feat: add AddDaySafe, AddMonthSafe, AddYearSafe

datetime/datetime.go

@@ -100,6 +100,61 @@ func AddYear(t time.Time, year int64) time.Time {
 	return t.AddDate(int(year), 0, 0)
 }
 
+// AddDaySafe add or sub days to the time and ensure that the returned date does not exceed the valid date of the target year and month.
+// Play: todo
+func AddDaySafe(t time.Time, days int) time.Time {
+	t = t.AddDate(0, 0, days)
+	year, month, day := t.Date()
+
+	lastDayOfMonth := time.Date(year, month+1, 0, 0, 0, 0, 0, t.Location()).Day()
+
+	if day > lastDayOfMonth {
+		t = time.Date(year, month, lastDayOfMonth, t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), t.Location())
+	}
+
+	return t
+}
+
+// AddMonthSafe add or sub months to the time and ensure that the returned date does not exceed the valid date of the target year and month.
+// Play: todo
+func AddMonthSafe(t time.Time, months int) time.Time {
+	year := t.Year()
+	month := int(t.Month()) + months
+
+	for month > 12 {
+		month -= 12
+		year++
+	}
+	for month < 1 {
+		month += 12
+		year--
+	}
+
+	daysInMonth := time.Date(year, time.Month(month+1), 0, 0, 0, 0, 0, time.UTC).Day()
+
+	day := t.Day()
+	if day > daysInMonth {
+		day = daysInMonth
+	}
+
+	return time.Date(year, time.Month(month), day, t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), t.Location())
+}
+
+// AddYearSafe add or sub years to the time and ensure that the returned date does not exceed the valid date of the target year and month.
+// Play: todo
+func AddYearSafe(t time.Time, years int) time.Time {
+	year, month, day := t.Date()
+	year += years
+
+	if month == time.February && day == 29 {
+		if !IsLeapYear(year) {
+			day = 28
+		}
+	}
+
+	return time.Date(year, month, day, t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), t.Location())
+}
+
 // GetNowDate return format yyyy-mm-dd of current date.
 // Play: https://go.dev/play/p/PvfkPpcpBBf
 func GetNowDate() string {

datetime/datetime_example_test.go

@@ -90,6 +90,60 @@ func ExampleAddYear() {
 	// 2019-01-01
 }
 
+func ExampleAddDaySafe() {
+	leapYearDate1, _ := time.Parse("2006-01-02", "2024-02-29")
+	result1 := AddDaySafe(leapYearDate1, 1)
+
+	leapYearDate2, _ := time.Parse("2006-01-02", "2024-03-01")
+	result2 := AddDaySafe(leapYearDate2, -1)
+
+	nonLeapYearDate1, _ := time.Parse("2006-01-02", "2025-02-28")
+	result3 := AddDaySafe(nonLeapYearDate1, 1)
+
+	nonLeaYearDate2, _ := time.Parse("2006-01-02", "2025-03-01")
+	result4 := AddDaySafe(nonLeaYearDate2, -1)
+
+	fmt.Println(result1.Format("2006-01-02"))
+	fmt.Println(result2.Format("2006-01-02"))
+	fmt.Println(result3.Format("2006-01-02"))
+	fmt.Println(result4.Format("2006-01-02"))
+
+	// Output:
+	// 2024-03-01
+	// 2024-02-29
+	// 2025-03-01
+	// 2025-02-28
+}
+
+func ExampleAddMonthSafe() {
+	date1, _ := time.Parse("2006-01-02", "2025-01-31")
+	result1 := AddMonthSafe(date1, 1)
+
+	date2, _ := time.Parse("2006-01-02", "2024-02-29")
+	result2 := AddMonthSafe(date2, -1)
+
+	fmt.Println(result1.Format("2006-01-02"))
+	fmt.Println(result2.Format("2006-01-02"))
+
+	// Output:
+	// 2025-02-28
+	// 2024-01-29
+}
+
+func ExampleAddYearSafe() {
+	date, _ := time.Parse("2006-01-02", "2020-02-29")
+
+	result1 := AddYearSafe(date, 1)
+	result2 := AddYearSafe(date, -1)
+
+	fmt.Println(result1.Format("2006-01-02"))
+	fmt.Println(result2.Format("2006-01-02"))
+
+	// Output:
+	// 2021-02-28
+	// 2019-02-28
+}
+
 func ExampleGetNowDate() {
 	result := GetNowDate()
 

datetime/datetime_test.go

@@ -309,6 +309,129 @@ func TestAddMonth(t *testing.T) {
 
 }
 
+func TestAddDaySafe(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestAddDaySafe")
+
+	tests := []struct {
+		inputDate string
+		days      int
+		expected  string
+	}{
+		{"2025-01-31", 10, "2025-02-10"},
+		{"2025-01-01", 30, "2025-01-31"},
+		{"2025-01-31", 1, "2025-02-01"},
+		{"2025-02-28", 1, "2025-03-01"},
+		{"2024-02-29", 1, "2024-03-01"},
+		{"2024-02-29", 365, "2025-02-28"},
+
+		{"2025-01-31", -10, "2025-01-21"},
+		{"2025-01-01", -30, "2024-12-02"},
+		{"2025-02-01", -1, "2025-01-31"},
+		{"2025-03-01", -1, "2025-02-28"},
+		{"2024-03-01", -1, "2024-02-29"},
+
+		{"2025-01-31", -31, "2024-12-31"},
+		{"2025-12-31", 1, "2026-01-01"},
+	}
+
+	for _, tt := range tests {
+		date, _ := time.Parse("2006-01-02", tt.inputDate)
+		result := AddDaySafe(date, tt.days)
+		assert.Equal(tt.expected, result.Format("2006-01-02"))
+	}
+}
+
+func TestAddMonthSafe(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestAddMonthSafe")
+
+	tests := []struct {
+		inputDate string
+		months    int
+		expected  string
+	}{
+		{
+			inputDate: "2025-01-31",
+			months:    1,
+			expected:  "2025-02-28",
+		},
+		{
+			inputDate: "2025-01-31",
+			months:    -1,
+			expected:  "2024-12-31",
+		},
+		{
+			inputDate: "2025-12-31",
+			months:    1,
+			expected:  "2026-01-31",
+		},
+		{
+			inputDate: "2025-01-31",
+			months:    -1,
+			expected:  "2024-12-31",
+		},
+		{
+			inputDate: "2024-02-29",
+			months:    1,
+			expected:  "2024-03-29",
+		},
+		{
+			inputDate: "2024-02-29",
+			months:    -1,
+			expected:  "2024-01-29",
+		},
+	}
+
+	for _, tt := range tests {
+		date, _ := time.Parse("2006-01-02", tt.inputDate)
+		result := AddMonthSafe(date, tt.months)
+		assert.Equal(tt.expected, result.Format("2006-01-02"))
+	}
+
+}
+
+func TestAddYearSafe(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestAddYearSafe")
+
+	tests := []struct {
+		inputDate string
+		years     int
+		expected  string
+	}{
+		{
+			inputDate: "2020-02-29",
+			years:     1,
+			expected:  "2021-02-28",
+		},
+		{
+			inputDate: "2020-02-29",
+			years:     2,
+			expected:  "2022-02-28",
+		},
+		{
+			inputDate: "2020-02-29",
+			years:     -1,
+			expected:  "2019-02-28",
+		},
+		{
+			inputDate: "2020-02-29",
+			years:     -2,
+			expected:  "2018-02-28",
+		},
+	}
+
+	for _, tt := range tests {
+		date, _ := time.Parse("2006-01-02", tt.inputDate)
+		result := AddYearSafe(date, tt.years)
+		assert.Equal(tt.expected, result.Format("2006-01-02"))
+	}
+}
+
 func TestGetNowDate(t *testing.T) {
 	t.Parallel()