Add hCaptcha support (#25019)

app/controllers/concerns/captcha_concern.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module CaptchaConcern
+  extend ActiveSupport::Concern
+  include Hcaptcha::Adapters::ViewMethods
+
+  included do
+    helper_method :render_captcha
+  end
+
+  def captcha_available?
+    ENV['HCAPTCHA_SECRET_KEY'].present? && ENV['HCAPTCHA_SITE_KEY'].present?
+  end
+
+  def captcha_enabled?
+    captcha_available? && Setting.captcha_enabled
+  end
+
+  def captcha_user_bypass?
+    false
+  end
+
+  def captcha_required?
+    captcha_enabled? && !captcha_user_bypass?
+  end
+
+  def check_captcha!
+    return true unless captcha_required?
+
+    if verify_hcaptcha
+      true
+    else
+      if block_given?
+        message = flash[:hcaptcha_error]
+        flash.delete(:hcaptcha_error)
+        yield message
+      end
+      false
+    end
+  end
+
+  def extend_csp_for_captcha!
+    policy = request.content_security_policy
+    return unless captcha_required? && policy.present?
+
+    %w(script_src frame_src style_src connect_src).each do |directive|
+      values = policy.send(directive)
+      values << 'https://hcaptcha.com' unless values.include?('https://hcaptcha.com') || values.include?('https:')
+      values << 'https://*.hcaptcha.com' unless values.include?('https://*.hcaptcha.com') || values.include?('https:')
+      policy.send(directive, *values)
+    end
+  end
+
+  def render_captcha
+    return unless captcha_required?
+
+    hcaptcha_tags
+  end
+end