From 8e23a9fbcbf016aac224d2fafce488aebbb68ba0 Mon Sep 17 00:00:00 2001
From: guigou <guigoucrypto@gmail.com>
Date: Fri, 22 Nov 2024 11:28:18 +0100
Subject: [PATCH] add get_finalized_head method

---
 crates/pink-libs/subrpc/Cargo.toml |  2 +-
 crates/pink-libs/subrpc/src/lib.rs | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/crates/pink-libs/subrpc/Cargo.toml b/crates/pink-libs/subrpc/Cargo.toml
index 6d37d0629..b5639f7d7 100644
--- a/crates/pink-libs/subrpc/Cargo.toml
+++ b/crates/pink-libs/subrpc/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "pink-subrpc"
-version = "0.7.0"
+version = "0.8.0"
 authors = ["Phala Network"]
 edition = "2021"
 license = "Apache-2.0"
diff --git a/crates/pink-libs/subrpc/src/lib.rs b/crates/pink-libs/subrpc/src/lib.rs
index 08dd81219..654dc6782 100644
--- a/crates/pink-libs/subrpc/src/lib.rs
+++ b/crates/pink-libs/subrpc/src/lib.rs
@@ -154,6 +154,24 @@ pub fn get_block_hash(
     Ok(H256(hash))
 }
 
+/// Gets the latest hash of the finalized header
+pub fn get_finalized_head(
+    rpc_node: &str,
+) -> core::result::Result<H256, Error> {
+    let data = format!(
+        r#"{{"id":1, "jsonrpc":"2.0", "method": "chain_getFinalizedHead"}}"#
+    )
+        .into_bytes();
+    let resp_body = call_rpc(rpc_node, data)?;
+    let genesis_hash: GenesisHash = json::from_slice(&resp_body).or(Err(Error::InvalidBody))?;
+    // bypass prefix 0x
+    let genesis_hash_result = &genesis_hash.result[2..];
+    let decoded_hash = hex::decode(genesis_hash_result).or(Err(Error::InvalidBody))?;
+    let hash: [u8; 32] = decoded_hash.try_into().or(Err(Error::InvalidBody))?;
+    Ok(H256(hash))
+}
+
+
 /// Gets revalant block header by given block hash
 /// Only work with chains define generic patterns like `Header<u32, BlakeTwo256>`
 pub fn get_header(
@@ -422,6 +440,13 @@ mod tests {
         );
     }
 
+    #[test]
+    fn can_get_finalized_head() {
+        pink_chain_extension::mock_ext::mock_all_ext();
+        let finalized_head = get_finalized_head("https://kusama-rpc.polkadot.io");
+        assert!(finalized_head.is_ok(), "failed to query finalized_head");
+    }
+
     #[test]
     fn can_correctly_encode() {
         let genesis_hash: [u8; 32] =