feat: recurring transactions

internal/service/recurring_event_test.go

@@ -0,0 +1,183 @@
+package service
+
+import (
+	"testing"
+	"time"
+
+	"git.juancwu.dev/juancwu/budgit/internal/model"
+)
+
+func mustLoad(t *testing.T, name string) *time.Location {
+	t.Helper()
+	loc, err := time.LoadLocation(name)
+	if err != nil {
+		t.Fatalf("LoadLocation(%q): %v", name, err)
+	}
+	return loc
+}
+
+func intPtr(v int) *int { return &v }
+
+func TestNextFireAfter_Daily(t *testing.T) {
+	loc := mustLoad(t, "America/New_York")
+	ev := &model.RecurringEvent{
+		Frequency:     model.RecurringFrequencyDaily,
+		IntervalCount: 1,
+		FireHour:      9,
+		FireMinute:    30,
+	}
+	// "after" = 2026-05-01 14:00 NY → next fire same day's 09:30 already passed,
+	// so should be 2026-05-02 09:30 NY.
+	after := time.Date(2026, 5, 1, 14, 0, 0, 0, loc)
+	got, err := nextFireAfter(ev, after, loc)
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := time.Date(2026, 5, 2, 9, 30, 0, 0, loc)
+	if !got.Equal(want) {
+		t.Errorf("daily next: got %v want %v", got.In(loc), want)
+	}
+}
+
+func TestNextFireAfter_DailyEvery3Days(t *testing.T) {
+	loc := mustLoad(t, "UTC")
+	ev := &model.RecurringEvent{
+		Frequency:     model.RecurringFrequencyDaily,
+		IntervalCount: 3,
+		FireHour:      8,
+		FireMinute:    0,
+	}
+	after := time.Date(2026, 5, 1, 8, 0, 1, 0, loc) // 1 second past today's fire
+	got, _ := nextFireAfter(ev, after, loc)
+	want := time.Date(2026, 5, 4, 8, 0, 0, 0, loc)
+	if !got.Equal(want) {
+		t.Errorf("got %v want %v", got, want)
+	}
+}
+
+func TestNextFireAfter_Weekly(t *testing.T) {
+	loc := mustLoad(t, "UTC")
+	// Every Tuesday (DayOfWeek=2) at 10:00, after Wed 2026-05-06.
+	dow := 2
+	ev := &model.RecurringEvent{
+		Frequency:     model.RecurringFrequencyWeekly,
+		IntervalCount: 1,
+		DayOfWeek:     &dow,
+		FireHour:      10,
+		FireMinute:    0,
+	}
+	after := time.Date(2026, 5, 6, 12, 0, 0, 0, loc) // Wed 12:00
+	got, _ := nextFireAfter(ev, after, loc)
+	want := time.Date(2026, 5, 12, 10, 0, 0, 0, loc) // following Tue
+	if !got.Equal(want) {
+		t.Errorf("got %v want %v", got, want)
+	}
+}
+
+func TestNextFireAfter_MonthlyDayClamp(t *testing.T) {
+	loc := mustLoad(t, "UTC")
+	// Every month on day 31. Jan 31 → Feb 28 (2026 not leap).
+	dom := 31
+	ev := &model.RecurringEvent{
+		Frequency:     model.RecurringFrequencyMonthly,
+		IntervalCount: 1,
+		DayOfMonth:    &dom,
+		FireHour:      0,
+		FireMinute:    0,
+	}
+	after := time.Date(2026, 1, 31, 0, 0, 1, 0, loc)
+	got, _ := nextFireAfter(ev, after, loc)
+	want := time.Date(2026, 2, 28, 0, 0, 0, 0, loc)
+	if !got.Equal(want) {
+		t.Errorf("got %v want %v", got, want)
+	}
+	// Then Feb 28 → Mar 31 (anchor preserved).
+	got2, _ := nextFireAfter(ev, want, loc)
+	want2 := time.Date(2026, 3, 31, 0, 0, 0, 0, loc)
+	if !got2.Equal(want2) {
+		t.Errorf("got2 %v want2 %v", got2, want2)
+	}
+}
+
+func TestNextFireAfter_Yearly(t *testing.T) {
+	loc := mustLoad(t, "UTC")
+	dom := 15
+	moy := 6
+	ev := &model.RecurringEvent{
+		Frequency:     model.RecurringFrequencyYearly,
+		IntervalCount: 1,
+		DayOfMonth:    &dom,
+		MonthOfYear:   &moy,
+		FireHour:      12,
+		FireMinute:    0,
+	}
+	after := time.Date(2026, 6, 15, 12, 0, 1, 0, loc)
+	got, _ := nextFireAfter(ev, after, loc)
+	want := time.Date(2027, 6, 15, 12, 0, 0, 0, loc)
+	if !got.Equal(want) {
+		t.Errorf("got %v want %v", got, want)
+	}
+}
+
+func TestNextFireAfter_TimezoneCrossesUTCBoundary(t *testing.T) {
+	loc := mustLoad(t, "America/Los_Angeles")
+	// 09:00 LA daily. From 2026-05-01 17:00 UTC (10:00 LA), already past, so
+	// next is 2026-05-02 09:00 LA = 16:00 UTC.
+	ev := &model.RecurringEvent{
+		Frequency:     model.RecurringFrequencyDaily,
+		IntervalCount: 1,
+		FireHour:      9,
+		FireMinute:    0,
+	}
+	after := time.Date(2026, 5, 1, 17, 0, 0, 0, time.UTC)
+	got, _ := nextFireAfter(ev, after, loc)
+	want := time.Date(2026, 5, 2, 16, 0, 0, 0, time.UTC) // PDT, UTC-7
+	if !got.Equal(want) {
+		t.Errorf("got %v want %v", got, want)
+	}
+}
+
+func TestFirstFireOnOrAfter_SameDayBeforeFire(t *testing.T) {
+	loc := mustLoad(t, "UTC")
+	// Daily at 09:00, start date 2026-05-10 → first fire 2026-05-10 09:00.
+	got, err := firstFireOnOrAfter(model.RecurringFrequencyDaily, 1, nil, nil, nil, 9, 0, loc, time.Date(2026, 5, 10, 0, 0, 0, 0, loc))
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := time.Date(2026, 5, 10, 9, 0, 0, 0, loc)
+	if !got.Equal(want) {
+		t.Errorf("got %v want %v", got, want)
+	}
+}
+
+func TestFirstFireOnOrAfter_WeeklyShiftsToTargetDayOfWeek(t *testing.T) {
+	loc := mustLoad(t, "UTC")
+	// Start 2026-05-04 (Mon), target weekday Friday (5) → first fire 2026-05-08.
+	got, _ := firstFireOnOrAfter(model.RecurringFrequencyWeekly, 1, intPtr(5), nil, nil, 8, 0, loc, time.Date(2026, 5, 4, 0, 0, 0, 0, loc))
+	want := time.Date(2026, 5, 8, 8, 0, 0, 0, loc)
+	if !got.Equal(want) {
+		t.Errorf("got %v want %v", got, want)
+	}
+}
+
+func TestAddMonths(t *testing.T) {
+	tests := []struct {
+		y int
+		m time.Month
+		n int
+		wy int
+		wm time.Month
+	}{
+		{2026, time.January, 1, 2026, time.February},
+		{2026, time.December, 1, 2027, time.January},
+		{2026, time.November, 3, 2027, time.February},
+		{2026, time.January, 12, 2027, time.January},
+		{2026, time.January, 25, 2028, time.February},
+	}
+	for _, tt := range tests {
+		gy, gm := addMonths(tt.y, tt.m, tt.n)
+		if gy != tt.wy || gm != tt.wm {
+			t.Errorf("addMonths(%d,%v,%d) = %d,%v; want %d,%v", tt.y, tt.m, tt.n, gy, gm, tt.wy, tt.wm)
+		}
+	}
+}