manage single point serie

Author: jycouet

app/utils/chart-data-buckets.ts

@@ -101,15 +101,14 @@ export function buildMonthlyEvolution(
   return entries.map(([month, value], i) => {
     const [y, m] = month.split('-').map(Number) as [number, number]
     const total = daysInMonth(y, m - 1)
+    const isFirst = i === 0
+    const isLast = i === entries.length - 1
 
-    if (i === 0 && rangeStartIso) {
-      const startDay = Number(rangeStartIso.split('-')[2])
-      if (startDay > 1) value = fillPartialBucket(value, total - startDay + 1, total)
-    }
-    if (i === entries.length - 1 && rangeEndIso) {
-      const endDay = Number(rangeEndIso.split('-')[2])
-      if (endDay < total) value = fillPartialBucket(value, endDay, total)
-    }
+    const startDay = isFirst && rangeStartIso ? Number(rangeStartIso.split('-')[2]) : 1
+    const endDay = isLast && rangeEndIso ? Number(rangeEndIso.split('-')[2]) : total
+    const actualDays = endDay - startDay + 1
+
+    if (actualDays < total) value = fillPartialBucket(value, actualDays, total)
 
     return { month, value, timestamp: parseIsoDate(`${month}-01`).getTime() }
   })
@@ -132,18 +131,20 @@ export function buildYearlyEvolution(
   return entries.map(([year, value], i) => {
     const total = daysInYear(Number(year))
     const yearStart = parseIsoDate(`${year}-01-01`)
-
-    if (i === 0 && rangeStartIso) {
-      const dayOfYear = Math.floor(
-        (parseIsoDate(rangeStartIso).getTime() - yearStart.getTime()) / DAY_MS,
-      )
-      if (dayOfYear > 0) value = fillPartialBucket(value, total - dayOfYear, total)
-    }
-    if (i === entries.length - 1 && rangeEndIso) {
-      const actualDays =
-        Math.floor((parseIsoDate(rangeEndIso).getTime() - yearStart.getTime()) / DAY_MS) + 1
-      if (actualDays < total) value = fillPartialBucket(value, actualDays, total)
-    }
+    const isFirst = i === 0
+    const isLast = i === entries.length - 1
+
+    const startOffset =
+      isFirst && rangeStartIso
+        ? Math.floor((parseIsoDate(rangeStartIso).getTime() - yearStart.getTime()) / DAY_MS)
+        : 0
+    const endOffset =
+      isLast && rangeEndIso
+        ? Math.floor((parseIsoDate(rangeEndIso).getTime() - yearStart.getTime()) / DAY_MS) + 1
+        : total
+    const actualDays = endOffset - startOffset
+
+    if (actualDays < total) value = fillPartialBucket(value, actualDays, total)
 
     return { year, value, timestamp: yearStart.getTime() }
   })

test/unit/app/utils/chart-data-buckets.spec.ts

@@ -138,6 +138,19 @@ describe('buildMonthlyEvolution', () => {
     expect(buildMonthlyEvolution([])).toEqual([])
   })
 
+  it('scales single month partial on both ends without double-scaling', () => {
+    // 2025-01-10 to 2025-01-20 = 11 days out of 31
+    const daily = Array.from({ length: 11 }, (_, i) => ({
+      day: `2025-01-${String(i + 10).padStart(2, '0')}`,
+      value: 10,
+    }))
+
+    const result = buildMonthlyEvolution(daily, '2025-01-10', '2025-01-20')
+
+    expect(result).toHaveLength(1)
+    expect(result[0]!.value).toBe(Math.round((110 * 31) / 11))
+  })
+
   it('scales up partial first month', () => {
     const daily = Array.from({ length: 14 }, (_, i) => ({
       day: `2025-03-${String(i + 18).padStart(2, '0')}`,
@@ -188,6 +201,20 @@ describe('buildYearlyEvolution', () => {
     expect(buildYearlyEvolution([])).toEqual([])
   })
 
+  it('scales single year partial on both ends without double-scaling', () => {
+    // 2025-04-01 to 2025-06-30 = 91 days out of 365
+    const daily = Array.from({ length: 91 }, (_, i) => {
+      const d = new Date(Date.UTC(2025, 3, 1))
+      d.setUTCDate(d.getUTCDate() + i)
+      return { day: d.toISOString().slice(0, 10), value: 10 }
+    })
+
+    const result = buildYearlyEvolution(daily, '2025-04-01', '2025-06-30')
+
+    expect(result).toHaveLength(1)
+    expect(result[0]!.value).toBe(Math.round((910 * 365) / 91))
+  })
+
   it('scales up partial first year', () => {
     const daily = Array.from({ length: 184 }, (_, i) => {
       const d = new Date(Date.UTC(2025, 6, 1))