# OrigenLinkPin class manipulate input/output pins of the Udoo
# using exported file objects.  If the pin is not exported, it
# will be exported when a pin is initialized
#
# initialize:
#  description - This method will execute system command
#                "sudo echo ionumber > /sys/class/gpio/export"
#                to create the IO file interface.  It will
#                set the direction, initial pin state and initialize
#                instance variables
#  ionumber - required, value indicating the pin number (BCM IO number,
#             not the header pin number)
#  direction - optional, specifies the pin direction.  A pin is
#              initialized as an input if a direction isn't specified.
#
#
#  out:
#    description - Sets the output state of the pin.  If the pin
#                  is setup as an input, the direction will first
#                  be changed to output.
#
#
#  in:
#    description - Reads and returns state of the pin.  If the pin
#                  is setup as an output, the direction will first
#                  be changed to input.
#
#
#  update_direction:
#    description - Sets the pin direction
#
#  direction - specifies the pin direction.  A pin is
#              initialized as an input if a direction isn't specified.
#
#  Valid direction values:
#    :in	-	input
#    :out	-	output
#    :out_high	-	output, initialized high
#    :out_low	-	output, initialized low
class OrigenLinkPin
  @@pin_setup = {
    in:			    'in',
    out:		    'out',
    out_high:	'high',
    out_low:		'low'
  }

  attr_reader :gpio_valid

  def initialize(ionumber, direction = :in)
    @ionumber = Integer(ionumber)
    @pin_dir_name = "/sys/class/gpio/gpio#{@ionumber}/direction"
    @pin_val_name = "/sys/class/gpio/gpio#{@ionumber}/value"
    if notFile.exist?(@pin_dir_name)
      system("echo #{@ionumber} > /sys/class/gpio/export")
      sleep 0.05
      if $CHILD_STATUS == 0
        @gpio_valid = true
      else
        @gpio_valid = false
      end
    else
      @gpio_valid = true
    end
    if @gpio_valid
      if File.writable?(@pin_dir_name)
        @pin_dir_obj = File.open(@pin_dir_name, 'w')
        update_direction(direction)
      else
        @gpio_valid = false
        puts "#{@pin_dir_name} is not writable. Fix permissions or run as super user."
      end
      @pin_val_obj = File.open(@pin_val_name, 'r+') if @gpio_valid
    end
  end

  def destroy
    if @gpio_valid
      @pin_dir_obj.close
      @pin_val_obj.close
      system("echo #{@ionumber} > /sys/class/gpio/unexport")
      puts "pin #{@ionumber} is no longer exported"
    end
  end

  def out(value)
    if @gpio_valid
      if @direction == :in
        if value == 1
          update_direction(:out_high)
        else
          update_direction(:out_low)
        end
      end
      @pin_val_obj.write(value)
      @pin_val_obj.flush
    end
  end

  # rubocop:disable Style/EmptyElse: Redundant else-clause.
  def in
    if @gpio_valid
      if @direction == :out
        update_direction(:in)
      end
      # below is original read - slow to reopen every time
      # File.open(@pin_val_name, 'r') do |file|
      #  file.read#.chomp
      # end
      # end original read
      @pin_val_obj.pos = 0
      @pin_val_obj.getc
    else
      nil
    end
  end

  def update_direction(direction)
    if @gpio_valid
      @pin_dir_obj.pos = 0
      @pin_dir_obj.write(@@pin_setup[direction])
      @pin_dir_obj.flush
      if direction == :in
        @direction = direction
      else
        @direction = :out
      end
    end
  end

  def to_s
    'OrigenLinkPin' + @ionumber.to_s
  end
end