1 files changed, 73 insertions, 4 deletions

diff --git a/src/cli.rs b/src/cli.rs
index b6e2fc94..f756b96f 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -77,6 +77,14 @@ fn channel_set(args: &[String]) -> std::io::Result<i32> {
         return Ok(2);
     };
 
+    if let Some(reason) = channel_set_preview_rejection(
+        channel,
+        crate::update::preview_channel_rejection_for_current_install(),
+    ) {
+        eprintln!("{reason}.");
+        return Ok(1);
+    }
+
     let path = crate::config::config_path();
     let content = if path.exists() {
         std::fs::read_to_string(&path)?
@@ -112,11 +120,23 @@ fn channel_set(args: &[String]) -> std::io::Result<i32> {
         "Herdr update channel set to {channel} in {}.",
         path.display()
     );
-    if channel == "preview" {
-        println!("Run `herdr update` to install the latest preview build when ready.");
-    } else {
-        println!("Run `herdr update` to install the latest stable release when ready.");
+
+    match channel_set_install_action(
+        crate::update::package_manager_channel_update_guidance_for_current_install(),
+    ) {
+        ChannelSetInstallAction::PrintGuidance(guidance) => {
+            println!("{guidance}");
+            return Ok(0);
+        }
+        ChannelSetInstallAction::RunSelfUpdate => {}
     }
+
+    if let Err(err) = crate::update::self_update(crate::update::SelfUpdateOptions::default()) {
+        eprintln!("update failed: {err}");
+        eprintln!("Run `herdr update` to retry.");
+        return Ok(1);
+    }
+
     Ok(0)
 }
 
@@ -129,6 +149,30 @@ fn parse_channel_set_arg(args: &[String]) -> Option<&str> {
     }
 }
 
+fn channel_set_preview_rejection(
+    channel: &str,
+    install_rejection: Option<&'static str>,
+) -> Option<&'static str> {
+    (channel == "preview")
+        .then_some(install_rejection)
+        .flatten()
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum ChannelSetInstallAction {
+    RunSelfUpdate,
+    PrintGuidance(&'static str),
+}
+
+fn channel_set_install_action(
+    package_manager_guidance: Option<&'static str>,
+) -> ChannelSetInstallAction {
+    match package_manager_guidance {
+        Some(guidance) => ChannelSetInstallAction::PrintGuidance(guidance),
+        None => ChannelSetInstallAction::RunSelfUpdate,
+    }
+}
+
 fn print_channel_help() {
     eprintln!("herdr channel commands:");
     eprintln!("  herdr channel show                  print the configured update channel");
@@ -848,4 +892,29 @@ mod tests {
             None
         );
     }
+
+    #[test]
+    fn channel_set_rejects_package_managed_preview_before_config_write() {
+        assert_eq!(
+            super::channel_set_preview_rejection("preview", Some("no preview")),
+            Some("no preview")
+        );
+        assert_eq!(
+            super::channel_set_preview_rejection("stable", Some("no preview")),
+            None
+        );
+        assert_eq!(super::channel_set_preview_rejection("preview", None), None);
+    }
+
+    #[test]
+    fn channel_set_skips_self_update_for_package_manager_guidance() {
+        assert_eq!(
+            super::channel_set_install_action(Some("use package manager")),
+            super::ChannelSetInstallAction::PrintGuidance("use package manager")
+        );
+        assert_eq!(
+            super::channel_set_install_action(None),
+            super::ChannelSetInstallAction::RunSelfUpdate
+        );
+    }
 }