Add a link to WebIDE on project page in all cases

Add a link to the WebIDE on project page in case the user doesn't have
write access to the repo. Clicking the link will actually create a fork
first and then redirect to the WebIDE in the forked repo.

A confirm modal is shown before forking the project.

The button would not appear if the user cannot create a fork or an MR
in the fork.

.haml-lint_todo.yml

@@ -356,6 +356,7 @@ linters:
       - 'app/views/shared/_auto_devops_implicitly_enabled_banner.html.haml'
       - 'app/views/shared/_commit_message_container.html.haml'
       - 'app/views/shared/_confirm_modal.html.haml'
+      - 'app/views/shared/_confirm_fork_modal.html.haml'
       - 'app/views/shared/_delete_label_modal.html.haml'
       - 'app/views/shared/_group_form.html.haml'
       - 'app/views/shared/_group_tips.html.haml'

app/helpers/blob_helper.rb

@@ -32,6 +32,14 @@ module BlobHelper
     File.join(segments)
   end
 
+  def ide_fork_and_edit_path(project = @project, ref = @ref, path = @path, options = {})
+    if current_user
+      project_forks_path(project,
+                        namespace_key: current_user&.namespace&.id,
+                        continue: edit_blob_fork_params(ide_edit_path(project, ref, path)))
+    end
+  end
+
   def encode_ide_path(path)
     url_encode(path).gsub('%2F', '/')
   end

app/views/projects/tree/_tree_header.html.haml

@@ -41,7 +41,7 @@
                   %li
                     = link_to '#modal-create-new-dir', { 'data-target' => '#modal-create-new-dir', 'data-toggle' => 'modal' } do
                       #{ _('New directory') }
-                - elsif can?(current_user, :fork_project, @project) && can?(current_user, :create_merge_request_in, @project)
+                - elsif can_create_mr_from_fork
                   %li
                     - continue_params = { to: project_new_blob_path(@project, @id),
                                           notice: edit_in_new_fork_notice,
@@ -81,10 +81,15 @@
 
   = render 'projects/find_file_link'
 
-  - if can_collaborate
+  - if can_create_mr_from_fork
     = succeed " " do
-      = link_to ide_edit_path(@project, @ref, @path), class: 'btn btn-default qa-web-ide-button' do
-        = _('Web IDE')
+      - if can_collaborate || current_user&.already_forked?(@project)
+        = link_to ide_edit_path(@project, @ref, @path), class: 'btn btn-default qa-web-ide-button' do
+          = _('Web IDE')
+      - else
+        = link_to '#modal-confirm-fork', class: 'btn btn-default qa-web-ide-button', data: { target: '#modal-confirm-fork', toggle: 'modal'} do
+          = _('Web IDE')
+        = render 'shared/confirm_fork_modal', fork_path: ide_fork_and_edit_path(@project, @ref, @path)
 
   - if show_xcode_link?(@project)
     .project-action-button.project-xcode.inline

app/views/shared/_confirm_fork_modal.html.haml

+#modal-confirm-fork.modal.qa-confirm-fork-modal
+  .modal-dialog
+    .modal-content
+      .modal-header
+        %h3.page-title= _('Fork project?')
+        %button.close{ type: "button", "data-dismiss": "modal", "aria-label" => _('Close') }
+          %span{ "aria-hidden": true } ×
+      .modal-body.p-3
+        %p= sprintf(_("You're not allowed to %{tag_start}edit%{tag_end} files in this project directly. Please fork this project, make your changes there, and submit a merge request."), { tag_start: '', tag_end: ''})
+      .modal-footer
+        = link_to _('Cancel'), '#', class: "btn btn-cancel", "data-dismiss" => "modal"
+        = link_to _('Fork project'), fork_path, class: 'btn btn-success', method: :post

changelogs/unreleased/29835-webide-fork.yml

+---
+title: Web IDE button should fork and open forked project when selected from read-only
+  project
+merge_request: 17672
+author:
+type: added

locale/gitlab.pot

@@ -7247,6 +7247,9 @@ msgstr ""
 msgid "Fork project"
 msgstr ""
 
+msgid "Fork project?"
+msgstr ""
+
 msgid "ForkedFromProjectPath|Forked from"
 msgstr ""
 

spec/helpers/blob_helper_spec.rb

@@ -270,4 +270,32 @@ describe BlobHelper do
       end
     end
   end
+
+  describe '#ide_fork_and_edit_path' do
+    let(:project) { create(:project) }
+    let(:current_user) { create(:user) }
+    let(:can_push_code) { true }
+
+    before do
+      allow(helper).to receive(:current_user).and_return(current_user)
+      allow(helper).to receive(:can?).and_return(can_push_code)
+    end
+
+    it 'returns path to fork the repo with a redirect param to the full IDE path' do
+      uri = URI(helper.ide_fork_and_edit_path(project, "master", ""))
+      params = CGI.unescape(uri.query)
+
+      expect(uri.path).to eq("/#{project.namespace.path}/#{project.path}/-/forks")
+      expect(params).to include("continue[to]=/-/ide/project/#{project.namespace.path}/#{project.path}/edit/master")
+      expect(params).to include("namespace_key=#{current_user.namespace.id}")
+    end
+
+    context 'when user is not logged in' do
+      let(:current_user) { nil }
+
+      it 'returns nil' do
+        expect(helper.ide_fork_and_edit_path(project, "master", "")).to be_nil
+      end
+    end
+  end
 end

spec/views/projects/tree/_tree_header.html.haml_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'projects/tree/_tree_header' do
+  let(:project) { create(:project, :repository) }
+  let(:current_user) { create(:user) }
+  let(:repository) { project.repository }
+
+  before do
+    assign(:project, project)
+    assign(:repository, repository)
+    assign(:id, File.join('master', ''))
+    assign(:ref, 'master')
+
+    allow(view).to receive(:current_user).and_return(current_user)
+    allow(view).to receive(:can_collaborate_with_project?) { true }
+  end
+
+  it 'does not render the WebIDE button when user cannot create fork or cannot open MR' do
+    allow(view).to receive(:can?) { false }
+
+    render
+
+    expect(rendered).not_to have_link('Web IDE')
+  end
+
+  it 'renders the WebIDE button when user can create fork and can open MR in project' do
+    allow(view).to receive(:can?) { true }
+
+    render
+
+    expect(rendered).to have_link('Web IDE')
+  end
+
+  it 'opens a popup confirming a fork if the user can create fork/MR but cannot collaborate with the project' do
+    allow(view).to receive(:can?) { true }
+    allow(view).to receive(:can_collaborate_with_project?) { false }
+
+    render
+
+    expect(rendered).to have_link('Web IDE', href: '#modal-confirm-fork')
+  end
+end