Initial release of Discourse

lib/site_setting_extension.rb

@@ -0,0 +1,230 @@
+module SiteSettingExtension
+
+  module Types
+    String = 1
+    Time = 2 
+    Fixnum = 3
+    Float = 4
+    Bool = 5
+    Null = 6
+  end
+
+  def mutex
+    @mutex ||= Mutex.new
+  end
+
+  def current
+    @@containers ||= {}
+    @@containers[RailsMultisite::ConnectionManagement.current_db] ||= {}
+  end
+
+  def defaults
+    @defaults ||= {} 
+  end
+
+  def setting(name, default = nil, type = nil)
+    mutex.synchronize do  
+      self.defaults[name] = default
+      current_value = current.has_key?(name) ? current[name] : default
+      setup_methods(name, current_value)
+    end
+  end
+
+  # just like a setting, except that it is available in javascript via DiscourseSession 
+  def client_setting(name, defualt = nil, type = nil)
+    setting(name,defualt,type)
+    @@client_settings ||= []
+    @@client_settings << name
+  end
+
+  def client_settings
+    @@client_settings 
+  end
+
+
+  def client_settings_json
+    Rails.cache.fetch(SiteSettingExtension.client_settings_cache_key, expires_in: 30.minutes) do
+      MultiJson.dump(Hash[*@@client_settings.map{|n| [n, self.send(n)]}.flatten])
+    end
+  end
+
+  # Retrieve all settings
+  def all_settings
+    @defaults.map do |s, v|
+      {setting: s,
+       description: description(s),
+       default: v,
+       value: send(s).to_s}
+    end
+  end
+
+  def description(setting)
+    I18n.t("site_settings.#{setting}")
+  end
+
+  # table is not in the db yet, initial migration, etc
+  def table_exists?
+    @table_exists = ActiveRecord::Base.connection.table_exists? 'site_settings' if @table_exists == nil
+    @table_exists
+  end
+
+  def self.client_settings_cache_key
+    "client_settings_json"
+  end
+
+  # refresh all the site settings
+  def refresh!  
+    return unless table_exists? 
+    mutex.synchronize do 
+      ensure_listen_for_changes
+      old = current
+      changes = []
+      deletions = []
+
+      all_settings = SiteSetting.select([:name,:value,:data_type])
+      new_hash =  Hash[*(all_settings.map{|s| [s.name.intern, convert(s.value,s.data_type)]}.to_a.flatten)]
+
+      # add defaults
+      new_hash = defaults.merge(new_hash)
+
+      new_hash.each do |name, value|
+        changes << [name,value] if !old.has_key?(name) || old[name] != value
+      end
+
+      old.each do |name,value| 
+        deletions << [name,value] unless new_hash.has_key?(name)        
+      end
+
+      if deletions.length > 0 || changes.length > 0
+        @current = new_hash
+        changes.each do |name, val| 
+          setup_methods name, val 
+        end
+        deletions.each do |name,val|
+          setup_methods name, defaults[name]
+        end
+      end
+
+      $redis.del(SiteSettingExtension.client_settings_cache_key)
+    end
+  end
+
+  def ensure_listen_for_changes
+    unless @subscribed
+      pid = process_id
+      MessageBus.subscribe("/site_settings") do |msg| 
+        message = msg.data
+        if message["process"] != pid 
+          begin
+            # picks a db
+            MessageBus.on_connect.call(msg.site_id) 
+            SiteSetting.refresh!
+          ensure
+            MessageBus.on_disconnect.call(msg.site_id)
+          end
+        end
+      end
+      @subscribed = true
+    end
+  end
+
+  def process_id
+    @@process_id ||= SecureRandom.uuid
+  end
+
+  def remove_override!(name)
+    return unless table_exists? 
+    SiteSetting.where(:name => name).destroy_all
+  end
+
+  def add_override!(name,val)
+    return unless table_exists?
+
+    setting = SiteSetting.where(:name => name).first
+    type = get_data_type(defaults[name])
+    
+    if type == Types::Bool && val != true && val != false
+      val = (val == "t" || val == "true")
+    end
+
+    if type == Types::Fixnum && !(Fixnum === val)
+      val = val.to_i
+    end
+
+    if setting
+      setting.value = val
+      setting.data_type = type 
+      setting.save
+    else 
+      SiteSetting.create!(:name => name, :value => val, :data_type => type)
+    end
+
+    MessageBus.publish('/site_settings', {process: process_id})
+  end
+
+
+  protected 
+
+  def get_data_type(val)
+    return Types::Null if val.nil?
+
+    if String === val
+      Types::String
+    elsif Fixnum === val 
+      Types::Fixnum
+    elsif TrueClass === val || FalseClass === val 
+      Types::Bool
+    else 
+      raise ArgumentError.new :val
+    end
+  end
+
+  def convert(value, type)
+    case type 
+    when Types::Fixnum
+      value.to_i
+    when Types::String
+      value
+    when Types::Bool
+      value == "t"
+    when Types::Null
+      nil
+    end
+  end
+
+
+  def setup_methods(name, current_value)
+
+    # trivial multi db support, we can optimize this later 
+    db = RailsMultisite::ConnectionManagement.current_db
+    
+    @@containers ||= {}
+    @@containers[db] ||= {}
+    @@containers[db][name] = current_value
+
+    setter = ("#{name}=").sub("?","")
+
+    eval "define_singleton_method :#{name} do 
+      c = @@containers[RailsMultisite::ConnectionManagement.current_db]
+      c = c[name] if c
+      c
+    end
+    
+    define_singleton_method :#{setter} do |val|
+      add_override!(:#{name}, val)
+      refresh!
+    end
+    "
+  end
+
+  def method_missing(method, *args, &block)
+    as_question = method.to_s.gsub(/\?$/, '')
+    if respond_to?(as_question) 
+      return send(as_question, *args, &block)  
+    end
+    super(method, *args, &block)
+  end
+
+
+end
+