module Process

def create(args)
  create3(args).first
end

def create3(args)
  unless args.is_a?(Hash)
    raise TypeError, "hash keyword arguments expected"
  end
  valid_keys = %w{
    app_name command_line inherit creation_flags cwd environment
    startup_info thread_inherit process_inherit close_handles with_logon
    domain password elevated
  }
  valid_si_keys = %w{
    startf_flags desktop title x y x_size y_size x_count_chars
    y_count_chars fill_attribute sw_flags stdin stdout stderr
  }
  # Set default values
  hash = {
    "app_name" => nil,
    "creation_flags" => 0,
    "close_handles" => true,
  }
  # Validate the keys, and convert symbols and case to lowercase strings.
  args.each do |key, val|
    key = key.to_s.downcase
    unless valid_keys.include?(key)
      raise ArgumentError, "invalid key '#{key}'"
    end
    hash[key] = val
  end
  si_hash = {}
  # If the startup_info key is present, validate its subkeys
  hash["startup_info"]&.each do |key, val|
    key = key.to_s.downcase
    unless valid_si_keys.include?(key)
      raise ArgumentError, "invalid startup_info key '#{key}'"
    end
    si_hash[key] = val
  end
  # The +command_line+ key is mandatory unless the +app_name+ key
  # is specified.
  unless hash["command_line"]
    if hash["app_name"]
      hash["command_line"] = hash["app_name"]
      hash["app_name"] = nil
    else
      raise ArgumentError, "command_line or app_name must be specified"
    end
  end
  env = nil
  # Retrieve the environment variables for the specified user.
  if hash["with_logon"]
    logon, passwd, domain = format_creds_from_hash(hash)
    logon_type = hash["elevated"] ? LOGON32_LOGON_BATCH : LOGON32_LOGON_INTERACTIVE
    token = logon_user(logon, domain, passwd, logon_type)
    logon_ptr = FFI::MemoryPointer.from_string(logon)
    profile = PROFILEINFO.new.tap do |dat|
      dat[:dwSize]     = dat.size
      dat[:dwFlags]    = 1
      dat[:lpUserName] = logon_ptr
    end
    load_user_profile(token, profile.pointer)
    env_list = retrieve_environment_variables(token)
  end
  # The env string should be passed as a string of ';' separated paths.
  if hash["environment"]
    env = env_list.nil? ? hash["environment"] : merge_env_variables(env_list, hash["environment"])
    unless env.respond_to?(:join)
      env = hash["environment"].split(File::PATH_SEPARATOR)
    end
    env = env.map { |e| e + 0.chr }.join("") + 0.chr
    env.to_wide_string! if hash["with_logon"]
  end
  # Process SECURITY_ATTRIBUTE structure
  process_security = nil
  if hash["process_inherit"]
    process_security = SECURITY_ATTRIBUTES.new
    process_security[:nLength] = 12
    process_security[:bInheritHandle] = 1
  end
  # Thread SECURITY_ATTRIBUTE structure
  thread_security = nil
  if hash["thread_inherit"]
    thread_security = SECURITY_ATTRIBUTES.new
    thread_security[:nLength] = 12
    thread_security[:bInheritHandle] = 1
  end
  # Automatically handle stdin, stdout and stderr as either IO objects
  # or file descriptors. This won't work for StringIO, however. It also
  # will not work on JRuby because of the way it handles internal file
  # descriptors.
  #
  %w{stdin stdout stderr}.each do |io|
    if si_hash[io]
      if si_hash[io].respond_to?(:fileno)
        handle = get_osfhandle(si_hash[io].fileno)
      else
        handle = get_osfhandle(si_hash[io])
      end
      if handle == INVALID_HANDLE_VALUE
        ptr = FFI::MemoryPointer.new(:int)
        if windows_version >= 6 && get_errno(ptr) == 0
          errno = ptr.read_int
        else
          errno = FFI.errno
        end
        raise SystemCallError.new("get_osfhandle", errno)
      end
      # Most implementations of Ruby on Windows create inheritable
      # handles by default, but some do not. RF bug #26988.
      bool = SetHandleInformation(
        handle,
        HANDLE_FLAG_INHERIT,
        HANDLE_FLAG_INHERIT
      )
      raise SystemCallError.new("SetHandleInformation", FFI.errno) unless bool
      si_hash[io] = handle
      si_hash["startf_flags"] ||= 0
      si_hash["startf_flags"] |= STARTF_USESTDHANDLES
      hash["inherit"] = true
    end
  end
  procinfo  = PROCESS_INFORMATION.new
  startinfo = STARTUPINFO.new
  unless si_hash.empty?
    startinfo[:cb]              = startinfo.size
    startinfo[:lpDesktop]       = si_hash["desktop"] if si_hash["desktop"]
    startinfo[:lpTitle]         = si_hash["title"] if si_hash["title"]
    startinfo[:dwX]             = si_hash["x"] if si_hash["x"]
    startinfo[:dwY]             = si_hash["y"] if si_hash["y"]
    startinfo[:dwXSize]         = si_hash["x_size"] if si_hash["x_size"]
    startinfo[:dwYSize]         = si_hash["y_size"] if si_hash["y_size"]
    startinfo[:dwXCountChars]   = si_hash["x_count_chars"] if si_hash["x_count_chars"]
    startinfo[:dwYCountChars]   = si_hash["y_count_chars"] if si_hash["y_count_chars"]
    startinfo[:dwFillAttribute] = si_hash["fill_attribute"] if si_hash["fill_attribute"]
    startinfo[:dwFlags]         = si_hash["startf_flags"] if si_hash["startf_flags"]
    startinfo[:wShowWindow]     = si_hash["sw_flags"] if si_hash["sw_flags"]
    startinfo[:cbReserved2]     = 0
    startinfo[:hStdInput]       = si_hash["stdin"] if si_hash["stdin"]
    startinfo[:hStdOutput]      = si_hash["stdout"] if si_hash["stdout"]
    startinfo[:hStdError]       = si_hash["stderr"] if si_hash["stderr"]
  end
  app = nil
  cmd = nil
  # Convert strings to wide character strings if present
  if hash["app_name"]
    app = hash["app_name"].to_wide_string
  end
  if hash["command_line"]
    cmd = hash["command_line"].to_wide_string
  end
  if hash["cwd"]
    cwd = hash["cwd"].to_wide_string
  end
  inherit = hash["inherit"] ? 1 : 0
  if hash["with_logon"]
    logon, passwd, domain = format_creds_from_hash(hash)
    hash["creation_flags"] |= CREATE_UNICODE_ENVIRONMENT
    winsta_name = get_windows_station_name
    # If running in the service windows station must do a log on to get
    # to the interactive desktop. The running process user account must have
    # the 'Replace a process level token' permission.  This is necessary as
    # the logon (which happens with CreateProcessWithLogon) must have an
    # interactive windows station to attach to, which is created with the
    # LogonUser call with the LOGON32_LOGON_INTERACTIVE flag.
    #
    # User Access Control (UAC) only applies to interactive logons, so we
    # can simulate running a command 'elevated' by running it under a separate
    # logon as a batch process.
    if hash["elevated"] || winsta_name =~ /^Service-0x0-.*$/i
      logon_type = hash["elevated"] ? LOGON32_LOGON_BATCH : LOGON32_LOGON_INTERACTIVE
      token      = logon_user(logon, domain, passwd, logon_type)
      logon_ptr  = FFI::MemoryPointer.from_string(logon)
      profile    = PROFILEINFO.new.tap do |dat|
        dat[:dwSize]     = dat.size
        dat[:dwFlags]    = 1
        dat[:lpUserName] = logon_ptr
      end
      if logon_has_roaming_profile?
        msg = %w{
          Mixlib does not currently support executing commands as users
          configured with Roaming Profiles. [%s]
        }.join(" ") % logon.encode("UTF-8").unpack("A*")
        raise UnsupportedFeature.new(msg)
      end
      load_user_profile(token, profile.pointer)
      create_process_as_user(token, app, cmd, process_security,
        thread_security, inherit, hash["creation_flags"], env,
        cwd, startinfo, procinfo)
    else
      create_process_with_logon(logon, domain, passwd, LOGON_WITH_PROFILE,
        app, cmd, hash["creation_flags"], env, cwd, startinfo, procinfo)
    end
  else
    create_process(app, cmd, process_security, thread_security, inherit,
      hash["creation_flags"], env, cwd, startinfo, procinfo)
  end
  # Automatically close the process and thread handles in the
  # PROCESS_INFORMATION struct unless explicitly told not to.
  if hash["close_handles"]
    CloseHandle(procinfo[:hProcess])
    CloseHandle(procinfo[:hThread])
    # Clear these fields so callers don't attempt to close the handle
    # which can result in the wrong handle being closed or an
    # exception in some circumstances.
    procinfo[:hProcess] = 0
    procinfo[:hThread] = 0
  end
  process = ProcessInfo.new(
    procinfo[:hProcess],
    procinfo[:hThread],
    procinfo[:dwProcessId],
    procinfo[:dwThreadId]
  )
  [ process, profile, token ]
end

def create_environment_block(env_pointer, token)
  unless CreateEnvironmentBlock(env_pointer, token, false)
    raise SystemCallError.new("CreateEnvironmentBlock", FFI.errno)
  end
  true
end

def create_process(app, cmd, process_security, thread_security, inherit,
  creation_flags, env, cwd, startinfo, procinfo)
  bool = CreateProcessW(
    app,               # App name
    cmd,               # Command line
    process_security,  # Process attributes
    thread_security,   # Thread attributes
    inherit,           # Inherit handles?
    creation_flags,    # Creation flags
    env,               # Environment
    cwd,               # Working directory
    startinfo,         # Startup Info
    procinfo           # Process Info
  )
  unless bool
    raise SystemCallError.new("CreateProcessW", FFI.errno)
  end
end

def create_process_as_user(token, app, cmd, process_security,
  thread_security, inherit, creation_flags, env, cwd, startinfo, procinfo)
  bool = CreateProcessAsUserW(
    token,            # User token handle
    app,              # App name
    cmd,              # Command line
    process_security, # Process attributes
    thread_security,  # Thread attributes
    inherit,          # Inherit handles
    creation_flags,   # Creation Flags
    env,              # Environment
    cwd,              # Working directory
    startinfo,        # Startup Info
    procinfo          # Process Info
  )
  unless bool
    msg = case FFI.errno
          when ERROR_PRIVILEGE_NOT_HELD
            [
              %{CreateProcessAsUserW (User '%s' must hold the 'Replace a process},
              %{level token' and 'Adjust Memory Quotas for a process' permissions.},
              %{Logoff the user after adding this right to make it effective.)},
            ].join(" ") % ::ENV["USERNAME"]
          else
            "CreateProcessAsUserW failed."
          end
    raise SystemCallError.new(msg, FFI.errno)
  end
end

def create_process_with_logon(logon, domain, passwd, logon_flags, app, cmd,
  creation_flags, env, cwd, startinfo, procinfo)
  bool = CreateProcessWithLogonW(
    logon,           # User
    domain,          # Domain
    passwd,          # Password
    logon_flags,     # Logon flags
    app,             # App name
    cmd,             # Command line
    creation_flags,  # Creation flags
    env,             # Environment
    cwd,             # Working directory
    startinfo,       # Startup Info
    procinfo         # Process Info
  )
  unless bool
    raise SystemCallError.new("CreateProcessWithLogonW", FFI.errno)
  end
end

def destroy_environment_block(env_pointer)
  unless DestroyEnvironmentBlock(env_pointer)
    raise SystemCallError.new("DestroyEnvironmentBlock", FFI.errno)
  end
  true
end

def environment_list_to_hash(env_var)
  Hash[ env_var.map { |pair| pair.split("=", 2) } ]
end

def format_creds_from_hash(hash)
  logon = hash["with_logon"].to_wide_string
  if hash["password"]
    passwd = hash["password"].to_wide_string
  else
    raise ArgumentError, "password must be specified if with_logon is used"
  end
  if hash["domain"]
    domain = hash["domain"].to_wide_string
  end
  [ logon, passwd, domain ]
end

def get_profile_type
  ptr = FFI::MemoryPointer.new(:uint)
  unless GetProfileType(ptr)
    raise SystemCallError.new("GetProfileType", FFI.errno)
  end
  ptr.read_uint
end

def get_windows_station_name
  winsta_name = FFI::MemoryPointer.new(:char, 256)
  return_size = FFI::MemoryPointer.new(:ulong)
  bool = GetUserObjectInformationA(
    GetProcessWindowStation(),  # Window station handle
    UOI_NAME,                   # Information to get
    winsta_name,                # Buffer to receive information
    winsta_name.size,           # Size of buffer
    return_size                 # Size filled into buffer
  )
  unless bool
    raise SystemCallError.new("GetUserObjectInformationA", FFI.errno)
  end
  winsta_name.read_string(return_size.read_ulong)
end

def load_user_profile(token, profile_ptr)
  unless LoadUserProfileW(token, profile_ptr)
    raise SystemCallError.new("LoadUserProfileW", FFI.errno)
  end
  true
end

def logon_has_roaming_profile?
  get_profile_type >= 2
end

def logon_user(user, domain, passwd, type, provider = LOGON32_PROVIDER_DEFAULT)
  token = FFI::MemoryPointer.new(:ulong)
  bool = LogonUserW(
    user,                       # User
    domain,                     # Domain
    passwd,                     # Password
    type,                       # Logon Type
    provider,                   # Logon Provider
    token                       # User token handle
  )
  unless bool
    if (FFI.errno == ERROR_LOGON_TYPE_NOT_GRANTED) && (type == LOGON32_LOGON_BATCH)
      user_utf8 = user.encode( "UTF-8", invalid: :replace, undef: :replace, replace: "" ).delete("\0")
      raise SystemCallError.new("LogonUserW (User '#{user_utf8}' must hold 'Log on as a batch job' permissions.)", FFI.errno)
    else
      raise SystemCallError.new("LogonUserW", FFI.errno)
    end
  end
  token.read_ulong
end

def merge_env_variables(fetched_env, current_env)
  env_hash_1 = environment_list_to_hash(fetched_env)
  env_hash_2 = environment_list_to_hash(current_env)
  merged_env = env_hash_2.merge(env_hash_1)
  merged_env.map { |k, v| "#{k}=#{v}" }
end

def retrieve_environment_variables(token)
  env_list = []
  env_pointer = FFI::MemoryPointer.new(:pointer)
  create_environment_block(env_pointer, token)
  str_ptr = env_pointer.read_pointer
  offset = 0
  loop do
    new_str_pointer = str_ptr + offset
    break if new_str_pointer.read_string(2) == ENVIRONMENT_BLOCK_ENDS
    environment = new_str_pointer.read_wstring
    env_list << environment
    offset = offset + environment.length * 2 + 2
  end
  # To free the buffer when we have finished with the environment block
  destroy_environment_block(str_ptr)
  env_list
end

def unload_user_profile(token, profile)
  if profile[:hProfile] == 0
    warn "\n\nWARNING: Profile not loaded\n"
  else
    unless UnloadUserProfile(token, profile[:hProfile])
      raise SystemCallError.new("UnloadUserProfile", FFI.errno)
    end
  end
  true
end