module Carto
  module Db
    class UserSchemaMover
      # Approach: move object by object (tables, views, materialized and functions)
      STEPS_STRATEGY = :move_schema_content_step_by_step

      STRATEGIES = [STEPS_STRATEGY].freeze

      def initialize(user)
        @user = user
      end

      def default_strategy
        STEPS_STRATEGY
      end

      def move_objects(new_schema, strategy = default_strategy)
        raise "Not valid: #{strategy}" unless STRATEGIES.include?(strategy)

        old_schema = @user.database_schema

        @user.database_schema = new_schema
        @user.this.update database_schema: new_schema

        send(strategy, old_schema, new_schema)
      end

      private

      # Moves the schema by moving tables, views...
      def move_schema_content_step_by_step(old_schema, new_schema)
        @user.in_database(as: :superuser) do |conn|
          database = Database.new(@user.database_name, conn)
          database.create_schema(new_schema)
          @user.db_service.rebuild_quota_trigger_with_database(conn)

          conn.transaction do
            @user.real_tables(old_schema).
              each { |t| move_table_to_schema(t, conn, old_schema, new_schema) }

            views(conn, old_schema).
              each { |v| move_view_to_schema(v, conn, old_schema, new_schema) }

            materialized_views(conn, old_schema).
              each { |v| move_materialized_view_to_schema(v, conn, old_schema, new_schema) }

            functions(conn, old_schema).
              each { |f| move_function_to_schema(f, conn, old_schema, new_schema) }
          end
        end
      end

      def move_table_to_schema(table, database, old_schema, new_schema)
        old_name = "#{old_schema}.#{table[:relname]}"

        was_cartodbfied = cdb_drop_triggers(table, database, old_schema)

        database.run(%{ ALTER TABLE #{old_name} SET SCHEMA "#{new_schema}" })

        cdb_cartodbfy(table, database, new_schema) if was_cartodbfied
      end

      def cdb_drop_triggers(table, database, schema)
        name = "#{schema}.#{table[:relname]}"

        cartodbfied = Carto::UserTable.find_by_user_id_and_name(@user.id, table[:relname]).present?

        database.run(%{ SELECT cartodb._CDB_drop_triggers('#{name}'::REGCLASS) }) if cartodbfied

        cartodbfied
      end

      def cdb_cartodbfy(table, database, schema)
        name = "#{schema}.#{table[:relname]}"

        database.run(%{ SELECT cartodb.CDB_CartodbfyTable('#{schema}'::TEXT, '#{name}'::REGCLASS) })
      end

      def move_view_to_schema(view, database, old_schema, new_schema)
        old_name = "#{old_schema}.#{view.name}"

        database.run(%{ ALTER VIEW #{old_name} SET SCHEMA "#{new_schema}" })
      end

      def move_materialized_view_to_schema(view, database, old_schema, new_schema)
        old_name = "#{old_schema}.#{view.name}"

        database.run(%{ ALTER MATERIALIZED VIEW #{old_name} SET SCHEMA "#{new_schema}" })
      end

      def move_function_to_schema(function, database, old_schema, new_schema)
        old_name = "#{old_schema}.#{function.name}"

        database.run(%{ ALTER FUNCTION #{old_name}(#{function.argument_data_types}) SET SCHEMA "#{new_schema}" })
      end

      def views(db, schema = @user.database_schema, owner_role = @user.database_username)
        Carto::Db::Database.new(@user.database_name, db).views(schema, owner_role, 'v')
      end

      def materialized_views(db, schema = @user.database_schema, owner_role = @user.database_username)
        Carto::Db::Database.new(@user.database_name, db).views(schema, owner_role, 'm')
      end

      def functions(db, schema = @user.database_schema, owner_role = @user.database_username)
        Carto::Db::Database.new(@user.database_name, db).functions(schema, owner_role)
      end
    end
  end
end