#views/app_mailers/send_invitation_email.html.haml
!!! 5
%html(lang="en-US")
  %body
  %p You are inivited by #{@invitation.inviter.full_name} to join Myflix!
  %p= @invitation.message
  %p= link_to "Accept this invitation", register_with_token_url(@invitation.token)

resources :users, only: [:create, :show]
  get 'register/:token', to: "users#new_with_invitation_token", as: 'register_with_token'

#users_controller_spec.rb
describe "GET new_with_invitation_token" do
  it "render the :new view template" do
    invitation = Fabricate(:invitation)
    get :new_with_invitation_token, token: invitation.token
    expect(response).to render_template :new
  end

  it "sets @user with recipient's email" do
    invitation = Fabricate(:invitation)
    get :new_with_invitation_token, token: invitation.token
    expect(assigns(:user).email).to eq(invitation.recipient_email)
  end

  it "sets @invitation_token" do
    invitation = Fabricate(:invitation)
    get :new_with_invitation_token, token: invitation.token
    expect(assigns(:invitation_token)).to eq(invitation.token)
  end

  it "redirects to expired token page for invalid tokens" do
    get :new_with_invitation_token, token: 'asdffdhh'
    expect(response).to redirect_to expired_token_path
  end

#fabricators/invitation_fabricators.rb
Fabricator(:invitation) do
  recipient_name { Faker::Name.name }
  recipient_email { Faker::Internet.email }
  message { Faker::Lorem.paragraphs(2).join(" ") }
end

class AddTokenToInvitations < ActiveRecord::Migration
  def change
    add_column :invitations, :token, :string
  end
end

#users_controller.rb
  def new_with_invitation_token
    invitation = Invitation.where(token: params[:token]).first
    if invitation
      @user = User.new(email: invitation.recipient_email)
      @invitation_token = invitation.token
      render :new
    else
      redirect_to expired_token_path
    end
  end

  private
  def user_params
    params.require(:user).permit!
  end

  def handle_invitations
    if params[:invitation_token].present?
      invitation = Invitation.where(token: params[:invitation_token]).first
      @user.follow(invitation.inviter)
      invitation.inviter.follow(@user)
      invitation.update_column(:token, nil)
    end
  end
end

#users/new.html.haml
%section.register.container
  .row
    .col-sm-10.col-sm-offset-1
      = bootstrap_form_for @user, html: { class: "form-horizontal"} do |f|
        %header
          %h1 Register
        %fieldset
          .col-sm-6
            = f.email_field :email, label: "Email Address"
            = f.password_field :password
            = f.text_field :full_name, label: "Full Name"
            = hidden_field_tag :invitation_token, @invitation_token
        %fieldset.actions.control-group.col-sm-offset-0
          .controls
            %input(type="submit" value="Sign Up" class="btn btn-default")

#users_controller_spec.rb
   describe "POST create" do
    context "with valid input" do
      before { post :create, user: Fabricate.attributes_for(:user) }
      it "creates the user" do
        expect(User.count).to eq(1)
      end
      it "redirects to th sign on page" do
        expect(response).to redirect_to sign_in_path
      end

      it "makes the user follow the inviter" do
        alice = Fabricate(:user)
        invitation = Fabricate(:invitation, inviter: alice, recipient_email: 'jam@jamblack.com')
        post :create, user: {email: 'jam@jamblack.com', password: 'password', full_name: 'Jam Black'}, invitation_token: invitation.token
        jam = User.where(email: 'jam@jamblack.com').first
        expect(jam.follows?(alice)).to be_true
      end

      it "makes the inviter follow the user" do
        alice = Fabricate(:user)
        invitation = Fabricate(:invitation, inviter: alice, recipient_email: 'jam@jamblack.com')
        post :create, user: {email: 'jam@jamblack.com', password: 'password', full_name: 'Jam Black'}, invitation_token: invitation.token
        jam = User.where(email: 'jam@jamblack.com').first
        expect(alice.follows?(jam)).to be_true
      end
      it "expires the invitation upon acceptance" do
        alice = Fabricate(:user)
        invitation = Fabricate(:invitation, inviter: alice, recipient_email: 'jam@jamblack.com')
        post :create, user: {email: 'jam@jamblack.com', password: 'password', full_name: 'Jam Black'}, invitation_token: invitation.token
        jam = User.where(email: 'jam@jamblack.com').first
        expect(Invitation.first.token).to be_nil
      end
    end

describe "#follows?" do
    it "returns true if the user has a following relationship with another user" do
      alice = Fabricate(:user)
      bob = Fabricate(:user)
      Fabricate(:relationship, leader: bob, follower: alice)
      expect(alice.follows?(bob)).to be_true
    end

    it "returns false if the user does not have a following relationship with another user" do
      alice = Fabricate(:user)
      bob = Fabricate(:user)
      Fabricate(:relationship, leader: alice, follower: bob)
      expect(alice.follows?(bob)).to be_false
    end
  end

  describe "#follow" do
    it "follows another user" do
      alice = Fabricate(:user)
      bob = Fabricate(:user)
      alice.follow(bob)
      expect(alice.follows?(bob)).to be_true
    end

    it "does not follow one self" do
      alice = Fabricate(:user)
      alice.follow(alice)
      expect(alice.follows?(alice)).to be_false
    end
  end
end

#users.rb
  def follows?(another_user)
    following_relationships.map(&:leader).include?(another_user)
  end

  def can_follow?(another_user)
    !(self.follows?(another_user) || self == another_user)
  end

  def follow(another_user)
    following_relationships.create(leader: another_user) if can_follow?(another_user)
  end
end