init folder watch command

src/folder/command/mod.rs

@@ -3,6 +3,7 @@ mod delete;
 mod expunge;
 mod list;
 mod purge;
+mod watch;
 
 use anyhow::Result;
 use clap::Subcommand;
@@ -11,7 +12,7 @@ use crate::{config::TomlConfig, printer::Printer};
 
 use self::{
     create::FolderCreateCommand, delete::FolderDeleteCommand, expunge::FolderExpungeCommand,
-    list::FolderListCommand, purge::FolderPurgeCommand,
+    list::FolderListCommand, purge::FolderPurgeCommand, watch::FolderWatchCommand,
 };
 
 /// Manage folders.
@@ -26,6 +27,9 @@ pub enum FolderSubcommand {
     #[command(alias = "lst")]
     List(FolderListCommand),
 
+    #[command()]
+    Watch(FolderWatchCommand),
+
     #[command()]
     Expunge(FolderExpungeCommand),
 
@@ -41,6 +45,7 @@ impl FolderSubcommand {
         match self {
             Self::Create(cmd) => cmd.execute(printer, config).await,
             Self::List(cmd) => cmd.execute(printer, config).await,
+            Self::Watch(cmd) => cmd.execute(printer, config).await,
             Self::Expunge(cmd) => cmd.execute(printer, config).await,
             Self::Purge(cmd) => cmd.execute(printer, config).await,
             Self::Delete(cmd) => cmd.execute(printer, config).await,

src/folder/command/watch.rs

@@ -0,0 +1,42 @@
+use anyhow::Result;
+use clap::Parser;
+use log::info;
+
+use crate::{
+    account::arg::name::AccountNameFlag, backend::Backend, cache::arg::disable::CacheDisableFlag,
+    config::TomlConfig, folder::arg::name::FolderNameArg, printer::Printer,
+};
+
+/// Watch a folder for changes.
+///
+/// This command allows you to watch a new folder using the given
+/// name.
+#[derive(Debug, Parser)]
+pub struct FolderWatchCommand {
+    #[command(flatten)]
+    pub folder: FolderNameArg,
+
+    #[command(flatten)]
+    pub cache: CacheDisableFlag,
+
+    #[command(flatten)]
+    pub account: AccountNameFlag,
+}
+
+impl FolderWatchCommand {
+    pub async fn execute(self, printer: &mut impl Printer, config: &TomlConfig) -> Result<()> {
+        info!("executing folder watch command");
+
+        let folder = &self.folder.name;
+
+        let some_account_name = self.account.name.as_ref().map(String::as_str);
+        let (toml_account_config, account_config) = config
+            .clone()
+            .into_account_configs(some_account_name, self.cache.disable)?;
+        let backend = Backend::new(toml_account_config, account_config.clone(), false).await?;
+
+        printer.print_log(format!("Start watching folder {folder} for changes…"))?;
+
+        backend.watch_emails(&folder).await
+    }
+}