charmite/calendar.go

package main

import (
	"fmt"
	"strings"
	"time"

	"github.com/charmbracelet/lipgloss"
	"github.com/dustin/go-humanize"
)

type calendarTime struct {
	time.Time
}

//      June 2025
// Su Mo Tu We Th Fr Sa
//  1  2  3  4  5  6  7
//  8  9 10 11 12 13 14
// 15 16 17 18 19 20 21
// 22 23 24 25 26 27 28
// 29 30

var dayCols = map[int]time.Weekday{
	0: time.Monday,
	1: time.Tuesday,
	2: time.Wednesday,
	3: time.Thursday,
	4: time.Friday,
	5: time.Saturday,
	6: time.Sunday,
}

const brailleStart = 0x2800
const brailleEnd = 0x28FF

var baseStyle = lipgloss.NewStyle().Width(7 * 3)

var weekdayStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#2222f2"))
var weekendStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#ff0022"))
var monthNameStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#00dd80"))
var yearStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#a0dd10"))
var calendarTitle = baseStyle.AlignHorizontal(lipgloss.Center)
var dayStyle = lipgloss.NewStyle()
var dayStartStyle = dayStyle.Background(lipgloss.Color("#555555"))
var highlightStyle = dayStyle.Foreground(lipgloss.Color("#000000")).Background(lipgloss.Color("#ffffff")).Blink(true)

// calendar takes three calendarTime's, the calendar month to show, the "start" calendar time
// (shown with a underline) and the highlighted calendarTime.
func calendar(t calendarTime, start calendarTime, hl calendarTime, styles map[string]lipgloss.Style) string {
	f, _ := t.firstLastDays()
	out := calendarTitle.Render(fmt.Sprintf("%s %s", monthNameStyle.Render(f.Month().String()), yearStyle.Render(fmt.Sprint(f.Year()))))
	out += "\n"
	out += weekdayStyle.Render(" Mo Tu We Th Fr ")
	out += weekendStyle.Render("Sa Su")
	out += "\n"

	at := f
	col := 0
	lines := 0
	for {
		if at.Weekday() == dayCols[col] {

			// codePoint := brailleStart + rand.Intn(brailleEnd-brailleStart+1)
			// brailleChar := rune(codePoint)

			// if rand.Intn(100) < 80 {
			// 	brailleChar = ' '
			// }
			// pre := lipgloss.NewStyle().Foreground(lipgloss.Color("#d00010")).Render(string(brailleChar))

			dayStyle := dayStyle
			specialStyle, ok := styles[at.Format(time.DateOnly)]
			if ok {
				dayStyle = specialStyle
			}

			dayString := fmt.Sprintf("%2d", at.Day())
			padding := 3 - len(fmt.Sprint(at.Day()))
			padding = 1
			out += strings.Repeat(" ", padding)

			if at.dayEqual(hl) {
				out += highlightStyle.Render(dayString)
			} else if at.dayEqual(start) {
				out += dayStartStyle.Render(dayString)
			} else {
				out += dayStyle.Render(dayString)
			}
		} else {
			col++
			out += "   "
			continue
		}

		at = calendarTime{at.AddDate(0, 0, 1)}
		if at.Month() != f.Month() {
			break
		}

		col++
		if col > 6 {
			out += "\n"
			col = 0
			lines++
		}
	}

	for lines < 6 {
		out += "\n"
		lines++
	}
	out += "\n"
	return out

}

func (ct calendarTime) dayEqual(t calendarTime) bool {
	y1, m1, d1 := ct.Date()
	y2, m2, d2 := t.Date()
	if y1 == y2 && m1 == m2 && d1 == d2 {
		return true
	}
	return false
}

func (ct calendarTime) firstLastDays() (calendarTime, calendarTime) {
	loc := ct.Location()
	y, m, _ := ct.Date()
	first := time.Date(y, m, 1, 0, 0, 0, 0, loc)
	m++
	if m > 12 {
		y++
	}
	last := time.Date(y, m, 1, 0, 0, 0, 0, loc).AddDate(0, 0, -1)
	return calendarTime{first}, calendarTime{last}
}

func (ct calendarTime) addDay() calendarTime {
	return calendarTime{ct.AddDate(0, 0, 1)}
}
func (ct calendarTime) subDay() calendarTime {
	return calendarTime{ct.AddDate(0, 0, -1)}
}

func (ct calendarTime) addWeek() calendarTime {
	return calendarTime{ct.AddDate(0, 0, 7)}
}
func (ct calendarTime) subWeek() calendarTime {
	return calendarTime{ct.AddDate(0, 0, -7)}
}
func (ct calendarTime) addMonth() calendarTime {
	return calendarTime{ct.AddDate(0, 1, 0)}
}
func (ct calendarTime) subMonth() calendarTime {
	return calendarTime{ct.AddDate(0, -1, 0)}
}

func (ct calendarTime) to(t calendarTime) string {
	from := t.Time
	to := ct.Time
	rel := humanize.RelTime(t.Time, ct.Time, "earlier", "later")
	days := int(from.Sub(to).Hours() / 24)

	return fmt.Sprintf("%s / %d days", rel, days)
}