utils.go

package main

import (
	"math"
	"time"

	"github.com/mshafiee/swephgo"
)

/* general helpers */

func jdToUTC(jd *float64) time.Time {
	year := make([]int, 1)
	month := make([]int, 1)
	day := make([]int, 1)
	hour := make([]float64, 1)
	swephgo.Revjul(*jd, swephgo.SeGregCal, year, month, day, hour)
	h := int(hour[0])
	m := int(60 * (hour[0] - float64(h)))
	utc := time.Date(year[0], time.Month(month[0]), day[0], h, m, 0, 0, time.UTC)
	return utc
}

func jdToLocal(jd *float64) time.Time {
	utc := jdToUTC(jd)
	return utc.In(location)
}

func julian(d time.Time) *float64 {
	h := float64(d.Hour()) + float64(d.Minute())/60 + float64(d.Second())/3600
	jd := swephgo.Julday(d.Year(), int(d.Month()), d.Day(), h, swephgo.SeGregCal)
	return &jd
}

/* Begining of the Day */
func bod(t time.Time) time.Time {
	year, month, day := t.Date()
	return time.Date(year, month, day, 0, 0, 0, 0, time.Local)
}

/* Noon of the Day */
func nod(t time.Time) time.Time {
	year, month, day := t.Date()
	return time.Date(year, month, day, 12, 0, 0, 0, time.Local)
}

func smallestSignedAngleBetween(x float64, y float64) float64 {
	return math.Min(2.0*math.Pi-math.Abs(x-y), math.Abs(x-y))
}

func fixangle(a float64) float64 {
	return (a - 360*math.Floor(a/360))
}

func rad2deg(r float64) float64 {
	return (r * 180) / math.Pi
}

func deg2rad(d float64) float64 {
	return (d * math.Pi) / 180
}

func bool2int(b bool) int {
	if b {
		return 1
	}
	return 0
}

func binarySearch(start Moon, end Moon, fullMoon bool) Moon {
	half := end.date.Sub(start.date).Seconds() / 2
	mDate := start.date.Add(time.Second * time.Duration(half))
	phase, _ := Phase(mDate, swephgo.SeMoon)

	newStart := start
	newEnd := end
	middle := Moon{
		date:  mDate,
		phase: phase,
	}

	if fullMoon {
		if start.phase < end.phase {
			newStart = middle
		} else {
			newEnd = middle
		}
	} else {
		if end.phase < start.phase {
			newStart = middle
		} else {
			newEnd = middle
		}
	}
	if newEnd.date.Sub(newStart.date).Minutes() < 1.0 {
		return newEnd
	}
	return binarySearch(newStart, newEnd, fullMoon)
}

func moonEmoji(icon string) string {
	switch icon {
	case "New Moon":
		return ":new_moon:"
	case "Waxing Crescent":
		return ":waxing_crescent_moon:"
	case "First Quarter":
		return ":first_quarter_moon:"
	case "Waxing Gibbous":
		return ":waxing_gibbous_moon:"
	case "Full Moon":
		return ":full_moon:"
	case "Waning Gibbous":
		return ":waning_gibbous_moon:"
	case "Third Quarter":
		return ":last_quarter_moon:"
	case "Waning Crescent":
		return ":waning_crescent_moon:"
	default:
		return ":star:"
	}
}