feat: use AprilTag instead of QR code

lib/components_elixir/inventory/storage_location.ex

@@ -7,13 +7,14 @@ defmodule ComponentsElixir.Inventory.StorageLocation do
   """
   use Ecto.Schema
   import Ecto.Changeset
+  import Ecto.Query
 
   alias ComponentsElixir.Inventory.{StorageLocation, Component}
 
   schema "storage_locations" do
     field :name, :string
     field :description, :string
-    field :qr_code, :string
+    field :apriltag_id, :integer
     field :is_active, :boolean, default: true
 
     # Computed/virtual fields - not stored in database
@@ -31,13 +32,14 @@ defmodule ComponentsElixir.Inventory.StorageLocation do
     @doc false
   def changeset(storage_location, attrs) do
     storage_location
-    |> cast(attrs, [:name, :description, :parent_id, :is_active])
+    |> cast(attrs, [:name, :description, :parent_id, :is_active, :apriltag_id])
     |> validate_required([:name])
     |> validate_length(:name, min: 1, max: 100)
     |> validate_length(:description, max: 500)
+    |> validate_apriltag_id()
     |> foreign_key_constraint(:parent_id)
     |> validate_no_circular_reference()
-    |> put_qr_code()
+    |> put_apriltag_id()
   end
 
   # Prevent circular references (location being its own ancestor)
@@ -79,19 +81,24 @@ defmodule ComponentsElixir.Inventory.StorageLocation do
   end
 
   @doc """
-  Returns the QR code format for this storage location.
-  Format: SL:{level}:{qr_code}:{parent_qr_or_ROOT}
+  Returns the AprilTag format for this storage location.
+  Returns the AprilTag ID that corresponds to this location.
   """
-  def qr_format(storage_location, parent \\ nil) do
-    parent_code = if parent, do: parent.qr_code, else: "ROOT"
-    "SL:#{storage_location.level}:#{storage_location.qr_code}:#{parent_code}"
+  def apriltag_format(storage_location) do
+    storage_location.apriltag_id
   end
 
   # Private functions for changeset processing
 
-  defp put_qr_code(changeset) do
-    case get_field(changeset, :qr_code) do
-      nil -> put_change(changeset, :qr_code, generate_qr_code())
+  defp validate_apriltag_id(changeset) do
+    changeset
+    |> validate_number(:apriltag_id, greater_than_or_equal_to: 0, less_than_or_equal_to: 586)
+    |> unique_constraint(:apriltag_id, message: "AprilTag ID is already in use")
+  end
+
+  defp put_apriltag_id(changeset) do
+    case get_field(changeset, :apriltag_id) do
+      nil -> put_change(changeset, :apriltag_id, get_next_available_apriltag_id())
       _ -> changeset
     end
   end
@@ -118,16 +125,22 @@ defmodule ComponentsElixir.Inventory.StorageLocation do
     "#{compute_path(parent)}/#{name}"
   end
 
-  defp generate_qr_code do
-    # Generate a unique 6-character alphanumeric code
-    chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+  defp get_next_available_apriltag_id do
+    # Get all used AprilTag IDs
+    used_ids = ComponentsElixir.Repo.all(
+      from sl in ComponentsElixir.Inventory.StorageLocation,
+      where: not is_nil(sl.apriltag_id),
+      select: sl.apriltag_id
+    )
 
-    1..6
-    |> Enum.map(fn _ ->
-      chars
-      |> String.graphemes()
-      |> Enum.random()
-    end)
-    |> Enum.join()
+    # Find the first available ID (0-586)
+    0..586
+    |> Enum.find(&(&1 not in used_ids))
+    |> case do
+      nil ->
+        # All IDs are used - this should be handled at the application level
+        raise "All AprilTag IDs are in use"
+      id -> id
+    end
   end
 end