Add new calendar and deprecate old

internal/glance/widget-old-calendar.go

@@ -0,0 +1,86 @@
+package glance
+
+import (
+	"context"
+	"html/template"
+	"time"
+)
+
+var oldCalendarWidgetTemplate = mustParseTemplate("old-calendar.html", "widget-base.html")
+
+type oldCalendarWidget struct {
+	widgetBase  `yaml:",inline"`
+	Calendar    *calendar
+	StartSunday bool `yaml:"start-sunday"`
+}
+
+func (widget *oldCalendarWidget) initialize() error {
+	widget.withTitle("Calendar").withCacheOnTheHour()
+
+	return nil
+}
+
+func (widget *oldCalendarWidget) update(ctx context.Context) {
+	widget.Calendar = newCalendar(time.Now(), widget.StartSunday)
+	widget.withError(nil).scheduleNextUpdate()
+}
+
+func (widget *oldCalendarWidget) Render() template.HTML {
+	return widget.renderTemplate(widget, oldCalendarWidgetTemplate)
+}
+
+type calendar struct {
+	CurrentDay        int
+	CurrentWeekNumber int
+	CurrentMonthName  string
+	CurrentYear       int
+	Days              []int
+}
+
+// TODO: very inflexible, refactor to allow more customizability
+// TODO: allow changing between showing the previous and next week and the entire month
+func newCalendar(now time.Time, startSunday bool) *calendar {
+	year, week := now.ISOWeek()
+	weekday := now.Weekday()
+	if !startSunday {
+		weekday = (weekday + 6) % 7 // Shift Monday to 0
+	}
+
+	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) - 7
+
+	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()
+}