require 'openssl'
require 'base64'
require 'json'

module Fastlane
  module PageGenerator
    def self.generate(config)
      if config[:installation_password]
        generate_private(config)
      else
        generate_public(config)
      end
    end

    def self.generate_private(config)
      UI.message("Generating private installation page with password `#{config[:installation_password]}`...")
      eth = Fastlane::ErbTemplateHelper
      html_template = eth.load_from_path("#{__dir__}/../templates/secure_installation_template.erb")
      installation_link, salt, iv = encrypt(config[:url], config[:installation_password])
      eth.render(html_template, {
        url: installation_link,
        salt: salt,
        iv: iv,
        app_version: config[:app_version],
        build_number: config[:build_number],
        app_name: config[:app_name],
        app_icon: config[:app_icon],
        platform: config[:platform]
      })
    end
    private_class_method :generate_private

    def self.generate_public(config)
      UI.message("Generating public installation page...")
      eth = Fastlane::ErbTemplateHelper
      html_template = eth.load_from_path("#{__dir__}/../templates/installation_template.erb")
      eth.render(html_template, {
        url: config[:url],
        app_version: config[:app_version],
        build_number: config[:build_number],
        app_name: config[:app_name],
        app_icon: config[:app_icon],
        platform: config[:platform]
      })
    end
    private_class_method :generate_public

    def self.encrypt(url, password)
      salt = OpenSSL::Random.random_bytes(32)
      iter = 128
      key_len = 32
      key = OpenSSL::PKCS5.pbkdf2_hmac_sha1(password, salt, iter, key_len)

      cipher = OpenSSL::Cipher::AES256.new(:CBC)
      cipher.encrypt
      cipher.key = key

      random_iv = cipher.random_iv
      iv = Base64.encode64(random_iv).delete "\n"
      to_json = { url: url.to_s }.to_json
      var = cipher.update(to_json.to_s) + cipher.final

      installation_link = Base64.encode64(var).delete "\n"
      salt = Base64.encode64(salt).delete "\n"
      return installation_link, salt, iv
    end
    private_class_method :encrypt
  end
end