Merge branch 'api-dev-can-push' into 'master'

API: Expose 'developers_can_push' for branches

## What does this MR do?

Adds support for the `developers_can_push` flag for the branches API. It also supports creating protected branches with that flag.

## Are there points in the code the reviewer needs to double check?

The API call requires an optional boolean parameter `developers_can_push`. If it is not either `true` or `false`, it should not update the value. I'm not sure if this is the right way to do it.

Right now it always returns `200`. Maybe the `PUT` method should return different status codes depending if it really created or updated a branch.

## What are the relevant issue numbers?

Closes #12735 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5208

3 files changed, 36 insertions, 4 deletions

diff --git a/lib/api/branches.rb b/lib/api/branches.rb
index d467eb9d474..35efe4f2e4a 100644
--- a/lib/api/branches.rb
+++ b/lib/api/branches.rb
@@ -36,6 +36,8 @@ module API
       # Parameters:
       #   id (required) - The ID of a project
       #   branch (required) - The name of the branch
+      #   developers_can_push (optional) - Flag if developers can push to that branch
+      #   developers_can_merge (optional) - Flag if developers can merge to that branch
       # Example Request:
       #   PUT /projects/:id/repository/branches/:branch/protect
       put ':id/repository/branches/:branch/protect',
@@ -43,9 +45,20 @@ module API
         authorize_admin_project
 
         @branch = user_project.repository.find_branch(params[:branch])
-        not_found!("Branch") unless @branch
+        not_found!('Branch') unless @branch
         protected_branch = user_project.protected_branches.find_by(name: @branch.name)
-        user_project.protected_branches.create(name: @branch.name) unless protected_branch
+        developers_can_push = to_boolean(params[:developers_can_push])
+        developers_can_merge = to_boolean(params[:developers_can_merge])
+
+        if protected_branch
+          protected_branch.developers_can_push = developers_can_push unless developers_can_push.nil?
+          protected_branch.developers_can_merge = developers_can_merge unless developers_can_merge.nil?
+          protected_branch.save
+        else
+          user_project.protected_branches.create(name: @branch.name,
+                                                 developers_can_push: developers_can_push || false,
+                                                 developers_can_merge: developers_can_merge || false)
+        end
 
         present @branch, with: Entities::RepoObject, project: user_project
       end
diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 3c79a00eb8c..d6fed1a1eed 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -125,9 +125,21 @@ module API
         end
       end
 
-      expose :protected do |repo, options|
+      expose :protected do |repo_obj, options|
         if options[:project]
-          options[:project].protected_branch? repo.name
+          options[:project].protected_branch? repo_obj.name
+        end
+      end
+
+      expose :developers_can_push do |repo_obj, options|
+        if options[:project]
+          options[:project].developers_can_push_to_protected_branch? repo_obj.name
+        end
+      end
+
+      expose :developers_can_merge do |repo_obj, options|
+        if options[:project]
+          options[:project].developers_can_merge_to_protected_branch? repo_obj.name
         end
       end
     end
diff --git a/lib/api/helpers.rb b/lib/api/helpers.rb
index 73557cf7db6..d6e4eb2afd7 100644
--- a/lib/api/helpers.rb
+++ b/lib/api/helpers.rb
@@ -9,6 +9,13 @@ module API
       [ true, 1, '1', 't', 'T', 'true', 'TRUE', 'on', 'ON' ].include?(value)
     end
 
+    def to_boolean(value)
+      return true if value =~ /^(true|t|yes|y|1|on)$/i
+      return false if value =~ /^(false|f|no|n|0|off)$/i
+
+      nil
+    end
+
     def find_user_by_private_token
       token_string = (params[PRIVATE_TOKEN_PARAM] || env[PRIVATE_TOKEN_HEADER]).to_s
       User.find_by_authentication_token(token_string) || User.find_by_personal_access_token(token_string)