feat(dossier): commune champ is an autocomplete now

app/models/champs/commune_champ.rb

@@ -1,6 +1,6 @@
 class Champs::CommuneChamp < Champs::TextChamp
   store_accessor :value_json, :code_departement, :code_postal
-  before_validation :on_code_postal_change
+  before_save :on_codes_change, if: :should_refresh_after_code_change?
 
   def for_export
     [to_s, code? ? code : '', departement? ? departement_code_and_name : '']
@@ -37,7 +37,7 @@ class Champs::CommuneChamp < Champs::TextChamp
   alias postal_code code_postal
 
   def name
-    if code?
+    if departement? && code?
       APIGeoService.commune_name(code_departement, code).presence || safe_to_s
     else
       safe_to_s
@@ -45,7 +45,7 @@ class Champs::CommuneChamp < Champs::TextChamp
   end
 
   def to_s
-    if code?
+    if departement? && code_postal? && code?
       name = APIGeoService.commune_name(code_departement, code)
       name.present? ? "#{name} (#{code_postal})" : safe_to_s
     else
@@ -69,46 +69,29 @@ class Champs::CommuneChamp < Champs::TextChamp
     end
   end
 
-  def value=(code)
-    if code.blank? || !code_postal?
-      self.code_departement = nil
-      self.external_id = nil
-      super(nil)
-    else
-      commune = communes.find { _1[:code] == code }
-      if commune.present?
-        self.code_departement = commune[:departement_code]
-        self.external_id = commune[:code]
-        super(commune[:name])
-      else
-        self.code_departement = nil
-        self.external_id = nil
-        super(nil)
-      end
-    end
-  end
-
-  def html_label?
-    false
-  end
-
-  def legend_label?
-    true
-  end
-
   private
 
   def safe_to_s
     value.present? ? value.to_s : ''
   end
 
-  def on_code_postal_change
-    if code_postal_changed?
-      if communes.one?
-        self.value = communes.first[:code]
-      else
-        self.value = nil
-      end
+  def on_codes_change
+    return if !code?
+
+    commune = communes.find { _1[:code] == code }
+
+    if commune.present?
+      self.code_departement = commune[:departement_code]
+      self.value = commune[:name]
+    else
+      self.code_departement = nil
+      self.code_postal = nil
+      self.external_id = nil
+      self.value = nil
     end
   end
+
+  def should_refresh_after_code_change?
+    !departement? || code_postal_changed? || external_id_changed?
+  end
 end

app/models/types_de_champ/prefill_commune_type_de_champ.rb

@@ -32,7 +32,7 @@ class TypesDeChamp::PrefillCommuneTypeDeChamp < TypesDeChamp::PrefillTypeDeChamp
   end
 
   def code_postal_and_commune_attributes(champ, postal_code, commune_code)
-    code_postal_attributes(champ, postal_code).merge(value: commune_code)
+    code_postal_attributes(champ, postal_code).merge(external_id: commune_code)
   end
 
   def departements