// Copyright The OpenTelemetry 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 tools provides helper functions used in scripts within the
// internal/tools module, as well as imports needed for a build with the
// "tools" build tag.
package tools

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

// FindRepoRoot retrieves the root of the repository containing the current working directory.
// Beginning at the current working directory (dir), the algorithm checks if joining the ".git"
// suffix, such as "dir.get", is a valid file. Otherwise, it will continue checking the dir's
// parent directory until it reaches the repo root or returns an error if it cannot be found.
func FindRepoRoot() (string, error) {
	start, err := os.Getwd()
	if err != nil {
		return "", err
	}

	dir := start
	for {
		_, err := os.Stat(filepath.Join(dir, ".git"))
		if errors.Is(err, os.ErrNotExist) {
			dir = filepath.Dir(dir)
			// From https://golang.org/pkg/path/filepath/#Dir:
			// The returned path does not end in a separator unless it is the root directory.
			if strings.HasSuffix(dir, string(filepath.Separator)) {
				return "", fmt.Errorf("unable to find git repository enclosing working dir %s", start)
			}
			continue
		}

		if err != nil {
			return "", err
		}

		return dir, nil
	}
}