fix group structure

 class Group < ApplicationRecord
-  belongs_to :user, -> { with_deleted }, inverse_of: :groups
   belongs_to :pool, -> { with_deleted }, inverse_of: :groups
+  has_and_belongs_to_many :users, inverse_of: :groups
+
+  validates :name, :pool, presence: true
 end

@@ -17,7 +17,6 @@ class Pool < ApplicationRecord
 
   has_many :matches, dependent: :destroy, inverse_of: :pool
   has_many :groups, inverse_of: :pool
-  has_many :users, through: :groups, inverse_of: :pools
 
   scope :active, -> { where(active: true) }
   accepts_nested_attributes_for :matches, reject_if: :all_blank,

@@ -27,8 +27,7 @@ class User < ApplicationRecord
   before_save :encrypt_password
 
   has_many :bets, inverse_of: :user
-  has_many :groups, inverse_of: :user
-  has_many :pools, through: :groups, inverse_of: :users
+  has_and_belongs_to_many :groups, inverse_of: :users
 
   has_and_belongs_to_many :roles, inverse_of: :users,
                         class_name: 'HeimdallEngine::Role',

@@ -10,5 +10,6 @@ Rails.application.routes.draw do
 
   namespace :admin do
     resources :pools
+    resources :groups
   end
 end

 class CreateGroups < ActiveRecord::Migration[5.0]
   def change
     create_table :groups do |t|
-      t.integer :user_id, index: true
       t.integer :pool_id, index: true
+      t.string :name
       t.timestamps
     end
   end

+class CreateGroupUser < ActiveRecord::Migration[5.0]
+  def change
+    create_table :group_users do |t|
+      t.integer :group_id, index: true
+      t.integer :user_id, index: true
+    end
+  end
+end

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20180611152223) do
+ActiveRecord::Schema.define(version: 20180611152633) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -24,13 +24,19 @@ ActiveRecord::Schema.define(version: 20180611152223) do
     t.integer "points"
   end
 
-  create_table "groups", force: :cascade do |t|
+  create_table "group_users", force: :cascade do |t|
+    t.integer "group_id"
     t.integer "user_id"
+    t.index ["group_id"], name: "index_group_users_on_group_id", using: :btree
+    t.index ["user_id"], name: "index_group_users_on_user_id", using: :btree
+  end
+
+  create_table "groups", force: :cascade do |t|
     t.integer  "pool_id"
+    t.string   "name"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["pool_id"], name: "index_groups_on_pool_id", using: :btree
-    t.index ["user_id"], name: "index_groups_on_user_id", using: :btree
   end
 
   create_table "heimdall_engine_role_abilities", force: :cascade do |t|