Move conflict detection code to GridWeapon

app/models/grid_weapon.rb

@@ -8,20 +8,58 @@ class GridWeapon < ApplicationRecord
   belongs_to :weapon_key2, class_name: 'WeaponKey', foreign_key: :weapon_key2_id, optional: true
   belongs_to :weapon_key3, class_name: 'WeaponKey', foreign_key: :weapon_key3_id, optional: true
 
+  validate :compatible_with_position
+  validate :no_conflicts
+
+  # Helper methods
+  def blueprint
+    GridWeaponBlueprint
+  end
+
   def weapon
     Weapon.find(weapon_id)
   end
 
   def weapon_keys
-    weapon_keys = []
-    weapon_keys.push(weapon_key1) unless weapon_key1.nil?
-    weapon_keys.push(weapon_key2) unless weapon_key2.nil?
-    weapon_keys.push(weapon_key3) unless weapon_key3.nil?
-
-    weapon_keys
+    [weapon_key1, weapon_key2, weapon_key3].compact
   end
 
-  def blueprint
-    GridWeaponBlueprint
+  private
+
+  # Conflict management methods
+
+  # Validates whether the weapon can be added to the desired position
+  def compatible_with_position
+    return unless [9, 10, 11].include?(position.to_i) && ![11, 16, 17, 28, 29].include?(series)
+
+    errors.add(:series, 'must be compatible with position')
+  end
+
+  # Validates whether the desired weapon key can be added to the weapon
+  def compatible_with_key
+    weapon_keys.each do |key|
+      errors.add(:weapon_keys, 'must be compatible with weapon') unless weapon.compatible_with_key?(key)
+    end
+  end
+
+  # Validates whether there is a conflict with the party
+  def no_conflicts
+    # Check if the grid weapon conflicts with any of the other grid weapons in the party
+    errors.add(:series, 'must not conflict with existing weapons') unless conflicts(party).nil?
+  end
+
+  # Returns conflicting weapons if they exist
+  def conflicts(party)
+    return unless limit
+
+    party.weapons.find do |weapon|
+      series_match = series == weapon.weapon.series
+      weapon if series_match || opus_or_draconic? && weapon.opus_or_draconic?
+    end
+  end
+
+  # Returns whether the weapon is included in the Draconic or Dark Opus series
+  def opus_or_draconic?
+    [2, 3].include?(series)
   end
 end

app/models/weapon.rb

@@ -27,4 +27,8 @@ class Weapon < ApplicationRecord
   def display_resource(weapon)
     weapon.name_en
   end
+
+  def compatible_with_key?(key)
+    key.series == series
+  end
 end