// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0

package getter

import (
	"fmt"
	"net/url"
	"os"
	"runtime"
	"syscall"

	"github.com/bgentry/go-netrc/netrc"
	"github.com/mitchellh/go-homedir"
)

// addAuthFromNetrc adds auth information to the URL from the user's
// netrc file if it can be found. This will only add the auth info
// if the URL doesn't already have auth info specified and the
// the username is blank.
func addAuthFromNetrc(u *url.URL) error {
	// If the URL already has auth information, do nothing
	if u.User != nil && u.User.Username() != "" {
		return nil
	}

	// Get the netrc file path
	path := os.Getenv("NETRC")
	if path == "" {
		filename := ".netrc"
		if runtime.GOOS == "windows" {
			filename = "_netrc"
		}

		var err error
		path, err = homedir.Expand("~/" + filename)
		if err != nil {
			return err
		}
	}

	// If the file is not a file, then do nothing
	if fi, err := os.Stat(path); err != nil {
		// File doesn't exist, do nothing
		if serr, ok := err.(*os.PathError); ok && (os.IsNotExist(serr.Err) || serr.Err == syscall.ENOTDIR) {
			return nil
		}

		// Some other error!
		return err
	} else if fi.IsDir() {
		// File is directory, ignore
		return nil
	}

	// Load up the netrc file
	net, err := netrc.ParseFile(path)
	if err != nil {
		return fmt.Errorf("Error parsing netrc file at %q: %s", path, err)
	}

	machine := net.FindMachine(u.Host)
	if machine == nil {
		// Machine not found, no problem
		return nil
	}

	// Set the user info
	u.User = url.UserPassword(machine.Login, machine.Password)
	return nil
}
