module FFMPEG
  # @since 1.0.0-beta2
  class RecorderOptions
    DEFAULT_LOG_FILE = 'ffmpeg.log'

    def initialize(options)
      @options = verify_options options
    end

    #
    # Returns given recording format
    #
    def format
      determine_format
    end

    #
    # Returns given framerate
    #
    def framerate
      @options[:framerate]
    end

    #
    # Returns given input file or infile
    #
    def infile
      @options[:infile]
    end

    #
    # Returns given output filepath
    #
    def output
      @options[:output]
    end

    #
    # Returns given values that are optional
    #
    def advanced
      @options[:advanced]
    end

    #
    # Returns given log filename
    #
    def log
      @options[:log] || DEFAULT_LOG_FILE
    end

    #
    # Returns given log_level
    #
    def log_level
      @options[:log_level]
    end

    #
    # Returns all given options
    #
    def all
      @options
    end

    #
    # Returns a String with all options parsed as a String,
    # ready for the ffmpeg process to use
    #
    def parsed
      vals = "-f #{determine_format} "
      vals << "-r #{@options[:framerate]} "
      vals << advanced_options if @options[:advanced]
      vals << "-i #{determine_infile} "
      vals << @options[:output]
      vals << ffmpeg_log_to(@options[:log]) # If provided
    end

    private

    #
    # Verifies the required options are provided and returns
    # the given options Hash
    #
    def verify_options(options)
      missing_options = required_options.select { |req| options[req].nil? }
      err             = "Required options are missing: #{missing_options}"
      raise(ArgumentError, err) unless missing_options.empty?

      options
    end

    #
    # Returns Array of required options sa Symbols
    #
    def required_options
      # -r framerate
      # -i input
      # output
      return %i[framerate infile output] unless OS.linux?

      %i[framerate output] # Linux
    end

    #
    # Returns advanced options parsed and ready for ffmpeg to receive.
    #
    def advanced_options
      return nil unless @options[:advanced]
      raise(ArgumentError, ':advanced cannot be empty.') if options[:advanced].empty?

      arr = []
      options[:advanced].each do |k, v|
        arr.push "-#{k} #{v}"
      end
      arr.join(' ') + ' '
    end

    #
    # Returns logging command with user given log file
    # from options or the default file.
    #
    def ffmpeg_log_to(file)
      file ||= DEFAULT_LOG_FILE
      " 2> #{file}"
    end

    #
    # Returns final infile parameter.
    # Adds title= qualifier to infile parameter
    # unless the user is recording the desktop.
    #
    def determine_infile
      # x11grab doesn't support window capture
      return ':0.0' if OS.linux?

      return @options[:infile] if @options[:infile] == 'desktop'

      # Windows only
      %("title=#{@options[:infile]}")
    end

    #
    # Returns format based on the current OS.
    #
    def determine_format
      return @options[:format] if @options[:format]

      if OS.windows?
        'gdigrab'
      elsif OS.linux?
        'x11grab'
      elsif OS.mac?
        'avfoundation'
      else
        raise NotImplementedError, 'Your OS is not supported.'
      end
    end
  end
end