feat: added getStakeColdkey to staking precompile

Author: Shr1ftyy

runtime/src/precompiles/solidity/staking.abi

@@ -39,5 +39,24 @@
         "outputs": [],
         "stateMutability": "payable",
         "type": "function"
+    },
+    {
+        "inputs": [
+            {
+                "internalType": "bytes32",
+                "name": "coldkey",
+                "type": "bytes32"
+            }
+        ],
+        "name": "getStakeColdkey",
+        "outputs": [
+            {
+                "internalType": "uint256",
+                "name": "",
+                "type": "uint256"
+            }
+        ],
+        "stateMutability": "view",
+        "type": "function"
     }
 ]

runtime/src/precompiles/solidity/staking.sol

@@ -42,4 +42,16 @@ interface IStaking {
    * - The existing stake amount must be not lower than specified amount
    */
   function removeStake(bytes32 hotkey, uint256 amount, uint16 netuid) external;
+
+  /**
+   * @dev Returns the amount of RAO staked by the coldkey associated with the hotkey.
+   *
+   * This function allows external accounts and contracts to query the amount of RAO staked by the coldkey
+   * associated with the coldkey, which effectively calls `get_coldkey_stake` on the subtensor pallet with
+   * specified coldkey as a parameter.
+   *
+   * @param coldkey The coldkey public key (32 bytes).
+   * @return The amount of RAO staked by the coldkey associated with the hotkey.
+   */
+  function getStakeColdkey(bytes32 coldkey) external view returns (uint256);
 }

runtime/src/precompiles/staking.rs

@@ -59,6 +59,9 @@ impl StakingPrecompile {
             id if id == get_method_id("removeStake(bytes32,uint256,uint16)") => {
                 Self::remove_stake(handle, &method_input)
             }
+            id if id == get_method_id("getStakeColdkey(bytes32)") => {
+                Self::get_stake_coldkey(&method_input)
+            }
             _ => Err(PrecompileFailure::Error {
                 exit_status: ExitError::InvalidRange,
             }),
@@ -110,6 +113,22 @@ impl StakingPrecompile {
         Self::dispatch(handle, call)
     }
 
+    fn get_stake_coldkey(data: &[u8]) -> PrecompileResult {
+        // TODO: rename parse_hotkey to parse_key or something?
+        let coldkey: AccountId32 = Self::parse_hotkey(data)?.into();
+
+        // get total stake of coldkey
+        let total_stake = pallet_subtensor::TotalColdkeyStake::<Runtime>::get(coldkey);
+        let result_u256 = U256::from(total_stake);
+        let mut result = [0_u8; 32];
+        U256::to_big_endian(&result_u256, &mut result);
+
+        Ok(PrecompileOutput {
+            exit_status: ExitSucceed::Returned,
+            output: result.into(),
+        })
+    }
+
     fn parse_hotkey(data: &[u8]) -> Result<[u8; 32], PrecompileFailure> {
         if data.len() < 32 {
             return Err(PrecompileFailure::Error {