Add a champs/dossier_link endpoint and use it to fetch dossier info

app/controllers/champs/dossier_link_controller.rb

@@ -0,0 +1,11 @@
+class Champs::DossierLinkController < ApplicationController
+  before_action :authenticate_logged_user!
+
+  def show
+    if params[:dossier].key?(:champs_attributes)
+      @dossier_id = params[:dossier][:champs_attributes][params[:position]][:value]
+    else
+      @dossier_id = params[:dossier][:champs_private_attributes][params[:position]][:value]
+    end
+  end
+end

app/views/champs/dossier_link/show.js.erb

@@ -0,0 +1,3 @@
+<%= render_to_element('.dossier-link .help-block',
+  partial: 'shared/champs/dossier_link/help_block',
+  locals: { id: @dossier_id }) %>

app/views/shared/champs/dossier_link/_help_block.html.haml

@@ -0,0 +1,8 @@
+- if id.present?
+  - dossier = logged_user.dossiers.find_by(id: id)
+  - if dossier.blank?
+    %p.text-warning
+      Ce dossier est inconnu
+  - else
+    %p.text-info
+      %span.dossier-text-summary= sanitize(dossier.text_summary)

app/views/shared/dossiers/editable_champs/_dossier_link.html.haml

@@ -1,18 +1,9 @@
-- dossier = Dossier.find_by(id: champ.value)
-- show_text_summary = dossier.present?
-- show_warning = !show_text_summary && champ.value.present?
-- text_summary = sanitize(dossier&.text_summary)
-
 .dossier-link
   = form.number_field :value,
     placeholder: "Numéro de dossier",
     autocomplete: 'off',
-    'data-type': 'dossier-link',
+    required: champ.mandatory?,
-    required: champ.mandatory?
+    data: { remote: true, url: champs_dossier_link_path(form.index) }
 
   .help-block
-    %p.text-info{ style: show_text_summary ? nil : 'display: none;' }
+    = render partial: 'shared/champs/dossier_link/help_block', locals: { id: champ.value }
-      %span.dossier-text-summary= text_summary
-
-    %p.text-warning{ style: show_warning ? nil : 'display: none;' }
-      Ce dossier est inconnu

config/routes.rb

@@ -111,6 +111,7 @@ Rails.application.routes.draw do
 
   namespace :champs do
     get ':champ_id/siret' => 'siret#index', as: 'siret'
+    get ':position/dossier_link', to: 'dossier_link#show', as: :dossier_link
   end
 
   namespace :commencer do

spec/controllers/champs/dossier_link_controller_spec.rb

@@ -0,0 +1,56 @@
+require 'spec_helper'
+
+describe Champs::DossierLinkController, type: :controller do
+  let(:user) { create(:user) }
+  let(:procedure) { create(:procedure, :published) }
+
+  describe '#show' do
+    let(:dossier) { create(:dossier, user: user, procedure: procedure) }
+
+    context 'when user is connected' do
+      render_views
+      before { sign_in user }
+
+      let(:params) do
+        {
+          dossier: {
+            champs_attributes: {
+              '1' => { value: "#{dossier_id}" }
+            }
+          },
+          position: '1'
+        }
+      end
+      let(:dossier_id) { dossier.id }
+
+      context 'when the dossier exist' do
+        before {
+          get :show, params: params, format: 'js'
+        }
+
+        it 'returns the procedure name' do
+          expect(response.body).to include('Dossier en brouillon')
+          expect(response.body).to include(procedure.libelle)
+          expect(response.body).to include(procedure.organisation)
+        end
+      end
+
+      context 'when the dossier does not exist' do
+        let(:dossier_id) { '13' }
+        before {
+          get :show, params: params, format: 'js'
+        }
+
+        it { expect(response.body).to include('Ce dossier est inconnu') }
+      end
+    end
+
+    context 'when user is not connected' do
+      before {
+        get :show, params: { position: '1' }, format: 'js'
+      }
+
+      it { expect(response.code).to eq('401') }
+    end
+  end
+end