package cobol

import (
	"errors"
	"time"

	"google.golang.org/protobuf/types/known/timestamppb"
)

// returns a human readable duration
func Since(aLongTimeAgo any) string {
	s, err := SinceCheck(aLongTimeAgo)
	if errors.Is(err, Broken) {
		return "bad"
	}
	if errors.Is(err, NoTime) {
		return "nope"
	}
	return s
}

// returns a human readable duration
// also returns errors
func SinceCheck(mightBeRecently any) (string, error) {
	dur, err := GetSince(mightBeRecently)
	return FormatDuration(dur), err
}

func GetSince(maybeTime any) (time.Duration, error) {
	var t time.Time
	var err error

	switch v := maybeTime.(type) {
	case time.Time:
		// If the type is time.Time, 'v' is now a time.Time variable.
		t = v
	case *timestamppb.Timestamp:
		// If it's a protobuf Timestamp pointer (most common case),
		// 'v' is a *timestamppb.Timestamp. We must convert it.
		// It's also good to check if it's a valid timestamp.
		if v.IsValid() {
			t = v.AsTime()
		} else {
			err = errors.New("pb time invalid")
		}

	case timestamppb.Timestamp:
		// Handle the less common case of a value type instead of a pointer.
		if v.IsValid() {
			t = v.AsTime()
		}
	default:
		err = errors.Join(err, NoTime)
	}
	if err != nil {
		return time.Since(t), err
	}

	return time.Since(t), nil
}