✨ feat(labels): create labels module to manage Gmail labels

- Implemented `Labels` struct for managing Gmail labels.
- Added functions to retrieve and map labels.
- Added logging for label names.

src/labels.rs

@@ -0,0 +1,113 @@
+use std::collections::HashMap;
+
+use google_gmail1::{
+    Gmail,
+    api::{Label, ListLabelsResponse},
+    hyper_rustls::{HttpsConnector, HttpsConnectorBuilder},
+    hyper_util::{
+        client::legacy::{Client, connect::HttpConnector},
+        rt::TokioExecutor,
+    },
+    yup_oauth2::{ApplicationSecret, InstalledFlowAuthenticator, InstalledFlowReturnMethod},
+};
+
+use crate::{Credential, Error};
+
+/// Default for the maximum number of results to return on a page
+pub const DEFAULT_MAX_RESULTS: &str = "10";
+
+/// Struct to capture configuration for List API call.
+pub struct Labels {
+    hub: Gmail<HttpsConnector<HttpConnector>>,
+    label_list: Vec<Label>,
+    label_map: HashMap<String, String>,
+}
+
+impl std::fmt::Debug for Labels {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Labels")
+            .field("label_list", &self.label_list)
+            .field("label_map", &self.label_map)
+            .finish()
+    }
+}
+
+impl Labels {
+    /// Create a new List struct and add the Gmail api connection.
+    pub async fn new(credential: &str) -> Result<Self, Error> {
+        let (config_dir, secret) = {
+            let config_dir = crate::utils::assure_config_dir_exists("~/.cull-gmail")?;
+
+            let secret: ApplicationSecret = Credential::load_json_file(credential).into();
+            (config_dir, secret)
+        };
+
+        let executor = TokioExecutor::new();
+        let connector = HttpsConnectorBuilder::new()
+            .with_native_roots()
+            .unwrap()
+            .https_or_http()
+            .enable_http1()
+            .build();
+
+        let client = Client::builder(executor.clone()).build(connector.clone());
+
+        let auth = InstalledFlowAuthenticator::with_client(
+            secret,
+            InstalledFlowReturnMethod::HTTPRedirect,
+            Client::builder(executor).build(connector),
+        )
+        .persist_tokens_to_disk(format!("{config_dir}/gmail1"))
+        .build()
+        .await
+        .unwrap();
+
+        Ok(Labels {
+            hub: Gmail::new(client, auth),
+            label_list: Vec::new(),
+            label_map: HashMap::new(),
+        })
+    }
+
+    /// Get the labels for the authorised account
+    pub async fn get_labels(&mut self) -> Result<(), Error> {
+        let call = self.hub.users().labels_list("me");
+        let (_response, list) = call.doit().await.map_err(Box::new)?;
+
+        self.log_label_names(&list).await?;
+
+        if let Some(labels) = list.labels {
+            let mut label_map = HashMap::new();
+            for label in &labels {
+                if label.id.is_some() && label.name.is_some() {
+                    let label = label.clone();
+                    label_map.insert(label.name.unwrap(), label.id.unwrap());
+                }
+            }
+            self.label_list = labels;
+            self.label_map = label_map;
+        }
+
+        Ok(())
+    }
+
+    async fn log_label_names(&self, list: &ListLabelsResponse) -> Result<(), Error> {
+        if let Some(labels) = &list.labels {
+            for label in labels {
+                if let Some(name) = &label.name {
+                    log::info!("{name}");
+                } else {
+                    log::warn!("No name for label {:?}", label.id);
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Return the id for the name from the labels map.
+    /// Returns `None` if the name is not found in the map.
+    pub fn get_label_id(&self, name: &str) -> Option<String> {
+        self.label_map.get(name).cloned()
+    }
+}