my-log/tools/parse_date.go

package tools

import (
	"strconv"
	"time"

	dp "github.com/markusmobius/go-dateparser"
	"github.com/markusmobius/go-dateparser/date"
)

const DateFormat = "January 02, 2006 at 03:04:05PM -0700"

// These are somewhat arbitrary, but reasonably useful min and max times
var (
	MinTime = time.Unix(-2208988800, 0) // Jan 1, 1900
	MaxTime = MinTime.Add(1<<63 - 1)
)

func ParseDate(in string) (t time.Time, err error) {
	if in == "min" {
		return MinTime, nil
	}
	if in == "max" {
		return MaxTime, nil
	}

	var er error
	for _, format := range []string{time.RFC3339, DateFormat} {
		if t, er = time.ParseInLocation(format, in, nil); er == nil {
			return
		}
	}

	var ts int64
	if ts, er = strconv.ParseInt(in, 10, 0); er == nil {
		t = time.Unix(ts, 0)
		return
	}

	conf := dp.Configuration{
		CurrentTime:        time.Now().Local(),
		ReturnTimeAsPeriod: true,
		Languages:          []string{"en"},
	}

	d, err := dp.Parse(&conf, in)
	t = d.Time
	if err != nil {
		return
	}

	y, mon, day, h, loc := t.Year(), t.Month(), t.Day(), t.Hour(), t.Location()

	switch d.Period {
	case date.Second:
		t = t.Truncate(time.Second)
	case date.Minute:
		t = t.Truncate(time.Minute)
	case date.Hour:
		t = time.Date(y, mon, day, h, 0, 0, 0, loc)
	case date.Day:
		t = time.Date(y, mon, day, 0, 0, 0, 0, loc)
	case date.Month:
		t = time.Date(y, mon, 1, 0, 0, 0, 0, loc)
	case date.Year:
		t = time.Date(y, 1, 1, 0, 0, 0, 0, loc)
	}

	return
}