Initial commit

internal/feed/calendar.go

@@ -0,0 +1,53 @@
+package feed
+
+import "time"
+
+// TODO: very inflexible, refactor to allow more customizability
+// TODO: allow changing first day of week
+// TODO: allow changing between showing the previous and next week and the entire month
+func NewCalendar(now time.Time) *Calendar {
+	year, week := now.ISOWeek()
+	weekday := now.Weekday()
+
+	if weekday == 0 {
+		weekday = 7
+	}
+
+	currentMonthDays := daysInMonth(now.Month(), year)
+
+	var previousMonthDays int
+
+	if previousMonthNumber := now.Month() - 1; previousMonthNumber < 1 {
+		previousMonthDays = daysInMonth(12, year-1)
+	} else {
+		previousMonthDays = daysInMonth(previousMonthNumber, year)
+	}
+
+	startDaysFrom := now.Day() - int(weekday+6)
+
+	days := make([]int, 21)
+
+	for i := 0; i < 21; i++ {
+		day := startDaysFrom + i
+
+		if day < 1 {
+			day = previousMonthDays + day
+		} else if day > currentMonthDays {
+			day = day - currentMonthDays
+		}
+
+		days[i] = day
+	}
+
+	return &Calendar{
+		CurrentDay:        now.Day(),
+		CurrentWeekNumber: week,
+		CurrentMonthName:  now.Month().String(),
+		CurrentYear:       year,
+		Days:              days,
+	}
+}
+
+func daysInMonth(m time.Month, year int) int {
+	return time.Date(year, m+1, 0, 0, 0, 0, 0, time.UTC).Day()
+}