Add Keyspace retrieve and save

Add Keyspace management based on persistent_term, with tests

Signed-off-by: Eddy Babetto <eddy.babetto@secomind.com>

lib/astarte_core/cql_utils.ex

@@ -167,4 +167,41 @@ defmodule Astarte.Core.CQLUtils do
 
     eid
   end
+
+  @spec realm_name_to_keyspace_name(nonempty_binary(), nonempty_binary()) :: nonempty_binary()
+  def realm_name_to_keyspace_name(realm_name, astarte_instance_id \\ "default")
+
+  def realm_name_to_keyspace_name("", _) do
+    raise "EmptyRealm"
+  end
+
+  def realm_name_to_keyspace_name(realm_name, astarte_instance_id)
+      when is_binary(realm_name) do
+    case :persistent_term.get(realm_name, nil) do
+      nil ->
+        if String.length(astarte_instance_id <> realm_name) < 48 do
+          keyspace_name =
+            (astarte_instance_id <> realm_name)
+            |> String.replace("-", "")
+            |> String.replace("_", "")
+            |> String.downcase()
+
+          :persistent_term.put(realm_name, keyspace_name)
+          keyspace_name
+        else
+          keyspace_name =
+            Base.url_encode64(astarte_instance_id <> realm_name, padding: false)
+            |> String.replace("-", "")
+            |> String.replace("_", "")
+            |> String.slice(0..47)
+            |> String.downcase()
+
+          :persistent_term.put(realm_name, keyspace_name)
+          keyspace_name
+        end
+
+      value ->
+        value
+    end
+  end
 end

test/astarte_core/cql_utils_test.exs

@@ -1,6 +1,7 @@
 defmodule CQLUtilsTest do
   use ExUnit.Case
   alias Astarte.Core.CQLUtils
+  alias Astarte.Core.Realm
 
   test "interface name to table name" do
     assert CQLUtils.interface_name_to_table_name("com.ispirata.Hemera.DeviceLog", 1) ==
@@ -148,4 +149,47 @@ defmodule CQLUtilsTest do
     assert Astarte.Core.CQLUtils.endpoint_id("com.foo", 2, "/a/%{something}/foo") !=
              Astarte.Core.CQLUtils.endpoint_id("com.foo", 2, "/a/%{something}/bar")
   end
+
+  test "realm name does not get encoded, persistent_term exists" do
+    assert CQLUtils.realm_name_to_keyspace_name("example", "atestinstance") ==
+             "atestinstanceexample"
+
+    assert Realm.valid_name?(CQLUtils.realm_name_to_keyspace_name("example", "atestinstance")) ==
+             true
+
+    :persistent_term.erase("example")
+  end
+
+  test "realm name gets encoded, persistent_term exists" do
+    assert CQLUtils.realm_name_to_keyspace_name(
+             "averyveryverylongrealmnamejustforthistest",
+             "atestinstance"
+           ) ==
+             "yxrlc3rpbnn0yw5jzwf2zxj5dmvyexzlcnlsb25ncmvhbg1u"
+
+    assert Realm.valid_name?(
+             CQLUtils.realm_name_to_keyspace_name(
+               "averyveryverylongrealmnamejustforthistest",
+               "atestinstance"
+             )
+           ) == true
+
+    :persistent_term.erase("averyveryverylongrealmnamejustforthistest")
+  end
+
+  test "realm name is empty, persistent_term exists" do
+    assert_raise RuntimeError, ~r/^EmptyRealm/, fn ->
+      CQLUtils.realm_name_to_keyspace_name("", "atestinstance")
+    end
+  end
+
+  test "realm name is not empty, persistent_term does not exists" do
+    assert CQLUtils.realm_name_to_keyspace_name("example") ==
+             "defaultexample"
+
+    assert Realm.valid_name?(CQLUtils.realm_name_to_keyspace_name("example")) ==
+             true
+
+    :persistent_term.erase("example")
+  end
 end