Implement feeHistory usage for Gas cost prediction

- Add method `decodeHex` for `Arrays<T> where T: DecodableFromHex`.
- Add feeHistory request.
- Add public feeHistory API call
- Move GasOracle from `Web3` scope to `web3.Eth` scope (watch out case of first "w")
- Change Oracle struct to work with feeHistory API call.
- Refactor `JSONRPCmethod` to make it more explicit.
- Refactor `InfuraWebsockerMethod` with a styling.

Author: yaroslavyaroslav

Sources/web3swift/Convenience/Decodable+Extensions.swift

@@ -95,20 +95,33 @@ extension KeyedDecodingContainer {
         return try decode(type, forKey: key)
     }
 
-    /// Decodes a value of the given key from Hex to BigUInt
+    /// Decodes a value of the given key from Hex to `DecodableFromHex`
     ///
     /// Currently this method supports only `Data.Type`, `BigUInt.Type`, `Date.Type`
     ///
     /// - Parameter type: Generic type `T` wich conforms to `DecodableFromHex` protocol
     /// - Parameter key: The key that the decoded value is associated with.
     /// - Returns: A decoded value of type `BigUInt`
-    /// - throws: `Web3Error.dataError` if value associated with key are unable
-    ///   to be initialized as `BigUInt`.
+    /// - throws: `Web3Error.dataError` if value associated with key are unable to be initialized as `DecodableFromHex`.
     public func decodeHex<T: DecodableFromHex>(to type: T.Type, key: KeyedDecodingContainer<K>.Key) throws -> T {
         let string = try self.decode(String.self, forKey: key)
         guard let number = T(fromHex: string) else { throw Web3Error.dataError }
         return number
     }
+
+    /// Decodes a value of the given key from Hex to `[DecodableFromHex]`
+    ///
+    /// Currently this method supports only `Data.Type`, `BigUInt.Type`, `Date.Type`
+    ///
+    /// - Parameter type: Array of a generic type `T` wich conforms to `DecodableFromHex` protocol
+    /// - Parameter key: The key that the decoded value is associated with.
+    /// - Returns: A decoded value of type `BigUInt`
+    /// - throws: `Web3Error.dataError` if value associated with key are unable to be initialized as `[DecodableFromHex]`.
+    public func decodeHex<T: DecodableFromHex>(to type: Array<T>.Type, key: KeyedDecodingContainer<K>.Key) throws -> Array<T> {
+        var container = try self.nestedUnkeyedContainer(forKey: key)
+        guard let array = try? container.decode(type) else { throw Web3Error.dataError }
+        return array
+    }
 }
 
 public protocol DecodableFromHex: Decodable {

Sources/web3swift/Promises/Promise+Web3+Eth+FeeHistory.swift

@@ -0,0 +1,31 @@
+//
+//  Promise+Web3+Eth+FeeHistory.swift
+//  web3swift
+//
+//  Created by Yaroslav on 11.04.2022.
+//  Copyright © 2022 web3swift. All rights reserved.
+//
+
+import Foundation
+import PromiseKit
+import BigInt
+
+extension web3.Eth {
+//    public func feeHistory(blockCount: Int = 10, onBlock: String = "latest", percentiles:[Double] = [25, 50, 75]) -> Promise<FeeHistory> {
+//        return feeHistory(address: addr, onBlock: onBlock)
+//    }
+    public func feeHistory(blockCount: Int, block: String, percentiles:[Double]) throws -> Promise<Oracle.FeeHistory> {
+        let request = JSONRPCRequestFabric.prepareRequest(.feeHistory, parameters: [blockCount.description.addHexPrefix(), block, percentiles])
+        let rp = web3.dispatch(request)
+        let queue = web3.requestDispatcher.queue
+        return rp.map(on: queue) { response in
+            guard let value: Oracle.FeeHistory = response.getValue() else {
+                if response.error != nil {
+                    throw Web3Error.nodeError(desc: response.error!.message)
+                }
+                throw Web3Error.nodeError(desc: "Invalid value from Ethereum node")
+            }
+            return value
+        }
+    }
+}

Sources/web3swift/Web3/Web3+Eth.swift

@@ -352,4 +352,9 @@ extension web3.Eth {
         return sendERC20tokensWithKnownDecimals(tokenAddress: tokenAddress, from: from, to: to, amount: value, transactionOptions: mergedOptions)
     }
 
+    public func feeHistory(blockCount: Int = 10, block: String = "latest", percentiles:[Double] = [25, 50, 75]) throws -> Oracle.FeeHistory {
+        let result = try self.feeHistory(blockCount: blockCount, block: block, percentiles: percentiles).wait()
+        return result
+    }
+
 }

Sources/web3swift/Web3/Web3+GasOracle.swift

@@ -9,40 +9,42 @@
 import Foundation
 import BigInt
 
-extension Web3 {
+extension web3.Eth {
     /// Oracle is the class to do a transaction fee suggestion
-    ///
-    /// Designed for EIP-1559 transactions only.
     final public class Oracle {
-        private var latestBlock: Block?
 
         /// Web3 provider by which accessing to the blockchain
         private let web3Provider: web3
 
         /// Ethereum scope shortcut
         private var eth: web3.Eth { web3Provider.eth }
 
+        /// Block to start getting history
+        var block: String
+
         /// Count of blocks to calculate statistics
-        public private(set) var blockCount: BigUInt
+        var blockCount: BigUInt
 
         /// Count of transactions to filter block for tip calculation
-        public private(set) var transactionCount: BigUInt
+        var percentiles: [Double]
 
         /// Oracle initializer
         /// - Parameters:
         ///   - provider: Web3 Ethereum provider
+        ///   - block: Number of block from which counts starts
         ///   - blockCount: Count of block to calculate statistics
-        ///   - transactionCount: Count of transaction to filter block for tip calculation
-        public init(_ provider: web3, blockCount: BigUInt = 20, transactionCount: BigUInt = 50) {
+        ///   - percentiles: Percentiles of fees which will split in fees history
+        public init(_ provider: web3, block: String = "latest", blockCount: BigUInt = 20, percentiles: [Double] = [25, 50, 75]) {
             self.web3Provider = provider
+            self.block = block
             self.blockCount = blockCount
-            self.transactionCount = transactionCount
+            self.percentiles = percentiles
         }
 
-        private func calcBaseFee(for block: Block?) -> BigUInt {
-            guard let block = block else { return 0 }
-            return Web3.calcBaseFee(block) ?? 0
-        }
+//        private func calcBaseFee(for block: Block?) -> BigUInt {
+//            guard let block = block else { return 0 }
+//            return Web3.calcBaseFee(block) ?? 0
+//        }
 
         private func calculateStatistic(for statistic: Statistic, data: [BigUInt]) throws -> BigUInt {
             let noAnomalyArray = data.cropAnomalyValues()
@@ -59,23 +61,29 @@ extension Web3 {
             case .maximum:
                 // Checking that suggestedBaseFee is not lower than it will be in the next block
                 // because in the maximum statistic we should guarantee that transaction would be included in it.
-                return max(calcBaseFee(for: latestBlock), unwrappedArray.max()!)
+//                return max(calcBaseFee(for: latestBlock), unwrappedArray.max()!)
+                return unwrappedArray.max()!
             }
             // swiftlint:enable force_unwrapping
         }
 
+//        private func suggestGasValues( statistic: Statistic) throws -> FeeHistory {
+//
+//        }
+
         private func suggestTipValue(_ statistic: Statistic) throws -> BigUInt {
+
             let latestBlockNumber = try eth.getBlockNumber()
 
             var block: Block
 
             // TODO: Make me work with cache
             repeat {
                 block = try eth.getBlockByNumber(latestBlockNumber, fullTransactions: true)
-            } while block.transactions.count < transactionCount
+            } while block.transactions.count < 20
 
             // Storing last block to calculate baseFee of the next block
-            latestBlock = block
+//            latestBlock = block
 
             let transactionsTips = block.transactions
                 .compactMap { t -> EthereumTransaction? in
@@ -92,7 +100,7 @@ extension Web3 {
             let latestBlockNumber = try eth.getBlockNumber()
 
             // Assigning last block to object var to predict baseFee of the next block
-            latestBlock = try eth.getBlockByNumber(latestBlockNumber)
+//            latestBlock = try eth.getBlockByNumber(latestBlockNumber)
             // TODO: Make me work with cache
             let lastNthBlocksBaseFees = try (latestBlockNumber - blockCount ... latestBlockNumber)
                 .map { try eth.getBlockByNumber($0) }
@@ -106,7 +114,7 @@ extension Web3 {
             let latestBlockNumber = try eth.getBlockNumber()
 
             // Assigning last block to object var to predict baseFee of the next block
-            latestBlock = try eth.getBlockByNumber(latestBlockNumber)
+//            latestBlock = try eth.getBlockByNumber(latestBlockNumber)
             // TODO: Make me work with cache
             let lastNthBlockGasPrice = try (latestBlockNumber - blockCount ... latestBlockNumber)
                 .map { try eth.getBlockByNumber($0, fullTransactions: true) }
@@ -123,7 +131,7 @@ extension Web3 {
     }
 }
 
-public extension Web3.Oracle {
+public extension web3.Eth.Oracle {
     // MARK: - Base Fee
     /// Base fee amount based on last Nth blocks
     ///
@@ -175,7 +183,7 @@ public extension Web3.Oracle {
     }
 }
 
-public extension Web3.Oracle {
+public extension web3.Eth.Oracle {
     // TODO: Make me struct and encapsulate math within to make me extendable
     enum Statistic {
         /// Mininum statistic
@@ -189,6 +197,33 @@ public extension Web3.Oracle {
     }
 }
 
+public extension web3.Eth.Oracle {
+    struct FeeHistory {
+        let baseFeePerGas: [BigUInt]
+        let gasUsedRatio: [Double]
+        let oldestBlock: BigUInt
+        let reward: [[BigUInt]]
+    }
+}
+
+extension web3.Eth.Oracle.FeeHistory: Decodable {
+    enum CodingKeys: String, CodingKey {
+        case baseFeePerGas
+        case gasUsedRatio
+        case oldestBlock
+        case reward
+    }
+
+    public init(from decoder: Decoder) throws {
+        let values = try decoder.container(keyedBy: CodingKeys.self)
+
+        self.baseFeePerGas = try values.decodeHex(to: [BigUInt].self, key: .baseFeePerGas)
+        self.gasUsedRatio = try values.decodeHex(to: [Double].self, key: .gasUsedRatio)
+        self.oldestBlock = try values.decodeHex(to: BigUInt.self, key: .oldestBlock)
+        self.reward = try values.decodeHex(to: [[BigUInt]].self, key: .reward)
+    }
+}
+
 extension Array where Element: Comparable {
 
     /// Sorts array and drops most and least values.

Sources/web3swift/Web3/Web3+Methods.swift

@@ -8,64 +8,68 @@ import Foundation
 
 public enum JSONRPCmethod: String, Encodable {
 
+    // 0 parameter in call
     case gasPrice = "eth_gasPrice"
     case blockNumber = "eth_blockNumber"
     case getNetwork = "net_version"
+    case getAccounts = "eth_accounts"
+    case getTxPoolStatus = "txpool_status"
+    case getTxPoolContent = "txpool_content"
+    case getTxPoolInspect = "txpool_inspect"
+    case estimateGas = "eth_estimateGas"
+
+    // 1 parameter in call
     case sendRawTransaction = "eth_sendRawTransaction"
     case sendTransaction = "eth_sendTransaction"
-    case estimateGas = "eth_estimateGas"
-    case call = "eth_call"
-    case getTransactionCount = "eth_getTransactionCount"
-    case getBalance = "eth_getBalance"
-    case getCode = "eth_getCode"
-    case getStorageAt = "eth_getStorageAt"
     case getTransactionByHash = "eth_getTransactionByHash"
     case getTransactionReceipt = "eth_getTransactionReceipt"
-    case getAccounts = "eth_accounts"
-    case getBlockByHash = "eth_getBlockByHash"
-    case getBlockByNumber = "eth_getBlockByNumber"
     case personalSign = "eth_sign"
     case unlockAccount = "personal_unlockAccount"
     case createAccount = "personal_createAccount"
     case getLogs = "eth_getLogs"
-    case getTxPoolInspect = "txpool_inspect"
-    case getTxPoolStatus = "txpool_status"
-    case getTxPoolContent = "txpool_content"
+
+    // 2 parameters in call
+    case call = "eth_call"
+    case getTransactionCount = "eth_getTransactionCount"
+    case getBalance = "eth_getBalance"
+    case getStorageAt = "eth_getStorageAt"
+    case getCode = "eth_getCode"
+    case getBlockByHash = "eth_getBlockByHash"
+    case getBlockByNumber = "eth_getBlockByNumber"
+
+    // 3 parameters in call
+    case feeHistory = "eth_feeHistory"
 
     public var requiredNumOfParameters: Int {
-        get {
-            switch self {
-            case .call:
-                return 2
-            case .getTransactionCount:
-                return 2
-            case .getBalance:
-                return 2
-            case .getStorageAt:
-                return 2
-            case .getCode:
-                return 2
-            case .getBlockByHash:
-                return 2
-            case .getBlockByNumber:
-                return 2
-            case .gasPrice:
-                return 0
-            case .blockNumber:
-                return 0
-            case .getNetwork:
-                return 0
-            case .getAccounts:
-                return 0
-            case .getTxPoolStatus:
-                return 0
-            case .getTxPoolContent:
-                return 0
-            case .getTxPoolInspect:
-                return 0
-            default:
-                return 1
-            }
+        switch self {
+        case .gasPrice,
+                .blockNumber,
+                .getNetwork,
+                .getAccounts,
+                .getTxPoolStatus,
+                .getTxPoolContent,
+                .getTxPoolInspect,
+                .estimateGas:
+            return 0
+        case .sendRawTransaction,
+                .sendTransaction,
+                .getTransactionByHash,
+                .getTransactionReceipt,
+                .personalSign,
+                .unlockAccount,
+                .createAccount,
+                .getLogs:
+            return 1
+        case .call,
+                .getTransactionCount,
+                .getBalance,
+                .getStorageAt,
+                .getCode,
+                .getBlockByHash,
+                .getBlockByNumber:
+            return 2
+        case .feeHistory:
+            return 3
         }
     }
 }