defmodule Ash.Notifier.PubSub do
require Logger
@publish %Spark.Dsl.Entity{
name: :publish,
target: Ash.Notifier.PubSub.Publication,
describe: """
Configure a given action to publish its results over a given topic.
See the [PubSub](/documentation/topics/pub_sub.md) and [Notifiers](/documentation/topics/notifiers.md) guides for more.
""",
examples: [
"publish :create, \"created\"",
"""
publish :assign, "assigned"
"""
],
schema: Ash.Notifier.PubSub.Publication.schema(),
args: [:action, :topic]
}
@publish_all %Spark.Dsl.Entity{
name: :publish_all,
target: Ash.Notifier.PubSub.Publication,
describe: """
Works just like `publish`, except that it takes a type
and publishes all actions of that type
See the [PubSub](/documentation/topics/pub_sub.md) and [Notifiers](/documentation/topics/notifiers.md) guides for more.
""",
examples: [
"publish_all :create, \"created\""
],
schema: Ash.Notifier.PubSub.Publication.publish_all_schema(),
args: [:type, :topic]
}
@pub_sub %Spark.Dsl.Section{
name: :pub_sub,
describe: """
A section for configuring how resource actions are published over pubsub
See the [PubSub](/documentation/topics/pub_sub.md) and [Notifiers](/documentation/topics/notifiers.md) guide for more.
""",
examples: [
"""
pub_sub do
module MyEndpoint
prefix "post"
publish :destroy, ["foo", :id]
publish :update, ["bar", :name] event: "name_change"
publish_all :create, "created"
end
"""
],
entities: [
@publish,
@publish_all
],
no_depend_modules: [:module],
schema: [
module: [
type: :atom,
doc: "The module to call `broadcast/3` on e.g module.broadcast(topic, event, message).",
required: true
],
prefix: [
type: :string,
doc:
"A prefix for all pubsub messages, e.g `users`. A message with `created` would be published as `users:created`"
],
delimiter: [
type: :string,
doc: "A delimiter for building topics. Default is a colon (:)"
],
broadcast_type: [
type: {:one_of, [:notification, :phoenix_broadcast, :broadcast]},
default: :notification,
doc: """
What shape the event payloads will be in. See
"""
],
name: [
type: :atom,
doc: "A named pub sub to pass as the first argument to broadcast."
]
]
}
@sections [@pub_sub]
@moduledoc """
A pubsub notifier extension.
"""
use Spark.Dsl.Extension, sections: @sections
@deprecated "use Ash.Notifier.PubSub.Info.publications/1 instead"
defdelegate publications(resource), to: Ash.Notifier.PubSub.Info
@deprecated "use Ash.Notifier.PubSub.Info.module/1 instead"
defdelegate module(resource), to: Ash.Notifier.PubSub.Info
@deprecated "use Ash.Notifier.PubSub.Info.prefix/1 instead"
defdelegate prefix(resource), to: Ash.Notifier.PubSub.Info
@deprecated "use Ash.Notifier.PubSub.Info.name/1 instead"
defdelegate name(resource), to: Ash.Notifier.PubSub.Info
use Ash.Notifier
alias Ash.Notifier.PubSub.Info
@doc false
def notify(%Ash.Notifier.Notification{resource: resource} = notification) do
resource
|> publications()
|> Enum.filter(&matches?(&1, notification.action))
|> Enum.each(&publish_notification(&1, notification))
end
@doc false
def requires_original_data?(resource, action) do
resource
|> publications()
|> Enum.filter(&(&1.previous_values? && matches?(&1, action)))
|> Enum.flat_map(fn publish ->
publish.topic
|> List.flatten()
|> Enum.filter(&is_atom/1)
end)
|> Enum.any?(&Ash.Resource.Info.attribute(resource, &1))
end
defp publish_notification(publish, notification) do
debug? = Application.get_env(:ash, :pub_sub)[:debug?] || false
event = publish.event || to_string(notification.action.name)
prefix = prefix(notification.resource) || ""
delimiter = Info.delimiter(notification.resource)
topics =
publish.topic
|> fill_template(notification, delimiter, publish.previous_values?)
|> Enum.map(fn topic ->
case {prefix, topic} do
{"", ""} -> ""
{prefix, ""} -> prefix
{"", topic} -> topic
{prefix, topic} -> "#{prefix}#{delimiter}#{topic}"
end
end)
if debug? do
Logger.debug("""
Broadcasting to topics #{inspect(topics)} via #{inspect(module(notification.resource))}.broadcast
Notification:
#{inspect(notification)}
""")
end
Enum.each(topics, fn topic ->
args =
case name(notification.resource) do
nil ->
[topic, event, to_payload(topic, event, notification)]
pub_sub ->
payload = to_payload(topic, event, notification)
[pub_sub, topic, payload]
end
args =
case publish.dispatcher do
nil ->
args
dispatcher ->
args ++ dispatcher
end
apply(module(notification.resource), :broadcast, args)
end)
end
def to_payload(topic, event, notification) do
case Ash.Notifier.PubSub.Info.broadcast_type(notification.resource) do
:phoenix_broadcast ->
%{
__struct__: Phoenix.Socket.Broadcast,
topic: topic,
event: event,
payload: notification
}
:broadcast ->
%{
topic: topic,
event: event,
payload: notification
}
:notification ->
notification
end
end
defp fill_template(topic, _notification, _delimiter, _previous_values?) when is_binary(topic),
do: [topic]
defp fill_template(topic, notification, delimiter, previous_values?) do
topic
|> all_combinations_of_values(notification, notification.action.type, previous_values?)
|> Enum.map(&List.flatten/1)
|> Enum.map(&Enum.join(&1, delimiter))
|> Enum.uniq()
end
defp all_combinations_of_values(
items,
notification,
action_type,
_previous_values?,
trail \\ []
)
defp all_combinations_of_values([], _, _, _previous_values?, trail), do: [Enum.reverse(trail)]
defp all_combinations_of_values(
[nil | rest],
notification,
action_type,
previous_values?,
trail
) do
all_combinations_of_values(rest, notification, action_type, previous_values?, trail)
end
defp all_combinations_of_values(
[item | rest],
notification,
action_type,
previous_values?,
trail
)
when is_binary(item) do
all_combinations_of_values(rest, notification, action_type, previous_values?, [item | trail])
end
defp all_combinations_of_values(
[:_tenant | rest],
notification,
action_type,
previous_values?,
trail
) do
if notification.changeset.tenant do
all_combinations_of_values(rest, notification, action_type, previous_values?, [
notification.changeset.tenant | trail
])
else
[]
end
end
defp all_combinations_of_values([:_pkey | rest], notification, type, true, trail)
when type in [:update, :destroy] do
pkey = Ash.Resource.Info.primary_key(notification.changeset.resource)
pkey_value_before_change = Enum.map_join(pkey, "-", &Map.get(notification.changeset.data, &1))
pkey_value_after_change = Enum.map_join(pkey, "-", &Map.get(notification.data, &1))
[pkey_value_before_change, pkey_value_after_change]
|> Enum.uniq()
|> Enum.flat_map(fn possible_value ->
all_combinations_of_values(rest, notification, type, true, [
possible_value | trail
])
end)
end
defp all_combinations_of_values([:_pkey | rest], notification, type, _, trail)
when type in [:update, :destroy] do
pkey = Ash.Resource.Info.primary_key(notification.changeset.resource)
pkey_value_after_change = Enum.map_join(pkey, "-", &Map.get(notification.data, &1))
all_combinations_of_values(rest, notification, type, false, [pkey_value_after_change | trail])
end
defp all_combinations_of_values(
[:_pkey | rest],
notification,
action_type,
previous_values?,
trail
) do
pkey = notification.changeset.resource
all_combinations_of_values(rest, notification, action_type, previous_values?, [
Enum.map_join(pkey, "-", &Map.get(notification.data, &1)) | trail
])
end
defp all_combinations_of_values([item | rest], notification, type, true, trail)
when is_atom(item) and type in [:update, :destroy] do
value_before_change = Map.get(notification.changeset.data, item)
value_after_change = Map.get(notification.data, item)
[value_before_change, value_after_change]
|> Enum.filter(&publishable_value?(&1, notification))
|> Enum.uniq()
|> Enum.flat_map(fn possible_value ->
all_combinations_of_values(rest, notification, type, true, [possible_value | trail])
end)
end
defp all_combinations_of_values([item | rest], notification, type, _, trail)
when is_atom(item) and type in [:update, :destroy] do
value_after_change = Map.get(notification.data, item)
if publishable_value?(value_after_change, notification) do
all_combinations_of_values(rest, notification, type, false, [value_after_change | trail])
else
[]
end
end
defp all_combinations_of_values(
[item | rest],
notification,
action_type,
previous_values?,
trail
)
when is_atom(item) do
value = Map.get(notification.data, item)
if publishable_value?(value, notification) do
all_combinations_of_values(rest, notification, action_type, previous_values?, [
value | trail
])
else
[]
end
end
defp all_combinations_of_values(
[item | rest],
notification,
action_type,
previous_values?,
trail
)
when is_list(item) do
Enum.flat_map(item, fn possible_value ->
all_combinations_of_values(
[possible_value | rest],
notification,
action_type,
previous_values?,
trail
)
end)
end
defp publishable_value?(nil, _notification), do: false
defp publishable_value?(%Ash.NotLoaded{field: field}, notification) do
Logger.warning(
"Not publishing notification `#{inspect(notification.topic)}` for #{inspect(notification.resource)} because `#{field}` is not loaded"
)
false
end
defp publishable_value?(%Ash.ForbiddenField{field: field}, notification) do
Logger.warning(
"Not publishing notification `#{inspect(notification.topic)}` for #{inspect(notification.resource)} because `#{field}` is an `%Ash.ForbiddenField{}`"
)
false
end
defp publishable_value?(_, _), do: true
defp matches?(%{action: action}, %{name: action}), do: true
defp matches?(%{type: type}, %{type: type}), do: true
defp matches?(_, _), do: false
end
