package goutil

import (
	"errors"
	"io"
	"math"
	"os"
	"regexp"
	"time"

	"github.com/hako/durafmt"
)

func FilterToAlnum(input string) string {
	re := regexp.MustCompile("[^a-zA-Z0-9]+")
	return re.ReplaceAllString(input, "")
}

func TimeDiffHuman(first time.Time, second time.Time) string {
	if first.Before(second) {
		return durafmt.ParseShort(second.Sub(first)).String()
	} else {
		return durafmt.ParseShort(first.Sub(second)).String()
	}
}

// Does anyone else use uints for things that are always >=0 like counts and
func TimeDiffAbsSeconds(first time.Time, second time.Time) uint {
	return uint(math.Abs(first.Sub(second).Truncate(time.Second).Seconds()))
}

func Mkdirp(p string) error {
	src, err := os.Stat(p)
	if os.IsNotExist(err) {
		errDir := os.MkdirAll(p, 0755)
		if errDir != nil {
			return errDir
		}

		return nil
	}
	if src.Mode().IsRegular() {
		return errors.New("file already exists at path")
	}
	return nil
}

// straight outta stackoverflow
// https://stackoverflow.com/questions/21060945/simple-way-to-copy-a-file-in-golang
func CopyFile(src, dst string) (err error) {
	in, err := os.Open(src)
	if err != nil {
		return
	}
	defer in.Close()
	out, err := os.Create(dst)
	if err != nil {
		return
	}
	defer func() {
		cerr := out.Close()
		if err == nil {
			err = cerr
		}
	}()
	if _, err = io.Copy(out, in); err != nil {
		return
	}
	err = out.Sync()
	return
}

const milliInSecond int64 = 1000
const microInSecond int64 = 1000000
const nsInSecond int64 = 1000000000

func TimeFromUnixMilli(input int64) time.Time {
	var wholeSeconds int64 = input / milliInSecond
	var remainderMillis int64 = input - (wholeSeconds * milliInSecond)
	var remainderNano int64 = remainderMillis * 1000000
	return time.Unix(wholeSeconds, remainderNano)
}

func TimeFromUnixMicro(input int64) time.Time {
	var wholeSeconds int64 = input / microInSecond
	var remainderMicros int64 = input - (wholeSeconds * microInSecond)
	var remainderNano int64 = remainderMicros * 1000
	return time.Unix(wholeSeconds, remainderNano)
}

func TimeFromWebKit(input int64) time.Time {
	// webkit time is stupid and uses 1601-01-01 for epoch
	// it's 11644473600 seconds behind unix 1970-01-01 epoch
	// it's also in microseconds
	unixMicrosCorrected := input - (11644473600 * 1000000)
	return TimeFromUnixMicro(unixMicrosCorrected)
}