How I will make a perfect time Reduction in golang? - go

Question

I'm making a cron job for the booking charge automatic. The admin set the automatic charge after 2 hour of booking completion then I Get all the booking completed before 2 hours from the current time and charge them automatic. But the problem arise in the end of the day is that current_date= 10/10/2018 current_time= 1:00AM and automatic_charge_hours= 2 (hours) means it will get all the bookings which are completed 2 hours before the current_time and current_date. In 24hour format it will get all the bookings of the 23 hours(11:00PM of date 09/10/2018) of the previous date . But in my condition it will turn it into zero below is my condition:-
package main
import (
"fmt"
"time"
"strings"
)
func main() {
timeZone, _ := time.LoadLocation("America/New_York")
currDate := time.Now().In(timeZone).Format("2006-01-02 00:00:00 -0000")
onlyDate := strings.Split(currDate, " ")
hours, _ := 1, 0
if hours-int(2) < 0 {
hours = 0
} else {
hours = hours - int(2)
}
fmt.Println(hours, onlyDate[0])
}
playground link https://play.golang.org/p/w7LIoTp9xN0
How will I change it. Any suggestions please.

Answer 1

if hours-int(2) < 0 {
hours = 0
} else {
hours = hours - int(2)
}
Explicitly sets hours to zero when hours are negative.
If you change hours = 0 to hours = 24 + (hours-int(2)) it returns 23.
See https://play.golang.org/p/FyXIn5gjIXk
Anyhow, Instead of manipulating hours by hand, you should use time functions.
Update: Use time functions:
package main
import (
"fmt"
"time"
)
func main() {
t, err := time.Parse("01.02.2006 03:04:00", "10.10.2018 01:00:00")
if err != nil {
panic(err)
}
then := t.Add(time.Duration( -2 ) * time.Hour)
fmt.Printf("%v\n", then)
}
https://play.golang.org/p/0r6q7Vvai2h

Answer 2

You only have to change the condition little bit for the hours like below:-
func main() {
timeZone, _ := time.LoadLocation("America/New_York")
currDate := time.Now().In(timeZone).Format("2006-01-02 00:00:00 -0000")
onlyDate := strings.Split(currDate, " ")
hours, _ := 1, 0
hours = hours-int(2)
fmt.Println(hours)
if hours <= -1 {
hours = 24 + hours
currDate = time.Now().In(timeZone).AddDate(0, 0, -1).Format("2006-01-02 00:00:00 -0000")
fmt.Println(currDate)
}
fmt.Println(hours, onlyDate[0])
}
AddDate() is the function in the time package you can see in the https://golang.org/pkg/time/