package nasin

import "os"
import "path/filepath"

// ApplicationUserDataDir returns the directory path where an application can
// store its user data files. If the directory does not exist, it will be
// created.
func ApplicationUserDataDir (app ApplicationDescription) (string, error) {
	return userMkdirAll(app.ID, userDataDir)
}

// ApplicationSystemDataDirs returns a list of directory paths where an
// application can look for its system-level data files. Directories returned
// by this function may or may not actually exist. This function may return an
// empty slice on some platforms.
func ApplicationSystemDataDirs (app ApplicationDescription) ([]string, error) {
	return systemDirs(app.ID, systemDataDirs)
}

// ApplicationUserConfigDir returns the directory path where an application can
// store its user configuration files.
func ApplicationUserConfigDir (app ApplicationDescription) (string, error) {
	return userMkdirAll(app.ID, userConfigDir)
}

// ApplicationSystemDataDirs returns a list of directory paths where an
// application can look for its system-level configuration files. Directories
// returned by this function may or may not actually exist. This function may
// return an empty slice on some platforms.
func ApplicationSystemConfigDirs (app ApplicationDescription) ([]string, error) {
	return systemDirs(app.ID, systemConfigDirs)
}

// ApplicationUserCacheDir returns the directory path where an application can
// store its user cache files.
func ApplicationUserCacheDir (app ApplicationDescription) (string, error) {
	return userMkdirAll(app.ID, userCacheDir)
}

func userMkdirAll (sub string, getter func () (string, error)) (string, error) {
	path, err := getter()
	if err != nil { return "", err }
	path = filepath.Join(path, sub)
	err = os.MkdirAll(path, 0700)
	if err != nil { return "", err }
	return path, nil
}

func systemDirs (sub string, getter func () ([]string, error)) ([]string, error) {
	paths, err := getter()
	if err != nil { return nil, err }
	specificPaths := make([]string, len(paths))
	for index, path := range paths {
		specificPaths[index] = filepath.Join(path, sub)
	}
	return specificPaths, nil
}