package module

import (
	"fmt"
	"net/url"
	"os"
	"os/exec"
)

// HgGetter is a Getter implementation that will download a module from
// a Mercurial repository.
type HgGetter struct{}

func (g *HgGetter) Get(dst string, u *url.URL) error {
	if _, err := exec.LookPath("hg"); err != nil {
		return fmt.Errorf("hg must be available and on the PATH")
	}

	_, err := os.Stat(dst)
	if err != nil && !os.IsNotExist(err) {
		return err
	}
	if err != nil {
		if err := g.clone(dst, u); err != nil {
			return err
		}
	}

	if err:= g.pull(dst, u); err != nil {
		return err
	}

	return g.update(dst, u)
}

func (g *HgGetter) clone(dst string, u *url.URL) error {
	cmd := exec.Command("hg", "clone", "-U", u.String(), dst)
	return getRunCommand(cmd)
}

func (g *HgGetter) pull(dst string, u *url.URL) error {
	cmd := exec.Command("hg", "pull")
	cmd.Dir = dst
	return getRunCommand(cmd)
}

func (g *HgGetter) update(dst string, u *url.URL) error {
	cmd := exec.Command("hg", "update")
	cmd.Dir = dst
	return getRunCommand(cmd)
}