<h5>Rails SNS 로그인 구현</h5>
  <ol>
    <li>1. Oauth2.0 이해</li>
    <li>2. Gem과 기본 페이지 생성</li>
    <li>3. Devise 설정하기</li>
    <li>3-2. config 설정</li>
    <li>4-1. 모델 설정</li>
    <li>4-2. 컨트롤러 설정</li>
    <li>4-3. 뷰 설정</li>
  </ol>

gem 'devise'
gem 'omniauth'
gem 'omniauth-facebook'
gem "omniauth-google-oauth2"
gem 'omniauth-kakao', :git => 'git://github.com/hcn1519/omniauth-kakao'

bundle install

rails g controller visitor main
rails g controller register info1 info2

rails generate devise:install
rails generate devise user

rails generate devise:views
rails generate devise:controllers user

rails g migration add_colums_to_users profile_img:string

rails g model identity user:references provider:string uid:string

rake db:migrate

# config/route.rb

devise_for :users, :controllers => { omniauth_callbacks: 'user/omniauth_callbacks'}

# config/initializers/devise.rb

# config.omniauth :facebook, "key", "secret", 여기에 직접 key를 넣지 마세요

config.omniauth :facebook, ENV["Facebook_Key"], ENV["Facebook_Secret"]
config.omniauth :google_oauth2, ENV["Google_Key"], ENV["Google_Secret"]
config.omniauth :kakao, ENV["Kakao_Key"], :redirect_path => "/users/auth/kakao/callback"

# Gemfile
gem figaro

bundle install
bundle exec figaro install

# config/application.yml

Facebook_Key: "실제 발급 받은 키"
Facebook_Secret: "실제 발급 받은 비밀번호"

# app/models/user.rb

class User < ApplicationRecord
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable, :omniauthable

  def self.find_for_oauth(auth, signed_in_resource = nil)

    # user와 identity가 nil이 아니라면 받는다

    identity = Identity.find_for_oauth(auth)
    user = signed_in_resource ? signed_in_resource : identity.user

    # user가 nil이라면 새로 만든다.

    if user.nil?

      # 이미 있는 이메일인지 확인한다.

      email = auth.info.email
      user = User.where(:email => email).first

      unless self.where(email: auth.info.email).exists?
        # 없다면 새로운 데이터를 생성한다.

        if user.nil?
          # 카카오는 email을 제공하지 않음

          if auth.provider == "kakao"
            # provider(회사)별로 데이터를 제공해주는 hash의 이름이 다릅니다.

            # 각각의 omnaiuth별로 auth hash가 어떤 경로로, 어떤 이름으로 제공되는지 확인하고 설정해주세요.

            user = User.new(
              profile_img: auth.info.image,
              # 이 부분은 AWS S3와 연동할 때 프로필 이미지를 저장하기 위해 필요한 부분입니다.

              # remote_profile_img_url: auth.info.image.gsub('http://','https://'),

              password: Devise.friendly_token[0,20]
            )

          else
            user = User.new(
              email: auth.info.email,
              profile_img: auth.info.image,
              # remote_profile_img_url: auth.info.image.gsub('http://','https://'),

              password: Devise.friendly_token[0,20]
            )
          end
          user.save!
        end
      end
    end

    if identity.user != user
      identity.user = user
      identity.save!
    end
    user

  end

  # email이 없어도 가입이 되도록 설정

  def email_required?
    false
  end
end

# app/models/identity.rb

class Identity < ActiveRecord::Base
  belongs_to :user
  validates_presence_of :uid, :provider
  validates_uniqueness_of :uid, :scope => :provider

  def self.find_for_oauth(auth)
    find_or_create_by(uid: auth.uid, provider: auth.provider)
  end
end

# app/controllers/user/omniauth_callback_controller.rb

class User::OmniauthCallbacksController < Devise::OmniauthCallbacksController
  def self.provides_callback_for(provider)
    class_eval %Q{
      def #{provider}
        @user = User.find_for_oauth(env["omniauth.auth"], current_user)

        if @user.persisted?
          sign_in_and_redirect @user, event: :authentication
        else
          session["devise.#{provider}_data"] = env["omniauth.auth"]
          redirect_to new_user_registration_url
        end
      end
    }
  end
  [:kakao, :facebook, :google_oauth2].each do |provider|
    provides_callback_for provider
  end
  # provider별로 서로 다른 로그인 경로 설정

  def after_sign_in_path_for(resource)
    auth = request.env['omniauth.auth']
    @identity = Identity.find_for_oauth(auth)
    @user = User.find(current_user.id)
    if @user.persisted?
      if @identity.provider == "kakao"
        register_info2_path
      else
        register_info1_path
      end
    else
      visitor_main_path
    end
  end
end

app/views/devise   -- registrations -- new.html.erb
                   -- sessions      -- new.html.erb
                   -- shared        -- _links.html.erb
   /views/register -- _common_info.html.erb
                   -- info1.html.erb
                   -- info2.html.erb
   /views/visitor  -- main.html.erb

app/assets/stylesheets -- application.scss
                       -- register.scss
                       -- signupin.scss
                       -- visitoer.scss

# app/views/devise/registrations/new.html.erb
# 회원 가입과 관련된 부분입니다.
<%= stylesheet_link_tag 'signupin', media: 'all', 'data-turbolinks-track' => true %>

<div class="ui middle aligned center aligned grid loginForm">
  <div class="column loginColumn">
    <h2 class="ui orange image header loginImage">
      회원가입
    </h2>
  <%= form_for(resource, as: resource_name, url: registration_path(resource_name), :html => {class: "ui large form"}) do |f| %>
    <%= devise_error_messages! %>
    <div class="ui raised segment loginBox">
      <div class="field">
        <%= f.label :email, :class => 'ui left aligned header' %>
        <%= f.email_field :email %>
      </div>

      <div class="field">
        <%= f.label :name, '비밀번호', :class => 'ui left aligned header' %>
        <!--<% if @minimum_password_length %>
        <em>(<%= @minimum_password_length %> 자 이상이어야 합니다.)</em>
        <% end %><br />-->
        <%= f.password_field :password, autocomplete: "off", :placeholder => '6자 이상이어야 합니다.' %>
      </div>

      <div class="field">
        <%= f.label :name, '비밀번호 확인', :class => 'ui left aligned header' %>
        <%= f.password_field :password_confirmation, autocomplete: "off" %>
      </div>

      <div class="actions">
        <%= f.submit "회원가입", :class => 'ui fluid small yellow submit button'%>
      </div>
        <% end %>
    </div>
    <%= render "devise/shared/links" %>
  </div>
</div>

# app/views/devise/sessions/new.html.erb
# 로그인과 관련된 부분입니다.
<%= stylesheet_link_tag 'signupin', media: 'all', 'data-turbolinks-track' => true %>

<div class="ui middle aligned center aligned grid loginForm">
  <div class="column loginColumn">
    <h2 class="ui orange image header loginImage">
      회원가입
    </h2>
  <%= form_for(resource, as: resource_name, url: registration_path(resource_name), :html => {class: "ui large form"}) do |f| %>
    <%= devise_error_messages! %>
    <div class="ui raised segment loginBox">
      <div class="field">
        <%= f.label :email, :class => 'ui left aligned header' %>
        <%= f.email_field :email %>
      </div>

      <div class="field">
        <%= f.label :name, '비밀번호', :class => 'ui left aligned header' %>
        <!--<% if @minimum_password_length %>
        <em>(<%= @minimum_password_length %> 자 이상이어야 합니다.)</em>
        <% end %><br />-->
        <%= f.password_field :password, autocomplete: "off", :placeholder => '6자 이상이어야 합니다.' %>
      </div>

      <div class="field">
        <%= f.label :name, '비밀번호 확인', :class => 'ui left aligned header' %>
        <%= f.password_field :password_confirmation, autocomplete: "off" %>
      </div>

      <div class="actions">
        <%= f.submit "회원가입", :class => 'ui fluid small yellow submit button'%>
      </div>
        <% end %>
    </div>
    <%= render "devise/shared/links" %>
  </div>
</div>

# app/views/devise/shared/_links.html.erb
# 소셜 로그인 버튼을 수정하는 부분입니다.
<%- if devise_mapping.omniauthable? %>
  <div>
    <%- resource_class.omniauth_providers.each do |provider| %>
      <%= link_to omniauth_authorize_path(resource_name, provider) do %>
        <%- if provider.to_s == "google_oauth2" %>
          <% provider = "google plus" %>
        <% end %>
        <button class="ui fluid large <%= provider %> icon button sns">
          <i class="<%= provider %> icon" style="float: left"></i>
          <% if provider.to_s == "facebook" %>
            <% sns = '페이스북' %>
          <% elsif provider.to_s == "google plus" %>
            <% sns = '구글' %>
          <% else %>
            <% sns = '카카오' %>
          <% end %>
          <%= sns %> 계정으로 로그인
        </button>
      <% end -%>
    <% end -%>
  </div>
<% end -%>
<%- if controller_name != 'sessions' %>
    <%= link_to "로그인", new_session_path(resource_name) %>
<% end -%>

<%- if devise_mapping.recoverable? && controller_name != 'passwords' && controller_name != 'registrations' %>
    <%= link_to "비밀번호 찾기", new_password_path(resource_name) %>&nbsp; | &nbsp;
<% end -%>

<%- if devise_mapping.registerable? && controller_name != 'registrations' %>
    <%= link_to "가입하기", new_registration_path(resource_name), :name => 'test' %>
<% end -%>

<%- if devise_mapping.confirmable? && controller_name != 'confirmations' %>
  <%= link_to "Didn't receive confirmation instructions?", new_confirmation_path(resource_name) %><br />
<% end -%>

<%- if devise_mapping.lockable? && resource_class.unlock_strategy_enabled?(:email) && controller_name != 'unlocks' %>
  <%= link_to "Didn't receive unlock instructions?", new_unlock_path(resource_name) %><br />
<% end -%>
<!--"Sign in with #{OmniAuth::Utils.camelize(provider)}"-->