fn build()

in core/src/services/dropbox/builder.rs [191:255]
61 lines of code
4 McCabe index (conditional complexity)

    fn build(&mut self) -> Result<Self::Accessor> {
        let root = normalize_root(&self.root.take().unwrap_or_default());
        let client = if let Some(client) = self.http_client.take() {
            client
        } else {
            HttpClient::new().map_err(|err| {
                err.with_operation("Builder::build")
                    .with_context("service", Scheme::Dropbox)
            })?
        };

        let signer = match (self.access_token.take(), self.refresh_token.take()) {
            (Some(access_token), None) => DropboxSigner {
                access_token,
                // We will never expire user specified token.
                expires_in: DateTime::<Utc>::MAX_UTC,
                ..Default::default()
            },
            (None, Some(refresh_token)) => {
                let client_id = self.client_id.take().ok_or_else(|| {
                    Error::new(
                        ErrorKind::ConfigInvalid,
                        "client_id must be set when refresh_token is set",
                    )
                    .with_context("service", Scheme::Dropbox)
                })?;
                let client_secret = self.client_secret.take().ok_or_else(|| {
                    Error::new(
                        ErrorKind::ConfigInvalid,
                        "client_secret must be set when refresh_token is set",
                    )
                    .with_context("service", Scheme::Dropbox)
                })?;

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

        Ok(DropboxBackend {
            core: Arc::new(DropboxCore {
                root,
                signer: Arc::new(Mutex::new(signer)),
                client,
            }),
        })
    }