My first Ruby "app".

cdlib.rb

# -*- coding: utf-8 -*-

VERSION = "1.0"
DEFAULT_LIBRARY = "library.cdlib"

class Library
  attr_reader :entry_fields
  attr_accessor :path
  
  def initialize(path=DEFAULT_LIBRARY)
    begin
      @library = Marshal.load(File.open(path, 'r:binary'))
    rescue
      @library = { cds: [] }
      
      if path == DEFAULT_LIBRARY
        @path = path
      else
        @path = nil
      end
    else
      @path = path
    end
    
    @dirty = false
    @entry_fields = {
      artist: "Artist",
      title: "Title",
      year: "Year",
      genre: "Genre",
      tracks: "Tracks count",
      comment: "Comment"
    }
  end
  
  def dirty?()
    return @dirty
  end
  
  def has_file?()
    return @path != nil
  end
  
  def add()
    record = {}
    @entry_fields.each do |key, value|
      print "#{value}: "
      record[key] = STDIN.readline.chomp()
    end
    @library[:cds] << record
    @dirty = true
  end
  
  def list()
    @library[:cds].each_with_index do |item, index|
      puts cd_to_str(item, index)
    end
  end
  
  def save()
    if @path != nil
      Marshal.dump(@library, File.open(@path, 'w:binary'))
      @dirty = false
    end
  end
  
  def search(terms)
    idx = 0
    @library[:cds].each do |item|
      terms.each do |key, value|
        if item[key].index(Regexp.new("#{value}", Regexp::IGNORECASE)) != nil
          puts cd_to_str(item, idx)
          idx += 1
          break
        end
      end
    end
  end
  
  private
  def cd_to_str(item, index)
    return %Q|#{index + 1}. "#{item[:title]}" by #{item[:artist]} (#{item[:year]})|
  end
end

def ask_for_file_path(check_if_exists=true)
  path = nil
  loop do
    print "File path? "
    path = STDIN.readline.chomp()
    
    if path == ''
      next
    end
    
    if check_if_exists == true
      if File.file?(path) == true
        break
      end
    else
      break
    end
  end
  
  return path
end

def load_library()
  path = ask_for_file_path()
  return Library.new(path)
end

def menu()
  puts
  puts "[1] List CDs."
  puts "[2] Find a CD."
  puts "[3] Add a CD."
  puts "[4] Save the library."
  puts "---------------------"
  puts "[C] Create a new library."
  puts "[L] Load another library."
  puts "[Q] Quit."
  puts
  print "Your choice? "
  return STDIN.readline.chomp.downcase()
end

def main()
  title = "CD Library version #{VERSION} by Tomek Wójcik"
  puts title
  puts "-" * title.length
  
  library = nil
  
  if File.file?(DEFAULT_LIBRARY) == false
    print "Default library not found. [C]reate a new one or [L]oad existing? "
    choice = STDIN.readline.chomp.downcase()
    if choice == 'c'
      library = Library.new(DEFAULT_LIBRARY)
    else
      library = load_library()
    end
  else
    library = Library.new()
  end
  
  save_library = Proc.new do
    if library.has_file? == false
      path = ask_for_file_path(false)
      library.path = path
    end
    library.save()
  end
  
  save_dirty_library = Proc.new do
    if library.dirty? == true
      puts
      print "The library has been changed. Do you wish to save your changes [Y/n]? "
      choice = STDIN.readline.chomp.downcase
      if choice == 'y'
        save_library.call()
      end
    end
  end
  
  at_exit do
    save_dirty_library.call()
  end
  
  loop do
    case menu()
    when 'q'
      break
    when '1'
      library.list()
      print 'Press [ENTER] to continue'
      STDIN.readline()
    when '2'
      terms = {}
      library.entry_fields.each do |key, value|
        print "#{value}? "
        search = STDIN.readline.chomp()
        if search != ""
          terms[key] = search
        end
      end
      library.search(terms)
      print 'Press [ENTER] to continue'
      STDIN.readline()
    when '3'
      library.add()
    when '4'
      save_library.call()
    when 'c'
      save_dirty_library.call()
      library = Library.new(nil)
    when 'l'
      save_dirty_library.call()
      library = load_library()
    end
  end
end

main()