package main

import (
	"context"
	"crypto/tls"
	"fmt"
	"regexp"
	"strings"

	"github.com/golang/glog"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	ldap "gopkg.in/ldap.v3"

	pb "code.hackerspace.pl/hscloud/cluster/prodvider/proto"
)

var (
	reUsername = regexp.MustCompile(`^[a-zA-Z0-9_\.]+$`)
)

func (p *prodvider) Authenticate(ctx context.Context, req *pb.AuthenticateRequest) (*pb.AuthenticateResponse, error) {
	username := strings.TrimSpace(req.Username)
	if username == "" || !reUsername.MatchString(username) {
		return nil, status.Error(codes.InvalidArgument, "invalid username")
	}

	password := req.Password
	if password == "" {
		return &pb.AuthenticateResponse{
			Result: pb.AuthenticateResponse_RESULT_INVALID_CREDENTIALS,
		}, nil
	}

	tlsConfig := &tls.Config{}
	lconn, err := ldap.DialTLS("tcp", flagLDAPServer, tlsConfig)
	if err != nil {
		glog.Errorf("ldap.DialTLS: %v", err)
		return nil, status.Error(codes.Unavailable, "could not context LDAP")
	}
	defer lconn.Close()

	dn := fmt.Sprintf(flagLDAPBindDN, username)
	err = lconn.Bind(dn, password)

	if err != nil {
		if ldap.IsErrorWithCode(err, ldap.LDAPResultInvalidCredentials) {
			return &pb.AuthenticateResponse{
				Result: pb.AuthenticateResponse_RESULT_INVALID_CREDENTIALS,
			}, nil
		}

		glog.Errorf("ldap.Bind: %v", err)
		return nil, status.Error(codes.Unavailable, "could not query LDAP")
	}

	groups, err := p.groupMemberships(lconn, username)
	if err != nil {
		return nil, err
	}

	if !groups["kubernetes-users"] && !groups["staff"] {
		return nil, status.Error(codes.PermissionDenied, "not part of staff or kubernetes-users")
	}

	err = p.kubernetesSetupUser(username)
	if err != nil {
		glog.Errorf("kubernetesSetupUser(%v): %v", username, err)
		return nil, status.Error(codes.Unavailable, "could not set up objects in Kubernetes")
	}

	keys, err := p.kubernetesCreds(username)
	if err != nil {
		glog.Errorf("kubernetesCreds(%q): %v", username, err)
		return nil, status.Error(codes.Unavailable, "could not generate k8s keys")
	}
	return &pb.AuthenticateResponse{
		Result:         pb.AuthenticateResponse_RESULT_AUTHENTICATED,
		KubernetesKeys: keys,
	}, nil
}

func (p *prodvider) groupMemberships(lconn *ldap.Conn, username string) (map[string]bool, error) {
	searchRequest := ldap.NewSearchRequest(
		flagLDAPGroupSearchBase,
		ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false,
		fmt.Sprintf("(uniqueMember=%s)", fmt.Sprintf(flagLDAPBindDN, username)),
		[]string{"dn", "cn"},
		nil,
	)

	sr, err := lconn.Search(searchRequest)
	if err != nil {
		glog.Errorf("ldap.Search: %v", err)
		return nil, status.Error(codes.Unavailable, "could not query LDAP for group")
	}

	res := make(map[string]bool)
	for _, entry := range sr.Entries {
		cn := entry.GetAttributeValue("cn")
		res[cn] = true
	}

	return res, nil
}