package rpc

import (
	"crypto/tls"
	"fmt"
	"strconv"

	jcstypes "gitlink.org.cn/cloudream/jcs-pub/common/types"
	"golang.org/x/net/context"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/peer"
	"google.golang.org/grpc/status"
)

const (
	ClientAPISNIV1   = "rpc.client.jcs-pub.v1"
	InternalAPISNIV1 = "rpc.internal.jcs-pub.v1"

	MetaUserID        = "x-jcs-user-id"
	MetaAccessTokenID = "x-jcs-access-token-id"
	MetaNonce         = "x-jcs-nonce"
	MetaSignature     = "x-jcs-signature"
	MetaTokenAuthInfo = "x-jcs-token-auth-info"
)

type AccessTokenAuthInfo struct {
	UserID        jcstypes.UserID
	AccessTokenID jcstypes.AccessTokenID
	Nonce         string
	Signature     string
}

type AccessTokenVerifier interface {
	Verify(authInfo AccessTokenAuthInfo) bool
}

type AccessTokenProvider interface {
	MakeAuthInfo() (AccessTokenAuthInfo, error)
}

func (s *ServerBase) tlsConfigSelector(hello *tls.ClientHelloInfo) (*tls.Config, error) {
	switch hello.ServerName {
	case ClientAPISNIV1:
		return &tls.Config{
			Certificates: []tls.Certificate{s.serverCert},
			ClientAuth:   tls.NoClientCert,
			NextProtos:   []string{"h2"},
		}, nil
	case InternalAPISNIV1:
		return &tls.Config{
			Certificates: []tls.Certificate{s.serverCert},
			ClientAuth:   tls.RequireAndVerifyClientCert,
			ClientCAs:    s.rootCA,
			NextProtos:   []string{"h2"},
		}, nil

	default:
		return nil, fmt.Errorf("unknown server name: %s", hello.ServerName)
	}
}

func (s *ServerBase) authUnary(
	ctx context.Context,
	req interface{},
	info *grpc.UnaryServerInfo,
	handler grpc.UnaryHandler,

) (resp any, err error) {
	pr, ok := peer.FromContext(ctx)
	if !ok {
		return nil, status.Error(codes.Unauthenticated, "no peer found in context")
	}

	tlsInfo, ok := pr.AuthInfo.(credentials.TLSInfo)
	if !ok {
		return nil, status.Error(codes.Unauthenticated, "no tls info found in peer")
	}

	// 如果是使用interanl ServerName通过的TLS认证，则直接放行
	if tlsInfo.State.ServerName == InternalAPISNIV1 {
		return handler(ctx, req)
	}

	// 如果是无需认证的API，则直接放行
	if s.noAuthAPIs[info.FullMethod] {
		return handler(ctx, req)
	}

	// 否则要进行额外的Token认证

	if !s.accessTokenAuthAPIs[info.FullMethod] {
		return nil, status.Error(codes.Unauthenticated, "unauthorized access")
	}

	meta, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return nil, status.Error(codes.Unauthenticated, "no metadata found in context")
	}

	userIDs := meta.Get(MetaUserID)
	if len(userIDs) != 1 {
		return nil, status.Error(codes.Unauthenticated, "missing or multiple user ids in metadata")
	}
	userID, err := strconv.ParseInt(userIDs[0], 10, 64)
	if err != nil {
		return nil, status.Error(codes.Unauthenticated, "invalid user id in metadata")
	}

	accessTokenIDs := meta.Get(MetaAccessTokenID)
	if len(accessTokenIDs) != 1 {
		return nil, status.Error(codes.Unauthenticated, "missing or multiple access token ids in metadata")
	}

	nonce := meta.Get(MetaNonce)
	if len(nonce) != 1 {
		return nil, status.Error(codes.Unauthenticated, "missing or multiple nonces in metadata")
	}

	signature := meta.Get(MetaSignature)
	if len(signature) != 1 {
		return nil, status.Error(codes.Unauthenticated, "missing or multiple signatures in metadata")
	}

	authInfo := AccessTokenAuthInfo{
		UserID:        jcstypes.UserID(userID),
		AccessTokenID: jcstypes.AccessTokenID(accessTokenIDs[0]),
		Nonce:         nonce[0],
		Signature:     signature[0],
	}
	if !s.tokenVerifier.Verify(authInfo) {
		return nil, status.Error(codes.Unauthenticated, "invalid access token")
	}

	ctx = context.WithValue(ctx, MetaTokenAuthInfo, authInfo)
	return handler(ctx, req)
}

func (s *ServerBase) authStream(
	srv any,
	stream grpc.ServerStream,
	info *grpc.StreamServerInfo,
	handler grpc.StreamHandler,
) error {
	pr, ok := peer.FromContext(stream.Context())
	if !ok {
		return status.Error(codes.Unauthenticated, "no peer found in context")
	}

	tlsInfo, ok := pr.AuthInfo.(credentials.TLSInfo)
	if !ok {
		return status.Error(codes.Unauthenticated, "no tls info found in peer")
	}

	// 如果是使用interanl ServerName通过的TLS认证，则直接放行
	if tlsInfo.State.ServerName == InternalAPISNIV1 {
		return handler(srv, stream)
	}

	// 如果是无需认证的API，则直接放行
	if s.noAuthAPIs[info.FullMethod] {
		return handler(srv, stream)
	}

	// 否则要进行额外的Token认证

	if !s.accessTokenAuthAPIs[info.FullMethod] {
		return status.Error(codes.Unauthenticated, "unauthorized access")
	}

	meta, ok := metadata.FromIncomingContext(stream.Context())
	if !ok {
		return status.Error(codes.Unauthenticated, "no metadata found in context")
	}

	userIDs := meta.Get(MetaUserID)
	if len(userIDs) != 1 {
		return status.Error(codes.Unauthenticated, "missing or multiple user ids in metadata")
	}
	userID, err := strconv.ParseInt(userIDs[0], 10, 64)
	if err != nil {
		return status.Error(codes.Unauthenticated, "invalid user id in metadata")
	}

	accessTokenIDs := meta.Get(MetaAccessTokenID)
	if len(accessTokenIDs) != 1 {
		return status.Error(codes.Unauthenticated, "missing or multiple access token ids in metadata")
	}

	nonce := meta.Get(MetaNonce)
	if len(nonce) != 1 {
		return status.Error(codes.Unauthenticated, "missing or multiple nonces in metadata")
	}

	signature := meta.Get(MetaSignature)
	if len(signature) != 1 {
		return status.Error(codes.Unauthenticated, "missing or multiple signatures in metadata")
	}

	authInfo := AccessTokenAuthInfo{
		UserID:        jcstypes.UserID(userID),
		AccessTokenID: jcstypes.AccessTokenID(accessTokenIDs[0]),
		Nonce:         nonce[0],
		Signature:     signature[0],
	}

	if !s.tokenVerifier.Verify(authInfo) {
		return status.Error(codes.Unauthenticated, "invalid access token")
	}

	return handler(srv, &serverStream{stream, context.WithValue(stream.Context(), MetaTokenAuthInfo, authInfo)})
}

type serverStream struct {
	grpc.ServerStream
	ctx context.Context
}

func (s *serverStream) Context() context.Context {
	return s.ctx
}

func GetAuthInfo(ctx context.Context) (AccessTokenAuthInfo, bool) {
	val := ctx.Value(MetaTokenAuthInfo)
	if val == nil {
		return AccessTokenAuthInfo{}, false
	}
	authInfo, ok := val.(AccessTokenAuthInfo)
	return authInfo, ok
}