Generate triggers to apply permissions in sqlite

clients/typescript/src/_generated/protocol/satellite.ts

@@ -687,6 +687,14 @@ export interface SatPerms {
   userId: string;
   rules: SatPerms_Rules | undefined;
   roles: SatPerms_Role[];
+  /**
+   * `triggers` is the sql code to install these permissions as triggers in
+   * the local db.
+   * The assumption is that the entire message is compressed before sending
+   * over the wire so just include the trigger sql directly rather than
+   * compress it separately.
+   */
+  triggers: string;
 }
 
 export enum SatPerms_Privilege {
@@ -4312,7 +4320,7 @@ export const SatShapeDataEnd = {
 messageTypeRegistry.set(SatShapeDataEnd.$type, SatShapeDataEnd);
 
 function createBaseSatPerms(): SatPerms {
-  return { $type: "Electric.Satellite.SatPerms", id: Long.ZERO, userId: "", rules: undefined, roles: [] };
+  return { $type: "Electric.Satellite.SatPerms", id: Long.ZERO, userId: "", rules: undefined, roles: [], triggers: "" };
 }
 
 export const SatPerms = {
@@ -4331,6 +4339,9 @@ export const SatPerms = {
     for (const v of message.roles) {
       SatPerms_Role.encode(v!, writer.uint32(34).fork()).ldelim();
     }
+    if (message.triggers !== "") {
+      writer.uint32(42).string(message.triggers);
+    }
     return writer;
   },
 
@@ -4369,6 +4380,13 @@ export const SatPerms = {
 
           message.roles.push(SatPerms_Role.decode(reader, reader.uint32()));
           continue;
+        case 5:
+          if (tag !== 42) {
+            break;
+          }
+
+          message.triggers = reader.string();
+          continue;
       }
       if ((tag & 7) === 4 || tag === 0) {
         break;
@@ -4390,6 +4408,7 @@ export const SatPerms = {
       ? SatPerms_Rules.fromPartial(object.rules)
       : undefined;
     message.roles = object.roles?.map((e) => SatPerms_Role.fromPartial(e)) || [];
+    message.triggers = object.triggers ?? "";
     return message;
   },
 };

components/electric/lib/electric/postgres/extension/schema_loader/version.ex

@@ -121,6 +121,28 @@ defmodule Electric.Postgres.Extension.SchemaLoader.Version do
     end
   end
 
+  def direct_fks(
+        %__MODULE__{} = version,
+        {_, _} = relation,
+        {target_schema, target_table} = target
+      ) do
+    with {:ok, table_schema} = table(version, relation) do
+      table_schema.constraints
+      |> Stream.filter(&match?({:foreign, _}, &1.constraint))
+      |> Enum.find(fn %{constraint: {:foreign, %{pk_table: %{schema: sname, name: tname}}}} ->
+        sname == target_schema && tname == target_table
+      end)
+      |> case do
+        nil ->
+          {:error,
+           "no foreign key found from #{Electric.Utils.inspect_relation(relation)} to #{Electric.Utils.inspect_relation(target)}"}
+
+        %{constraint: {:foreign, %{fk_cols: fk_cols, pk_cols: pk_cols}}} ->
+          {:ok, fk_cols, pk_cols}
+      end
+    end
+  end
+
   @spec fk_graph(t()) :: Graph.t()
   def fk_graph(%__MODULE__{fk_graph: fk_graph}) do
     fk_graph

components/electric/lib/electric/postgres/schema/fk_graph.ex

@@ -10,26 +10,61 @@ defmodule Electric.Postgres.Schema.FkGraph do
   key relations in a separate map of `%{relation() => %{relation() => [column_name()]}}`.
   """
   alias Electric.Postgres.Schema.Proto
+  alias Electric.Postgres.Extension.SchemaLoader
+
+  defstruct [:graph, fks: %{}, pks: %{}]
+
+  @type relation() :: Electric.Postgres.relation()
+  @type name() :: Electric.Postgres.name()
+  @type fks() :: [name(), ...]
+  @type pks() :: [name(), ...]
+  @type join() ::
+          {:many_to_one, {relation(), fks()}, {relation(), pks()}}
+          | {:one_to_many, {relation(), pks()}, {relation(), fks()}}
+
+  @type t() :: %__MODULE__{
+          graph: Graph.t(),
+          fks: %{relation() => %{relation() => fks()}},
+          pks: %{relation() => pks()}
+        }
+  @type edge() :: {relation(), relation(), label: fks()} | {relation(), relation(), fks()}
 
-  defstruct [:graph, fks: %{}]
+  @spec for_schema(SchemaLoader.Version.t()) :: t()
+  def for_schema(%SchemaLoader.Version{schema: schema}) do
+    for_schema(schema)
+  end
 
   def for_schema(%Proto.Schema{tables: tables}) do
-    tables
-    |> Stream.flat_map(fn %Proto.Table{constraints: constraints, name: name} ->
-      constraints
-      |> Stream.filter(&match?(%{constraint: {:foreign, _}}, &1))
-      |> Enum.map(fn %{constraint: {:foreign, fk}} ->
-        {{name.schema, name.name}, {fk.pk_table.schema, fk.pk_table.name}, fk.fk_cols}
+    fks =
+      tables
+      |> Enum.flat_map(fn %Proto.Table{constraints: constraints, name: name} ->
+        constraints
+        |> Stream.filter(&match?(%{constraint: {:foreign, _}}, &1))
+        |> Enum.map(fn %{constraint: {:foreign, fk}} ->
+          {{name.schema, name.name}, {fk.pk_table.schema, fk.pk_table.name}, fk.fk_cols}
+        end)
+      end)
+
+    pks =
+      tables
+      |> Stream.flat_map(fn %Proto.Table{constraints: constraints, name: name} ->
+        constraints
+        |> Stream.filter(&match?(%{constraint: {:primary, _}}, &1))
+        |> Enum.map(fn %{constraint: {:primary, pk}} ->
+          {{name.schema, name.name}, pk.keys}
+        end)
       end)
-    end)
-    |> new()
+      |> Map.new()
+
+    new(fks, pks)
   end
 
   defp new_graph do
     Graph.new(type: :undirected, vertex_identifier: & &1)
   end
 
-  def new(edges) do
+  @spec new([edge()], %{relation() => pks()}) :: t()
+  def new(edges, pks) do
     {graph, fks} =
       edges
       |> Enum.reduce({new_graph(), %{}}, fn edge, {graph, fks} ->
@@ -43,7 +78,7 @@ defmodule Electric.Postgres.Schema.FkGraph do
         }
       end)
 
-    %__MODULE__{graph: graph, fks: fks}
+    %__MODULE__{graph: graph, fks: fks, pks: pks}
   end
 
   defp normalise_edge({{_, _} = v1, {_, _} = v2, label: fk_columns}) when is_list(fk_columns) do
@@ -54,40 +89,83 @@ defmodule Electric.Postgres.Schema.FkGraph do
     {v1, v2, fk_columns}
   end
 
+  @doc """
+  Give the foreign keys on table `relation` that place it in the scope defined by `root`.
+  """
+  @spec foreign_keys(t(), relation(), relation()) :: fks() | nil
   # [VAX-1626] we don't support recursive relations
   def foreign_keys(%__MODULE__{}, {_, _} = root, root) do
-    []
+    nil
   end
 
   def foreign_keys(%__MODULE__{fks: fks} = fk_graph, {_, _} = root, {_, _} = relation) do
     # we guard against looking for a fk ref to the same table above so relation_path/3 is always
-    # going to return a list of at least 2 items or nil if there is no route between the two
+    # going to return a list of at least 2 items or `nil` if there is no route between the two
     # tables
 
-    case path(fk_graph, root, relation) do
-      [r1 | _] ->
-        case Map.get(fks, r1, nil) do
-          table_fks when is_map(table_fks) ->
-            # this gives us a list of the fks pointing out of this table
-            # we now need to find which of those live within the `root` scope
-            Enum.filter(table_fks, fn {fk_relation, _fk_cols} ->
-              is_list(path(fk_graph, root, fk_relation))
-            end)
-
-          _ ->
-            []
-        end
-
-      nil ->
-        []
+    with [r1 | _] <- path(fk_graph, root, relation),
+         table_fks when is_map(table_fks) <- Map.get(fks, r1, nil) do
+      # this gives us a list of the fks pointing out of this table
+      # we now need to find which of those live within the `root` scope
+      Enum.filter(table_fks, fn {fk_relation, _fk_cols} ->
+        is_list(path(fk_graph, root, fk_relation))
+      end)
     end
   end
 
+  @doc """
+  Get a relation path from the `target` table to the `root` table, defined by a foreign key
+  constraints between all tables in the path.
+  """
+  @spec path(t(), root :: relation(), target :: relation()) :: [relation(), ...] | nil
   def path(%__MODULE__{}, {_, _} = root, root) do
     [root]
   end
 
   def path(%__MODULE__{graph: graph}, {_, _} = root, {_, _} = relation) do
     Graph.get_shortest_path(graph, relation, root)
   end
+
+  @doc """
+  Get the foreign key path information between the `root` table and the given `relation`.
+
+  Each entry in the path is either
+  - `{:many_to_one, {from_table, foreign_key_columns}, {to_table, primary_key_columns}}`, or
+  - `{:one_to_many, {from_table, primary_key_columns}, {to_table, foreign_key_columns}}`
+
+  depending on the relation between the two tables.
+  """
+  @spec fk_path(t(), relation(), relation()) :: [join()] | nil
+  def fk_path(%__MODULE__{} = fk_graph, {_, _} = root, {_, _} = relation) do
+    with [_ | _] = path <- path(fk_graph, root, relation) do
+      path
+      |> Enum.chunk_every(2, 1, :discard)
+      |> Enum.map(fn [a, b] -> join(fk_graph, a, b) end)
+    end
+  end
+
+  @doc """
+  Given the two tables `source` and `target` describe the fk relation between them, either
+  `:many_to_one` or `:one_to_many`.
+
+  See `fk_path/3` above.
+  """
+  @spec join(t(), relation(), relation()) :: join()
+  def join(%__MODULE__{fks: fks, pks: pks}, {_, _} = source, {_, _} = target) do
+    cond do
+      fks = get_in(fks, [source, target]) ->
+        {:many_to_one, {source, fks}, {target, Map.fetch!(pks, target)}}
+
+      fks = get_in(fks, [target, source]) ->
+        {:one_to_many, {source, Map.fetch!(pks, source)}, {target, fks}}
+    end
+  end
+
+  @doc """
+  Return the primary key columns for the given relation.
+  """
+  @spec primary_keys(t(), relation()) :: {:ok, pks()} | :error
+  def primary_keys(%__MODULE__{pks: pks}, {_, _} = table) do
+    Map.fetch(pks, table)
+  end
 end

components/electric/lib/electric/satellite/permissions.ex

@@ -347,6 +347,15 @@ defmodule Electric.Satellite.Permissions do
     }
   end
 
+  @doc """
+  Generate list of `#{Permissions.Role}` structs for all our currently assigned roles plus the
+  `Anyone` and `Authenticated` roles (if applicable).
+  """
+  @spec assigned_roles(t()) :: [Role.t()]
+  def assigned_roles(perms) do
+    build_roles(perms.source.roles, perms.auth, perms.source.rules.assigns)
+  end
+
   @doc """
   Pass the transaction to the write buffer so it can reset itself when its pending writes have
   completed the loop back from pg and are now in the underlying shape graph.
@@ -684,7 +693,7 @@ defmodule Electric.Satellite.Permissions do
       end
 
     {:error,
-     "user does not have permission to " <>
+     "permissions: user does not have permission to " <>
        action <> Electric.Utils.inspect_relation(relation)}
   end