fix shotgroup changesets

lib/cannery/activity_log/shot_group.ex

@@ -4,8 +4,9 @@ defmodule Cannery.ActivityLog.ShotGroup do
   """
 
   use Ecto.Schema
+  import CanneryWeb.Gettext
   import Ecto.Changeset
-  alias Cannery.{Accounts.User, ActivityLog.ShotGroup, Ammo.AmmoGroup}
+  alias Cannery.{Accounts.User, ActivityLog.ShotGroup, Ammo.AmmoGroup, Repo}
   alias Ecto.{Changeset, UUID}
 
   @primary_key {:id, :binary_id, autogenerate: true}
@@ -37,21 +38,71 @@ defmodule Cannery.ActivityLog.ShotGroup do
   @type id :: UUID.t()
 
   @doc false
-  @spec create_changeset(new_shot_group(), attrs :: map()) :: Changeset.t(new_shot_group())
-  def create_changeset(shot_group, attrs) do
+  @spec create_changeset(new_shot_group(), User.t(), AmmoGroup.t(), attrs :: map()) ::
+          Changeset.t(new_shot_group())
+  def create_changeset(
+        shot_group,
+        %User{id: user_id},
+        %AmmoGroup{id: ammo_group_id, user_id: user_id} = ammo_group,
+        attrs
+      )
+      when not (user_id |> is_nil()) and not (ammo_group_id |> is_nil()) do
     shot_group
-    |> cast(attrs, [:count, :notes, :date, :ammo_group_id, :user_id])
+    |> change(user_id: user_id)
+    |> change(ammo_group_id: ammo_group_id)
+    |> cast(attrs, [:count, :notes, :date])
     |> validate_number(:count, greater_than: 0)
+    |> validate_create_shot_group_count(ammo_group)
     |> validate_required([:count, :ammo_group_id, :user_id])
   end
 
+  defp validate_create_shot_group_count(changeset, %AmmoGroup{count: ammo_group_count}) do
+    if changeset |> Changeset.get_field(:count) > ammo_group_count do
+      error = dgettext("errors", "Count must be less than %{count}", count: ammo_group_count)
+      changeset |> Changeset.add_error(:count, error)
+    else
+      changeset
+    end
+  end
+
   @doc false
-  @spec update_changeset(t() | new_shot_group(), attrs :: map()) ::
+  @spec update_changeset(t() | new_shot_group(), User.t(), attrs :: map()) ::
           Changeset.t(t() | new_shot_group())
-  def update_changeset(shot_group, attrs) do
+  def update_changeset(
+        %ShotGroup{user_id: user_id} = shot_group,
+        %User{id: user_id} = user,
+        attrs
+      )
+      when not (user_id |> is_nil()) do
     shot_group
     |> cast(attrs, [:count, :notes, :date])
     |> validate_number(:count, greater_than: 0)
     |> validate_required([:count])
+    |> validate_update_shot_group_count(shot_group, user)
+  end
+
+  defp validate_update_shot_group_count(
+         changeset,
+         %ShotGroup{count: count} = shot_group,
+         %User{id: user_id}
+       )
+       when not (user_id |> is_nil()) do
+    %{ammo_group: %AmmoGroup{count: ammo_group_count, user_id: ^user_id}} =
+      shot_group |> Repo.preload(:ammo_group)
+
+    new_shot_group_count = changeset |> Changeset.get_field(:count)
+    shot_diff_to_add = new_shot_group_count - count
+
+    cond do
+      shot_diff_to_add > ammo_group_count ->
+        error = dgettext("errors", "Count must be less than %{count}", count: ammo_group_count)
+        changeset |> Changeset.add_error(:count, error)
+
+      new_shot_group_count <= 0 ->
+        changeset |> Changeset.add_error(:count, dgettext("errors", "Count must be at least 1"))
+
+      true ->
+        changeset
+    end
   end
 end