Add new and update_value to ProcessState

src/process.rs

@@ -26,6 +26,52 @@ pub struct ProcessState {
 }
 
 impl ProcessState {
+    pub fn new(commited_in: OutPoint, clear_state: Map<String, Value>) -> anyhow::Result<Self> {
+        let mut keys = Map::new();
+        let mut encrypted = Map::new();
+
+        let clear_pcd = Value::Object(clear_state);
+        let commitments = clear_pcd.hash_all_fields(commited_in)?;
+
+        let keys_to_encrypt: Vec<String> = commitments.keys().map(|k| k.clone()).collect();
+        clear_pcd.encrypt_fields(&keys_to_encrypt, &mut keys, &mut encrypted)?;
+
+        let res = Self {
+            commited_in,
+            pcd_commitment: Value::Object(commitments),
+            encrypted_pcd: Value::Object(encrypted),
+            keys,
+            validation_tokens: vec![],
+        };
+        
+        Ok(res)
+    }
+
+    pub fn update_value(&mut self, key: &str, new_value: Value) -> anyhow::Result<()> {
+        // First decrypt values
+        let mut clear_pcd = self.decrypt_pcd()?;
+        if let Some(value) = clear_pcd.get_mut(key) {
+            // We can only update a value we can decrypt
+            if let None = self.keys.get(key) {
+                return Err(anyhow::Error::msg("Trying to update a value we can't access"));
+            }
+            // We replace the clear value by the new_value
+            *value = new_value;
+        } else {
+            return Err(anyhow::Error::msg(format!("{} doesn't exist", key)))
+        }
+
+        // Update the commitment
+        self.pcd_commitment = Value::Object(clear_pcd.hash_all_fields(self.commited_in)?);
+
+        // Todo for now we rehash everything, which is a bit wasteful but fine for a proto
+
+        // Update the encrypted value
+        clear_pcd.encrypt_fields(&[key.to_string()], &mut self.keys, self.encrypted_pcd.as_object_mut().unwrap())?;
+        
+        Ok(())
+    }
+
     pub fn decrypt_pcd(&self) -> anyhow::Result<Value> {
         let mut fields2plain = Map::new();
         let fields2commit = self.pcd_commitment.to_value_object()?;