// From a local repo find out the current branch name if there is one.
func findCurrentBranch(repo v.Repo) string {
	msg.Debug("Attempting to find current branch for %s", repo.Remote())
	// Svn and Bzr don't have default branches.
	if repo.Vcs() == v.Svn || repo.Vcs() == v.Bzr {
		return ""
	}

	if repo.Vcs() == v.Git {
		c := exec.Command("git", "symbolic-ref", "--short", "HEAD")
		c.Dir = repo.LocalPath()
		c.Env = envForDir(c.Dir)
		out, err := c.CombinedOutput()
		if err != nil {
			msg.Debug("Unable to find current branch for %s, error: %s", repo.Remote(), err)
			return ""
		}
		return strings.TrimSpace(string(out))
	}

	if repo.Vcs() == v.Hg {
		c := exec.Command("hg", "branch")
		c.Dir = repo.LocalPath()
		c.Env = envForDir(c.Dir)
		out, err := c.CombinedOutput()
		if err != nil {
			msg.Debug("Unable to find current branch for %s, error: %s", repo.Remote(), err)
			return ""
		}
		return strings.TrimSpace(string(out))
	}

	return ""
}

// NotFound attempts to retrieve a package when not found in the local vendor/
// folder. It will attempt to get it from the remote location info.
func (m *MissingPackageHandler) NotFound(pkg string, addTest bool) (bool, error) {
	root := util.GetRootFromPackage(pkg)
	// Skip any references to the root package.
	if root == m.Config.Name {
		return false, nil
	}

	dest := filepath.Join(m.destination, root)

	// This package may have been placed on the list to look for when it wasn't
	// downloaded but it has since been downloaded before coming to this entry.
	if _, err := os.Stat(dest); err == nil {
		// Make sure the location contains files. It may be an empty directory.
		empty, err := gpath.IsDirectoryEmpty(dest)
		if err != nil {
			return false, err
		}
		if empty {
			msg.Warn("%s is an existing location with no files. Fetching a new copy of the dependency.", dest)
			msg.Debug("Removing empty directory %s", dest)
			err := os.RemoveAll(dest)
			if err != nil {
				msg.Debug("Installer error removing directory %s: %s", dest, err)
				return false, err
			}
		} else {
			msg.Debug("Found %s", dest)
			return true, nil
		}
	}

	msg.Info("Fetching %s into %s", pkg, m.destination)

	d := m.Config.Imports.Get(root)
	if d == nil && addTest {
		d = m.Config.DevImports.Get(root)
	}

	// If the dependency is nil it means the Config doesn't yet know about it.
	if d == nil {
		d, _ = m.Use.Get(root)
		// We don't know about this dependency so we create a basic instance.
		if d == nil {
			d = &cfg.Dependency{Name: root}
		}
		if addTest {
			m.Config.DevImports = append(m.Config.DevImports, d)
		} else {
			m.Config.Imports = append(m.Config.Imports, d)
		}
	}
	if err := VcsGet(d, dest, m.home, m.cache, m.cacheGopath, m.useGopath); err != nil {
		return false, err
	}
	return true, nil
}

func (m *memCache) put(name, version string) {
	m.Lock()
	defer m.Unlock()
	m.t[name] = true
	sv, err := semver.NewVersion(version)
	if err != nil {
		msg.Debug("Ignoring %s version %s: %s", name, version, err)
		return
	}

	latest, found := m.latest[name]
	if found {
		lv, err := semver.NewVersion(latest)
		if err == nil {
			if sv.GreaterThan(lv) {
				m.latest[name] = version
			}
		}
	} else {
		m.latest[name] = version
	}

	found = false
	for _, v := range m.versions[name] {
		if v == version {
			found = true
		}
	}
	if !found {
		m.versions[name] = append(m.versions[name], version)
	}
}

// GodepWorkspace removes any Godeps/_workspace directories and makes sure
// any rewrites are undone.
// Note, this is not concuccency safe.
func GodepWorkspace(v string) error {
	vPath = v
	if _, err := os.Stat(vPath); err != nil {
		if os.IsNotExist(err) {
			msg.Debug("Vendor directory does not exist.")
		}

		return err
	}

	err := filepath.Walk(vPath, stripGodepWorkspaceHandler)
	if err != nil {
		return err
	}

	// Walk the marked projects to make sure rewrites are undone.
	for k := range godepMark {
		msg.Info("Removing Godep rewrites for %s", k)
		err := filepath.Walk(k, rewriteGodepfilesHandler)
		if err != nil {
			return err
		}
	}

	return nil
}

func stripGodepWorkspaceHandler(path string, info os.FileInfo, err error) error {
	// Skip the base vendor directory
	if path == vPath {
		return nil
	}

	name := info.Name()
	p := filepath.Dir(path)
	pn := filepath.Base(p)
	if name == "_workspace" && pn == "Godeps" {
		if _, err := os.Stat(path); err == nil {
			if info.IsDir() {
				// Marking this location to make sure rewrites are undone.
				pp := filepath.Dir(p)
				godepMark[pp] = true

				msg.Info("Removing: %s", path)
				return os.RemoveAll(path)
			}

			msg.Debug("%s is not a directory. Skipping removal", path)
			return nil
		}
	}
	return nil
}

func (m *MissingPackageHandler) NotFound(pkg string) (bool, error) {
	root := util.GetRootFromPackage(pkg)

	// Skip any references to the root package.
	if root == m.Config.Name {
		return false, nil
	}

	dest := filepath.Join(m.destination, root)

	// This package may have been placed on the list to look for when it wasn't
	// downloaded but it has since been downloaded before coming to this entry.
	if _, err := os.Stat(dest); err == nil {
		msg.Debug("Found %s", dest)
		return true, nil
	}

	msg.Info("Fetching %s into %s", pkg, m.destination)

	d := m.Config.Imports.Get(root)
	// If the dependency is nil it means the Config doesn't yet know about it.
	if d == nil {
		d = m.Use.Get(root)
		// We don't know about this dependency so we create a basic instance.
		if d == nil {
			d = &cfg.Dependency{Name: root}
		}

		m.Config.Imports = append(m.Config.Imports, d)
	}
	if err := VcsGet(d, dest, m.home, m.cache, m.cacheGopath, m.useGopath); err != nil {
		return false, err
	}
	return true, nil
}

// LazyConcurrentUpdate updates only deps that are not already checkout out at the right version.
//
// This is only safe when updating from a lock file.
func LazyConcurrentUpdate(deps []*cfg.Dependency, cwd string, i *Installer, c *cfg.Config) error {

	newDeps := []*cfg.Dependency{}
	for _, dep := range deps {
		destPath := filepath.Join(i.VendorPath(), dep.Name)

		// Get a VCS object for this directory
		repo, err := dep.GetRepo(destPath)
		if err != nil {
			newDeps = append(newDeps, dep)
			continue
		}

		ver, err := repo.Version()
		if err != nil {
			newDeps = append(newDeps, dep)
			continue
		}

		if ver == dep.Reference {
			msg.Info("--> Found desired version %s %s!", dep.Name, dep.Reference)
			continue
		}

		msg.Debug("--> Queue %s for update (%s != %s).", dep.Name, ver, dep.Reference)
		newDeps = append(newDeps, dep)
	}
	if len(newDeps) > 0 {
		return ConcurrentUpdate(newDeps, cwd, i, c)
	}

	return nil
}

// Unlock unlocks a particular key name
func Unlock(name string) {
	msg.Debug("Unlocking %s", name)
	lockSync.Lock()
	if m, ok := lockData[name]; ok {
		m.Unlock()
	}

	lockSync.Unlock()
}

func findCurrentBranch(repo vcs.Repo) string {
	msg.Debug("Attempting to find current branch for %s", repo.Remote())
	// Svn and Bzr don't have default branches.
	if repo.Vcs() == vcs.Svn || repo.Vcs() == vcs.Bzr {
		return ""
	}

	if repo.Vcs() == vcs.Git || repo.Vcs() == vcs.Hg {
		ver, err := repo.Current()
		if err != nil {
			msg.Debug("Unable to find current branch for %s, error: %s", repo.Remote(), err)
			return ""
		}
		return ver
	}

	return ""
}

// StripVcs removes VCS metadata (.git, .hg, .bzr, .svn) from the vendor/
// directory.
func StripVcs() error {
	if _, err := os.Stat(VendorDir); err != nil {
		if os.IsNotExist(err) {
			msg.Debug("Vendor directory does not exist.")
		}

		return err
	}
	return filepath.Walk(VendorDir, stripHandler)
}

// EnsureVendorDir ensures that a vendor/ directory is present in the cwd.
func EnsureVendorDir() {
	fi, err := os.Stat(gpath.VendorDir)
	if err != nil {
		msg.Debug("Creating %s", gpath.VendorDir)
		if err := os.MkdirAll(gpath.VendorDir, os.ModeDir|0755); err != nil {
			msg.Die("Could not create %s: %s", gpath.VendorDir, err)
		}
	} else if !fi.IsDir() {
		msg.Die("Vendor is not a directory")
	}
}

// Lock locks a particular key name
func Lock(name string) {
	lockSync.Lock()
	m, ok := lockData[name]
	if !ok {
		m = &sync.Mutex{}
		lockData[name] = m
	}
	lockSync.Unlock()
	msg.Debug("Locking %s", name)
	m.Lock()
}

// sliceToQueue is a special-purpose function for unwrapping a slice of
// dependencies into a queue of fully qualified paths.
func sliceToQueue(deps []*cfg.Dependency, basepath string) *list.List {
	l := list.New()
	for _, e := range deps {
		if len(e.Subpackages) > 0 {
			for _, v := range e.Subpackages {
				ip := e.Name
				if v != "." && v != "" {
					ip = ip + "/" + v
				}
				msg.Debug("Adding local Import %s to queue", ip)
				l.PushBack(filepath.Join(basepath, filepath.FromSlash(ip)))
			}
		} else {
			msg.Debug("Adding local Import %s to queue", e.Name)
			l.PushBack(filepath.Join(basepath, filepath.FromSlash(e.Name)))
		}

	}
	return l
}

// VcsGet figures out how to fetch a dependency, and then gets it.
//
// VcsGet installs into the cache.
func VcsGet(dep *cfg.Dependency) error {

	key, err := cp.Key(dep.Remote())
	if err != nil {
		msg.Die("Cache key generation error: %s", err)
	}
	location := cp.Location()
	d := filepath.Join(location, "src", key)

	repo, err := dep.GetRepo(d)
	if err != nil {
		return err
	}
	// If the directory does not exist this is a first cache.
	if _, err = os.Stat(d); os.IsNotExist(err) {
		msg.Debug("Adding %s to the cache for the first time", dep.Name)
		err = repo.Get()
		if err != nil {
			return err
		}
		branch := findCurrentBranch(repo)
		if branch != "" {
			msg.Debug("Saving default branch for %s", repo.Remote())
			c := cp.RepoInfo{DefaultBranch: branch}
			err = cp.SaveRepoData(key, c)
			if err == cp.ErrCacheDisabled {
				msg.Debug("Unable to cache default branch because caching is disabled")
			} else if err != nil {
				msg.Debug("Error saving %s to cache. Error: %s", repo.Remote(), err)
			}
		}
	} else {
		msg.Debug("Updating %s in the cache", dep.Name)
		err = repo.Update()
		if err != nil {
			return err
		}
	}

	return nil
}

// Load pulls the mirrors into memory
func Load() error {
	home := gpath.Home()

	op := filepath.Join(home, "mirrors.yaml")

	var ov *Mirrors
	if _, err := os.Stat(op); os.IsNotExist(err) {
		msg.Debug("No mirrors.yaml file exists")
		ov = &Mirrors{
			Repos: make(MirrorRepos, 0),
		}
		return nil
	} else if err != nil {
		ov = &Mirrors{
			Repos: make(MirrorRepos, 0),
		}
		return err
	}

	var err error
	ov, err = ReadMirrorsFile(op)
	if err != nil {
		return fmt.Errorf("Error reading existing mirrors.yaml file: %s", err)
	}

	msg.Info("Loading mirrors from mirrors.yaml file")
	for _, o := range ov.Repos {
		msg.Debug("Found mirror: %s to %s (%s)", o.Original, o.Repo, o.Vcs)
		no := &mirror{
			Repo: o.Repo,
			Vcs:  o.Vcs,
		}
		mirrors[o.Original] = no
	}

	return nil
}

// StripVendor removes nested vendor and Godeps/_workspace/ directories.
func StripVendor() error {
	searchPath, _ := Vendor()
	if _, err := os.Stat(searchPath); err != nil {
		if os.IsNotExist(err) {
			msg.Debug("Vendor directory does not exist.")
		}

		return err
	}

	err := filepath.Walk(searchPath, func(path string, info os.FileInfo, err error) error {
		// Skip the base vendor directory
		if path == searchPath {
			return nil
		}

		name := info.Name()
		if name == "vendor" {
			if _, err := os.Stat(path); err == nil {
				if info.IsDir() {
					msg.Info("Removing: %s", path)
					return os.RemoveAll(path)
				}

				msg.Debug("%s is not a directory. Skipping removal", path)
				return nil
			}
		}
		return nil
	})
	if err != nil {
		return err
	}

	return strip.GodepWorkspace(searchPath)
}

func stripHandler(path string, info os.FileInfo, err error) error {

	name := info.Name()
	if name == ".git" || name == ".bzr" || name == ".svn" || name == ".hg" {
		if _, err := os.Stat(path); err == nil {
			if info.IsDir() {
				msg.Info("Removing: %s", path)
				return os.RemoveAll(path)
			}

			msg.Debug("%s is not a directory. Skipping removal", path)
			return nil
		}
	}
	return nil
}

// Plugin attempts to find and execute a plugin based on a command.
//
// Exit code 99 means the plugin was never executed. Code 1 means the program
// exited badly.
func Plugin(command string, args []string) {

	cwd, err := os.Getwd()
	if err != nil {
		msg.ExitCode(99)
		msg.Die("Could not get working directory: %s", err)
	}

	cmd := "glide-" + command
	var fullcmd string
	if fullcmd, err = exec.LookPath(cmd); err != nil {
		fullcmd = cwd + "/" + cmd
		if _, err := os.Stat(fullcmd); err != nil {
			msg.ExitCode(99)
			msg.Die("Command %s does not exist.", cmd)
		}
	}

	// Turning os.Args first argument from `glide` to `glide-command`
	args[0] = cmd
	// Removing the first argument (command)
	removed := false
	for i, v := range args {
		if removed == false && v == command {
			args = append(args[:i], args[i+1:]...)
			removed = true
		}
	}
	pa := os.ProcAttr{
		Files: []*os.File{os.Stdin, os.Stdout, os.Stderr},
		Dir:   cwd,
	}

	msg.Debug("Delegating to plugin %s (%v)\n", fullcmd, args)

	proc, err := os.StartProcess(fullcmd, args, &pa)
	if err != nil {
		msg.Err("Failed to execute %s: %s", cmd, err)
		os.Exit(98)
	}

	if _, err := proc.Wait(); err != nil {
		msg.Err(err.Error())
		os.Exit(1)
	}
}

// ResolveAll takes a list of packages and returns an inclusive list of all
// vendored dependencies.
//
// While this will scan all of the source code it can find, it will only return
// packages that were either explicitly passed in as deps, or were explicitly
// imported by the code.
//
// Packages that are either CGO or on GOROOT are ignored. Packages that are
// on GOPATH, but not vendored currently generate a warning.
//
// If one of the passed in packages does not exist in the vendor directory,
// an error is returned.
func (r *Resolver) ResolveAll(deps []*cfg.Dependency) ([]string, error) {
	queue := sliceToQueue(deps, r.VendorDir)

	loc, err := r.ResolveLocal(false)
	if err != nil {
		return []string{}, err
	}
	for _, l := range loc {
		msg.Debug("Adding local Import %s to queue", l)
		queue.PushBack(l)
	}

	if r.ResolveAllFiles {
		return r.resolveList(queue)
	}
	return r.resolveImports(queue)
}

// StripVendor removes nested vendor and Godeps/_workspace/ directories.
func StripVendor() error {
	if _, err := os.Stat(VendorDir); err != nil {
		if os.IsNotExist(err) {
			msg.Debug("Vendor directory does not exist.")
		}

		return err
	}

	err := filepath.Walk(VendorDir, stripVendorHandler)
	if err != nil {
		return err
	}

	err = strip.GodepWorkspace(VendorDir)

	return err
}