require 'mork/grid_omr'
require 'mork/mimage'
require 'mork/mimage_list'

module Mork
  class SheetOMR

    def initialize(path, nitems=nil, grom=nil)
      raise IOError, "File '#{path}' not found" unless File.exists? path
      @grom   = GridOMR.new grom
      @nitems = case nitems
                when nil
                  [@grom.max_choices_per_question] * @grom.max_questions
                when Fixnum
                  [@grom.max_choices_per_question] * nitems
                when Array
                  nitems
                end
      @mim    = Mimage.new path, @nitems, @grom
    end

    def valid?
      @mim.valid?
    end

    def status
      @mim.status
    end

    # barcode
    #
    # returns the sheet barcode as an integer
    def barcode
      return if not_registered
      barcode_string.to_i(2)
    end

    # barcode_string
    #
    # returns the sheet barcode as a string of 0s and 1s. The string is barcode_bits
    # bits long, with most significant bits to the left
    def barcode_string
      return if not_registered
      cs = @grom.barcode_bits.times.inject("") { |c, v| c << barcode_bit_string(v) }
      cs.reverse
    end

    # marked?(question, choice)
    #
    # returns true if the specified question/choice cell has been darkened
    # false otherwise
    def marked?(q, c)
      return if not_registered
      @mim.marked? q, c
    end

    # TODO: define method ‘mark’ to retrieve the choice array for a single item


    # mark_array(range)
    #
    # returns an array of arrays of marked choices.
    # takes either a range of questions, an array of questions, or a fixnum,
    # in which case the choices for the first n questions will be returned.
    # if called without arguments, all available choices will be evaluated.
    def mark_array(r = nil)
      return if not_registered
      question_range(r).collect do |q|
        cho = []
        (0...@grom.max_choices_per_question).each do |c|
          cho << c if marked?(q, c)
        end
        cho
      end
    end

    # mark_char_array(range)
    #
    # returns an array of arrays of the characters corresponding to marked choices.
    # WARNING: at this time, only the latin sequence 'A, B, C...' is supported.
    # takes either a range of questions, an array of questions, or a fixnum,
    # in which case the choices for the first n questions will be returned.
    # if called without arguments, all available choices will be evaluated.
    def mark_char_array(r = nil)
      return if not_registered
      question_range(r).collect do |q|
        cho = []
        (0...@grom.max_choices_per_question).each do |c|
          cho << (65+c).chr if marked?(q, c)
        end
        cho
      end
    end

    def mark_logical_array(r = nil)
      return if not_registered
      question_range(r).collect do |q|
        (0...@grom.max_choices_per_question).collect {|c| marked?(q, c)}
      end
    end

    # ================
    # = HIGHLIGHTING =
    # ================

    def outline(cells)
      return if not_registered
      raise "Invalid ‘cells’ argument" unless cells.kind_of? Array
      @mim.outline cells
    end

    def cross(cells)
      return if not_registered
      raise "Invalid ‘cells’ argument" unless cells.kind_of? Array
      @mim.cross cells
    end

    def cross_marked
      return if not_registered
      @mim.cross mark_array
    end

    def highlight_marked
      return if not_registered
      @mim.highlight_cells mark_array
    end

    def highlight_all_choices
      return if not_registered
      @mim.highlight_all_choices
    end

    def highlight_barcode
      return if not_registered
      @mim.highlight_barcode barcode_string
    end

    # write(output_path_file_name)
    #
    # writes out a copy of the source image after registration;
    # the output image will also contain any previously applied overlays;
    # if the argument is omitted, the image is created in-place,
    # i.e. the original source image is overwritten.
    def write(fname=nil)
      return if not_registered
      @mim.write(fname)
    end

    # # write_raw(output_path_file_name)
    # #
    # # writes out a copy of the source image before registration;
    # # the output image will also contain any previously applied overlays
    # # if the argument is omitted, the image is created in-place,
    # # i.e. the original source image is overwritten.
    # def write_raw(fname=nil)
    #   @mim.write(fname, false)
    # end

    def write_registration(fname)
      @mim.highlight_rm_areas
      @mim.highlight_rm_centers
      @mim.write fname, false
    end

    # ============================================================#
    private                                                       #
    # ============================================================#

    def barcode_bit_string(i)
      @mim.barcode_bit?(i) ? "1" : "0"
    end

    def question_range(r)
      # TODO: help text: although not API, people need to know this!
      if r.nil?
        (0...@nitems.length)
      elsif r.is_a? Fixnum
        (0...r)
      elsif r.is_a? Array
        r
      else
        raise "Invalid argument"
      end
    end

    def not_registered
      unless valid?
        puts "---=={ Unregistered image. Reason: '#{@mim.status.inspect}' }==---"
        true
      end
    end
  end
end