Merge branch 'zj-slash-commands-mattermost' into 'master'

Slash command for mattermost

Closes  #22540

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [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 it does - rebase it please)


See merge request !7438

8 files changed, 313 insertions, 5 deletions

diff --git a/lib/api/helpers.rb b/lib/api/helpers.rb
index 84cc9200d1b..2c593dbb4ea 100644
--- a/lib/api/helpers.rb
+++ b/lib/api/helpers.rb
@@ -85,8 +85,8 @@ module API
       end
     end
 
-    def project_service
-      @project_service ||= user_project.find_or_initialize_service(params[:service_slug].underscore)
+    def project_service(project = user_project)
+      @project_service ||= project.find_or_initialize_service(params[:service_slug].underscore)
       @project_service || not_found!("Service")
     end
 
diff --git a/lib/api/services.rb b/lib/api/services.rb
index fc8598daa32..4d23499aa39 100644
--- a/lib/api/services.rb
+++ b/lib/api/services.rb
@@ -1,10 +1,10 @@
 module API
   # Projects API
   class Services < Grape::API
-    before { authenticate! }
-    before { authorize_admin_project }
-
     resource :projects do
+      before { authenticate! }
+      before { authorize_admin_project }
+
       # Set <service_slug> service for project
       #
       # Example Request:
@@ -59,5 +59,28 @@ module API
         present project_service, with: Entities::ProjectService, include_passwords: current_user.is_admin?
       end
     end
+
+    resource :projects do
+      desc 'Trigger a slash command' do
+        detail 'Added in GitLab 8.13'
+      end
+      post ':id/services/:service_slug/trigger' do
+        project = Project.find_with_namespace(params[:id]) || Project.find_by(id: params[:id])
+
+        # This is not accurate, but done to prevent leakage of the project names
+        not_found!('Service') unless project
+
+        service = project_service(project)
+
+        result = service.try(:active?) && service.try(:trigger, params)
+
+        if result
+          status result[:status] || 200
+          present result
+        else
+          not_found!('Service')
+        end
+      end
+    end
   end
 end
diff --git a/lib/gitlab/chat_commands/base_command.rb b/lib/gitlab/chat_commands/base_command.rb
new file mode 100644
index 00000000000..e59d69b72b9
--- /dev/null
+++ b/lib/gitlab/chat_commands/base_command.rb
@@ -0,0 +1,49 @@
+module Gitlab
+  module ChatCommands
+    class BaseCommand
+      QUERY_LIMIT = 5
+
+      def self.match(_text)
+        raise NotImplementedError
+      end
+
+      def self.help_message
+        raise NotImplementedError
+      end
+
+      def self.available?(_project)
+        raise NotImplementedError
+      end
+
+      def self.allowed?(_user, _ability)
+        true
+      end
+
+      def self.can?(object, action, subject)
+        Ability.allowed?(object, action, subject)
+      end
+
+      def execute(_)
+        raise NotImplementedError
+      end
+
+      def collection
+        raise NotImplementedError
+      end
+
+      attr_accessor :project, :current_user, :params
+
+      def initialize(project, user, params = {})
+        @project, @current_user, @params = project, user, params.dup
+      end
+
+      private
+
+      def find_by_iid(iid)
+        resource = collection.find_by(iid: iid)
+
+        readable?(resource) ? resource : nil
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/chat_commands/command.rb b/lib/gitlab/chat_commands/command.rb
new file mode 100644
index 00000000000..5f131703d40
--- /dev/null
+++ b/lib/gitlab/chat_commands/command.rb
@@ -0,0 +1,61 @@
+module Gitlab
+  module ChatCommands
+    class Command < BaseCommand
+      COMMANDS = [
+        Gitlab::ChatCommands::IssueShow,
+        Gitlab::ChatCommands::IssueCreate,
+      ].freeze
+
+      def execute
+        command, match = match_command
+
+        if command
+          if command.allowed?(project, current_user)
+            present command.new(project, current_user, params).execute(match)
+          else
+            access_denied
+          end
+        else
+          help(help_messages)
+        end
+      end
+
+      private
+
+      def match_command
+        match = nil
+        service = available_commands.find do |klass|
+          match = klass.match(command)
+        end
+
+        [service, match]
+      end
+
+      def help_messages
+        available_commands.map(&:help_message)
+      end
+
+      def available_commands
+        COMMANDS.select do |klass|
+          klass.available?(project)
+        end
+      end
+
+      def command
+        params[:text]
+      end
+
+      def help(messages)
+        Mattermost::Presenter.help(messages, params[:command])
+      end
+
+      def access_denied
+        Mattermost::Presenter.access_denied
+      end
+
+      def present(resource)
+        Mattermost::Presenter.present(resource)
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/chat_commands/issue_command.rb b/lib/gitlab/chat_commands/issue_command.rb
new file mode 100644
index 00000000000..f1bc36239d5
--- /dev/null
+++ b/lib/gitlab/chat_commands/issue_command.rb
@@ -0,0 +1,17 @@
+module Gitlab
+  module ChatCommands
+    class IssueCommand < BaseCommand
+      def self.available?(project)
+        project.issues_enabled? && project.default_issues_tracker?
+      end
+
+      def collection
+        project.issues
+      end
+
+      def readable?(issue)
+        self.class.can?(current_user, :read_issue, issue)
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/chat_commands/issue_create.rb b/lib/gitlab/chat_commands/issue_create.rb
new file mode 100644
index 00000000000..98338ebfa27
--- /dev/null
+++ b/lib/gitlab/chat_commands/issue_create.rb
@@ -0,0 +1,24 @@
+module Gitlab
+  module ChatCommands
+    class IssueCreate < IssueCommand
+      def self.match(text)
+        /\Aissue\s+create\s+(?<title>[^\n]*)\n*(?<description>.*)\z/.match(text)
+      end
+
+      def self.help_message
+        'issue create <title>\n<description>'
+      end
+
+      def self.allowed?(project, user)
+        can?(user, :create_issue, project)
+      end
+
+      def execute(match)
+        title = match[:title]
+        description = match[:description]
+
+        Issues::CreateService.new(project, current_user, title: title, description: description).execute
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/chat_commands/issue_show.rb b/lib/gitlab/chat_commands/issue_show.rb
new file mode 100644
index 00000000000..f5bceb038e5
--- /dev/null
+++ b/lib/gitlab/chat_commands/issue_show.rb
@@ -0,0 +1,17 @@
+module Gitlab
+  module ChatCommands
+    class IssueShow < IssueCommand
+      def self.match(text)
+        /\Aissue\s+show\s+(?<iid>\d+)/.match(text)
+      end
+
+      def self.help_message
+        "issue show <id>"
+      end
+
+      def execute(match)
+        find_by_iid(match[:iid])
+      end
+    end
+  end
+end
diff --git a/lib/mattermost/presenter.rb b/lib/mattermost/presenter.rb
new file mode 100644
index 00000000000..bfbb089eb02
--- /dev/null
+++ b/lib/mattermost/presenter.rb
@@ -0,0 +1,117 @@
+module Mattermost
+  class Presenter
+    class << self
+      include Gitlab::Routing.url_helpers
+
+      def authorize_chat_name(url)
+        message = if url
+                    ":wave: Hi there! Before I do anything for you, please [connect your GitLab account](#{url})."
+                  else
+                    ":sweat_smile: Couldn't identify you, nor can I autorize you!"
+                  end
+
+        ephemeral_response(message)
+      end
+
+      def help(commands, trigger)
+        if commands.none?
+          ephemeral_response("No commands configured")
+        else
+          commands.map! { |command| "#{trigger} #{command}" }
+          message = header_with_list("Available commands", commands)
+
+          ephemeral_response(message)
+        end
+      end
+
+      def present(resource)
+        return not_found unless resource
+
+        if resource.respond_to?(:count)
+          if resource.count > 1
+            return multiple_resources(resource)
+          elsif resource.count == 0
+            return not_found
+          else
+            resource = resource.first
+          end
+        end
+
+        single_resource(resource)
+      end
+
+      def access_denied
+        ephemeral_response("Whoops! That action is not allowed. This incident will be [reported](https://xkcd.com/838/).")
+      end
+
+      private
+
+      def not_found
+        ephemeral_response("404 not found! GitLab couldn't find what you were looking for! :boom:")
+      end
+
+      def single_resource(resource)
+        return error(resource) if resource.errors.any? || !resource.persisted?
+
+        message = "### #{title(resource)}"
+        message << "\n\n#{resource.description}" if resource.description
+
+        in_channel_response(message)
+      end
+
+      def multiple_resources(resources)
+        resources.map! { |resource| title(resource) }
+
+        message = header_with_list("Multiple results were found:", resources)
+
+        ephemeral_response(message)
+      end
+
+      def error(resource)
+        message = header_with_list("The action was not successful, because:", resource.errors.messages)
+
+        ephemeral_response(message)
+      end
+
+      def title(resource)
+        "[#{resource.to_reference} #{resource.title}](#{url(resource)})"
+      end
+
+      def header_with_list(header, items)
+        message = [header]
+
+        items.each do |item|
+          message << "- #{item}"
+        end
+
+        message.join("\n")
+      end
+
+      def url(resource)
+        url_for(
+          [
+            resource.project.namespace.becomes(Namespace),
+            resource.project,
+            resource
+          ]
+        )
+      end
+
+      def ephemeral_response(message)
+        {
+          response_type: :ephemeral,
+          text: message,
+          status: 200
+        }
+      end
+
+      def in_channel_response(message)
+        {
+          response_type: :in_channel,
+          text: message,
+          status: 200
+        }
+      end
+    end
+  end
+end