# Terminal
rails g migration change_published_to_published_on_posts

# db/migrate/20250406012935_change_published_to_published_on_posts.rb
class ChangePublishedToPublishedOnPosts < ActiveRecord::Migration[8.0]
  def up
    add_column :posts, :published_at, :datetime
    execute <<-SQL
      UPDATE posts
      SET published_at = updated_at
      WHERE published = TRUE
    SQL
    remove_column :posts, :published
    add_index :posts, :published_at
  end

  def down
    add_column :posts, :published, :boolean, default: false
    execute <<-SQL
      UPDATE posts
      SET published = (published_at IS NOT NULL AND published_at <= CURRENT_TIMESTAMP)
    SQL
    remove_column :posts, :published_at
  end
end

# app/controllers/posts_controller.rb
def index
  @posts = Post.published.order(published_at: :desc)
end

def post_params
  params.expect(post: [ :title, :published_at, :content ])
end

# app/models/post.rb
class Post < ApplicationRecord
  has_rich_text :content

  scope :published, -> { where(published_at: ..Time.current) }
  scope :scheduled, -> { where(published_at: Time.current..) }
  # scope :scheduled, -> { where("published_at > ?", Time.current) }
  scope :unpublished, -> { where(published_at: nil) }

  def published?
    published_at.present? && published_at.past?
  end

  def scheduled?
    published_at.present? && published_at.future?
  end
end

# app/views/posts/_form.html.erb
<div class="my-5 flex items-center gap-2">
  <%= form.label :published_at %>
  <%= form.datetime_field :published_at %>
</div>

# app/views/posts/_post.html.erb
<div>
  <%= "Published" if post.published? %>
  <%= "Scheduled" if post.scheduled? %>
  <%= "Unpublished" if !post.scheduled? && !post.published? %>
</div>