package meta

import (
	"regexp"
	"strconv"

	"github.com/photoprism/photoprism/pkg/clean"

	"github.com/dsoprea/go-exif/v3"
)

var GpsCoordsRegexp = regexp.MustCompile("[0-9\\.]+")
var GpsRefRegexp = regexp.MustCompile("[NSEW]+")
var GpsFloatRegexp = regexp.MustCompile("[+\\-]?(?:(?:0|[1-9]\\d*)(?:\\.\\d*)?|\\.\\d+)")

// GpsToLatLng returns the GPS latitude and longitude as float point number.
func GpsToLatLng(s string) (lat, lng float32) {
	// Emtpy?
	if s == "" {
		return 0, 0
	}

	// Floating point numbers?
	if fl := GpsFloatRegexp.FindAllString(s, -1); len(fl) == 2 {
		if lat, err := strconv.ParseFloat(fl[0], 64); err != nil {
			log.Infof("metadata: %s is not a valid gps position", clean.Log(fl[0]))
		} else if lng, err := strconv.ParseFloat(fl[1], 64); err == nil {
			return float32(lat), float32(lng)
		}
	}

	// Parse string values.
	co := GpsCoordsRegexp.FindAllString(s, -1)
	re := GpsRefRegexp.FindAllString(s, -1)

	if len(co) != 6 || len(re) != 2 {
		return 0, 0
	}

	latDeg := exif.GpsDegrees{
		Orientation: re[0][0],
		Degrees:     ParseFloat(co[0]),
		Minutes:     ParseFloat(co[1]),
		Seconds:     ParseFloat(co[2]),
	}

	lngDeg := exif.GpsDegrees{
		Orientation: re[1][0],
		Degrees:     ParseFloat(co[3]),
		Minutes:     ParseFloat(co[4]),
		Seconds:     ParseFloat(co[5]),
	}

	return float32(latDeg.Decimal()), float32(lngDeg.Decimal())
}

// GpsToDecimal returns the GPS latitude or longitude as decimal float point number.
func GpsToDecimal(s string) float32 {
	// Emtpy?
	if s == "" {
		return 0
	}

	// Floating point number?
	if f, err := strconv.ParseFloat(s, 64); err == nil {
		return float32(f)
	}

	// Parse string value.
	co := GpsCoordsRegexp.FindAllString(s, -1)
	re := GpsRefRegexp.FindAllString(s, -1)

	if len(co) != 3 || len(re) != 1 {
		return 0
	}

	latDeg := exif.GpsDegrees{
		Orientation: re[0][0],
		Degrees:     ParseFloat(co[0]),
		Minutes:     ParseFloat(co[1]),
		Seconds:     ParseFloat(co[2]),
	}

	return float32(latDeg.Decimal())
}

// ParseFloat returns a single GPS coordinate value as floating point number (degree, minute or second).
func ParseFloat(s string) float64 {
	// Empty?
	if s == "" {
		return 0
	}

	// Parse floating point number.
	if result, err := strconv.ParseFloat(s, 64); err != nil {
		log.Debugf("metadata: %s is not a valid gps position", clean.Log(s))
		return 0
	} else {
		return result
	}
}