# frozen_string_literal: true

require_relative "utils"

module Clipboard
  module Windows
    extend self

    CF_TEXT = 1
    CF_UNICODETEXT = 13
    GMEM_MOVEABLE = 2

    # get ffi function handlers
    begin
      require 'ffi'
    rescue LoadError
      raise LoadError, 'Could not load the required ffi gem, install it with: gem install ffi'
    end

    module User32
      extend FFI::Library
      ffi_lib "user32"
      ffi_convention :stdcall

      attach_function :open,  :OpenClipboard,    [ :long ], :long
      attach_function :close, :CloseClipboard,   [       ], :long
      attach_function :empty, :EmptyClipboard,   [       ], :long
      attach_function :get,   :GetClipboardData, [ :long ], :long
      attach_function :set,   :SetClipboardData, [ :long, :long ], :long
    end

    module Kernel32
      extend FFI::Library
      ffi_lib 'kernel32'
      ffi_convention :stdcall

      attach_function :lock,   :GlobalLock,   [ :long ], :pointer
      attach_function :unlock, :GlobalUnlock, [ :long ], :long
      attach_function :size,   :GlobalSize,   [ :long ], :long
      attach_function :alloc,  :GlobalAlloc,  [ :long, :long ], :long
    end

    # see http://www.codeproject.com/KB/clipboard/archerclipboard1.aspx
    def paste(_ = nil)
      data = "".dup
      if 0 != User32.open( 0 )
        hclip = User32.get( CF_UNICODETEXT )
        if hclip && 0 != hclip
          pointer_to_data = Kernel32.lock( hclip )
          # Windows Unicode is ended by two null bytes, so get the whole string
          size = Kernel32.size( hclip )
          data << pointer_to_data.get_bytes( 0, size - 2 )
          data.force_encoding("UTF-16LE")
          Kernel32.unlock( hclip )
        end
        User32.close( )
      end
      data
    end

    def clear
      if 0 != User32.open( 0 )
        User32.empty( )
        User32.close( )
      end
      paste
    end

    def copy(data_to_copy)
      if 0 != User32.open( 0 )
        User32.empty( )
        data = data_to_copy.encode("UTF-16LE") # TODO: catch bad encodings
        data << 0
        handler = Kernel32.alloc( GMEM_MOVEABLE, data.bytesize )
        pointer_to_data = Kernel32.lock( handler )
        pointer_to_data.put_bytes( 0, data, 0, data.bytesize )
        Kernel32.unlock( handler )
        User32.set( CF_UNICODETEXT, handler )
        User32.close( )
      else # don't touch anything
        Utils.popen "clip", data_to_copy # depends on clip (available by default since Vista)
      end
      paste
    end
  end
end