From f261151442d6c0e6d0d43dc36b68a3ba520cd3ee Mon Sep 17 00:00:00 2001
From: Didier Wenzek <didier.wenzek@free.fr>
Date: Thu, 11 Apr 2024 14:44:02 +0200
Subject: [PATCH] Move topic helper functions under MqttSchema

Signed-off-by: Didier Wenzek <didier.wenzek@free.fr>
---
 crates/core/tedge_api/src/mqtt_topics.rs    | 41 ++++++++++++++++++++-
 crates/core/tedge_api/src/workflow/state.rs | 32 +++++++---------
 2 files changed, 53 insertions(+), 20 deletions(-)

diff --git a/crates/core/tedge_api/src/mqtt_topics.rs b/crates/core/tedge_api/src/mqtt_topics.rs
index 31e69b243df..5810bb76b8e 100644
--- a/crates/core/tedge_api/src/mqtt_topics.rs
+++ b/crates/core/tedge_api/src/mqtt_topics.rs
@@ -83,6 +83,15 @@ impl MqttSchema {
         MqttSchema { root }
     }
 
+    /// Build the schema to be used to decode a topic
+    pub fn from_topic(topic: impl AsRef<str>) -> Self {
+        let (root, _) = topic
+            .as_ref()
+            .split_once('/')
+            .unwrap_or((topic.as_ref(), ""));
+        Self::with_root(root.to_string())
+    }
+
     /// Get the topic addressing a given entity channel
     /// ```
     /// # use tedge_api::mqtt_topics::{MqttSchema, Channel, EntityTopicId};
@@ -188,9 +197,37 @@ impl MqttSchema {
     pub fn error_topic(&self) -> Topic {
         Topic::new_unchecked(&format!("{0}/errors", self.root))
     }
-}
 
-impl MqttSchema {
+    /// Extract the entity identifier from a topic
+    ///
+    /// Note this function is not related to a specific topic root prefix
+    pub fn get_entity_id(topic: impl AsRef<str>) -> Option<String> {
+        match topic.as_ref().split('/').collect::<Vec<&str>>()[..] {
+            [_, t1, t2, t3, t4, ..] => Some(format!("{t1}/{t2}/{t3}/{t4}")),
+            _ => None,
+        }
+    }
+
+    /// Extract the operation name from a command topic
+    ///
+    /// Note this function is not related to a specific topic root prefix
+    pub fn get_operation_name(topic: impl AsRef<str>) -> Option<String> {
+        match topic.as_ref().split('/').collect::<Vec<&str>>()[..] {
+            [_, _, _, _, _, "cmd", op, ..] => Some(op.to_string()),
+            _ => None,
+        }
+    }
+
+    /// Extract the command instance identifier from a command topic
+    ///
+    /// Note this function is not related to a specific topic root prefix
+    pub fn get_command_id(topic: impl AsRef<str>) -> Option<String> {
+        match topic.as_ref().split('/').collect::<Vec<&str>>()[..] {
+            [_, _, _, _, _, "cmd", _, id] => Some(id.to_string()),
+            _ => None,
+        }
+    }
+
     fn parse(&self, topic: &str) -> Result<(EntityTopicId, Channel), EntityTopicError> {
         let (root, topic) = topic.split_once('/').ok_or(EntityTopicError::Root {
             expected: self.root.to_string(),
diff --git a/crates/core/tedge_api/src/workflow/state.rs b/crates/core/tedge_api/src/workflow/state.rs
index 3c661afd311..f52bdb2155a 100644
--- a/crates/core/tedge_api/src/workflow/state.rs
+++ b/crates/core/tedge_api/src/workflow/state.rs
@@ -271,9 +271,17 @@ impl GenericCommandState {
 
     /// Infer the topic of the invoking command, given a sub command topic
     fn infer_invoking_command_topic(sub_command_topic: &str) -> Option<String> {
-        match sub_command_topic.split('/').collect::<Vec<&str>>()[..] {
-            [pre, t1, t2, t3, t4, "cmd", _, sub_id] => Self::extract_invoking_command_id(sub_id)
-                .map(|(op, id)| format!("{pre}/{t1}/{t2}/{t3}/{t4}/cmd/{op}/{id}")),
+        let schema = MqttSchema::from_topic(sub_command_topic);
+        match schema.entity_channel_of(sub_command_topic) {
+            Ok((entity, Channel::Command { cmd_id, .. })) => {
+                Self::extract_invoking_command_id(&cmd_id).map(|(op, id)| {
+                    let channel = Channel::Command {
+                        operation: op.into(),
+                        cmd_id: id.into(),
+                    };
+                    schema.topic_for(&entity, &channel).as_ref().to_string()
+                })
+            }
             _ => None,
         }
     }
@@ -297,18 +305,15 @@ impl GenericCommandState {
     }
 
     fn target(&self) -> Option<String> {
-        match self.topic.name.split('/').collect::<Vec<&str>>()[..] {
-            [_, t1, t2, t3, t4, "cmd", _, _] => Some(format!("{t1}/{t2}/{t3}/{t4}")),
-            _ => None,
-        }
+        MqttSchema::get_entity_id(&self.topic)
     }
 
     pub fn operation(&self) -> Option<String> {
-        extract_command_identifier(&self.topic.name).map(|(operation, _)| operation)
+        MqttSchema::get_operation_name(&self.topic)
     }
 
     pub fn cmd_id(&self) -> Option<String> {
-        extract_command_identifier(&self.topic.name).map(|(_, cmd_id)| cmd_id)
+        MqttSchema::get_command_id(&self.topic)
     }
 
     pub fn is_init(&self) -> bool {
@@ -328,15 +333,6 @@ impl GenericCommandState {
     }
 }
 
-fn extract_command_identifier(topic: &str) -> Option<(String, String)> {
-    match topic.split('/').collect::<Vec<&str>>()[..] {
-        [_, _, _, _, _, "cmd", operation, cmd_id] => {
-            Some((operation.to_string(), cmd_id.to_string()))
-        }
-        _ => None,
-    }
-}
-
 impl GenericStateUpdate {
     pub fn empty_payload() -> Value {
         json!({})