require 'ffi'
require 'puppet/util/windows/string'

module Puppet::Util::Windows::APITypes
  module ::FFI
    WIN32_FALSE = 0

    # standard Win32 error codes
    ERROR_SUCCESS = 0
  end

  module ::FFI::Library
    # Wrapper method for attach_function + private
    def attach_function_private(*args)
      attach_function(*args)
      private args[0]
    end
  end

  class ::FFI::Pointer
    NULL_HANDLE = 0

    def self.from_string_to_wide_string(str, &block)
      str = Puppet::Util::Windows::String.wide_string(str)
      FFI::MemoryPointer.new(:byte, str.bytesize) do |ptr|
        # uchar here is synonymous with byte
        ptr.put_array_of_uchar(0, str.bytes.to_a)

        yield ptr
      end

      # ptr has already had free called, so nothing to return
      nil
    end

    def read_win32_bool
      # BOOL is always a 32-bit integer in Win32
      # some Win32 APIs return 1 for true, while others are non-0
      read_int32 != FFI::WIN32_FALSE
    end

    alias_method :read_dword, :read_uint32
    alias_method :read_win32_ulong, :read_uint32
    alias_method :read_qword, :read_uint64

    alias_method :read_hresult, :read_int32

    def read_handle
      type_size == 4 ? read_uint32 : read_uint64
    end

    alias_method :read_wchar, :read_uint16
    alias_method :read_word,  :read_uint16
    alias_method :read_array_of_wchar, :read_array_of_uint16

    def read_wide_string(char_length, dst_encoding = Encoding::UTF_8, encode_options = {})
      # char_length is number of wide chars (typically excluding NULLs), *not* bytes
      str = get_bytes(0, char_length * 2).force_encoding('UTF-16LE')
      str.encode(dst_encoding, str.encoding, encode_options)
    rescue Exception => e
      Puppet.debug "Unable to convert value #{str.nil? ? 'nil' : str.dump} to encoding #{dst_encoding} due to #{e.inspect}"
      raise
    end

    # @param max_char_length [Integer] Maximum number of wide chars to return (typically excluding NULLs), *not* bytes
    # @param null_terminator [Symbol] Number of number of null wchar characters, *not* bytes, that determine the end of the string
    #   null_terminator = :single_null, then the terminating sequence is two bytes of zero.   This is UNIT16 = 0
    #   null_terminator = :double_null, then the terminating sequence is four bytes of zero.  This is UNIT32 = 0
    # @param encode_options [Hash] Accepts the same option hash that may be passed to String#encode in Ruby
    def read_arbitrary_wide_string_up_to(max_char_length = 512, null_terminator = :single_null, encode_options = {})
      if null_terminator != :single_null && null_terminator != :double_null
        raise _("Unable to read wide strings with %{null_terminator} terminal nulls") % { null_terminator: null_terminator }
      end

      terminator_width = null_terminator == :single_null ? 1 : 2
      reader_method = null_terminator == :single_null ? :get_uint16 : :get_uint32

      # Look for a null terminating characters; if found, read up to that null (exclusive)
      (0...max_char_length - terminator_width).each do |i|
        return read_wide_string(i, Encoding::UTF_8, encode_options) if send(reader_method, (i * 2)) == 0
      end

      # String is longer than the max; read just to the max
      read_wide_string(max_char_length, Encoding::UTF_8, encode_options)
    end

    def read_win32_local_pointer(&block)
      ptr = nil
      begin
        ptr = read_pointer
        yield ptr
      ensure
        if ptr && ! ptr.null?
          if FFI::WIN32::LocalFree(ptr.address) != FFI::Pointer::NULL_HANDLE
            Puppet.debug "LocalFree memory leak"
          end
        end
      end

      # ptr has already had LocalFree called, so nothing to return
      nil
    end

    def read_com_memory_pointer(&block)
      ptr = nil
      begin
        ptr = read_pointer
        yield ptr
      ensure
        FFI::WIN32::CoTaskMemFree(ptr) if ptr && ! ptr.null?
      end

      # ptr has already had CoTaskMemFree called, so nothing to return
      nil
    end


    alias_method :write_dword, :write_uint32
    alias_method :write_word, :write_uint16
  end

  # FFI Types
  # https://github.com/ffi/ffi/wiki/Types

  # Windows - Common Data Types
  # https://msdn.microsoft.com/en-us/library/cc230309.aspx

  # Windows Data Types
  # https://msdn.microsoft.com/en-us/library/windows/desktop/aa383751(v=vs.85).aspx

  FFI.typedef :uint16, :word
  FFI.typedef :uint32, :dword
  # uintptr_t is defined in an FFI conf as platform specific, either
  # ulong_long on x64 or just ulong on x86
  FFI.typedef :uintptr_t, :handle
  FFI.typedef :uintptr_t, :hwnd

  # buffer_inout is similar to pointer (platform specific), but optimized for buffers
  FFI.typedef :buffer_inout, :lpwstr
  # buffer_in is similar to pointer (platform specific), but optimized for CONST read only buffers
  FFI.typedef :buffer_in, :lpcwstr
  FFI.typedef :buffer_in, :lpcolestr

  # string is also similar to pointer, but should be used for const char *
  # NOTE that this is not wide, useful only for A suffixed functions
  FFI.typedef :string, :lpcstr

  # pointer in FFI is platform specific
  # NOTE: for API calls with reserved lpvoid parameters, pass a FFI::Pointer::NULL
  FFI.typedef :pointer, :lpcvoid
  FFI.typedef :pointer, :lpvoid
  FFI.typedef :pointer, :lpword
  FFI.typedef :pointer, :lpbyte
  FFI.typedef :pointer, :lpdword
  FFI.typedef :pointer, :pdword
  FFI.typedef :pointer, :phandle
  FFI.typedef :pointer, :ulong_ptr
  FFI.typedef :pointer, :pbool
  FFI.typedef :pointer, :lpunknown

  # any time LONG / ULONG is in a win32 API definition DO NOT USE platform specific width
  # which is what FFI uses by default
  # instead create new aliases for these very special cases
  # NOTE: not a good idea to redefine FFI :ulong since other typedefs may rely on it
  FFI.typedef :uint32, :win32_ulong
  FFI.typedef :int32, :win32_long
  # FFI bool can be only 1 byte at times,
  # Win32 BOOL is a signed int, and is always 4 bytes, even on x64
  # https://blogs.msdn.com/b/oldnewthing/archive/2011/03/28/10146459.aspx
  FFI.typedef :int32, :win32_bool

  # BOOLEAN (unlike BOOL) is a BYTE - typedef unsigned char BYTE;
  FFI.typedef :uchar, :boolean

  # Same as a LONG, a 32-bit signed integer
  FFI.typedef :int32, :hresult

  # NOTE: FFI already defines (u)short as a 16-bit (un)signed like this:
  # FFI.typedef :uint16, :ushort
  # FFI.typedef :int16, :short

  # 8 bits per byte
  FFI.typedef :uchar, :byte
  FFI.typedef :uint16, :wchar

  module ::FFI::WIN32
    extend ::FFI::Library

    # https://msdn.microsoft.com/en-us/library/windows/desktop/aa373931(v=vs.85).aspx
    # typedef struct _GUID {
    #   DWORD Data1;
    #   WORD  Data2;
    #   WORD  Data3;
    #   BYTE  Data4[8];
    # } GUID;
    class GUID < FFI::Struct
      layout :Data1, :dword,
             :Data2, :word,
             :Data3, :word,
             :Data4, [:byte, 8]

      def self.[](s)
        raise _('Bad GUID format.') unless s =~ /^[0-9a-f]{8}-([0-9a-f]{4}-){3}[0-9a-f]{12}$/i

        new.tap do |guid|
          guid[:Data1] = s[0, 8].to_i(16)
          guid[:Data2] = s[9, 4].to_i(16)
          guid[:Data3] = s[14, 4].to_i(16)
          guid[:Data4][0] = s[19, 2].to_i(16)
          guid[:Data4][1] = s[21, 2].to_i(16)
          s[24, 12].split('').each_slice(2).with_index do |a, i|
            guid[:Data4][i + 2] = a.join('').to_i(16)
          end
        end
      end

      def ==(other) Windows.memcmp(other, self, size) == 0 end
    end

    # https://msdn.microsoft.com/en-us/library/windows/desktop/ms724950(v=vs.85).aspx
    # typedef struct _SYSTEMTIME {
    #   WORD wYear;
    #   WORD wMonth;
    #   WORD wDayOfWeek;
    #   WORD wDay;
    #   WORD wHour;
    #   WORD wMinute;
    #   WORD wSecond;
    #   WORD wMilliseconds;
    # } SYSTEMTIME, *PSYSTEMTIME;
    class SYSTEMTIME < FFI::Struct
      layout :wYear, :word,
             :wMonth, :word,
             :wDayOfWeek, :word,
             :wDay, :word,
             :wHour, :word,
             :wMinute, :word,
             :wSecond, :word,
             :wMilliseconds, :word

      def to_local_time
        Time.local(self[:wYear], self[:wMonth], self[:wDay],
          self[:wHour], self[:wMinute], self[:wSecond], self[:wMilliseconds] * 1000)
      end
    end

    # https://msdn.microsoft.com/en-us/library/windows/desktop/ms724284(v=vs.85).aspx
    # Contains a 64-bit value representing the number of 100-nanosecond
    # intervals since January 1, 1601 (UTC).
    # typedef struct _FILETIME {
    #   DWORD dwLowDateTime;
    #   DWORD dwHighDateTime;
    # } FILETIME, *PFILETIME;
    class FILETIME < FFI::Struct
      layout :dwLowDateTime, :dword,
             :dwHighDateTime, :dword
    end

    ffi_convention :stdcall

    # https://msdn.microsoft.com/en-us/library/windows/desktop/aa366730(v=vs.85).aspx
    # HLOCAL WINAPI LocalFree(
    #   _In_  HLOCAL hMem
    # );
    ffi_lib :kernel32
    attach_function :LocalFree, [:handle], :handle

    # https://msdn.microsoft.com/en-us/library/windows/desktop/ms724211(v=vs.85).aspx
    # BOOL WINAPI CloseHandle(
    #   _In_  HANDLE hObject
    # );
    ffi_lib :kernel32
    attach_function_private :CloseHandle, [:handle], :win32_bool

    # https://msdn.microsoft.com/en-us/library/windows/desktop/ms680722(v=vs.85).aspx
    # void CoTaskMemFree(
    #   _In_opt_  LPVOID pv
    # );
    ffi_lib :ole32
    attach_function :CoTaskMemFree, [:lpvoid], :void
  end
end
