require 'tempfile'

module RDvdSlideshow
  
  #
  # A SlideshowInput is responsible for building the input file used by dvd-slideshow.
  # 
  class SlideshowInput
    
    #
    # Initializes the file path and write the content of the file.
    # If no file path is given, a temp file is used (Tempfile).
    # The provided block is used to build the content of the file.
    # The file is flushed after writing.
    #
    def initialize(file_path=nil,&block)
      @file = file_path ? File.new(file_path,'w') : Tempfile.new('slideshow_input')
      
      block.call(self) if block
      @file.flush
    end
    
    # Path to the path where slideshow input configuration is written
    def file_path
      @file.path
    end
    
    #
    # Adds a new image
    #
    def image(path,duration,options={})
      write_line(path,duration,options,[:subtitle,:effect,:effect_params])
    end
    
    #
    # Adds a title
    #
    def title(duration,text)
      write_line("title",duration,{:text=>text},[:text])
    end
    
    #
    # Adds a title bar
    # Possible options are : _upper\_title_ and _lower\_title_
    #
    def titlebar(duration,options={})
      write_line("titlebar",duration,options,[:upper_title,:lower_title])
    end
    
    #
    # Adds a music
    # Possible options are : _subtitle_
    #
    def musictitle(duration,options={})
      write_line("musictitle",duration,options,[:subtitle])
    end
    
    def fadein(duration,options={})
      write_line("fadein",duration,options,[:subtitle])
    end
    
    def fadeout(duration,options={})
      write_line("fadeout",duration,options,[:subtitle])
    end
    
    #
    # Adds an exit command
    #
    def exit
      @file.puts "exit"
    end
    
    protected
    
    def separator
      ':'
    end
    
    def write_line(keyword,duration,options={},sorted_keys=[])
      @file.puts build_line(keyword,duration,options,sorted_keys)
    end
    
    def build_line(keyword,duration,options={},sorted_keys=[])
      line = keyword + separator + format_duration(duration)
      index = 0
      remaining_options = options.values.length
      while remaining_options > 0
        line << separator
        value = options[sorted_keys[index]]
        line << (value || "")
        index += 1
        remaining_options -= 1 if value
      end
      return line
    end
    
    def format_duration(duration)
       "%.3f" % duration.to_f
    end
    
  end

end