import SwiftSyntax
import SwiftSyntaxBuilder
import SwiftBasicFormat

class CodeGenerationFormat: BasicFormat {
  override var indentation: TriviaPiece { .spaces(indentationLevel * 2) }
}

let sourceFile = SourceFile {
  StructDecl("public struct SimpleError: Error") {
    VariableDecl("private let code: Int")
    InitializerDecl("""
      public init?(errorCode: Int) {
        guard errorCode > 0 else { return nil }
        self.code = errorCode
      }
      """)
  }
}

print(sourceFile.formatted(using: CodeGenerationFormat()))

public struct SimpleError: Error {
  private let code: Int
  public init ?(errorCode: Int) {
    guard errorCode > 0 else { 
      return nil 
    }
    self.code = errorCode
  }
}