hideOverlap: true,
             ...axis.axisLabel,
           },
-          minInterval,
+          minInterval: axis.minInterval ?? minInterval,
         } as XAXisOption;
       });
     }

src/components/chart/statistics-chart.ts

@@ -32,6 +32,7 @@ import {
 } from "../../data/recorder";
 import type { ECOption } from "../../resources/echarts/echarts";
 import type { HomeAssistant } from "../../types";
+import { getPeriodicAxisLabelConfig } from "./axis-label";
 import type { CustomLegendOption } from "./ha-chart-base";
 import "./ha-chart-base";
 
@@ -293,6 +294,22 @@ export class StatisticsChart extends LitElement {
           type: "time",
           min: startTime,
           max: this.endTime,
+          ...(this.period === "month" && {
+            minInterval: 28 * 24 * 3600 * 1000,
+            axisLabel: getPeriodicAxisLabelConfig(
+              "month",
+              this.hass.locale,
+              this.hass.config
+            ),
+          }),
+          ...(this.period === "year" && {
+            minInterval: 365 * 24 * 3600 * 1000,
+            axisLabel: getPeriodicAxisLabelConfig(
+              "year",
+              this.hass.locale,
+              this.hass.config
+            ),
+          }),
         },
         {
           id: "hiddenAxis",

src/panels/lovelace/cards/energy/common/energy-chart-options.ts

@@ -35,6 +35,7 @@ import { formatTime } from "../../../../../common/datetime/format_time";
 import type { ECOption } from "../../../../../resources/echarts/echarts";
 import { filterXSS } from "../../../../../common/util/xss";
 import type { StatisticPeriod } from "../../../../../data/recorder";
+import { getPeriodicAxisLabelConfig } from "../../../../../components/chart/axis-label";
 import { getSuggestedPeriod } from "../../../../../data/energy";
 
 // Number of days of padding when showing time axis in months
@@ -109,17 +110,7 @@ export function getCommonOptions(
       type: "time",
       min: subDays(start, MONTH_TIME_AXIS_PADDING),
       max: addDays(suggestedMax, MONTH_TIME_AXIS_PADDING),
-      axisLabel: {
-        formatter: {
-          year: "{yearStyle|{MMMM} {yyyy}}",
-          month: "{MMMM}",
-        },
-        rich: {
-          yearStyle: {
-            fontWeight: "bold",
-          },
-        },
-      },
+      axisLabel: getPeriodicAxisLabelConfig("month", locale, config),
       // For shorter month ranges, force splitting to ensure time axis renders
       // as whole month intervals. Limit the number of forced ticks to 6 months
       // (so a max calendar difference of 5) to reduce clutter.