package main

import (
	"flag"
	"fmt"

	"git.wntrmute.dev/kyle/goutils/die"
	"github.com/logocomune/maidenhead"
	geo "gopkg.in/billups/golang-geo.v2"
)

var qths = map[int]string{
	4:  "CM97",
	6:  "CM97cq",
	8:  "CM97cq53",
	10: "CM97cq53CI",
}

var kmToMile = 0.621371

func cToP(c maidenhead.Coordinate) *geo.Point {
	return geo.NewPoint(c.Lat, c.Lng)
}

func distBearing(qth, qsl string) (err error) {
	var cqth, cqsl maidenhead.Coordinate
	cqth.Lat, cqth.Lng, err = maidenhead.GridCenter(qth)
	if err != nil {
		return err
	}

	cqsl.Lat, cqsl.Lng, err = maidenhead.GridCenter(qsl)
	if err != nil {
		return err
	}

	pqth := cToP(cqth)
	pqsl := cToP(cqsl)
	dist := pqth.GreatCircleDistance(pqsl)
	bearing := pqth.BearingTo(pqsl)
	fmt.Printf("%s => %s: distance %0.2f miles, bearing %0.1f°\n",
		qth, qsl, dist*kmToMile, bearing)
	return nil
}

func main() {
	var lat, lon float64
	var precision int64

	flag.Float64Var(&lat, "lat", 0.0, "latitude of grid")
	flag.Float64Var(&lon, "lon", 0.0, "longitude of grid")
	flag.Int64Var(&precision, "d", 6, "number of digits")
	flag.Parse()

	if flag.NArg() == 0 {
		fmt.Println("nothing")
		return
	}

	cmd := flag.Arg(0)
	switch cmd {
	case "geo":
		grid, err := maidenhead.Locator(lat, lon, int(precision))
		die.If(err)

		fmt.Printf("%0.6f %0.6f: ", lat, lon)
		fmt.Println(grid)
	case "qth":
		grid, ok := qths[int(precision)]
		if !ok {
			fmt.Println(qths[6])
		} else {
			fmt.Println(grid)
		}
	case "db":
		var qth, qsl string
		if flag.NArg() == 2 {
			qsl = flag.Arg(1)
			qth = qths[len(qsl)]
		} else {
			qsl = flag.Arg(2)
			qth = flag.Arg(1)
		}

		err := distBearing(qth, qsl)
		die.If(err)
	}

}