Add API to upload media attachments

app/models/account.rb

@@ -31,6 +31,8 @@ class Account < ApplicationRecord
   has_many :following, through: :active_relationships,  source: :target_account
   has_many :followers, through: :passive_relationships, source: :account
 
+  has_many :media_attachments, dependent: :destroy
+
   MENTION_RE = /(?:^|\s|\.)@([a-z0-9_]+(?:@[a-z0-9\.\-]+)?)/i
 
   def follow!(other_account)

app/models/media_attachment.rb

@@ -0,0 +1,13 @@
+class MediaAttachment < ApplicationRecord
+  belongs_to :account, inverse_of: :media_attachments
+  belongs_to :status,  inverse_of: :media_attachments
+
+  has_attached_file :file
+  validates_attachment_content_type :file, content_type: /\Aimage\/.*\z/
+
+  validates :account, presence: true
+
+  def local?
+    self.remote_url.blank?
+  end
+end

app/models/status.rb

@@ -11,6 +11,7 @@ class Status < ApplicationRecord
   has_many :reblogs, foreign_key: 'reblog_of_id', class_name: 'Status', inverse_of: :reblog, dependent: :destroy
   has_many :replies, foreign_key: 'in_reply_to_id', class_name: 'Status', inverse_of: :thread
   has_many :mentions, dependent: :destroy
+  has_many :media_attachments, dependent: :destroy
 
   validates :account, presence: true
   validates :uri, uniqueness: true, unless: 'local?'