package cache_manager

import (
	"errors"
	"os"
	"path/filepath"
)

type CacheManager struct {
	Root string
}

// Creates a new cache manager rooted at <cacheRoot>.
//
// If <cacheRoot> does not exist, returns an error.
func NewCacheManager(cacheRoot string) (*CacheManager, error) {
	if _, err := os.Stat(cacheRoot); errors.Is(err, os.ErrNotExist) {
		return nil, errors.New("Cache root must exist.")
	}

	return &CacheManager{
		Root: cacheRoot,
	}, nil
}

// Returns a path prefixed with the cache root.
func (c CacheManager) Path(elems ...string) string {
	return filepath.Join(c.Root, filepath.Join(elems...))
}

// Checks whether a specific top-level items exists in the cache.
func (c CacheManager) Exists(key string) bool {
	if _, err := os.Stat(c.Path(key)); errors.Is(err, os.ErrNotExist) {
		return false
	}

	return true
}

// Deletes an element from the cache, if it exists.
func (c CacheManager) Evict(key string) {
	os.RemoveAll(c.Path(key))
}