package budget

import (
	"fmt"
	"os"
	"os/exec"
	"syscall"
)

func systemctl(args ...string) error {
	cmd := exec.Command("systemctl", append([]string{"--user"}, args...)...)
	cmd.Stdout, cmd.Stderr = os.Stdout, os.Stderr
	return cmd.Run()
}

func runArgs(c config, name, id string, command []string) ([]string, error) {
	if len(command) > 0 && command[0] == "--" {
		command = command[1:]
	}
	if len(command) == 0 {
		return nil, fmt.Errorf("a command is required")
	}
	values, err := c.assignments(name)
	if err != nil {
		return nil, err
	}
	slice := "app.slice"
	if name == "search" {
		slice = "search.slice"
	}
	args := []string{"systemd-run", "--user", "--scope", "--collect", "--quiet", "--unit=work-" + id, "--slice=" + slice}
	for _, value := range values {
		args = append(args, "--property="+value)
	}
	return append(append(args, "--"), command...), nil
}

func launch(c config, name string, command []string) error {
	id, err := randomID()
	if err != nil {
		return err
	}
	args, err := runArgs(c, name, id, command)
	if err != nil {
		return err
	}
	path, err := exec.LookPath(args[0])
	if err != nil {
		return err
	}
	return syscall.Exec(path, args, os.Environ())
}