import CryptoKit
import Foundation

enum XRPError: LocalizedError {
  case invalidBase58
  case invalidAddress
  case invalidSeed
  case unsupportedSeed
  case rpc(String)
  case network(String)

  var errorDescription: String? {
    switch self {
    case .invalidBase58: return "Invalid Base58 text"
    case .invalidAddress: return "Invalid XRP address"
    case .invalidSeed: return "Check the recovery phrase or secret"
    case .unsupportedSeed: return "Unsupported XRP secret"
    case .rpc(let message): return message
    case .network(let message): return message
    }
  }
}

enum XRPHash {
  static func sha256(_ bytes: [UInt8]) -> [UInt8] {
    Array(SHA256.hash(data: Data(bytes)))
  }

  static func sha512(_ bytes: [UInt8]) -> [UInt8] {
    Array(SHA512.hash(data: Data(bytes)))
  }

  /// First 32 bytes of SHA-512, used by the XRP Ledger everywhere.
  static func sha512Half(_ bytes: [UInt8]) -> [UInt8] {
    Array(sha512(bytes).prefix(32))
  }

  static func ripemd160(_ bytes: [UInt8]) -> [UInt8] {
    RIPEMD160.hash(bytes)
  }

  /// Base58Check double-SHA-256 checksum.
  static func checksum(_ bytes: [UInt8]) -> [UInt8] {
    Array(sha256(sha256(bytes)).prefix(4))
  }
}

enum Hex {
  static func encode(_ bytes: [UInt8]) -> String {
    bytes.map { String(format: "%02x", $0) }.joined()
  }

  static func decode(_ string: String) -> [UInt8]? {
    var text = string.trimmingCharacters(in: .whitespacesAndNewlines)
    if text.hasPrefix("0x") || text.hasPrefix("0X") { text = String(text.dropFirst(2)) }
    guard text.count % 2 == 0 else { return nil }
    var bytes: [UInt8] = []
    bytes.reserveCapacity(text.count / 2)
    var index = text.startIndex
    while index < text.endIndex {
      let next = text.index(index, offsetBy: 2)
      guard let byte = UInt8(text[index..<next], radix: 16) else { return nil }
      bytes.append(byte)
      index = next
    }
    return bytes
  }
}