require 'open3'

module FFMPEG
  class Transcoder
    def initialize(movie, output_file, options = EncodingOptions.new, transcoder_options = {})
      @movie = movie
      @output_file = output_file
      
      if options.is_a?(String) || options.is_a?(EncodingOptions)
        @raw_options = options
      elsif options.is_a?(Hash)
        @raw_options = EncodingOptions.new(options)
      else
        raise ArgumentError, "Unknown options format '#{options.class}', should be either EncodingOptions, Hash or String."
      end
      
      @transcoder_options = transcoder_options
      @errors = []
      
      apply_transcoder_options
    end
    
    def run
      command = "ffmpeg -y -i '#{@movie.path}' #{@raw_options} '#{@output_file}'"
      FFMPEG.logger.info("Running transcoding...\n#{command}\n")
      output = ""
      last_output = nil
      Open3.popen3(command) do |stdin, stdout, stderr|
        stderr.each("r") do |line|
          output << line
          if line =~ /time=(\d+.\d+)/
            time = $1.to_f
            progress = time / @movie.duration
            yield(progress) if block_given?
          end
          if line =~ /Unsupported codec/
            FFMPEG.logger.error "Failed encoding...\nCommand\n#{command}\nOutput\n#{output}\n"
            raise "Failed encoding: #{line}"
          end
        end
      end

      if encoding_succeeded?
        FFMPEG.logger.info "Transcoding of #{@movie.path} to #{@output_file} succeeded\n"
        yield(1.0) if block_given?
      else
        errors = @errors.empty? ? "" : " Errors: #{@errors.join(", ")}. "
        FFMPEG.logger.error "Failed encoding...\n#{command}\n\n#{output}\n#{errors}\n"
        raise "Failed encoding.#{errors}Full output: #{output}"
      end
      
      encoded
    end
    
    def encoding_succeeded?
      unless File.exists?(@output_file)
        @errors << "no output file created"
        return false
      end
      
      unless encoded.valid?
        @errors << "encoded file is invalid"
        return false
      end
      
      if validate_duration?
        precision = @raw_options[:duration] ? 1.5 : 1.1
        desired_duration = @raw_options[:duration] && @raw_options[:duration] < @movie.duration ? @raw_options[:duration] : @movie.duration
        if (encoded.duration >= (desired_duration * precision) or encoded.duration <= (desired_duration / precision))
          @errors << "encoded file duration differed from original/specified duration (wanted: #{desired_duration}sec, got: #{encoded.duration}sec)"
          return false
        end
      end
      
      true
    end
    
    def encoded
      @encoded ||= Movie.new(@output_file)
    end
    
    private
    def apply_transcoder_options
      return if @movie.calculated_aspect_ratio.nil?
      case @transcoder_options[:preserve_aspect_ratio].to_s
      when "width"
        new_height = @raw_options.width / @movie.calculated_aspect_ratio
        new_height = new_height.ceil.even? ? new_height.ceil : new_height.floor
        new_height += 1 if new_height.odd? # needed if new_height ended up with no decimals in the first place
        @raw_options[:resolution] = "#{@raw_options.width}x#{new_height}"
      when "height"
        new_width = @raw_options.height * @movie.calculated_aspect_ratio
        new_width = new_width.ceil.even? ? new_width.ceil : new_width.floor
        new_width += 1 if new_width.odd?
        @raw_options[:resolution] = "#{new_width}x#{@raw_options.height}"
      end
    end
    
    def validate_duration?
      return false if @movie.uncertain_duration?
      return false if %w(.jpg .png).include?(File.extname(@output_file))
      true
    end
  end
end