// Copyright 2019 The Kubernetes Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package pathutil

import (
	"path/filepath"
	"strings"

	"github.com/pkg/errors"

	"sigs.k8s.io/krew/pkg/constants"
)

// IsSubPath checks if the extending path is an extension of the basePath, it will return the extending path
// elements. Both paths have to be absolute or have the same root directory. The remaining path elements
func IsSubPath(basePath, subPath string) (string, bool) {
	extendingPath, err := filepath.Rel(basePath, subPath)
	if err != nil {
		return "", false
	}
	if strings.HasPrefix(extendingPath, "..") {
		return "", false
	}
	return extendingPath, true
}

// ReplaceBase will return a replacement path with replacement as a base of the path instead of the old base. a/b/c, a, d -> d/b/c
func ReplaceBase(path, old, replacement string) (string, error) {
	extendingPath, ok := IsSubPath(old, path)
	if !ok {
		return "", errors.Errorf("can't replace %q in %q, it is not a subpath", old, path)
	}
	return filepath.Join(replacement, extendingPath), nil
}

// CanonicalPluginName resolves a plugin's index and name from input string.
// If an index is not specified, the default index name is assumed.
func CanonicalPluginName(in string) (string, string) {
	if strings.Count(in, "/") == 0 {
		return constants.DefaultIndexName, in
	}
	p := strings.SplitN(in, "/", 2)
	return p[0], p[1]
}