module Gzsl

# File lib/gzsl.rb, line 5
def self.generate( output_file_path, image_file_paths )
  return false if image_file_paths.empty?
  
  File.open( output_file_path, "wb" ){|output_file|
    output_file.write Dastbytes::Binary.pack( :uint8, 0 )
    output_file.write Dastbytes::Binary.pack( :uint16, image_file_paths.size )
    image_file_paths.each{|image_file_path|
      File.open( image_file_path, "rb" ){|input_file|
        bytes = input_file.read
        output_file.write Dastbytes::Binary.pack( :uint32, bytes.size )
        output_file.write bytes
      }
    }
  }
  true
end

# File lib/gzsl.rb, line 22
def self.parse( path )
  return nil if ! File.exists?( path )
  
  gzsl_hash = {
    :flags  => 0,
    :images => []
  }
  File.open( path, "rb" ){|f|
    gzsl_hash[ :flags ] = Dastbytes::Binary.unpack( :uint8, f.read( 1 ) ).first
    Dastbytes::Binary.unpack( :uint16, f.read( 2 ) ).first.times{
      image_size = Dastbytes::Binary.unpack( :uint32, f.read( 4 ) ).first
      gzsl_hash[ :images ].push f.read( image_size )
    }
  }
  gzsl_hash
end