jcraigk/story_key

# frozen_string_literal: true
class StoryKey::Coercer < StoryKey::Base
  option :str
  option :bitsize, default: -> {}
  option :from
  option :to

  def call
    converted_str
  end

  private

  def binary_str
    bitsize ? bin.rjust(bitsize, '0') : bin
  end

  def bin
    @bin ||=
      case from.to_sym
      when :bin, :binary then str
      when :dec, :decimal then str.to_i.to_s(2)
      when :hex, :hexidecimal then str.hex.to_s(2)
      when :base58 then Base58.base58_to_int(str, :bitcoin).to_s(2)
      else raise_invalid_input
      end
  rescue ArgumentError
    raise_invalid_input
  end

  def raise_invalid_input
    raise StoryKey::InvalidFormat, "Invalid input format: #{from}"
  end

  def converted_str
    case to.to_sym
    when :bin, :binary then binary_str
    when :dec, :decimal then decimal_str
    when :hex, :hexidecimal then hexidecimal_str
    when :base58 then base58_str
    else raise StoryKey::InvalidFormat, "Invalid output format: #{to}"
    end
  end

  def decimal_str
    binary_str.reverse.chars.map.with_index do |digit, index|
      digit.to_i * (2**index)
    end.sum.to_s
  end

  def hexidecimal_str
    binary_str.to_i(2).to_s(16)
  end

  def base58_str
    Base58.int_to_base58(decimal_str.to_i, :bitcoin)
  end
end