Implement datum bytes fields chunks

To avoid the limitation of 128 bytes for the bytes fields in the datum,
we need to chunk these fields. This is a temporary fix that will be removed
when Cardano 1.36 is released.

Author: jpraynaud

mithril-common/src/chain_observer/model.rs

@@ -24,12 +24,11 @@ pub enum TxDatumError {
 pub struct TxDatum(pub String);
 
 impl TxDatum {
-    /// Retrieves the nth field of the datum with given type
-    pub fn get_nth_field_by_type(
+    /// Retrieves the fields of the datum with given type
+    pub fn get_fields_by_type(
         &self,
         type_name: &TxDatumFieldTypeName,
-        index: usize,
-    ) -> Result<Value, Box<dyn StdError>> {
+    ) -> Result<Vec<Value>, Box<dyn StdError>> {
         let tx_datum_raw = &self.0;
         // 1- Parse the Utxo raw data to a hashmap
         let v: HashMap<String, Value> = serde_json::from_str(tx_datum_raw).map_err(|e| {
@@ -48,22 +47,28 @@ impl TxDatum {
             )
         })?;
         // 3- Filter the vec (keep the ones that match the given type), and retrieve the nth entry of this filtered vec
-        let field_value = fields
+        Ok(fields
             .iter()
             .filter(|&field| field.get(type_name.to_string()).is_some())
-            .nth(index)
+            .map(|field| field.get(type_name.to_string()).unwrap().to_owned())
+            .collect::<_>())
+    }
+
+    /// Retrieves the nth field of the datum with given type
+    pub fn get_nth_field_by_type(
+        &self,
+        type_name: &TxDatumFieldTypeName,
+        index: usize,
+    ) -> Result<Value, Box<dyn StdError>> {
+        Ok(self
+            .get_fields_by_type(type_name)?
+            .get(index)
             .ok_or_else(|| {
                 TxDatumError::InvalidContent(
-                    format!(
-                        "Error: missing field at index {index}, tx datum was = '{tx_datum_raw}'"
-                    )
-                    .into(),
+                    format!("Error: missing field at index {index}").into(),
                 )
             })?
-            .get(type_name.to_string())
-            .unwrap();
-
-        Ok(field_value.to_owned())
+            .to_owned())
     }
 }
 
@@ -101,9 +106,29 @@ impl TxDatumBuilder {
 
     /// Add a field to the builder
     pub fn add_field(&mut self, field_value: TxDatumFieldValue) -> &mut TxDatumBuilder {
-        let mut field = HashMap::new();
-        field.insert(TxDatumFieldTypeName::from(&field_value), field_value);
-        self.fields.push(field);
+        match &field_value {
+            TxDatumFieldValue::Bytes(datum_str) => {
+                // TODO: Remove this chunking of the bytes fields once the cardano-cli 1.36.0+ is released
+                // The bytes fields are currently limited to 128 bytes and need to be chunked in multiple fields
+                let field_type = TxDatumFieldTypeName::from(&field_value);
+                let field_value_chunks = datum_str.as_bytes().chunks(128);
+                for field_value_chunk in field_value_chunks {
+                    let mut field = HashMap::new();
+                    field.insert(
+                        field_type,
+                        TxDatumFieldValue::Bytes(
+                            std::str::from_utf8(field_value_chunk).unwrap().to_string(),
+                        ),
+                    );
+                    self.fields.push(field);
+                }
+            }
+            _ => {
+                let mut field = HashMap::new();
+                field.insert(TxDatumFieldTypeName::from(&field_value), field_value);
+                self.fields.push(field);
+            }
+        }
 
         self
     }
@@ -135,6 +160,7 @@ mod test {
             .add_field(TxDatumFieldValue::Bytes("bytes1".to_string()))
             .add_field(TxDatumFieldValue::Bytes("bytes2".to_string()))
             .add_field(TxDatumFieldValue::Int(2))
+            .add_field(TxDatumFieldValue::Bytes("012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789".to_string()))
             .build()
             .expect("tx_datum build should not fail");
         tx_datum
@@ -143,7 +169,7 @@ mod test {
     #[test]
     fn test_build_tx_datum() {
         let tx_datum = dummy_tx_datum();
-        let tx_datum_expected = TxDatum(r#"{"constructor":0,"fields":[{"bytes":"bytes0"},{"int":0},{"int":1},{"bytes":"bytes1"},{"bytes":"bytes2"},{"int":2}]}"#.to_string());
+        let tx_datum_expected = TxDatum(r#"{"constructor":0,"fields":[{"bytes":"bytes0"},{"int":0},{"int":1},{"bytes":"bytes1"},{"bytes":"bytes2"},{"int":2},{"bytes":"01234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567"},{"bytes":"8901234567890123456789"}]}"#.to_string());
         assert_eq!(tx_datum_expected, tx_datum);
     }