Make PreviewCard records reuseable between statuses (#4642)

* Make PreviewCard records reuseable between statuses

**Warning!** Migration truncates preview_cards tablec

* Allow a wider thumbnail for link preview, display it in horizontal layout (#4648)

* Delete preview cards files before truncating

* Rename old table instead of truncating it

* Add mastodon:maintenance:remove_deprecated_preview_cards

* Ignore deprecated_preview_cards in schema definition

* Fix null behaviour

2 files changed, 37 insertions, 0 deletions

diff --git a/db/migrate/20170901141119_truncate_preview_cards.rb b/db/migrate/20170901141119_truncate_preview_cards.rb
new file mode 100644
index 000000000..4d9802f3b
--- /dev/null
+++ b/db/migrate/20170901141119_truncate_preview_cards.rb
@@ -0,0 +1,30 @@
+class TruncatePreviewCards < ActiveRecord::Migration[5.1]
+  def up
+    rename_table :preview_cards, :deprecated_preview_cards
+
+    create_table :preview_cards do |t|
+      t.string     :url, default: '', null: false, index: { unique: true }
+      t.string     :title, default: '', null: false
+      t.string     :description, default: '', null: false
+      t.attachment :image
+      t.integer    :type, default: 0, null: false
+      t.text       :html, default: '', null: false
+      t.string     :author_name, default: '', null: false
+      t.string     :author_url, default: '', null: false
+      t.string     :provider_name, default: '', null: false
+      t.string     :provider_url, default: '', null: false
+      t.integer    :width, default: 0, null: false
+      t.integer    :height, default: 0, null: false
+      t.timestamps
+    end
+  end
+
+  def down
+    if ActiveRecord::Base.connection.table_exists? 'deprecated_preview_cards'
+      drop_table :preview_cards
+      rename_table :deprecated_preview_cards, :preview_cards
+    else
+      raise ActiveRecord::IrreversibleMigration, 'Previous preview cards table has already been removed'
+    end
+  end
+end
diff --git a/db/migrate/20170901142658_create_join_table_preview_cards_statuses.rb b/db/migrate/20170901142658_create_join_table_preview_cards_statuses.rb
new file mode 100644
index 000000000..be7f533b5
--- /dev/null
+++ b/db/migrate/20170901142658_create_join_table_preview_cards_statuses.rb
@@ -0,0 +1,7 @@
+class CreateJoinTablePreviewCardsStatuses < ActiveRecord::Migration[5.1]
+  def change
+    create_join_table :preview_cards, :statuses do |t|
+      t.index [:status_id, :preview_card_id]
+    end
+  end
+end