class OsMapRef::InputProcessor

# File lib/os_map_ref/input_processor.rb, line 7
def initialize(input)
  @input = input
end

# File lib/os_map_ref/input_processor.rb, line 83
def determine_easting_and_northing
  match = easting_northing_pattern.match input
  easting = match[1]
  northing = match[3]
  length = northing.length > easting.length ? extended_length : normal_length
  [
    easting.ljust(normal_length, padding),
    northing.ljust(length, padding)
  ]
end

# File lib/os_map_ref/input_processor.rb, line 45
def determine_map_reference_elements
  match = map_reference_pattern.match input
  (1..3).collect { |n| match[n] }
end

# File lib/os_map_ref/input_processor.rb, line 79
def easting_and_northing
  @easting_and_northing ||= determine_easting_and_northing
end

# File lib/os_map_ref/input_processor.rb, line 26
def easting_northing_params
  {
    easting: easting_and_northing[0],
    northing: easting_and_northing[1]
  }
end

# File lib/os_map_ref/input_processor.rb, line 114
def easting_northing_pattern
  eastings = /\d{3,6}/  # 3 to 6 digits
  northings = /\d{3,7}/ # 3 to 7 digits
  decimals = /\.\d+/    # decimal point and trailing digits
  separator = /[\,\s]+/ # commas or spaces
  /(#{eastings}(#{decimals})?)#{separator}(#{northings}(#{decimals})?)/
end

# File lib/os_map_ref/input_processor.rb, line 94
def extended_length
  normal_length + 1
end

# File lib/os_map_ref/input_processor.rb, line 50
def grid_letters
  map_reference_elements[0]
end

# File lib/os_map_ref/input_processor.rb, line 54
def map_reference_easting
  map_reference_elements[1]
end

# File lib/os_map_ref/input_processor.rb, line 41
def map_reference_elements
  @map_reference_elements ||= determine_map_reference_elements
end

# File lib/os_map_ref/input_processor.rb, line 58
def map_reference_northing
  map_reference_elements[2]
end

# File lib/os_map_ref/input_processor.rb, line 22
def map_reference_params
  { map_reference: processed_map_reference }
end

# File lib/os_map_ref/input_processor.rb, line 75
def map_reference_pattern
  /([a-zA-Z]{2})\s*(\d{3,5})\s*(\d{3,6})/
end

# File lib/os_map_ref/input_processor.rb, line 98
def normal_length
  6
end

# File lib/os_map_ref/input_processor.rb, line 71
def northing_longer_than_easting?
  map_reference_northing.length > map_reference_easting.length
end

# File lib/os_map_ref/input_processor.rb, line 62
def padded_map_reference_easting
  map_reference_easting.ljust((normal_length - 1), padding)
end

# File lib/os_map_ref/input_processor.rb, line 66
def padded_map_reference_northing
  target_length = northing_longer_than_easting? ? extended_length : normal_length
  map_reference_northing.ljust((target_length - 1), padding)
end

# File lib/os_map_ref/input_processor.rb, line 102
def padding
  "0"
end

# File lib/os_map_ref/input_processor.rb, line 11
def params
  case input
  when map_reference_pattern
    map_reference_params
  when easting_northing_pattern
    easting_northing_params
  else
    raise OsMapRef::Error, "Unable to process input #{input}"
  end
end

# File lib/os_map_ref/input_processor.rb, line 33
def processed_map_reference
  [
    grid_letters.upcase,
    padded_map_reference_easting,
    padded_map_reference_northing
  ].join(" ")
end