Phase 1: standalone events, external_url on nodes

- Migration: node_id nullable on events and occurrences, add
  title/description/is_primary to events, external_url to nodes
- Existing events marked is_primary: true (were all 1:1 with nodes)
- Node: has_one :event -> has_many :events
- Event: belongs_to :node optional, validates title presence for
  standalone events, is_primary uniqueness scoped to node_id,
  display_title helper falling back through node title
- Occurrence: belongs_to :node optional, summary falls back to
  event.display_title
- nodes_helper: event_information uses events.first (interim; will
  be replaced in Phase 3 event UI)
- Tests: fix node.event -> node.events.first in event_test

4 files changed, 27 insertions, 24 deletions

diff --git a/app/helpers/nodes_helper.rb b/app/helpers/nodes_helper.rb
index a054a2e..d88d12a 100644
--- a/app/helpers/nodes_helper.rb
+++ b/app/helpers/nodes_helper.rb
@@ -30,12 +30,13 @@ module NodesHelper
   end
 
   def event_information
-    if @node.event
+    if @node.events.first
+      event = @node.events.first
       safe_join([
-        "#{@node.event.start_time.to_fs(:db)} - #{@node.event.end_time.to_fs(:db)} > ",
-        link_to('show', event_path(@node.event)),
-        ' ',
-        link_to('edit', edit_event_path(@node.event))
+        "#{event.start_time.to_fs(:db)} - #{event.end_time.to_fs(:db)} > ",
+        link_to('show', event_path(event)),
+        ' > ',
+        link_to('edit', edit_event_path(event))
       ])
     else
       safe_join([
diff --git a/app/models/event.rb b/app/models/event.rb
index 94a22e3..26c79e4 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -1,22 +1,25 @@
 class Event < ApplicationRecord
-  
-  # Associations
-  
-  has_many    :occurrences
-  belongs_to  :node
-  
-  # Callbacks
-  
-  after_save  :generate_occurences
-  
-  # Instance Methods
-  
+
+  belongs_to :node, optional: true
+  has_many   :occurrences
+
+  validates :title, presence: true, unless: -> { node_id.present? }
+  validates :is_primary, uniqueness: { scope: :node_id,
+    message: "only one primary event per node allowed" },
+    if: -> { is_primary? && node_id.present? }
+
+  after_save :generate_occurences
+
   def occurrences_in_range start_time, end_time
     self.occurrences.where(
       "start_time > ? AND end_time < ?",
       start_time, end_time
     )
-  end 
+  end
+
+  def display_title
+    title.presence || node&.head&.title || "Untitled event"
+  end
 
   private
     def generate_occurences
diff --git a/app/models/node.rb b/app/models/node.rb
index 92ecc12..ba94e2a 100644
--- a/app/models/node.rb
+++ b/app/models/node.rb
@@ -7,7 +7,7 @@ class Node < ApplicationRecord
   belongs_to  :head,  :class_name => "Page",  :foreign_key => :head_id, :dependent => :destroy, optional: true
   belongs_to  :draft, :class_name => "Page",  :foreign_key => :draft_id, :dependent => :destroy, optional: true
   has_many    :permissions, :dependent => :destroy
-  has_one     :event, :dependent => :destroy
+  has_many    :events, :dependent => :destroy
   belongs_to  :lock_owner, :class_name => "User", :foreign_key => :locking_user_id, optional: true
 
   # Callbacks
diff --git a/app/models/occurrence.rb b/app/models/occurrence.rb
index 3baf447..143124f 100644
--- a/app/models/occurrence.rb
+++ b/app/models/occurrence.rb
@@ -1,13 +1,12 @@
-# TODO Make a gem out of the c wrapper
 require 'chaos_calendar'
 
 class Occurrence < ApplicationRecord
   
   # Associations
   
-  belongs_to :node
+  belongs_to :node,  optional: true
   belongs_to :event
-  
+
   # Class Methods
   
   def self.find_in_range start_time, end_time
@@ -64,7 +63,7 @@ class Occurrence < ApplicationRecord
   # Instance Methods
   
   def summary
-    node.head.title
+    node&.head&.title || event.display_title
   end
-  
+
 end