From 3241dd7d9602cc10a5c035dba5a2044f3ad8f8dc Mon Sep 17 00:00:00 2001
From: Moritz <moritz.m@local-it.org>
Date: Mon, 22 Dec 2025 16:39:49 +0100
Subject: [PATCH] Fix cycle end calculation for misaligned cycle_start dates

Make cycle generation idempotent by skipping existing cycles
---
 lib/mv/membership_fees/calendar_cycles.ex | 24 ++++++++++++-------
 lib/mv/membership_fees/cycle_generator.ex | 28 ++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/lib/mv/membership_fees/calendar_cycles.ex b/lib/mv/membership_fees/calendar_cycles.ex
index 8a4ef24..9bc3afa 100644
--- a/lib/mv/membership_fees/calendar_cycles.ex
+++ b/lib/mv/membership_fees/calendar_cycles.ex
@@ -299,11 +299,15 @@ defmodule Mv.MembershipFees.CalendarCycles do
   end
 
   defp quarterly_cycle_end(cycle_start) do
-    case cycle_start.month do
-      1 -> Date.new!(cycle_start.year, 3, 31)
-      4 -> Date.new!(cycle_start.year, 6, 30)
-      7 -> Date.new!(cycle_start.year, 9, 30)
-      10 -> Date.new!(cycle_start.year, 12, 31)
+    # Ensure cycle_start is aligned to quarter boundary
+    # This handles cases where cycle_start might not be at the correct quarter start (e.g., month 12)
+    aligned_start = quarterly_cycle_start(cycle_start)
+
+    case aligned_start.month do
+      1 -> Date.new!(aligned_start.year, 3, 31)
+      4 -> Date.new!(aligned_start.year, 6, 30)
+      7 -> Date.new!(aligned_start.year, 9, 30)
+      10 -> Date.new!(aligned_start.year, 12, 31)
     end
   end
 
@@ -313,9 +317,13 @@ defmodule Mv.MembershipFees.CalendarCycles do
   end
 
   defp half_yearly_cycle_end(cycle_start) do
-    case cycle_start.month do
-      1 -> Date.new!(cycle_start.year, 6, 30)
-      7 -> Date.new!(cycle_start.year, 12, 31)
+    # Ensure cycle_start is aligned to half-year boundary
+    # This handles cases where cycle_start might not be at the correct half-year start (e.g., month 10)
+    aligned_start = half_yearly_cycle_start(cycle_start)
+
+    case aligned_start.month do
+      1 -> Date.new!(aligned_start.year, 6, 30)
+      7 -> Date.new!(aligned_start.year, 12, 31)
     end
   end
 
diff --git a/lib/mv/membership_fees/cycle_generator.ex b/lib/mv/membership_fees/cycle_generator.ex
index feb7b53..23889fb 100644
--- a/lib/mv/membership_fees/cycle_generator.ex
+++ b/lib/mv/membership_fees/cycle_generator.ex
@@ -386,18 +386,44 @@ defmodule Mv.MembershipFees.CycleGenerator do
           {:ok, cycle} ->
             {:ok, cycle, []}
 
+          {:error, %Ash.Error.Invalid{errors: [%Ash.Error.Changes.InvalidAttribute{private_vars: %{constraint: constraint, constraint_type: :unique}}]}} = error ->
+            # Cycle already exists (unique constraint violation) - skip it silently
+            # This makes the function idempotent and prevents errors on server restart
+            if constraint == "membership_fee_cycles_unique_cycle_per_member_index" do
+              {:skip, cycle_start}
+            else
+              {:error, {cycle_start, error}}
+            end
+
           {:error, reason} ->
             {:error, {cycle_start, reason}}
         end
       end)
 
-    {successes, errors} = Enum.split_with(results, &match?({:ok, _, _}, &1))
+    {successes, skips, errors} =
+      Enum.reduce(results, {[], [], []}, fn
+        {:ok, cycle, notifications}, {successes, skips, errors} ->
+          {[{:ok, cycle, notifications} | successes], skips, errors}
+
+        {:skip, cycle_start}, {successes, skips, errors} ->
+          {successes, [cycle_start | skips], errors}
+
+        {:error, error}, {successes, skips, errors} ->
+          {successes, skips, [error | errors]}
+      end)
 
     all_notifications =
       Enum.flat_map(successes, fn {:ok, _cycle, notifications} -> notifications end)
 
     if Enum.empty?(errors) do
       successful_cycles = Enum.map(successes, fn {:ok, cycle, _notifications} -> cycle end)
+
+      if Enum.any?(skips) do
+        Logger.debug(
+          "Skipped #{length(skips)} cycles that already exist for member #{member_id}"
+        )
+      end
+
       {:ok, successful_cycles, all_notifications}
     else
       Logger.warning("Some cycles failed to create: #{inspect(errors)}")