Introduce an Events API

* Meld the following disparate endpoints:
 * `/projects/:id/events`
 * `/events`
 * `/users/:id/events`
+ Add result filtering to the above endpoints:
 * action
 * target_type
 * before and after dates

2 files changed, 94 insertions, 0 deletions

diff --git a/app/finders/events_finder.rb b/app/finders/events_finder.rb
new file mode 100644
index 00000000000..b0450ddc1fd
--- /dev/null
+++ b/app/finders/events_finder.rb
@@ -0,0 +1,62 @@
+class EventsFinder
+  attr_reader :source, :params, :current_user
+
+  # Used to filter Events
+  #
+  # Arguments:
+  #   source - which user or project to looks for events on
+  #   current_user - only return events for projects visible to this user
+  #   params:
+  #     action: string
+  #     target_type: string
+  #     before: datetime
+  #     after: datetime
+  #
+  def initialize(params = {})
+    @source = params.delete(:source)
+    @current_user = params.delete(:current_user)
+    @params = params
+  end
+
+  def execute
+    events = source.events
+
+    events = by_current_user_access(events)
+    events = by_action(events)
+    events = by_target_type(events)
+    events = by_created_at_before(events)
+    events = by_created_at_after(events)
+
+    events
+  end
+
+  private
+
+  def by_current_user_access(events)
+    events.merge(ProjectsFinder.new(current_user: current_user).execute).references(:project)
+  end
+
+  def by_action(events)
+    return events unless Event::ACTIONS[params[:action]]
+
+    events.where(action: Event::ACTIONS[params[:action]])
+  end
+
+  def by_target_type(events)
+    return events unless Event::TARGET_TYPES[params[:target_type]]
+
+    events.where(target_type: Event::TARGET_TYPES[params[:target_type]])
+  end
+
+  def by_created_at_before(events)
+    return events unless params[:before]
+
+    events.where('events.created_at < ?', params[:before].beginning_of_day)
+  end
+
+  def by_created_at_after(events)
+    return events unless params[:after]
+
+    events.where('events.created_at > ?', params[:after].end_of_day)
+  end
+end
diff --git a/app/models/event.rb b/app/models/event.rb
index 46e89388bc1..d6d39473774 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -14,6 +14,30 @@ class Event < ActiveRecord::Base
   DESTROYED = 10
   EXPIRED   = 11 # User left project due to expiry
 
+  ACTIONS = HashWithIndifferentAccess.new(
+    created:    CREATED,
+    updated:    UPDATED,
+    closed:     CLOSED,
+    reopened:   REOPENED,
+    pushed:     PUSHED,
+    commented:  COMMENTED,
+    merged:     MERGED,
+    joined:     JOINED,
+    left:       LEFT,
+    destroyed:  DESTROYED,
+    expired:    EXPIRED
+  ).freeze
+
+  TARGET_TYPES = HashWithIndifferentAccess.new(
+    issue:          Issue,
+    milestone:      Milestone,
+    merge_request:  MergeRequest,
+    note:           Note,
+    project:        Project,
+    snippet:        Snippet,
+    user:           User
+  ).freeze
+
   RESET_PROJECT_ACTIVITY_INTERVAL = 1.hour
 
   delegate :name, :email, :public_email, :username, to: :author, prefix: true, allow_nil: true
@@ -55,6 +79,14 @@ class Event < ActiveRecord::Base
     def limit_recent(limit = 20, offset = nil)
       recent.limit(limit).offset(offset)
     end
+
+    def actions
+      ACTIONS.keys
+    end
+
+    def target_types
+      TARGET_TYPES.keys
+    end
   end
 
   def visible_to_user?(user = nil)