/
date-math.go
122 lines (104 loc) · 3.78 KB
/
date-math.go
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/* ****************************************************************************
Performs math on date/times
Author: thomas.cherry@gmail.com
Date: 2022-11-20
**************************************************************************** */
package main
import (
"os"
"fmt"
"time"
"flag"
)
/* ************************************************************************** */
// MARK: - Util functions
/**
Converts a formated string to a time structure
*/
func StringToTime(format string, input string) time.Time {
if len(format)<1 {
format = "2006-01-02T15:04:05"
}
parseTime, err := time.Parse(format, input)
if err != nil {
os.Stderr.WriteString(err.Error() + "\n")
parseTime, err = time.Parse("2006-01-02", input)
if err != nil {
fmt.Println(err)
}
}
return parseTime
}
/**
Adds a durration to a time, returning the new time
*/
func Add(working time.Time, num int, unit time.Duration) time.Time {
if num!=0 {
working = working.Add(time.Duration(num) * unit)
}
return working
}
/* ************************************************************************** */
// MARK: - App functions
func HelpMessageCallback() {
fmt.Fprintf(flag.CommandLine.Output(),
"date-math by thomas.cherry@gmail.com\n\n")
fmt.Fprintf(flag.CommandLine.Output(), "Usage of %s:\n\n", os.Args[0])
fmt.Fprintf(flag.CommandLine.Output(),
"\tcmd --older <date> --newer <newer>\n")
fmt.Fprintf(flag.CommandLine.Output(),
"\tcmd --date <date> --years <n> --days <n> --hours <n> --minutes <n> --seconds <n>\n")
fmt.Fprintf(flag.CommandLine.Output(), "\nFlags:\n")
flag.PrintDefaults()
}
func main() {
//overwrite the usage function
flag.Usage = HelpMessageCallback
//process command line arguments
format := flag.String("format", "2006-01-02T15:04:05",
"Golang date/time format")
older := flag.String("old", "",
"oldest date/time in 2006-01-02T15:04:05 format")
newer := flag.String("new", "",
"newest date/time in 2006-01-02T15:04:05 format")
date := flag.String("date", "",
"Date to work on in 2006-01-02T15:04:05 format")
years := flag.Int("years", 0, "years to add or subtract")
months := flag.Int("months", 0, "months to add or subtract")
days := flag.Int("days", 0, "days to add or subtract")
hours := flag.Int("hours", 0, "hours to add or subtract")
minutes := flag.Int("minutes", 0, "minutes to add or subtract")
seconds := flag.Int("seconds", 0, "seconds to add or subtract")
flag.Parse()
working := time.Now()
if *date!="" {
working = StringToTime(*format, *date)
} else if *newer!="" && *older!=""{
//find the durration between two date points
n := StringToTime(*format, *newer)
o := StringToTime(*format, *older)
dur := n.Sub(o)
d := int(dur.Hours()/24)
h := int(dur.Hours() - float64(d*24))
m := int(dur.Minutes() - float64(d*24*60) - float64(h*60))
s := int(dur.Seconds() -
float64(d*24*60*60) -
float64(h*60*60) -
float64(m*60))
fmt.Printf ("%dd %dh %dm %ds\n", d, h, m, s)
os.Exit(0)
} else if *newer!="" {
working = StringToTime(*format, *newer)
} else if *older!="" {
working = StringToTime(*format, *older)
}
orig := working
if *years!=0 {working = working.AddDate(*years, 0, 0)}
if *months!=0 {working = working.AddDate(0, *months, 0)}
if *days!=0 {working = working.AddDate(0, 0, *days)}
working = Add(working, *hours, time.Hour)
working = Add(working, *minutes, time.Minute)
working = Add(working, *seconds, time.Second)
fmt.Printf("orig\t%s\nnew\t%s\n", orig.Format(*format),
working.Format(*format))
}