package hdfs

import (
	"fmt"
	"os"
	"os/user"
	"strings"

	krb "github.com/jcmturner/gokrb5/v8/client"
	"github.com/jcmturner/gokrb5/v8/config"
	"github.com/jcmturner/gokrb5/v8/credentials"
)

// copy-paste from https://github.com/colinmarc/hdfs/blob/master/cmd/hdfs/kerberos.go
func getKerberosClient() (*krb.Client, error) {
	configPath := os.Getenv("KRB5_CONFIG")
	if configPath == "" {
		configPath = "/etc/krb5.conf"
	}

	cfg, err := config.Load(configPath)
	if err != nil {
		return nil, err
	}

	// Determine the ccache location from the environment, falling back to the
	// default location.
	ccachePath := os.Getenv("KRB5CCNAME")
	if strings.Contains(ccachePath, ":") {
		if strings.HasPrefix(ccachePath, "FILE:") {
			ccachePath = strings.SplitN(ccachePath, ":", 2)[1]
		} else {
			return nil, fmt.Errorf("unusable ccache: %s", ccachePath)
		}
	} else if ccachePath == "" {
		u, err := user.Current()
		if err != nil {
			return nil, err
		}

		ccachePath = fmt.Sprintf("/tmp/krb5cc_%s", u.Uid)
	}

	ccache, err := credentials.LoadCCache(ccachePath)
	if err != nil {
		return nil, err
	}

	client, err := krb.NewFromCCache(ccache, cfg)
	if err != nil {
		return nil, err
	}

	return client, nil
}