package auger

import (
	`io/fs`
	`os`
	`strings`

	`honnef.co/go/augeas`
)

/*
	NewAuger returns an auger.Aug.

	See:
		https://pkg.go.dev/honnef.co/go/augeas#readme-examples
		https://pkg.go.dev/honnef.co/go/augeas#New
	for the `root` and `loadPath` parameters
	(and, by extension, the `flags` paraemter; note that the `flags`
	is an auger.AugFlags, not an augeas.Flag!).

	`flags` may be nil.
*/
func NewAuger(root, loadPath string, flags *AugFlags) (aug *Aug, err error) {

	aug = new(Aug)

	if aug.aug, err = augeas.New(root, loadPath, flags.Eval()); err != nil {
		return
	}

	return
}

// NewAugerFromAugeas returns a wrapped auger.Aug from a (honnef.co/go/augeas).Augeas.
func NewAugerFromAugeas(orig augeas.Augeas) (aug *Aug) {

	aug = new(Aug)
	aug.aug = orig

	return
}

/*
	AugpathToFspath returns the filesystem path from an Augeas path.

	It is *required* and expected that the Augeas standard /files prefix be removed first;
	if not, it is assumed to be part of the filesystem path.

	If a valid path cannot be determined, fsPath will be empty.
*/
func AugpathToFspath(augPath string) (fsPath string, err error) {

	var path string
	var num int
	var augSplit []string = strings.Split(augPath, "/")

	num = len(augSplit)

	for i := num - 1; i >= 0; i-- {
		path = strings.Join(augSplit[:i], "/")
		if !fs.ValidPath(path) {
			continue
		}
		if _, err = os.Stat(path); err != nil {
			if os.IsNotExist(err) {
				err = nil
				continue
			} else {
				return
			}
		}

		fsPath = path
		return
	}

	return
}

// dedupePaths is used to reduce new to only unique entries that do not exist in existing.
func dedupePaths(new, existing []string) (missing []string) {

	var ok bool
	var m map[string]bool = make(map[string]bool)

	for _, path := range existing {
		m[path] = true
	}

	for _, path := range new {
		if _, ok = m[path]; !ok {
			missing = append(missing, path)
		}
	}

	return
}