Only allow one living monster_spawn per location

3 files changed, 15 insertions, 2 deletions

diff --git a/app/lib/activity_processor.rb b/app/lib/activity_processor.rb
index 4ba3609..d3bf5cb 100644
--- a/app/lib/activity_processor.rb
+++ b/app/lib/activity_processor.rb
@@ -118,8 +118,12 @@ class ActivityProcessor
         when "create_monster_spawn"
           next if rand > (result[:chance] || 1)
           monster = Monster.find_by_gid(result[:gid])
-          MonsterSpawn.create(monster: monster, location: @character.location)
-          @results.push({ type: type, monster: monster })
+          monster_spawn = MonsterSpawn.new(monster: monster, location: @character.location)
+          if monster_spawn.save
+            @results.push({ type: type, monster: monster })
+          else
+            @results.push({ type: "message", body: "A leviathan did not appear since there is already a leviathan at #{@character.location.name}." })
+          end
         else
           raise "Invalid result type (#{type})" # TODO: Improve this.
         end
diff --git a/app/models/monster_spawn.rb b/app/models/monster_spawn.rb
index 5162cc6..42db98a 100644
--- a/app/models/monster_spawn.rb
+++ b/app/models/monster_spawn.rb
@@ -7,6 +7,7 @@ class MonsterSpawn < ApplicationRecord
   after_create :send_chat_message
 
   validates :starting_hp, presence: true, numericality: { greater_than_or_equal_to: 1, only_integer: true }
+  validate :one_living_leviathan_per_location, on: :create
 
   def alive?
     self.remaining_hp > 0
@@ -28,4 +29,11 @@ class MonsterSpawn < ApplicationRecord
         ChatRoomChannel.broadcast_chat_message(chat_message)
       end
     end
+
+    def one_living_leviathan_per_location
+      # TODO: Don't load into memory
+      if location.monster_spawns.find { |ms| ms.alive? && ms != self }
+        errors.add(:chat, "A location can only have one monster spawn at a time.")
+      end
+    end
 end
diff --git a/app/views/look/look.html.erb b/app/views/look/look.html.erb
index 8b41e0f..ef0f6c4 100644
--- a/app/views/look/look.html.erb
+++ b/app/views/look/look.html.erb
@@ -3,6 +3,7 @@
   <p class="italic"><%= @location.description %></p>
 </div>
 
+<%# TODO: Don't load into memory %>
 <% @location.monster_spawns.select(&:alive?).each do |ms| %>
   <p class="text-yellow-400">A <%= ms.monster.name %> is ravaging this location! (<%= ms.remaining_hp %> HP)</p>
   <% activity = Activity.find_by_gid("beastslay_leviathan_#{@location.gid}") %>