package autotrader

import (
	"os/exec"
	"runtime"

	"golang.org/x/exp/constraints"
)

const floatComparisonTolerance = float64(1e-6)

// EasyIndex returns an index to the `n` -length object that allows for negative indexing. For example, EasyIndex(-1, 5) returns 4. This is similar to Python's negative indexing. The return value may be less than zero if (-i) > n.
func EasyIndex(i, n int) int {
	if i < 0 {
		return n + i
	}
	return i
}

func EqualApprox(a, b float64) bool {
	return Abs(a-b) < floatComparisonTolerance
}

func Abs[T constraints.Integer | constraints.Float](a T) T {
	if a < T(0) {
		return -a
	}
	return a
}

func Min[T constraints.Ordered](a, b T) T {
	if a < b {
		return a
	}
	return b
}

func Max[T constraints.Ordered](a, b T) T {
	if a > b {
		return a
	}
	return b
}

func LeverageToMargin(leverage float64) float64 {
	return 1 / leverage
}

func MarginToLeverage(margin float64) float64 {
	return 1 / margin
}

// Open opens the specified URL in the default browser of the user.
func Open(url string) error {
	var cmd string
	var args []string

	switch runtime.GOOS {
	case "windows":
		cmd = "cmd"
		args = []string{"/c", "start"}
	case "darwin":
		cmd = "open"
	default: // "linux", "freebsd", "openbsd", "netbsd"
		cmd = "xdg-open"
	}
	args = append(args, url)
	return exec.Command(cmd, args...).Start()
}