Rename Notifier to UserMailer

It's a convention in rails to name your mailers with a Mailer suffix, and is also common to name the class after the recipient (e.g. User, Admin). So UserMailer seems a reasonable choice.

app/mailers/user_mailer.rb

@@ -0,0 +1,228 @@
+class UserMailer < ApplicationMailer
+  include ActionView::Helpers::AssetUrlHelper
+
+  self.delivery_job = ActionMailer::MailDeliveryJob
+
+  default :from => Settings.email_from,
+          :return_path => Settings.email_return_path,
+          :auto_submitted => "auto-generated"
+  helper :application
+  before_action :set_shared_template_vars
+  before_action :attach_project_logo
+
+  def signup_confirm(user, token)
+    with_recipient_locale user do
+      @url = url_for(:controller => "users", :action => "confirm",
+                     :display_name => user.display_name,
+                     :confirm_string => token.token)
+
+      mail :to => user.email,
+           :subject => I18n.t("user_mailer.signup_confirm.subject")
+    end
+  end
+
+  def email_confirm(user, token)
+    with_recipient_locale user do
+      @address = user.new_email
+      @url = url_for(:controller => "users", :action => "confirm_email",
+                     :confirm_string => token.token)
+
+      mail :to => user.new_email,
+           :subject => I18n.t("user_mailer.email_confirm.subject")
+    end
+  end
+
+  def lost_password(user, token)
+    with_recipient_locale user do
+      @url = url_for(:controller => "users", :action => "reset_password",
+                     :token => token.token)
+
+      mail :to => user.email,
+           :subject => I18n.t("user_mailer.lost_password.subject")
+    end
+  end
+
+  def gpx_success(trace, possible_points)
+    with_recipient_locale trace.user do
+      @trace_name = trace.name
+      @trace_points = trace.size
+      @trace_description = trace.description
+      @trace_tags = trace.tags
+      @possible_points = possible_points
+
+      mail :to => trace.user.email,
+           :subject => I18n.t("user_mailer.gpx_notification.success.subject")
+    end
+  end
+
+  def gpx_failure(trace, error)
+    with_recipient_locale trace.user do
+      @trace_name = trace.name
+      @trace_description = trace.description
+      @trace_tags = trace.tags
+      @error = error
+
+      mail :to => trace.user.email,
+           :subject => I18n.t("user_mailer.gpx_notification.failure.subject")
+    end
+  end
+
+  def message_notification(message)
+    with_recipient_locale message.recipient do
+      @to_user = message.recipient.display_name
+      @from_user = message.sender.display_name
+      @text = message.body
+      @title = message.title
+      @readurl = message_url(message)
+      @replyurl = message_reply_url(message)
+      @author = @from_user
+
+      attach_user_avatar(message.sender)
+
+      mail :from => from_address(message.sender.display_name, "m", message.id, message.digest),
+           :to => message.recipient.email,
+           :subject => I18n.t("user_mailer.message_notification.subject_header", :subject => message.title)
+    end
+  end
+
+  def diary_comment_notification(comment, recipient)
+    with_recipient_locale recipient do
+      @to_user = recipient.display_name
+      @from_user = comment.user.display_name
+      @text = comment.body
+      @title = comment.diary_entry.title
+      @readurl = diary_entry_url(comment.diary_entry.user, comment.diary_entry, :anchor => "comment#{comment.id}")
+      @commenturl = diary_entry_url(comment.diary_entry.user, comment.diary_entry, :anchor => "newcomment")
+      @replyurl = new_message_url(comment.user, :message => { :title => "Re: #{comment.diary_entry.title}" })
+      @author = @from_user
+
+      attach_user_avatar(comment.user)
+
+      set_references("diary", comment.diary_entry)
+
+      mail :from => from_address(comment.user.display_name, "c", comment.id, comment.digest, recipient.id),
+           :to => recipient.email,
+           :subject => I18n.t("user_mailer.diary_comment_notification.subject", :user => comment.user.display_name)
+    end
+  end
+
+  def friendship_notification(friendship)
+    with_recipient_locale friendship.befriendee do
+      @friendship = friendship
+      @viewurl = user_url(@friendship.befriender)
+      @friendurl = make_friend_url(@friendship.befriender)
+      @author = @friendship.befriender.display_name
+
+      attach_user_avatar(@friendship.befriender)
+      mail :to => friendship.befriendee.email,
+           :subject => I18n.t("user_mailer.friendship_notification.subject", :user => friendship.befriender.display_name)
+    end
+  end
+
+  def note_comment_notification(comment, recipient)
+    with_recipient_locale recipient do
+      @noteurl = browse_note_url(comment.note)
+      @place = Nominatim.describe_location(comment.note.lat, comment.note.lon, 14, I18n.locale)
+      @comment = comment.body
+      @owner = recipient == comment.note.author
+      @event = comment.event
+
+      @commenter = if comment.author
+                     comment.author.display_name
+                   else
+                     I18n.t("user_mailer.note_comment_notification.anonymous")
+                   end
+
+      @author = @commenter
+      attach_user_avatar(comment.author)
+
+      set_references("note", comment.note)
+
+      subject = if @owner
+                  I18n.t("user_mailer.note_comment_notification.#{@event}.subject_own", :commenter => @commenter)
+                else
+                  I18n.t("user_mailer.note_comment_notification.#{@event}.subject_other", :commenter => @commenter)
+                end
+
+      mail :to => recipient.email, :subject => subject
+    end
+  end
+
+  def changeset_comment_notification(comment, recipient)
+    with_recipient_locale recipient do
+      @to_user = recipient.display_name
+      @changeset_url = changeset_url(comment.changeset)
+      @comment = comment.body
+      @owner = recipient == comment.changeset.user
+      @commenter = comment.author.display_name
+      @changeset_comment = comment.changeset.tags["comment"].presence
+      @time = comment.created_at
+      @changeset_author = comment.changeset.user.display_name
+      @author = @commenter
+
+      subject = if @owner
+                  I18n.t("user_mailer.changeset_comment_notification.commented.subject_own", :commenter => @commenter)
+                else
+                  I18n.t("user_mailer.changeset_comment_notification.commented.subject_other", :commenter => @commenter)
+                end
+
+      attach_user_avatar(comment.author)
+
+      set_references("changeset", comment.changeset)
+
+      mail :to => recipient.email, :subject => subject
+    end
+  end
+
+  private
+
+  def set_shared_template_vars
+    @root_url = root_url
+  end
+
+  def attach_project_logo
+    attachments.inline["logo.png"] = File.read(Rails.root.join("app/assets/images/osm_logo_30.png"))
+  end
+
+  def attach_user_avatar(user)
+    attachments.inline["avatar.png"] = user_avatar_file(user)
+  end
+
+  def user_avatar_file(user)
+    avatar = user&.avatar
+    if avatar&.attached?
+      if avatar.variable?
+        image = avatar.variant(:resize => "50x50>").processed
+        image.service.download(image.key)
+      else
+        avatar.blob.download
+      end
+    else
+      File.read(Rails.root.join("app/assets/images/avatar_small.png"))
+    end
+  end
+
+  def with_recipient_locale(recipient, &block)
+    I18n.with_locale(Locale.available.preferred(recipient.preferred_languages), &block)
+  end
+
+  def from_address(name, type, id, digest, user_id = nil)
+    if Settings.key?(:messages_domain) && domain = Settings.messages_domain
+      if user_id
+        "#{name} <#{type}-#{id}-#{user_id}-#{digest[0, 6]}@#{domain}>"
+      else
+        "#{name} <#{type}-#{id}-#{digest[0, 6]}@#{domain}>"
+      end
+    else
+      Settings.email_from
+    end
+  end
+
+  def set_references(scope, reference_object)
+    ref = "osm-#{scope}-#{reference_object.id}@#{Settings.server_url}"
+
+    headers["X-Entity-Ref-ID"] = ref
+    headers["In-Reply-To"] = ref
+    headers["References"] = ref
+  end
+end