Feature/currency preference

backend/src/db/mod.rs

@@ -39,6 +39,12 @@ pub async fn run_migrations(pool: &SqlitePool) -> Result<(), sqlx::Error> {
         .await
         .ok();
 
+
+    sqlx::query("ALTER TABLE users ADD COLUMN currency TEXT NOT NULL DEFAULT 'USD'")
+        .execute(pool)
+        .await
+        .ok();
+
     sqlx::query("UPDATE users SET retirement_savings = roth_ira WHERE retirement_savings = 0 AND roth_ira IS NOT NULL AND roth_ira > 0")
         .execute(pool)
         .await

backend/src/handlers/auth.rs

@@ -27,6 +27,7 @@ pub struct AuthRequest {
 pub struct AuthResponse {
     pub id: i64,
     pub username: String,
+    pub currency: String,
 }
 
 #[utoipa::path(
@@ -65,6 +66,7 @@ pub async fn register(
     Ok(Json(AuthResponse {
         id: result,
         username: payload.username,
+        currency: "USD".to_string(),
     }))
 }
 
@@ -87,8 +89,8 @@ pub async fn login(
     Json(payload): Json<AuthRequest>,
 ) -> Result<impl IntoResponse, PaymeError> {
     payload.validate()?;
-    let user: (i64, String, String) =
-        sqlx::query_as("SELECT id, username, password_hash FROM users WHERE username = ?")
+    let user: (i64, String, String, String) =
+        sqlx::query_as("SELECT id, username, password_hash, currency FROM users WHERE username = ?")
             .bind(&payload.username)
             .fetch_optional(&pool)
             .await?
@@ -128,6 +130,7 @@ pub async fn login(
         Json(AuthResponse {
             id: user.0,
             username: user.1,
+            currency: user.3,
         }),
     ))
 }
@@ -169,7 +172,7 @@ pub async fn me(
     State(pool): State<SqlitePool>,
     axum::Extension(claims): axum::Extension<Claims>,
 ) -> Result<Json<AuthResponse>, PaymeError> {
-    let user: (i64, String) = sqlx::query_as("SELECT id, username FROM users WHERE id = ?")
+    let user: (i64, String, String) = sqlx::query_as("SELECT id, username, currency FROM users WHERE id = ?")
         .bind(claims.sub)
         .fetch_optional(&pool)
         .await?
@@ -178,6 +181,7 @@ pub async fn me(
     Ok(Json(AuthResponse {
         id: user.0,
         username: user.1,
+        currency: user.2, // ADDED
     }))
 }
 
@@ -240,9 +244,16 @@ pub async fn change_username(
         .execute(&pool)
         .await?;
 
+    // ADDED: Fetch currency
+    let currency: (String,) = sqlx::query_as("SELECT currency FROM users WHERE id = ?")
+        .bind(claims.sub)
+        .fetch_one(&pool)
+        .await?;
+
     Ok(Json(AuthResponse {
         id: claims.sub,
         username: payload.new_username,
+        currency: currency.0, // ADDED
     }))
 }
 
@@ -359,3 +370,45 @@ pub async fn clear_all_data(
         Json(serde_json::json!({"message": "All data cleared"})),
     ))
 }
+#[derive(Deserialize, ToSchema, Validate)]
+pub struct ChangeCurrencyRequest {
+    #[validate(length(min = 3, max = 3))]
+    pub currency: String,
+}
+
+#[utoipa::path(
+    put,
+    path = "/api/auth/change-currency",
+    request_body = ChangeCurrencyRequest,
+    responses(
+        (status = 200, description = "Currency changed successfully", body = AuthResponse),
+        (status = 500, description = "Internal server error")
+    ),
+    tag = "Auth",
+    summary = "Change currency preference",
+    description = "Updates the authenticated user's preferred display currency."
+)]
+pub async fn change_currency(
+    State(pool): State<SqlitePool>,
+    axum::Extension(claims): axum::Extension<Claims>,
+    Json(payload): Json<ChangeCurrencyRequest>,
+) -> Result<Json<AuthResponse>, PaymeError> {
+    payload.validate()?;
+
+    sqlx::query("UPDATE users SET currency = ? WHERE id = ?")
+        .bind(&payload.currency)
+        .bind(claims.sub)
+        .execute(&pool)
+        .await?;
+
+    let user: (String,) = sqlx::query_as("SELECT username FROM users WHERE id = ?")
+        .bind(claims.sub)
+        .fetch_one(&pool)
+        .await?;
+
+    Ok(Json(AuthResponse {
+        id: claims.sub,
+        username: user.0,
+        currency: payload.currency,
+    }))
+}

backend/src/lib.rs

@@ -32,6 +32,7 @@ pub fn create_app(pool: SqlitePool) -> Router {
         .route("/api/auth/me", get(auth::me))
         .route("/api/auth/change-username", put(auth::change_username))
         .route("/api/auth/change-password", put(auth::change_password))
+        .route("/api/auth/change-currency", put(auth::change_currency))
         .route("/api/auth/clear-data", delete(auth::clear_all_data))
         .route("/api/export", get(auth::export_db))
         .route("/api/months", get(months::list_months))

backend/src/openapi/mod.rs

@@ -1,7 +1,7 @@
 use utoipa::OpenApi;
 
 use crate::handlers::{
-    auth::{AuthRequest, AuthResponse},
+    auth::{AuthRequest, AuthResponse, ChangeCurrencyRequest},
     budget::{CreateCategory, UpdateCategory, UpdateMonthlyBudget},
     export::{
         BudgetExport, CategoryExport, FixedExpenseExport, IncomeExport, ItemExport, MonthExport,
@@ -24,6 +24,7 @@ use crate::models::{
         crate::handlers::auth::login,
         crate::handlers::auth::logout,
         crate::handlers::auth::me,
+        crate::handlers::auth::change_currency,
         crate::handlers::export::export_json,
         crate::handlers::export::import_json,
         crate::handlers::budget::list_monthly_budgets,
@@ -58,6 +59,7 @@ use crate::models::{
     components(schemas(
         AuthRequest,
         AuthResponse,
+        ChangeCurrencyRequest,
         MonthlyBudget,
         UpdateMonthlyBudget,
         IncomeEntry,

frontend/src/api/client.ts

@@ -27,19 +27,19 @@ async function request<T>(
 export const api = {
   auth: {
     register: (username: string, password: string) =>
-      request<{ id: number; username: string }>("/auth/register", {
+      request<{ id: number; username: string; currency: string }>("/auth/register", {
         method: "POST",
         body: JSON.stringify({ username, password }),
       }),
     login: (username: string, password: string) =>
-      request<{ id: number; username: string }>("/auth/login", {
+      request<{ id: number; username: string; currency: string }>("/auth/login", {
         method: "POST",
         body: JSON.stringify({ username, password }),
       }),
     logout: () => request<void>("/auth/logout", { method: "POST" }),
-    me: () => request<{ id: number; username: string }>("/auth/me"),
+    me: () => request<{ id: number; username: string; currency: string }>("/auth/me"),
     changeUsername: (newUsername: string) =>
-      request<{ id: number; username: string }>("/auth/change-username", {
+      request<{ id: number; username: string; currency: string }>("/auth/change-username", {
         method: "PUT",
         body: JSON.stringify({ new_username: newUsername }),
       }),
@@ -48,6 +48,11 @@ export const api = {
         method: "PUT",
         body: JSON.stringify({ current_password: currentPassword, new_password: newPassword }),
       }),
+    changeCurrency: (currency: string) =>
+      request<{ id: number; username: string; currency: string }>("/auth/change-currency", {
+        method: "PUT",
+        body: JSON.stringify({ currency }),
+  }),  
     clearAllData: (password: string) =>
       request<{ message: string }>("/auth/clear-data", {
         method: "DELETE",

frontend/src/components/BudgetSection.tsx

@@ -6,6 +6,7 @@ import { Input } from "./ui/Input";
 import { Button } from "./ui/Button";
 import { ProgressBar } from "./ui/ProgressBar";
 import { Modal } from "./ui/Modal";
+import { useCurrency } from "../hooks/useCurrency";
 
 interface BudgetSectionProps {
   monthId: number;
@@ -23,6 +24,7 @@ export function BudgetSection({
   onUpdate,
 }: BudgetSectionProps) {
   const [isManaging, setIsManaging] = useState(false);
+  const { format } = useCurrency();
   const [isAddingCategory, setIsAddingCategory] = useState(false);
   const [editingCategoryId, setEditingCategoryId] = useState<number | null>(null);
   const [editingBudgetId, setEditingBudgetId] = useState<number | null>(null);
@@ -131,7 +133,7 @@ export function BudgetSection({
                     </span>
                     <div className="flex items-center gap-2">
                       <span className="text-xs text-charcoal-500 dark:text-charcoal-400">
-                        ${budget.spent_amount.toFixed(2)} / ${budget.allocated_amount.toFixed(2)}
+                        {format(budget.spent_amount)} / {format(budget.allocated_amount)}
                       </span>
                       {!isReadOnly && (
                         <button
@@ -198,7 +200,7 @@ export function BudgetSection({
                   <span className="text-sm">{cat.label}</span>
                   <div className="flex items-center gap-2">
                     <span className="text-xs text-charcoal-500">
-                      ${cat.default_amount.toFixed(2)}
+                      {format(cat.default_amount)}
                     </span>
                     <button
                       onClick={() => startEditCategory(cat)}

frontend/src/components/FixedExpenses.tsx

@@ -5,6 +5,7 @@ import { Card } from "./ui/Card";
 import { Input } from "./ui/Input";
 import { Button } from "./ui/Button";
 import { Modal } from "./ui/Modal";
+import { useCurrency } from "../hooks/useCurrency";
 
 interface FixedExpensesProps {
   expenses: FixedExpense[];
@@ -17,6 +18,7 @@ export function FixedExpenses({ expenses, onUpdate }: FixedExpensesProps) {
   const [editingId, setEditingId] = useState<number | null>(null);
   const [label, setLabel] = useState("");
   const [amount, setAmount] = useState("");
+  const { format } = useCurrency();
 
   const handleAdd = async () => {
     if (!label || !amount) return;
@@ -81,7 +83,7 @@ export function FixedExpenses({ expenses, onUpdate }: FixedExpensesProps) {
                 {expense.label}
               </span>
               <span className="text-sm text-charcoal-600 dark:text-charcoal-400">
-                ${expense.amount.toFixed(2)}
+                {format(expense.amount)}
               </span>
             </div>
           ))}
@@ -98,7 +100,7 @@ export function FixedExpenses({ expenses, onUpdate }: FixedExpensesProps) {
               Total
             </span>
             <span className="text-sm font-semibold text-charcoal-800 dark:text-sand-100">
-              ${total.toFixed(2)}
+              {format(total)}
             </span>
           </div>
         )}
@@ -142,7 +144,7 @@ export function FixedExpenses({ expenses, onUpdate }: FixedExpensesProps) {
                 <div className="flex items-center justify-between py-2 border-b border-sand-200 dark:border-charcoal-800">
                   <span className="text-sm">{expense.label}</span>
                   <div className="flex items-center gap-2">
-                    <span className="text-sm">${expense.amount.toFixed(2)}</span>
+                    <span className="text-sm">{format(expense.amount)}</span>
                     <button
                       onClick={() => startEdit(expense)}
                       className="p-1 hover:bg-sand-200 dark:hover:bg-charcoal-800"