# frozen_string_literal: true

require 'open3'
require 'base64'
require 'securerandom'

class Captcha
  attr_reader :image_base64, :solution, :solution_id

  NUMBERS = %w[1 2 3 4 5 6].freeze
  IMAGES  = %w[1 2 3 4 5 6].freeze

  CAPTCHA_ASSETS_BASE_PATH = 'app/assets/images/captcha'

  NUMBER_FILES = {
    '1' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, '1.png').to_s,
    '2' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, '2.png').to_s,
    '3' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, '3.png').to_s,
    '4' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, '4.png').to_s,
    '5' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, '5.png').to_s,
    '6' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, '6.png').to_s
  }.freeze

  IMAGE_FILES = {
    '1' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, 'i1.png').to_s,
    '2' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, 'i2.png').to_s,
    '3' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, 'i3.png').to_s,
    '4' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, 'i4.png').to_s,
    '5' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, 'i5.png').to_s,
    '6' => Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, 'i6.png').to_s
  }.freeze

  BACKGROUND_FILE = Rails.root.join(CAPTCHA_ASSETS_BASE_PATH, 'background.png').to_s

  GEOMETRY = {
    1 => '+0+0',   2 => '+120+0',   3 => '+240+0',
    4 => '+0+120', 5 => '+120+120', 6 => '+240+120',
    7 => '+0+240', 8 => '+120+240', 9 => '+240+240'
  }.freeze

  DISTORTION_1 = [
    %w[-implode .1].freeze,
    %w[-implode -.1].freeze
  ].freeze

  DISTORTION_2 = [
    %w[-swirl 10].freeze,
    %w[-swirl -10].freeze,
    %w[-swirl 20].freeze,
    %w[-swirl -20].freeze
  ].freeze

  DISTORTION_3 = [
    %w[-wave 5x180].freeze,
    %w[-wave 5x126].freeze,
    %w[-wave 10x180].freeze,
    %w[-wave 10x126].freeze
  ].freeze

  def initialize
    @solution = NUMBERS.zip(IMAGES.shuffle).to_h

    # 3x3 render grid
    grid = [*NUMBERS, nil, nil, nil].shuffle

    # Base arguments
    imagemagick_cmd = [
      '-page', '360x660', BACKGROUND_FILE
    ]

    # Add individual grid tiles
    grid.each_with_index do |num, i|
      next if num.nil?

      imagemagick_cmd += [IMAGE_FILES[@solution[num]], '-geometry', GEOMETRY[i + 1], '-composite']
      imagemagick_cmd += [NUMBER_FILES[num], '-geometry', GEOMETRY[i + 1], '-composite']
    end

    imagemagick_cmd += [DISTORTION_1.sample, DISTORTION_2.sample, DISTORTION_3.sample].shuffle.flatten
    imagemagick_cmd += ['-quality', '8', 'jpeg:-']

    image_data, = Open3.capture2('convert', *imagemagick_cmd)

    @image_base64 = Base64.encode64(image_data)

    # Store solution in redis so that we can prevent reuse
    @solution_id = "cp#{SecureRandom.hex(12)}"
    $redis.setex(@solution_id, 10.minutes.to_i, @solution.to_json)
  end

  def self.validate(solution_id, solution)
    # Delete key immediately. This may race, but the
    # impact should be minimal if a race succeeds.
    sol = $redis.get(solution_id)
    $redis.del(solution_id)

    return false if sol.blank?

    sol = JSON.parse(sol)

    # Ruby hash equality tests key/value equality, but not
    # key order equality, so this works.
    sol == solution
  rescue StandardError
    false
  end

  def self.options
    @@options ||= NUMBERS.map { |n| [I18n.translate("captcha.solutions.#{n}"), n] }.freeze
  end
end