From ae377cef02968c5e604a65d9756aa8bc0a1d851d Mon Sep 17 00:00:00 2001
From: Simon Claessens <gagalago@gmail.com>
Date: Thu, 21 Jan 2021 12:13:43 +0100
Subject: [PATCH] Implement the rename_view method

---
 lib/scenic/adapters/postgres.rb | 45 ++++++++++++++++++++++++++++++++-
 lib/scenic/command_recorder.rb  | 27 ++++++++++----------
 lib/scenic/statements.rb        | 33 ++++++++++++++++++++++++
 3 files changed, 90 insertions(+), 15 deletions(-)

diff --git a/lib/scenic/adapters/postgres.rb b/lib/scenic/adapters/postgres.rb
index 2c94e015..e45ab2b0 100644
--- a/lib/scenic/adapters/postgres.rb
+++ b/lib/scenic/adapters/postgres.rb
@@ -118,6 +118,21 @@ def drop_view(name)
         execute "DROP VIEW #{quote_table_name(name)};"
       end
 
+      # Renames a view in the database
+      #
+      # This is typically called in a migration via {Statements#rename_view}.
+      #
+      # @param from_name The previous name of the view to rename.
+      # @param to_name The next name of the view to rename.
+      #
+      # @return [void]
+      def rename_view(from_name, to_name)
+        execute <<~SQL
+          ALTER VIEW #{quote_table_name(from_name)}
+          RENAME TO #{quote_table_name(to_name)};
+        SQL
+      end
+
       # Creates a materialized view in the database
       #
       # @param name The name of the materialized view to create
@@ -183,6 +198,34 @@ def drop_materialized_view(name)
         execute "DROP MATERIALIZED VIEW #{quote_table_name(name)};"
       end
 
+      # Renames a materialized view in the database
+      #
+      # This is typically called in a migration via {Statements#rename_view}.
+      #
+      # @param from_name The previous name of the materialized view to rename.
+      # @param to_name The next name of the materialized view to rename.
+      # @raise [MaterializedViewsNotSupportedError] if the version of Postgres
+      #   in use does not support materialized views.
+      #
+      # @return [void]
+      def rename_materialized_view(from_name, to_name, rename_indexes: false)
+        raise_unless_materialized_views_supported
+        execute <<~SQL
+          ALTER MATERIALIZED VIEW #{quote_table_name(from_name)}
+          RENAME TO #{quote_table_name(to_name)};
+        SQL
+
+        if rename_indexes
+          Indexes.new(connection: connection)
+            .on(to_name)
+            .map(&:index_name)
+            .select { |name| name.match?(from_name) }
+            .each do |name|
+              rename_index to_name, name, name.sub(from_name, to_name)
+            end
+        end
+      end
+
       # Refreshes a materialized view from its SQL schema.
       #
       # This is typically called from application code via {Scenic.database}.
@@ -225,7 +268,7 @@ def refresh_materialized_view(name, concurrently: false, cascade: false)
       private
 
       attr_reader :connectable
-      delegate :execute, :quote_table_name, to: :connection
+      delegate :execute, :quote_table_name, :rename_index, to: :connection
 
       def connection
         Connection.new(connectable.connection)
diff --git a/lib/scenic/command_recorder.rb b/lib/scenic/command_recorder.rb
index 2638d455..f18173b4 100644
--- a/lib/scenic/command_recorder.rb
+++ b/lib/scenic/command_recorder.rb
@@ -3,20 +3,9 @@
 module Scenic
   # @api private
   module CommandRecorder
-    def create_view(*args)
-      record(:create_view, args)
-    end
-
-    def drop_view(*args)
-      record(:drop_view, args)
-    end
-
-    def update_view(*args)
-      record(:update_view, args)
-    end
-
-    def replace_view(*args)
-      record(:replace_view, args)
+    METHODS = %i[create_view drop_view update_view replace_view rename_view]
+    METHODS.each do |method|
+      define_method(method) { |*args| record(method, args) }
     end
 
     def invert_create_view(args)
@@ -36,6 +25,16 @@ def invert_replace_view(args)
       perform_scenic_inversion(:replace_view, args)
     end
 
+    def invert_rename_view(args)
+      options = args.extract_options!
+      old_name, new_name = args
+
+      args = [new_name, old_name]
+      args << options unless options.empty?
+
+      [:rename_view, args]
+    end
+
     private
 
     def perform_scenic_inversion(method, args)
diff --git a/lib/scenic/statements.rb b/lib/scenic/statements.rb
index 84bf24b0..3d9c1177 100644
--- a/lib/scenic/statements.rb
+++ b/lib/scenic/statements.rb
@@ -146,6 +146,31 @@ def replace_view(name, version: nil, revert_to_version: nil, materialized: false
       Scenic.database.replace_view(name, sql_definition)
     end
 
+    # Rename a database view by name.
+    #
+    # @param from_name [String, Symbol] The previous name of the database view.
+    # @param from_name [String, Symbol] The next name of the database view.
+    # @param materialized [Boolean, Hash] True if updating a materialized view.
+    #   Set to { rename_indexes: true } to rename materialized view indexes
+    #   by substituing in their name the previous view name
+    #   to the next view name. Defaults to false.
+    # @return The database response from executing the rename statement.
+    #
+    # @example Rename a view
+    #   drop_view(:engggggement_reports, :engagement_reports)
+    #
+    def rename_view(from_name, to_name, materialized: false)
+      if materialized
+        Scenic.database.rename_materialized_view(
+          from_name,
+          to_name,
+          rename_indexes: rename_indexes(materialized),
+        )
+      else
+        Scenic.database.rename_view(from_name, to_name)
+      end
+    end
+
     private
 
     def definition(name, version)
@@ -159,5 +184,13 @@ def no_data(materialized)
         false
       end
     end
+
+    def rename_indexes(materialized)
+      if materialized.is_a?(Hash)
+        materialized.fetch(:rename_indexes, false)
+      else
+        false
+      end
+    end
   end
 end