diff --git a/apps/finance/services/api/main/handler.go b/apps/finance/services/api/main/handler.go
index 2e05ca5..42cadba 100644
--- a/apps/finance/services/api/main/handler.go
+++ b/apps/finance/services/api/main/handler.go
@@ -117,6 +117,7 @@ var (
sharingTmpl = parseTmpl("templates/base.html", "templates/sharing.html")
goalsTmpl = parseTmpl("templates/base.html", "templates/goals.html")
networthTmpl = parseTmpl("templates/base.html", "templates/networth.html")
+ simulatorTmpl = parseTmpl("templates/base.html", "templates/simulator.html")
)
type authInfo struct {
@@ -1545,6 +1546,136 @@ func parseFloat(s string) float64 {
return f
}
+func (h *Handler) Simulator(w http.ResponseWriter, r *http.Request) {
+ ctx := r.Context()
+ a := getAuth(r)
+
+ txns, _ := h.store.getTransactions(ctx, a.UserID, bson.M{})
+ goals, _ := h.store.getGoals(ctx, a.UserID)
+
+ now := time.Now()
+ thisStart := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
+
+ // this month income + fixed costs
+ thisMonthIncome := int64(0)
+ totalFixed := int64(0)
+ fixedByMonth := make(map[string]map[int]int64)
+ threeAgo := thisStart.AddDate(0, -3, 0)
+ monthlySavings := make(map[string]struct{ income, saved int64 })
+
+ for _, t := range txns {
+ mk := t.Date.Format("2006-01")
+ if t.Date.Before(thisStart) {
+ // savings history: accumulate per month
+ ms := monthlySavings[mk]
+ if t.AmountCents > 0 {
+ ms.income += t.AmountCents
+ }
+ ms.saved += t.AmountCents
+ monthlySavings[mk] = ms
+
+ // fixed category detection over last 3 months
+ if !t.Date.Before(threeAgo) && FixedCategories[t.Category] && t.AmountCents < 0 {
+ mo := int(t.Date.Month())
+ if fixedByMonth[t.Category] == nil {
+ fixedByMonth[t.Category] = make(map[int]int64)
+ }
+ fixedByMonth[t.Category][mo] += -t.AmountCents
+ }
+ } else {
+ if t.AmountCents > 0 {
+ thisMonthIncome += t.AmountCents
+ }
+ }
+ }
+
+ // avg monthly fixed from last 3 months
+ for _, byMo := range fixedByMonth {
+ total := int64(0)
+ for _, v := range byMo {
+ total += v
+ }
+ totalFixed += total / int64(len(byMo))
+ }
+
+ // committed goal monthly totals
+ goalsCents := int64(0)
+ var simGoals []SimulatorGoal
+ for _, g := range goals {
+ remaining := g.TargetCents - g.SavedCents
+ if remaining <= 0 {
+ continue
+ }
+ ml := int64(monthsBetween(now, g.Deadline))
+ if ml < 1 {
+ ml = 1
+ }
+ monthly := remaining / ml
+ if g.Committed {
+ goalsCents += monthly
+ }
+ simGoals = append(simGoals, SimulatorGoal{
+ Name: g.Name,
+ MonthlyCents: monthly,
+ MonthsLeft: ml,
+ Committed: g.Committed,
+ })
+ }
+
+ disposable := thisMonthIncome - totalFixed - goalsCents
+
+ // average monthly savings over last 3 complete months
+ var avgSavings int64
+ count := 0
+ for _, ms := range monthlySavings {
+ if ms.income > 0 && ms.saved > 0 {
+ avgSavings += ms.saved
+ count++
+ }
+ }
+ if count > 0 {
+ avgSavings /= int64(count)
+ }
+
+ // savings rate history — sorted months
+ var monthKeys []string
+ for mk := range monthlySavings {
+ monthKeys = append(monthKeys, mk)
+ }
+ sortStrings(monthKeys)
+ var history []SavingsPoint
+ for _, mk := range monthKeys {
+ ms := monthlySavings[mk]
+ if ms.income <= 0 {
+ continue
+ }
+ rate := int(float64(ms.saved) / float64(ms.income) * 100)
+ if rate < -100 {
+ rate = -100
+ }
+ history = append(history, SavingsPoint{
+ Month: mk,
+ IncomeCents: ms.income,
+ SavedCents: ms.saved,
+ RatePct: rate,
+ })
+ }
+
+ render(w, simulatorTmpl, &SimulatorData{
+ UserID: a.UserID,
+ Email: a.Email,
+ Title: "What If",
+ Route: "simulator",
+ IncomeCents: thisMonthIncome,
+ FixedCents: totalFixed,
+ GoalsCents: goalsCents,
+ DisposableCents: disposable,
+ AvgSavingsCents: avgSavings,
+ Goals: simGoals,
+ SavingsHistory: history,
+ })
+}
+
func (h *Handler) NetWorth(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
a := getAuth(r)
@@ -1653,6 +1784,7 @@ func (h *Handler) RegisterRoutes(mux *http.ServeMux) {
mux.HandleFunc("GET /goals", h.Goals)
mux.HandleFunc("POST /goals", h.Goals)
mux.HandleFunc("GET /networth", h.NetWorth)
+ mux.HandleFunc("GET /simulator", h.Simulator)
mux.HandleFunc("GET /sharing", h.Sharing)
mux.HandleFunc("POST /sharing", h.Sharing)
mux.HandleFunc("DELETE /sharing/{viewer_id}", h.Sharing)
diff --git a/apps/finance/services/api/main/models.go b/apps/finance/services/api/main/models.go
index 455530c..d0af5d9 100644
--- a/apps/finance/services/api/main/models.go
+++ b/apps/finance/services/api/main/models.go
@@ -219,6 +219,38 @@ type SharingUser struct {
Email string
}
+type SimulatorGoal struct {
+ Name string
+ MonthlyCents int64
+ MonthsLeft int64
+ Committed bool
+}
+
+type SimulatorData struct {
+ UserID string
+ Email string
+ Title string
+ Route string
+
+ // current state passed to JS
+ IncomeCents int64
+ FixedCents int64 // recurring fixed costs (no goals)
+ GoalsCents int64 // committed goal contributions
+ DisposableCents int64 // income − fixed − goals
+ AvgSavingsCents int64 // 3-month avg monthly savings
+ Goals []SimulatorGoal
+
+ // savings rate history: one point per past month
+ SavingsHistory []SavingsPoint
+}
+
+type SavingsPoint struct {
+ Month string
+ IncomeCents int64
+ SavedCents int64
+ RatePct int
+}
+
type NetWorthPoint struct {
Month string // "2025-01"
AssetCents int64
diff --git a/apps/finance/services/api/main/templates/base.html b/apps/finance/services/api/main/templates/base.html
index cd9736f..12090e2 100644
--- a/apps/finance/services/api/main/templates/base.html
+++ b/apps/finance/services/api/main/templates/base.html
@@ -401,6 +401,7 @@
Portfolio
Goals
Net Worth
+ What If
Sharing
{{.Email}}
diff --git a/apps/finance/services/api/main/templates/simulator.html b/apps/finance/services/api/main/templates/simulator.html
new file mode 100644
index 0000000..e0b4528
--- /dev/null
+++ b/apps/finance/services/api/main/templates/simulator.html
@@ -0,0 +1,295 @@
+{{define "content"}}
+{{$d := .}}
+
+
+
What If…
+ adjust sliders to see the ripple effect
+
+
+
+
+
+
+
+
+
+{{if $d.SavingsHistory}}
+
+{{end}}
+
+
+{{end}}