require 'windows/error'
require 'windows/filesystem'
require 'windows/volume'

module Sys
   class Filesystem
      extend Windows::Error
      extend Windows::FileSystem
      extend Windows::Volume

      # Error raised if any of the Windows API functions fail.
      class Error < StandardError; end
      
      VERSION = '0.1.0'
      
      class Stat
         CASE_SENSITIVE_SEARCH      = 0x00000001  
         CASE_PRESERVED_NAMES       = 0x00000002  
         UNICODE_ON_DISK            = 0x00000004  
         PERSISTENT_ACLS            = 0x00000008  
         FILE_COMPRESSION           = 0x00000010  
         VOLUME_QUOTAS              = 0x00000020  
         SUPPORTS_SPARSE_FILES      = 0x00000040  
         SUPPORTS_REPARSE_POINTS    = 0x00000080  
         SUPPORTS_REMOTE_STORAGE    = 0x00000100  
         VOLUME_IS_COMPRESSED       = 0x00008000  
         SUPPORTS_OBJECT_IDS        = 0x00010000  
         SUPPORTS_ENCRYPTION        = 0x00020000  
         NAMED_STREAMS              = 0x00040000  
         READ_ONLY_VOLUME           = 0x00080000
         
         # The path of the file system.
         attr_reader :path

         # The file system block size.  MS Windows typically defaults to 4096.
         attr_reader :block_size

         # Fragment size. Meaningless at the moment.
         attr_reader :fragment_size

         # The total number of blocks available (used or unused) on the file
         # system.
         attr_reader :blocks

         # The total number of unused blocks.
         attr_reader :blocks_free

         # The total number of unused blocks available to unprivileged
         # processes. Identical to +blocks+ at the moment.
         attr_reader :blocks_available

         # Total number of files/inodes that can be created on the file system.
         # This attribute is always nil on MS Windows.
         attr_reader :files

         # Total number of free files/inodes that can be created on the file
         # system.  This attribute is always nil on MS Windows.
         attr_reader :files_free

         # Total number of available files/inodes for unprivileged processes
         # that can be created on the file system. This attribute is always
         # nil on MS Windows.
         attr_reader :files_available

         # The file system volume id.
         attr_reader :filesystem_id

         # A bit mask of file system flags.
         attr_reader :flags

         # The maximum length of a file name permitted on the file system.
         attr_reader :name_max

         # The file system type, e.g. NTFS, FAT, etc.
         attr_reader :base_type

         alias inodes files
         alias inodes_free files_free
         alias inodes_available files_available
      end
     
      # Returns a Filesystem::Stat object that contains information about the
      # +path+ file system.
      #
      def self.stat(path)
         bytes_avail = [0].pack('Q')
         bytes_free  = [0].pack('Q')
         total_bytes = [0].pack('Q')

         unless GetDiskFreeSpaceEx(path, bytes_avail, total_bytes, bytes_free)
            raise Error, get_last_error 
         end                           

         bytes_avail = bytes_avail.unpack('Q').first
         bytes_free  = bytes_free.unpack('Q').first
         total_bytes = total_bytes.unpack('Q').first

         sectors = [0].pack('Q')
         bytes   = [0].pack('Q')
         free    = [0].pack('Q')
         total   = [0].pack('Q')

         unless GetDiskFreeSpace(path, sectors, bytes, free, total)
            raise Error, get_last_error
         end

         sectors = sectors.unpack('Q').first
         bytes   = bytes.unpack('Q').first
         free    = free.unpack('Q').first
         total   = total.unpack('Q').first

         block_size   = sectors * bytes
         blocks_avail = total_bytes / block_size
         blocks_free  = bytes_free / block_size

         vol_name   = 0.chr * 260
         base_type  = 0.chr * 260
         vol_serial = [0].pack('L')
         name_max   = [0].pack('L')
         flags      = [0].pack('L')

         bool = GetVolumeInformation(
            path,
            vol_name,
            vol_name.size,
            vol_serial,
            name_max,
            flags,
            base_type,
            base_type.size
         )

         unless bool
            raise Error, get_last_error
         end

         vol_serial = vol_serial.unpack('L').first
         name_max   = name_max.unpack('L').first
         flags      = flags.unpack('L').first
         base_type  = base_type[/^[^\0]*/]

         stat_obj = Stat.new
         stat_obj.instance_variable_set(:@path, path)
         stat_obj.instance_variable_set(:@block_size, block_size)
         stat_obj.instance_variable_set(:@blocks, blocks_avail)
         stat_obj.instance_variable_set(:@blocks_available, blocks_avail)
         stat_obj.instance_variable_set(:@blocks_free, blocks_free)
         stat_obj.instance_variable_set(:@name_max, name_max)
         stat_obj.instance_variable_set(:@base_type, base_type)
         stat_obj.instance_variable_set(:@flags, flags)
         stat_obj.instance_variable_set(:@filesystem_id, vol_serial)
   
         stat_obj.freeze # Read-only object
      end
   end
end

# Some convenient methods for converting bytes to kb, mb, and gb.
# 
class Fixnum
   # call-seq:
   #  <tt>fix</tt>.to_kb
   #
   # Returns +fix+ in terms of kilobytes.
   def to_kb
      self / 1024
   end
   
   # call-seq:
   #  <tt>fix</tt>.to_mb
   #
   # Returns +fix+ in terms of megabytes.
   def to_mb
      self / 1048576
   end
   
   # call-seq:
   #  <tt>fix</tt>.to_gb
   #
   # Returns +fix+ in terms of gigabytes.
   def to_gb
      self / 1073741824
   end
end