Links, mainly...

app/models/link.rb

@@ -0,0 +1,51 @@
+class Link < ApplicationRecord
+  belongs_to :link_category
+  has_rich_text :description_html
+
+  validates :url, :text, presence: true
+  validate :check_url
+  validate :valid_url
+  
+  before_validation :ensure_absolute_url
+
+  def ok?
+    fail_count == 0
+  end
+
+  private
+
+  USER_AGENT = "Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/115.0"
+
+  def check_url(input = url, add_error = true)
+    response = begin
+      Net::HTTP.get_response(URI.parse(input), "User-Agent": USER_AGENT) 
+    rescue Socket::ResolutionError
+      errors.add(:url, :invalid) if add_error
+      return false
+    end
+      
+    case response
+    when Net::HTTPSuccess
+      self.last_check_at = Time.zone.now
+      self.fail_count = 0
+      
+      true
+    when Net::HTTPRedirection
+      check_url(response[:location])
+    else
+      self.last_check_at = Time.zone.now
+      self.fail_count += 1
+      errors.add(:url, :invalid) if add_error
+
+      false
+    end
+  end
+
+  def ensure_absolute_url
+    self.url = "https://#{self.url}" unless self.url.match?(%r{https{0,1}://.*})
+  end
+
+  def valid_url
+    errors.add(:url, :invalid) unless url.match /\A#{URI::regexp(['http', 'https'])}\z/
+  end
+end