fn build()

in core/src/services/gdrive/builder.rs [140:233]
80 lines of code
4 McCabe index (conditional complexity)

    fn build(self) -> Result<impl Access> {
        let root = normalize_root(&self.config.root.unwrap_or_default());
        debug!("backend use root {}", root);

        let info = AccessorInfo::default();
        info.set_scheme(Scheme::Gdrive)
            .set_root(&root)
            .set_native_capability(Capability {
                stat: true,
                stat_has_content_length: true,
                stat_has_content_type: true,
                stat_has_last_modified: true,

                read: true,

                list: true,
                list_has_content_type: true,
                list_has_content_length: true,
                list_has_etag: true,

                write: true,

                create_dir: true,
                delete: true,
                rename: true,
                copy: true,

                shared: true,

                ..Default::default()
            });

        // allow deprecated api here for compatibility
        #[allow(deprecated)]
        if let Some(client) = self.http_client {
            info.update_http_client(|_| client);
        }

        let accessor_info = Arc::new(info);
        let mut signer = GdriveSigner::new(accessor_info.clone());
        match (self.config.access_token, self.config.refresh_token) {
            (Some(access_token), None) => {
                signer.access_token = access_token;
                // We will never expire user specified access token.
                signer.expires_in = DateTime::<Utc>::MAX_UTC;
            }
            (None, Some(refresh_token)) => {
                let client_id = self.config.client_id.ok_or_else(|| {
                    Error::new(
                        ErrorKind::ConfigInvalid,
                        "client_id must be set when refresh_token is set",
                    )
                    .with_context("service", Scheme::Gdrive)
                })?;
                let client_secret = self.config.client_secret.ok_or_else(|| {
                    Error::new(
                        ErrorKind::ConfigInvalid,
                        "client_secret must be set when refresh_token is set",
                    )
                    .with_context("service", Scheme::Gdrive)
                })?;

                signer.refresh_token = refresh_token;
                signer.client_id = client_id;
                signer.client_secret = client_secret;
            }
            (Some(_), Some(_)) => {
                return Err(Error::new(
                    ErrorKind::ConfigInvalid,
                    "access_token and refresh_token cannot be set at the same time",
                )
                .with_context("service", Scheme::Gdrive))
            }
            (None, None) => {
                return Err(Error::new(
                    ErrorKind::ConfigInvalid,
                    "access_token or refresh_token must be set",
                )
                .with_context("service", Scheme::Gdrive))
            }
        };

        let signer = Arc::new(Mutex::new(signer));

        Ok(GdriveBackend {
            core: Arc::new(GdriveCore {
                info: accessor_info.clone(),
                root,
                signer: signer.clone(),
                path_cache: PathCacher::new(GdrivePathQuery::new(accessor_info, signer))
                    .with_lock(),
            }),
        })
    }