union Any {
  Start,
  StartRes,
  CodeFetch,
  CodeFetchRes,
  CodeCache,
  Exit,
  TimerStart,
  TimerReady,
  TimerClear,
  Environ,
  EnvironRes,
  FetchReq,
  FetchRes,
  MakeTempDir,
  MakeTempDirRes,
  Mkdir,
  ReadFile,
  ReadFileRes,
  WriteFile,
  RenameSync,
  StatSync,
  StatSyncRes,
  SetEnv,
}

enum ErrorKind: byte {
  NoError = 0,

  // io errors

  NotFound,
  PermissionDenied,
  ConnectionRefused,
  ConnectionReset,
  ConnectionAborted,
  NotConnected,
  AddrInUse,
  AddrNotAvailable,
  BrokenPipe,
  AlreadyExists,
  WouldBlock,
  InvalidInput,
  InvalidData,
  TimedOut,
  Interrupted,
  WriteZero,
  Other,
  UnexpectedEof,

  // url errors

  EmptyHost,
  IdnaError,
  InvalidPort,
  InvalidIpv4Address,
  InvalidIpv6Address,
  InvalidDomainCharacter,
  RelativeUrlWithoutBase,
  RelativeUrlWithCannotBeABaseBase,
  SetHostOnCannotBeABaseUrl,
  Overflow,

  // hyper errors

  HttpUser,
  HttpClosed,
  HttpCanceled,
  HttpParse,
  HttpOther,
}

table Base {
  cmd_id: uint32;
  sync: bool = true; // TODO(ry) Change default to false.
  error_kind: ErrorKind = NoError;
  error: string;
  msg: Any;
}

table Start {
  unused: int8;
}

table StartRes {
  cwd: string;
  argv: [string];
  debug_flag: bool;
  deps_flag: bool;
}

table CodeFetch {
  module_specifier: string;
  containing_file: string;
}

table CodeFetchRes {
  // If it's a non-http module, moduleName and filename will be the same.
  // For http modules, moduleName is its resolved http URL, and filename
  // is the location of the locally downloaded source code.
  module_name: string;
  filename: string;
  source_code: string;
  output_code: string; // Non-empty only if cached.
}

table CodeCache {
  filename: string;
  source_code: string;
  output_code: string;
}

table Exit {
  code: int;
}

table TimerStart {
  id: uint;
  delay: uint;
}

table TimerReady {
  id: uint;
  canceled: bool;
}

table TimerClear {
  id: uint;
}

table Environ {}

table SetEnv {
  key: string;
  value: string;
}

table EnvironRes {
  map: [EnvPair];
}

table EnvPair {
  key: string;
  value: string;
}

table FetchReq {
  id: uint;
  url: string;
  // header_line: [string];
}

table FetchRes {
  id: uint;
  status: int;
  header_line: [string];
  body: [ubyte];
}

table MakeTempDir {
  dir: string;
  prefix: string;
  suffix: string;
}

table MakeTempDirRes {
  path: string;
}

table Mkdir {
  path: string;
  mode: uint;
  // mode specified by https://godoc.org/os#FileMode
}

table ReadFile {
  filename: string;
}

table ReadFileRes {
  data: [ubyte];
}

table WriteFile {
  filename: string;
  data: [ubyte];
  perm: uint;
  // perm specified by https://godoc.org/os#FileMode
}

table RenameSync {
  oldpath: string;
  newpath: string;
}

table StatSync {
  filename: string;
  lstat: bool;
}

table StatSyncRes {
  is_file: bool;
  is_symlink: bool;
  len: ulong;
  modified:ulong;
  accessed:ulong;
  created:ulong;
}

root_type Base;