Merge branch 'issue_18656' into 'master'

Load issue templates from repository

part of #18656 


## 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 !4981

9 files changed, 241 insertions, 38 deletions

diff --git a/lib/api/templates.rb b/lib/api/templates.rb
index 18408797756..b9e718147e1 100644
--- a/lib/api/templates.rb
+++ b/lib/api/templates.rb
@@ -1,21 +1,28 @@
 module API
   class Templates < Grape::API
-    TEMPLATE_TYPES = {
-      gitignores:     Gitlab::Template::Gitignore,
-      gitlab_ci_ymls: Gitlab::Template::GitlabCiYml
+    GLOBAL_TEMPLATE_TYPES = {
+      gitignores:     Gitlab::Template::GitignoreTemplate,
+      gitlab_ci_ymls: Gitlab::Template::GitlabCiYmlTemplate
     }.freeze
 
-    TEMPLATE_TYPES.each do |template, klass|
+    helpers do
+      def render_response(template_type, template)
+        not_found!(template_type.to_s.singularize) unless template
+        present template, with: Entities::Template
+      end
+    end
+
+    GLOBAL_TEMPLATE_TYPES.each do |template_type, klass|
       # Get the list of the available template
       #
       # Example Request:
       #   GET /gitignores
       #   GET /gitlab_ci_ymls
-      get template.to_s do
+      get template_type.to_s do
         present klass.all, with: Entities::TemplatesList
       end
 
-      # Get the text for a specific template
+      # Get the text for a specific template present in local filesystem
       #
       # Parameters:
       #   name (required) - The name of a template
@@ -23,13 +30,10 @@ module API
       # Example Request:
       #   GET /gitignores/Elixir
       #   GET /gitlab_ci_ymls/Ruby
-      get "#{template}/:name" do
+      get "#{template_type}/:name" do
         required_attributes! [:name]
-
         new_template = klass.find(params[:name])
-        not_found!(template.to_s.singularize) unless new_template
-
-        present new_template, with: Entities::Template
+        render_response(template_type, new_template)
       end
     end
   end
diff --git a/lib/gitlab/template/base_template.rb b/lib/gitlab/template/base_template.rb
index 760ff3e614a..7ebec8e2cff 100644
--- a/lib/gitlab/template/base_template.rb
+++ b/lib/gitlab/template/base_template.rb
@@ -1,8 +1,9 @@
 module Gitlab
   module Template
     class BaseTemplate
-      def initialize(path)
+      def initialize(path, project = nil)
         @path = path
+        @finder = self.class.finder(project)
       end
 
       def name
@@ -10,23 +11,32 @@ module Gitlab
       end
 
       def content
-        File.read(@path)
+        @finder.read(@path)
+      end
+
+      def to_json
+        { name: name, content: content }
       end
 
       class << self
-        def all
-          self.categories.keys.flat_map { |cat| by_category(cat) }
+        def all(project = nil)
+          if categories.any?
+            categories.keys.flat_map { |cat| by_category(cat, project) }
+          else
+            by_category("", project)
+          end
         end
 
-        def find(key)
-          file_name = "#{key}#{self.extension}"
-
-          directory = select_directory(file_name)
-          directory ? new(File.join(category_directory(directory), file_name)) : nil
+        def find(key, project = nil)
+          path = self.finder(project).find(key)
+          path.present? ? new(path, project) : nil
         end
 
+        # Set categories as sub directories
+        # Example: { "category_name_1" => "directory_path_1", "category_name_2" => "directory_name_2" }
+        # Default is no category with all files in base dir of each class
         def categories
-          raise NotImplementedError
+          {}
         end
 
         def extension
@@ -37,29 +47,40 @@ module Gitlab
           raise NotImplementedError
         end
 
-        def by_category(category)
-          templates_for_directory(category_directory(category))
+        # Defines which strategy will be used to get templates files
+        # RepoTemplateFinder - Finds templates on project repository, templates are filtered perproject
+        # GlobalTemplateFinder - Finds templates on gitlab installation source, templates can be used in all projects
+        def finder(project = nil)
+          raise NotImplementedError
         end
 
-        def category_directory(category)
-          File.join(base_dir, categories[category])
+        def by_category(category, project = nil)
+          directory = category_directory(category)
+          files = finder(project).list_files_for(directory)
+
+          files.map { |f| new(f, project) }
         end
 
-        private
+        def category_directory(category)
+          return base_dir unless category.present?
 
-        def select_directory(file_name)
-          categories.keys.find do |category|
-            File.exist?(File.join(category_directory(category), file_name))
-          end
+          File.join(base_dir, categories[category])
         end
 
-        def templates_for_directory(dir)
-          dir << '/' unless dir.end_with?('/')
-          Dir.glob(File.join(dir, "*#{self.extension}")).select { |f| f =~ filter_regex }.map { |f| new(f) }
-        end
+        # If template is organized by category it returns { category_name: [{ name: template_name }, { name: template2_name }] }
+        # If no category is present returns [{ name: template_name }, { name: template2_name}]
+        def dropdown_names(project = nil)
+          return [] if project && !project.repository.exists?
 
-        def filter_regex
-          @filter_reges ||= /#{Regexp.escape(extension)}\z/
+          if categories.any?
+            categories.keys.map do |category|
+              files = self.by_category(category, project)
+              [category, files.map { |t| { name: t.name } }]
+            end.to_h
+          else
+            files = self.all(project)
+            files.map { |t| { name: t.name } }
+          end
         end
       end
     end
diff --git a/lib/gitlab/template/finders/base_template_finder.rb b/lib/gitlab/template/finders/base_template_finder.rb
new file mode 100644
index 00000000000..473b05257c6
--- /dev/null
+++ b/lib/gitlab/template/finders/base_template_finder.rb
@@ -0,0 +1,35 @@
+module Gitlab
+  module Template
+    module Finders
+      class BaseTemplateFinder
+        def initialize(base_dir)
+          @base_dir = base_dir
+        end
+
+        def list_files_for
+          raise NotImplementedError
+        end
+
+        def read
+          raise NotImplementedError
+        end
+
+        def find
+          raise NotImplementedError
+        end
+
+        def category_directory(category)
+          return @base_dir unless category.present?
+
+          @base_dir + @categories[category]
+        end
+
+        class << self
+          def filter_regex(extension)
+            /#{Regexp.escape(extension)}\z/
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/template/finders/global_template_finder.rb b/lib/gitlab/template/finders/global_template_finder.rb
new file mode 100644
index 00000000000..831da45191f
--- /dev/null
+++ b/lib/gitlab/template/finders/global_template_finder.rb
@@ -0,0 +1,38 @@
+# Searches and reads file present on Gitlab installation directory
+module Gitlab
+  module Template
+    module Finders
+      class GlobalTemplateFinder < BaseTemplateFinder
+        def initialize(base_dir, extension, categories = {})
+          @categories = categories
+          @extension  = extension
+          super(base_dir)
+        end
+
+        def read(path)
+          File.read(path)
+        end
+
+        def find(key)
+          file_name = "#{key}#{@extension}"
+
+          directory = select_directory(file_name)
+          directory ? File.join(category_directory(directory), file_name) : nil
+        end
+
+        def list_files_for(dir)
+          dir << '/' unless dir.end_with?('/')
+          Dir.glob(File.join(dir, "*#{@extension}")).select { |f| f =~ self.class.filter_regex(@extension) }
+        end
+
+        private
+
+        def select_directory(file_name)
+          @categories.keys.find do |category|
+            File.exist?(File.join(category_directory(category), file_name))
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/template/finders/repo_template_finder.rb b/lib/gitlab/template/finders/repo_template_finder.rb
new file mode 100644
index 00000000000..22c39436cb2
--- /dev/null
+++ b/lib/gitlab/template/finders/repo_template_finder.rb
@@ -0,0 +1,59 @@
+# Searches and reads files present on each Gitlab project repository
+module Gitlab
+  module Template
+    module Finders
+      class RepoTemplateFinder < BaseTemplateFinder
+        # Raised when file is not found
+        class FileNotFoundError < StandardError; end
+
+        def initialize(project, base_dir, extension, categories = {})
+          @categories     = categories
+          @extension      = extension
+          @repository     = project.repository
+          @commit         = @repository.head_commit if @repository.exists?
+
+          super(base_dir)
+        end
+
+        def read(path)
+          blob = @repository.blob_at(@commit.id, path) if @commit
+          raise FileNotFoundError if blob.nil?
+          blob.data
+        end
+
+        def find(key)
+          file_name = "#{key}#{@extension}"
+          directory = select_directory(file_name)
+          raise FileNotFoundError if directory.nil?
+
+          category_directory(directory) + file_name
+        end
+
+        def list_files_for(dir)
+          return [] unless @commit
+
+          dir << '/' unless dir.end_with?('/')
+
+          entries = @repository.tree(:head, dir).entries
+
+          names = entries.map(&:name)
+          names.select { |f| f =~ self.class.filter_regex(@extension) }
+        end
+
+        private
+
+        def select_directory(file_name)
+          return [] unless @commit
+
+          # Insert root as directory
+          directories = ["", @categories.keys]
+
+          directories.find do |category|
+            path = category_directory(category) + file_name
+            @repository.blob_at(@commit.id, path)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/template/gitignore.rb b/lib/gitlab/template/gitignore_template.rb
index 964fbfd4de3..8d2a9d2305c 100644
--- a/lib/gitlab/template/gitignore.rb
+++ b/lib/gitlab/template/gitignore_template.rb
@@ -1,6 +1,6 @@
 module Gitlab
   module Template
-    class Gitignore < BaseTemplate
+    class GitignoreTemplate < BaseTemplate
       class << self
         def extension
           '.gitignore'
@@ -16,6 +16,10 @@ module Gitlab
         def base_dir
           Rails.root.join('vendor/gitignore')
         end
+
+        def finder(project = nil)
+          Gitlab::Template::Finders::GlobalTemplateFinder.new(self.base_dir, self.extension, self.categories)
+        end
       end
     end
   end
diff --git a/lib/gitlab/template/gitlab_ci_yml.rb b/lib/gitlab/template/gitlab_ci_yml_template.rb
index 7f480fe33c0..8d1a1ed54c9 100644
--- a/lib/gitlab/template/gitlab_ci_yml.rb
+++ b/lib/gitlab/template/gitlab_ci_yml_template.rb
@@ -1,6 +1,6 @@
 module Gitlab
   module Template
-    class GitlabCiYml < BaseTemplate
+    class GitlabCiYmlTemplate < BaseTemplate
       def content
         explanation = "# This file is a template, and might need editing before it works on your project."
         [explanation, super].join("\n")
@@ -21,6 +21,10 @@ module Gitlab
         def base_dir
           Rails.root.join('vendor/gitlab-ci-yml')
         end
+
+        def finder(project = nil)
+          Gitlab::Template::Finders::GlobalTemplateFinder.new(self.base_dir, self.extension, self.categories)
+        end
       end
     end
   end
diff --git a/lib/gitlab/template/issue_template.rb b/lib/gitlab/template/issue_template.rb
new file mode 100644
index 00000000000..c6fa8d3eafc
--- /dev/null
+++ b/lib/gitlab/template/issue_template.rb
@@ -0,0 +1,19 @@
+module Gitlab
+  module Template
+    class IssueTemplate < BaseTemplate
+      class << self
+        def extension
+          '.md'
+        end
+
+        def base_dir
+          '.gitlab/issue_templates/'
+        end
+
+        def finder(project)
+          Gitlab::Template::Finders::RepoTemplateFinder.new(project, self.base_dir, self.extension, self.categories)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/template/merge_request_template.rb b/lib/gitlab/template/merge_request_template.rb
new file mode 100644
index 00000000000..f826c02f3b5
--- /dev/null
+++ b/lib/gitlab/template/merge_request_template.rb
@@ -0,0 +1,19 @@
+module Gitlab
+  module Template
+    class MergeRequestTemplate < BaseTemplate
+      class << self
+        def extension
+          '.md'
+        end
+
+        def base_dir
+          '.gitlab/merge_request_templates/'
+        end
+
+        def finder(project)
+          Gitlab::Template::Finders::RepoTemplateFinder.new(project, self.base_dir, self.extension, self.categories)
+        end
+      end
+    end
+  end
+end