Adds draft design doc

Signed-off-by: Konstantina Blazhukova <konstantina.blajukova@gmail.com>

docs/design/additional-endpoints.md

@@ -0,0 +1,160 @@
+# Design Document: ERC20/ERC721/ERC1155 Token Transfer Events API, Tokens Owned by an Address
+
+## Overview
+- This document outlines the design for implementing new endpoints allowing exposure of more EVM centric data, similar to Etherscan's and BlockScout's APIs.
++ The endpoints will support:
++ - ERC20 token transfers 
++ - ERC721 NFT transfers
++ - ERC1155 multi-token transfers
++ - Tokens owned by an address
+
+## Problem Statement
+- Currently MN doesn't support EVM centric queries, like token transfer events for specific standards like ERC20, ERC721, ERC1155 or balance of an address for a specific token.
+
+## Goals
+- Provide API endpoints to fetch token transfer events
++ - Support filtering by sender address
++ - Support filtering by block range
++ - Support filtering by specific token contract
++ - Support ERC20, ERC721, and ERC1155 token standards
+- Match Etherscan's response format for easy integration
+- Maintain performance with large datasets
+- Provide endpoints to fetch tokens owned by an address
+
+## Proposed Solution
+
+### Overview
+
+Introduce two new endpoints:
+- `getTokenTransfers` - to fetch token transfer events
+- `getTokensOwnedByAddress` - to fetch tokens owned by an address (TBD)
+
+##  `getTokenTransfers`
+
+### Components
+
+#### 1. EthImpl
+Main service class handling token transfer event logic:
+- Validates block ranges
+- Filters logs for token transfer events
+- Checks the contracts in the MN response for the token standard needed
+- Transforms logs to transfer events format
+
+#### 2. CommonService Integration
+Utilizes existing CommonService for:
+- Block range validation
+- Timestamp parameter handling
+
+#### 3. MirrorNodeClient Integration
+Uses MirrorNodeClient for:
+- Fetching contract logs
+- Block information retrieval
+
+### Data Flow
+```mermaid
+sequenceDiagram
+    Client->>EthImpl: getTokenTransfers()
+    EthImpl->>CommonService: getLogs()
+    CommonService->>CommonService: getLogsWithParams()
+    CommonService->>MirrorNodeClient: getContractResultsLogs()
+    MirrorNodeClient->>CommonService: ''
+    CommonService->>EthImpl: ''
+    EthImpl->>EthImpl: getErcRegistry()
+    EthImpl->>EthImpl: checkContracts()
+    EthImpl->>Client: Return Response
+```
+
+### Technical Details
+
+#### API Interfaces
+
+```typescript
+interface TokenTransferEvent {
+  blockNumber: string;
+  timeStamp: string;
+  hash: string;
+  nonce: number;
+  blockHash: string;
+  from: string;
+  contractAddress: string;
+  to: string;
+  tokenId?: string;
+  tokenName?: string;
+  tokenSymbol?: string;
+  tokenDecimal?: number;
+  transactionIndex: number;
+  gas: number;
+  gasPrice: number;
+  gasUsed: number;
+  cumulativeGasUsed: number;
+  input: string;
+  confirmations: number;
+}
+```
+
+#### Key Implementation Details
+
+The `getTokenTransfers` endpoint will be calling the same method in the `EthImpl` class which will accept the following parameters:
+
+- `address`: The address to filter transfers by
+- `fromBlock`: The starting block number
+- `toBlock`: The ending block number
+- `contractAddress`: The address of the token contract
+- `standard`: The token standard to filter by
+
+There are three possible cases:
+1. Only `contractAddress` is provided
+2. Only `address` is provided
+3. Both `address` and `contractAddress` are provided
+
+1. Validate the block range and take the timestamp range
+2. Get the logs from the MN for the given timestamp range and filter them by the address and contract address via the topic parameters
+3. Filter the results by checking the contract address returned in the ERC registry and if it matcches the standard
+4. Transform the logs to the format of the `TokenTransferEvent` interface
+
+
+#### Error Handling
+
+
+### Performance Considerations
+
+1. Possibly restrict the number of logs returned by the MN to a maximum of 10000
+2. Possibly restrict the block range to a maximum of 10000 blocks
+3. Consider the amount of resources required to check the ERC registry for each log
+
+### Security Considerations
+
+1. **Input Validation**
+   - Validates block ranges
+   - Validates address
+   - Validates contract addresses
+
+
+### Testing Requirements
+
+1. **Unit Tests**
+   - Test log filtering logic
+   - Test address matching
+   - Test token standard detection
+
+2. **Acceptance Tests**
+   - Test Mirror Node interaction
+   - Test complete flow with real data
+   - Test error scenarios
+   - Test different token standards
+
+3. **Performance Tests**
+   - Test with large block ranges
+   - Test with high-volume contracts
+
+### Future Improvements
+
+
+### Dependencies
+
+- ERC registry
+
+
+##  `getTokensOwnedByAddress`
+
+### TBD

packages/relay/src/lib/eth.ts

@@ -1,4 +1,4 @@
-/* -
+/*-
  *
  * Hedera JSON RPC Relay
  *