package transport

import (
	"context"
	"errors"
	"git.sch9.ru/new_gate/ms-tester/internal/lib"
	"git.sch9.ru/new_gate/ms-tester/pkg/models"
	sessionv1 "git.sch9.ru/new_gate/ms-tester/pkg/go/gen/proto/session/v1"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/status"
)

var defaultUser = &models.User{
	UserId:    nil,
	Role:      models.RoleSpectator.AsPointer(),
	UpdatedAt: nil,
}

func extractToken(ctx context.Context) string {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return ""
	}
	tokens := md.Get("token")

	if len(tokens) == 0 {
		return ""
	}

	return tokens[0]
}

func (s *TesterServer) readSessionAndReadUser(ctx context.Context, token string) (*models.User, error) {
	// FIXME: possible bottle neck: should we cache it? (think of it in future)
	// FIXME: maybe use single connection instead of multiple requests
	userId, err := s.sessionClient.Read(ctx, &sessionv1.ReadSessionRequest{Token: token})
	if err != nil {
		return nil, err
	}

	user, err := s.userService.ReadUserById(ctx, userId.GetUserId()) // FIXME: must be cached!
	if err != nil {
		if errors.Is(err, lib.ErrNotFound) {
			user = &models.User{
				UserId: lib.AsInt32P(userId.GetUserId()),
				Role:   models.RoleParticipant.AsPointer(),
			}
			err = s.userService.CreateUser(ctx, user)
			if err != nil {
				return nil, err
			}
		} else {
			return nil, err
		}
	}

	return user, nil
}

func insertUser(ctx context.Context, user *models.User) context.Context {
	return context.WithValue(ctx, "user", user)
}

func (s *TesterServer) AuthUnaryInterceptor() grpc.UnaryServerInterceptor {
	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
		token := extractToken(ctx)
		if token == "" {
			return handler(insertUser(ctx, defaultUser), req)
		}

		user, err := s.readSessionAndReadUser(ctx, token)
		if err != nil {
			return handler(insertUser(ctx, defaultUser), req)
		}

		return handler(insertUser(ctx, user), req)
	}
}

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

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

func (s *TesterServer) AuthStreamInterceptor() grpc.StreamServerInterceptor {
	return func(server interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
		ctx := ss.Context()

		token := extractToken(ctx)
		if token == "" {
			return handler(server, &ssWrapper{ServerStream: ss, ctx: insertUser(ctx, defaultUser)})
		}

		user, err := s.readSessionAndReadUser(ctx, token)
		if err != nil {
			return handler(server, &ssWrapper{ServerStream: ss, ctx: insertUser(ctx, defaultUser)})
		}

		return handler(server, &ssWrapper{ServerStream: ss, ctx: insertUser(ctx, user)})
	}
}

func ToGrpcError(err error) error {
	if err == nil {
		return nil
	}

	// should I use map instead?
	switch {
	case errors.Is(err, lib.ErrValidationFailed):
		return status.Error(codes.InvalidArgument, err.Error())
	case errors.Is(err, lib.ErrInternal):
		return status.Error(codes.Internal, err.Error())
	case errors.Is(err, lib.ErrExternal):
		return status.Error(codes.Unavailable, err.Error())
	case errors.Is(err, lib.ErrNoPermission):
		return status.Error(codes.PermissionDenied, err.Error())
	case errors.Is(err, lib.ErrUnknown):
		return status.Error(codes.Unknown, err.Error())
	case errors.Is(err, lib.ErrDeadlineExceeded):
		return status.Error(codes.DeadlineExceeded, err.Error())
	case errors.Is(err, lib.ErrNotFound):
		return status.Error(codes.NotFound, err.Error())
	case errors.Is(err, lib.ErrAlreadyExists):
		return status.Error(codes.AlreadyExists, err.Error())
	case errors.Is(err, lib.ErrConflict):
		return status.Error(codes.Unimplemented, err.Error())
	case errors.Is(err, lib.ErrUnimplemented):
		return status.Error(codes.Unimplemented, err.Error())
	case errors.Is(err, lib.ErrUnauthenticated):
		return status.Error(codes.Unauthenticated, err.Error())
	default:
		return status.Error(codes.Unknown, err.Error())
	}
}

func (s *TesterServer) ErrUnwrappingUnaryInterceptor() grpc.UnaryServerInterceptor {
	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
		resp, err := handler(ctx, req)
		return resp, ToGrpcError(err)
	}
}

func (s *TesterServer) ErrUnwrappingStreamInterceptor() grpc.StreamServerInterceptor {
	return func(server interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
		err := handler(server, ss)
		return ToGrpcError(err)
	}
}