refactor(core): combine execute_block impls (blockchain module) (#1575

)

**Motivation**
Both impls have the exact same code differing only by a couple lines.
Having two feature-gated copies only makes the code harder to follow and
refactor.
<!-- Why does this pull request exist? What are its goals? -->

**Description**
* Replaces the two feature-gated `execute_block` functions in the
blockchain module with a single non-gated `execute_block` function, and
only feature-gates the lines of code that differ between the two
features

<!-- A clear and concise general description of the changes this PR
introduces -->

<!-- Link to issues: Resolves #111, Resolves #222 -->

Closes #issue_number

crates/blockchain/blockchain.rs

@@ -15,7 +15,7 @@ use ethrex_core::types::{
 use ethrex_core::H256;
 
 use ethrex_storage::error::StoreError;
-use ethrex_storage::Store;
+use ethrex_storage::{AccountUpdate, Store};
 use ethrex_vm::{evm_state, execute_block, spec_id, EvmState, SpecId};
 
 //TODO: Implement a struct Chain or BlockChain to encapsulate
@@ -26,10 +26,7 @@ use ethrex_vm::{evm_state, execute_block, spec_id, EvmState, SpecId};
 /// canonical chain/head. Fork choice needs to be updated for that in a separate step.
 ///
 /// Performs pre and post execution validation, and updates the database with the post state.
-#[cfg(not(feature = "levm"))]
 pub fn add_block(block: &Block, storage: &Store) -> Result<(), ChainError> {
-    use ethrex_vm::get_state_transitions;
-
     let block_hash = block.header.compute_block_hash();
 
     // Validate if it can be the new head and find the parent
@@ -42,56 +39,19 @@ pub fn add_block(block: &Block, storage: &Store) -> Result<(), ChainError> {
 
     // Validate the block pre-execution
     validate_block(block, &parent_header, &state)?;
-
-    let receipts = execute_block(block, &mut state)?;
-
-    validate_gas_used(&receipts, &block.header)?;
-
-    let account_updates = get_state_transitions(&mut state);
-
-    // Apply the account updates over the last block's state and compute the new state root
-    let new_state_root = state
-        .database()
-        .ok_or(ChainError::StoreError(StoreError::MissingStore))?
-        .apply_account_updates(block.header.parent_hash, &account_updates)?
-        .ok_or(ChainError::ParentStateNotFound)?;
-
-    // Check state root matches the one in block header after execution
-    validate_state_root(&block.header, new_state_root)?;
-
-    // Check receipts root matches the one in block header after execution
-    validate_receipts_root(&block.header, &receipts)?;
-
-    store_block(storage, block.clone())?;
-    store_receipts(storage, receipts, block_hash)?;
-
-    Ok(())
-}
-
-/// Adds a new block to the store. It may or may not be canonical, as long as its ancestry links
-/// with the canonical chain and its parent's post-state is calculated. It doesn't modify the
-/// canonical chain/head. Fork choice needs to be updated for that in a separate step.
-///
-/// Performs pre and post execution validation, and updates the database with the post state.
-#[cfg(feature = "levm")]
-pub fn add_block(block: &Block, storage: &Store) -> Result<(), ChainError> {
-    let block_hash = block.header.compute_block_hash();
-
-    // Validate if it can be the new head and find the parent
-    let Ok(parent_header) = find_parent_header(&block.header, storage) else {
-        // If the parent is not present, we store it as pending.
-        storage.add_pending_block(block.clone())?;
-        return Err(ChainError::ParentNotFound);
+    let (receipts, account_updates): (Vec<Receipt>, Vec<AccountUpdate>) = {
+        // TODO: Consider refactoring both implementations so that they have the same signature
+        #[cfg(feature = "levm")]
+        {
+            execute_block(block, &mut state)?
+        }
+        #[cfg(not(feature = "levm"))]
+        {
+            let receipts = execute_block(block, &mut state)?;
+            let account_updates = ethrex_vm::get_state_transitions(&mut state);
+            (receipts, account_updates)
+        }
     };
-    let mut state = evm_state(storage.clone(), block.header.parent_hash);
-
-    // Validate the block pre-execution
-    validate_block(block, &parent_header, &state)?;
-
-    let (receipts, account_updates) = execute_block(block, &mut state)?;
-
-    // Note: these is commented because it is still being used in development.
-    // dbg!(&account_updates);
 
     validate_gas_used(&receipts, &block.header)?;