From 448ed204012ddc5907f24e15080e6737661d2409 Mon Sep 17 00:00:00 2001
From: Graham McIntire <graham@mcintire.me>
Date: Fri, 6 Mar 2026 13:40:08 -0600
Subject: [PATCH] feat: dynamic global billing defaults from
 ApplicationSettings

---
 lib/towerops/billing.ex                       | 46 ++++++++++--
 .../20260306192611_seed_billing_settings.exs  |  2 +-
 test/towerops/billing_test.exs                | 72 +++++++++++++++++--
 3 files changed, 109 insertions(+), 11 deletions(-)

diff --git a/lib/towerops/billing.ex b/lib/towerops/billing.ex
index f9bc2fb7..1b181cad 100644
--- a/lib/towerops/billing.ex
+++ b/lib/towerops/billing.ex
@@ -3,21 +3,55 @@ defmodule Towerops.Billing do
   Billing context for subscription and payment management.
 
   Integrates with Stripe for metered billing based on device count.
-  Pricing: $1/device/month after first 10 free devices.
+  Pricing: $2/device/month after first 10 free devices (configurable via ApplicationSettings).
   """
 
   alias Towerops.Billing.StripeClient
   alias Towerops.Organizations.Organization
   alias Towerops.Organizations.SubscriptionLimits
   alias Towerops.Repo
+  alias Towerops.Settings
 
   require Logger
 
   @default_free_devices 10
-  @default_price_per_device Decimal.new("1.00")
+  @default_price_per_device Decimal.new("2.00")
 
   # Public API
 
+  @doc """
+  Returns the default number of free devices from ApplicationSettings.
+  Falls back to module attribute (@default_free_devices = 10) if not configured.
+
+  Expected `value_type`: "integer"
+  """
+  def default_free_devices do
+    Settings.get_setting("default_free_devices") || @default_free_devices
+  end
+
+  @doc """
+  Returns the default price per device from ApplicationSettings.
+  Falls back to module attribute (@default_price_per_device = $2.00) if not configured.
+
+  Expected `value_type`: "decimal"
+  """
+  def default_price_per_device do
+    case Settings.get_setting("default_price_per_device") do
+      nil -> @default_price_per_device
+      %Decimal{} = decimal -> decimal
+    end
+  end
+
+  @doc """
+  Returns the Stripe Price ID from ApplicationSettings.
+  Falls back to STRIPE_PRICE_ID environment variable if not configured.
+
+  Expected `value_type`: "string"
+  """
+  def stripe_price_id do
+    Settings.get_setting("stripe_price_id") || Application.get_env(:towerops, :stripe_price_id)
+  end
+
   @doc """
   Create Stripe checkout session for organization to start paid subscription.
 
@@ -79,18 +113,18 @@ defmodule Towerops.Billing do
 
   @doc """
   Returns the effective number of free devices for an organization.
-  Uses custom override if set, otherwise the default (10).
+  Uses custom override if set, otherwise the global default from ApplicationSettings.
   """
   def effective_free_device_count(%Organization{} = org) do
-    org.custom_free_device_limit || @default_free_devices
+    org.custom_free_device_limit || default_free_devices()
   end
 
   @doc """
   Returns the effective price per device for an organization.
-  Uses custom override if set, otherwise the default ($1.00).
+  Uses custom override if set, otherwise the global default from ApplicationSettings.
   """
   def effective_price_per_device(%Organization{} = org) do
-    org.custom_price_per_device || @default_price_per_device
+    org.custom_price_per_device || default_price_per_device()
   end
 
   @doc """
diff --git a/priv/repo/migrations/20260306192611_seed_billing_settings.exs b/priv/repo/migrations/20260306192611_seed_billing_settings.exs
index fb7fbf11..145f0e5a 100644
--- a/priv/repo/migrations/20260306192611_seed_billing_settings.exs
+++ b/priv/repo/migrations/20260306192611_seed_billing_settings.exs
@@ -7,7 +7,7 @@ defmodule Towerops.Repo.Migrations.SeedBillingSettings do
     VALUES
       (gen_random_uuid(), 'default_free_devices', '10', 'integer',
        'Number of free devices included in all subscriptions', NOW(), NOW()),
-      (gen_random_uuid(), 'default_price_per_device', '2.00', 'string',
+      (gen_random_uuid(), 'default_price_per_device', '2.00', 'decimal',
        'Price per device per month (USD) after free tier', NOW(), NOW())
     ON CONFLICT (key) DO NOTHING;
     """
diff --git a/test/towerops/billing_test.exs b/test/towerops/billing_test.exs
index f7acbd92..7d5c1507 100644
--- a/test/towerops/billing_test.exs
+++ b/test/towerops/billing_test.exs
@@ -10,6 +10,7 @@ defmodule Towerops.BillingTest do
   alias Towerops.Billing.StripeClient
   alias Towerops.Organizations
   alias Towerops.Organizations.Organization
+  alias Towerops.Settings.ApplicationSetting
 
   setup do
     user = user_fixture()
@@ -204,7 +205,7 @@ defmodule Towerops.BillingTest do
 
   describe "estimated_monthly_cost/1" do
     test "returns correct cost calculation", %{organization: organization} do
-      # Create 25 devices (15 billable)
+      # Create 25 devices (15 billable at $2.00/device = $30.00)
       for _ <- 1..25 do
         device_fixture(%{organization_id: organization.id})
       end
@@ -212,7 +213,7 @@ defmodule Towerops.BillingTest do
       assert {:ok, %{devices: 25, billable: 15, cost_usd: cost}} =
                Billing.estimated_monthly_cost(organization)
 
-      assert Decimal.equal?(cost, Decimal.new(15))
+      assert Decimal.equal?(cost, Decimal.new("30.00"))
     end
 
     test "returns zero cost for free tier usage", %{organization: organization} do
@@ -257,7 +258,7 @@ defmodule Towerops.BillingTest do
     end
 
     test "returns effective values in estimated cost map", %{organization: organization} do
-      # Default org (no overrides): 10 free, $1.00/device
+      # Default org (no overrides): 10 free, $2.00/device
       for _ <- 1..15 do
         device_fixture(%{organization_id: organization.id})
       end
@@ -268,7 +269,7 @@ defmodule Towerops.BillingTest do
                 price_per_device: price
               }} = Billing.estimated_monthly_cost(organization)
 
-      assert Decimal.equal?(price, Decimal.new("1.00"))
+      assert Decimal.equal?(price, Decimal.new("2.00"))
     end
   end
 
@@ -387,4 +388,67 @@ defmodule Towerops.BillingTest do
       assert updated_org.payment_method_status == "requires_action"
     end
   end
+
+  describe "default_free_devices/0" do
+    test "returns value from ApplicationSettings when set" do
+      # Seed setting
+      {:ok, _} =
+        Repo.insert(%ApplicationSetting{
+          key: "default_free_devices",
+          value: "15",
+          value_type: "integer"
+        })
+
+      assert Billing.default_free_devices() == 15
+    end
+
+    test "falls back to module attribute when setting not found" do
+      # Ensure setting doesn't exist
+      Repo.delete_all(from s in ApplicationSetting, where: s.key == "default_free_devices")
+
+      assert Billing.default_free_devices() == 10
+    end
+  end
+
+  describe "default_price_per_device/0" do
+    test "returns value from ApplicationSettings when set" do
+      {:ok, _} =
+        Repo.insert(%ApplicationSetting{
+          key: "default_price_per_device",
+          value: "3.50",
+          value_type: "decimal"
+        })
+
+      assert Billing.default_price_per_device() == Decimal.new("3.50")
+    end
+
+    test "falls back to module attribute when setting not found" do
+      Repo.delete_all(
+        from s in ApplicationSetting,
+          where: s.key == "default_price_per_device"
+      )
+
+      assert Billing.default_price_per_device() == Decimal.new("2.00")
+    end
+  end
+
+  describe "stripe_price_id/0" do
+    test "returns value from ApplicationSettings when set" do
+      {:ok, _} =
+        Repo.insert(%ApplicationSetting{
+          key: "stripe_price_id",
+          value: "price_test123",
+          value_type: "string"
+        })
+
+      assert Billing.stripe_price_id() == "price_test123"
+    end
+
+    test "falls back to env var when setting not found" do
+      Repo.delete_all(from s in ApplicationSetting, where: s.key == "stripe_price_id")
+
+      # Env var is set in test config to "price_test_fake"
+      assert Billing.stripe_price_id() == "price_test_fake"
+    end
+  end
 end