require 'fs/iso9660/directory_entry'
require 'binary_struct'

module Iso9660
  class Directory
    # Find entry flags.
    FE_DIR = 0
    FE_FILE = 1
    FE_EITHER = 2

    # System Use Sharing Protocol header (for Rock Ridge in this implementation).
    SUSP = BinaryStruct.new([
      'a2', 'signature',
      'C',  'len',
      'C',  'version',
      'n',  'check',
      'C',  'skip_bytes'
    ])
    SUSP_SIGNATURE  = "SP"
    SUSP_SIZE       = 7
    SUSP_VERSION    = 1
    SUSP_CHECK_WORD = 0xbeef

    attr_reader :myEnt, :susp

    def initialize(bs, thisEntry)
      raise "Boot sector is nil." if bs.nil?
      raise "No directory entry specified." if thisEntry.nil?
      raise "Given entry is not a DirectoryEntry" if thisEntry.class.to_s != "Iso9660::DirectoryEntry"

      @bs = bs
      @myEnt = thisEntry
      @data = getDirData

      # Check for RockRidge extensions.
      @susp = checkRockRidge(DirectoryEntry.new(@data, @bs.suff))
    end

    def getDirData
      @bs.getSectors(@myEnt.fileStart, @myEnt.fileSize / @bs.sectorSize)
    end

    def globNames
      names = []
      globEntries.each { |de| names << de.name }
      names
    end

    def findEntry(name, _flags = FE_EITHER)
      # TODO: enable flags
      globEntries.each do |de|
        return de if de.name == name        # Joliet & RR are case sensitive.
        return de if de.name == name.upcase # ISO 9660 is ucase only.
      end
      nil
    end

    def globEntries
      # Prep flag bits.
      flags = EXT_NONE
      flags |= EXT_JOLIET if @bs.isJoliet?
      flags |= EXT_ROCKRIDGE if @susp

      # Glob entries.
      entries = []
      offset = 0
      loop do
        de = DirectoryEntry.new(@data[offset..-1], @bs.suff, flags)
        break if de.length == 0
        entries << de
        # Debugging only.
        # puts "#{de.dump}\n"
        offset += de.length
      end
      entries
    end

    def checkRockRidge(de)
      if de.sua
        susp = SUSP.decode(de.sua)
        return nil if susp['signature'] != SUSP_SIGNATURE
        return nil if susp['len'] != SUSP_SIZE
        return nil if susp['check'] != SUSP_CHECK_WORD
        raise "System Use Sharing Protocol version mismatch" if susp['version'] != SUSP_VERSION
        return susp
      end
      nil
    end
  end # class
end # module