feat: paginate getApprovedProviders with test coverage (#238)

Author: Chaitu-Tatipamula

service_contracts/abi/FilecoinWarmStorageServiceStateLibrary.abi.json

@@ -156,6 +156,16 @@
         "name": "service",
         "type": "FilecoinWarmStorageService",
         "internalType": "contract FilecoinWarmStorageService"
+      },
+      {
+        "name": "offset",
+        "type": "uint256",
+        "internalType": "uint256"
+      },
+      {
+        "name": "limit",
+        "type": "uint256",
+        "internalType": "uint256"
       }
     ],
     "outputs": [
@@ -167,6 +177,25 @@
     ],
     "stateMutability": "view"
   },
+  {
+    "type": "function",
+    "name": "getApprovedProvidersLength",
+    "inputs": [
+      {
+        "name": "service",
+        "type": "FilecoinWarmStorageService",
+        "internalType": "contract FilecoinWarmStorageService"
+      }
+    ],
+    "outputs": [
+      {
+        "name": "count",
+        "type": "uint256",
+        "internalType": "uint256"
+      }
+    ],
+    "stateMutability": "view"
+  },
   {
     "type": "function",
     "name": "getChallengesPerProof",

service_contracts/abi/FilecoinWarmStorageServiceStateView.abi.json

@@ -130,7 +130,18 @@
   {
     "type": "function",
     "name": "getApprovedProviders",
-    "inputs": [],
+    "inputs": [
+      {
+        "name": "offset",
+        "type": "uint256",
+        "internalType": "uint256"
+      },
+      {
+        "name": "limit",
+        "type": "uint256",
+        "internalType": "uint256"
+      }
+    ],
     "outputs": [
       {
         "name": "providerIds",
@@ -140,6 +151,19 @@
     ],
     "stateMutability": "view"
   },
+  {
+    "type": "function",
+    "name": "getApprovedProvidersLength",
+    "inputs": [],
+    "outputs": [
+      {
+        "name": "count",
+        "type": "uint256",
+        "internalType": "uint256"
+      }
+    ],
+    "stateMutability": "view"
+  },
   {
     "type": "function",
     "name": "getChallengesPerProof",

service_contracts/src/FilecoinWarmStorageServiceStateView.sol

@@ -50,8 +50,12 @@ contract FilecoinWarmStorageServiceStateView is IPDPProvingSchedule {
         return service.getAllPieceMetadata(dataSetId, pieceId);
     }
 
-    function getApprovedProviders() external view returns (uint256[] memory providerIds) {
-        return service.getApprovedProviders();
+    function getApprovedProviders(uint256 offset, uint256 limit) external view returns (uint256[] memory providerIds) {
+        return service.getApprovedProviders(offset, limit);
+    }
+
+    function getApprovedProvidersLength() external view returns (uint256 count) {
+        return service.getApprovedProvidersLength();
     }
 
     function getChallengesPerProof() external pure returns (uint64) {

service_contracts/src/lib/FilecoinWarmStorageServiceStateInternalLibrary.sol

@@ -415,28 +415,55 @@ library FilecoinWarmStorageServiceStateInternalLibrary {
     }
 
     /**
-     * @notice Get all approved provider IDs
+     * @notice Get approved provider IDs with optional pagination
      * @param service The service contract
-     * @return providerIds Array of all approved provider IDs
+     * @param offset Starting index (0-based). Use 0 to start from beginning
+     * @param limit Maximum number of providers to return. Use 0 to get all remaining providers
+     * @return providerIds Array of approved provider IDs
+     * @dev For large lists, use pagination to avoid gas limit issues. If limit=0,
+     * returns all remaining providers starting from offset. Example:
+     * getApprovedProviders(service, 0, 100) gets first 100 providers.
      */
-    function getApprovedProviders(FilecoinWarmStorageService service)
+    function getApprovedProviders(FilecoinWarmStorageService service, uint256 offset, uint256 limit)
         internal
         view
         returns (uint256[] memory providerIds)
     {
         bytes32 slot = StorageLayout.APPROVED_PROVIDER_IDS_SLOT;
-        uint256 length = uint256(service.extsload(slot));
+        uint256 totalLength = uint256(service.extsload(slot));
 
-        if (length == 0) {
+        if (totalLength == 0) {
             return new uint256[](0);
         }
 
-        bytes32[] memory result = service.extsloadStruct(keccak256(abi.encode(slot)), length);
+        if (offset >= totalLength) {
+            return new uint256[](0);
+        }
+
+        uint256 actualLength = limit;
+        if (limit == 0 || offset + limit > totalLength) {
+            actualLength = totalLength - offset;
+        }
+
+        bytes32 baseSlot = keccak256(abi.encode(slot));
+        bytes32 startSlot = bytes32(uint256(baseSlot) + offset);
+        bytes32[] memory paginatedResult = service.extsloadStruct(startSlot, actualLength);
+
         assembly ("memory-safe") {
-            providerIds := result
+            providerIds := paginatedResult
         }
     }
 
+    /**
+     * @notice Get the total number of approved providers
+     * @param service The service contract
+     * @return count Total number of approved providers
+     */
+    function getApprovedProvidersLength(FilecoinWarmStorageService service) internal view returns (uint256 count) {
+        bytes32 slot = StorageLayout.APPROVED_PROVIDER_IDS_SLOT;
+        return uint256(service.extsload(slot));
+    }
+
     /**
      * @notice Get the FilBeam Controller address
      * @param service The service contract

service_contracts/src/lib/FilecoinWarmStorageServiceStateLibrary.sol

@@ -411,28 +411,55 @@ library FilecoinWarmStorageServiceStateLibrary {
     }
 
     /**
-     * @notice Get all approved provider IDs
+     * @notice Get approved provider IDs with optional pagination
      * @param service The service contract
-     * @return providerIds Array of all approved provider IDs
+     * @param offset Starting index (0-based). Use 0 to start from beginning
+     * @param limit Maximum number of providers to return. Use 0 to get all remaining providers
+     * @return providerIds Array of approved provider IDs
+     * @dev For large lists, use pagination to avoid gas limit issues. If limit=0,
+     * returns all remaining providers starting from offset. Example:
+     * getApprovedProviders(service, 0, 100) gets first 100 providers.
      */
-    function getApprovedProviders(FilecoinWarmStorageService service)
+    function getApprovedProviders(FilecoinWarmStorageService service, uint256 offset, uint256 limit)
         public
         view
         returns (uint256[] memory providerIds)
     {
         bytes32 slot = StorageLayout.APPROVED_PROVIDER_IDS_SLOT;
-        uint256 length = uint256(service.extsload(slot));
+        uint256 totalLength = uint256(service.extsload(slot));
 
-        if (length == 0) {
+        if (totalLength == 0) {
             return new uint256[](0);
         }
 
-        bytes32[] memory result = service.extsloadStruct(keccak256(abi.encode(slot)), length);
+        if (offset >= totalLength) {
+            return new uint256[](0);
+        }
+
+        uint256 actualLength = limit;
+        if (limit == 0 || offset + limit > totalLength) {
+            actualLength = totalLength - offset;
+        }
+
+        bytes32 baseSlot = keccak256(abi.encode(slot));
+        bytes32 startSlot = bytes32(uint256(baseSlot) + offset);
+        bytes32[] memory paginatedResult = service.extsloadStruct(startSlot, actualLength);
+
         assembly ("memory-safe") {
-            providerIds := result
+            providerIds := paginatedResult
         }
     }
 
+    /**
+     * @notice Get the total number of approved providers
+     * @param service The service contract
+     * @return count Total number of approved providers
+     */
+    function getApprovedProvidersLength(FilecoinWarmStorageService service) public view returns (uint256 count) {
+        bytes32 slot = StorageLayout.APPROVED_PROVIDER_IDS_SLOT;
+        return uint256(service.extsload(slot));
+    }
+
     /**
      * @notice Get the FilBeam Controller address
      * @param service The service contract