Refactoring bootstate code in a self documenting way

Signed-off-by: Sayan Paul <paul.sayan@gmail.com>

Author: say-paul

src/main.rs

@@ -261,39 +261,62 @@ fn health_check() -> Result<()> {
     let mut previous_rollback = false;
 
     if !container_mode {
-        // Detect GRUB-level kernel fallback via deployment ID comparison.
-        // If mismatch, clear next_deployment_id immediately to prevent rollback loop.
-        let grub_fallback = detect_grub_fallback();
-        if grub_fallback {
-            previous_rollback = true;
-            log::info!("GRUB kernel fallback detected - new deployment failed to boot");
-            log::info!(
-                "Making GRUB fallback permanent by rolling back to the currently booted deployment"
-            );
-            match handle_rollback(true) {
-                Ok(()) => {
-                    log::info!("Rollback to previous deployment completed successfully");
-                    with_boot_rw(unset_next_deployment_id)
-                        .unwrap_or_else(|e| log::error!("Failed to clear next-deployment-id: {e}"));
+        enum BootState {
+            GrubFallback,
+            PreviousRollback,
+            NormalBoot,
+        }
+
+        let boot_state = if detect_grub_fallback() {
+            BootState::GrubFallback
+        } else if check_previous_rollback().unwrap_or(false) {
+            BootState::PreviousRollback
+        } else {
+            BootState::NormalBoot
+        };
+
+        match boot_state {
+            BootState::GrubFallback => {
+                previous_rollback = true;
+                log::info!("GRUB kernel fallback detected - new deployment failed to boot");
+                log::info!(
+                    "Making GRUB fallback permanent by rolling back to the currently booted deployment"
+                );
+                match handle_rollback(true) {
+                    Ok(()) => {
+                        log::info!("Rollback to previous deployment completed successfully");
+                        with_boot_rw(|| {
+                            unset_next_deployment_id()?;
+                            unset_fallback()
+                        })
+                        .unwrap_or_else(|e| {
+                            log::error!("Failed to clear grub vars after rollback: {e}")
+                        });
+                    }
+                    Err(e) => log::error!("Failed to make GRUB fallback permanent: {e}"),
                 }
-                Err(e) => log::error!("Failed to make GRUB fallback permanent: {e}"),
             }
-        } else if check_previous_rollback().unwrap_or(false) {
-            previous_rollback = true;
-            match detect_os_deployment() {
-                Some(manager) => log::info!(
-                    "FALLBACK BOOT DETECTED! Default {manager} deployment has been rolled back."
-                ),
-                None => log::info!("FALLBACK BOOT DETECTED! Cannot determine the deployment type."),
+            BootState::PreviousRollback => {
+                previous_rollback = true;
+                match detect_os_deployment() {
+                    Some(manager) => log::info!(
+                        "FALLBACK BOOT DETECTED! Default {manager} deployment has been rolled back."
+                    ),
+                    None => {
+                        log::info!("FALLBACK BOOT DETECTED! Cannot determine the deployment type.")
+                    }
+                }
+            }
+            BootState::NormalBoot => {
+                if get_fallback().unwrap_or(false) {
+                    log::info!(
+                        "Kernel booted successfully, disarming GRUB fallback before healthchecks"
+                    );
+                    with_boot_rw(unset_fallback).unwrap_or_else(|e: anyhow::Error| {
+                        log::error!("Failed to unset GRUB fallback: {e}")
+                    });
+                }
             }
-        }
-
-        // Disarm GRUB fallback entry if the kernel booted successfully
-        if get_fallback().unwrap_or(false) {
-            log::info!("Kernel booted successfully, disarming GRUB fallback before healthchecks");
-            with_boot_rw(unset_fallback).unwrap_or_else(|e: anyhow::Error| {
-                log::error!("Failed to unset GRUB fallback: {e}")
-            });
         }
     }