1 files changed, 74 insertions, 0 deletions
diff --git a/app/services/commits/create_service.rb b/app/services/commits/create_service.rb
new file mode 100644
index 00000000000..c58f04a252b
--- /dev/null
+++ b/app/services/commits/create_service.rb
@@ -0,0 +1,74 @@
+module Commits
+  class CreateService < ::BaseService
+    ValidationError = Class.new(StandardError)
+    ChangeError = Class.new(StandardError)
+
+    def initialize(*args)
+      super
+
+      @start_project = params[:start_project] || @project
+      @start_branch = params[:start_branch]
+      @branch_name = params[:branch_name]
+    end
+
+    def execute
+      validate!
+
+      new_commit = create_commit!
+
+      success(result: new_commit)
+    rescue ValidationError, ChangeError, Gitlab::Git::Index::IndexError, Repository::CommitError, GitHooksService::PreReceiveError => ex
+      error(ex.message)
+    end
+
+    private
+
+    def create_commit!
+      raise NotImplementedError
+    end
+
+    def raise_error(message)
+      raise ValidationError, message
+    end
+
+    def different_branch?
+      @start_branch != @branch_name || @start_project != @project
+    end
+
+    def validate!
+      validate_permissions!
+      validate_on_branch!
+      validate_branch_existance!
+
+      validate_new_branch_name! if different_branch?
+    end
+
+    def validate_permissions!
+      allowed = ::Gitlab::UserAccess.new(current_user, project: project).can_push_to_branch?(@branch_name)
+
+      unless allowed
+        raise_error("You are not allowed to push into this branch")
+      end
+    end
+
+    def validate_on_branch!
+      if !@start_project.empty_repo? && !@start_project.repository.branch_exists?(@start_branch)
+        raise_error('You can only create or edit files when you are on a branch')
+      end
+    end
+
+    def validate_branch_existance!
+      if !project.empty_repo? && different_branch? && repository.branch_exists?(@branch_name)
+        raise_error("A branch called '#{@branch_name}' already exists. Switch to that branch in order to make changes")
+      end
+    end
+
+    def validate_new_branch_name!
+      result = ValidateNewBranchService.new(project, current_user).execute(@branch_name)
+
+      if result[:status] == :error
+        raise_error("Something went wrong when we tried to create '#{@branch_name}' for you: #{result[:message]}")
+      end
+    end
+  end
+end