feat: add data manager system for background weather/calendar fetching

src/data/data_manager.cpp

@@ -0,0 +1,93 @@
+#include "data_manager.h"
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+
+namespace {
+
+constexpr unsigned long REFRESH_INTERVAL_MS = 10UL * 60UL * 1000UL;
+constexpr uint32_t TASK_STACK_WORDS = 16384; // 64 KB — JSON parsing needs headroom
+
+// --- Shared state between background task and main loop ---
+// The task is the only writer of s_weather/s_calendar; the main loop is the
+// only reader. Access to the data structs is serialized via s_mux (a
+// portMUX_TYPE critical section which, on ESP32, suspends task switches on
+// the current core). Simple flag/counter reads (bool/uint32_t) are atomic
+// on 32-bit Xtensa and only need `volatile`.
+static WeatherData s_weather;
+static CalendarData s_calendar;
+static volatile bool s_weatherOk = false;
+static volatile bool s_calendarOk = false;
+static volatile bool s_loading = false;
+static volatile uint32_t s_dataVersion = 0;
+static volatile unsigned long s_lastFetchMs = 0;
+static volatile bool s_refreshRequested = false;
+static portMUX_TYPE s_mux = portMUX_INITIALIZER_UNLOCKED;
+
+static void dataFetchTask(void *param) {
+    (void)param;
+    while (true) {
+        bool needRefresh = s_refreshRequested ||
+                           s_lastFetchMs == 0 ||
+                           (millis() - s_lastFetchMs) >= REFRESH_INTERVAL_MS;
+
+        if (needRefresh) {
+            s_refreshRequested = false;
+            s_loading = true;
+
+            WeatherData w = fetchWeather();
+            CalendarData c = fetchCalendar();
+
+            portENTER_CRITICAL(&s_mux);
+            if (w.valid) {
+                s_weather = std::move(w);
+                s_weatherOk = true;
+            } else {
+                s_weatherOk = false;
+            }
+            if (c.valid) {
+                s_calendar = std::move(c);
+                s_calendarOk = true;
+            } else {
+                s_calendarOk = false;
+            }
+            s_dataVersion++;
+            s_lastFetchMs = millis();
+            s_loading = false;
+            portEXIT_CRITICAL(&s_mux);
+        }
+
+        vTaskDelay(pdMS_TO_TICKS(1000));
+    }
+}
+
+} // namespace
+
+void dataManager_begin() {
+    s_lastFetchMs = 0; // ensure first iteration fetches immediately
+    xTaskCreatePinnedToCore(dataFetchTask, "dataFetch", TASK_STACK_WORDS,
+                            nullptr, 1, nullptr, 1);
+}
+
+void dataManager_tick() {}
+
+void dataManager_triggerRefresh() {
+    s_refreshRequested = true;
+}
+
+void dataManager_getWeather(WeatherData &out) {
+    portENTER_CRITICAL(&s_mux);
+    out = s_weather;
+    portEXIT_CRITICAL(&s_mux);
+}
+
+void dataManager_getCalendar(CalendarData &out) {
+    portENTER_CRITICAL(&s_mux);
+    out = s_calendar;
+    portEXIT_CRITICAL(&s_mux);
+}
+
+bool dataManager_isWeatherOk()    { return s_weatherOk; }
+bool dataManager_isCalendarOk()   { return s_calendarOk; }
+bool dataManager_isLoading()      { return s_loading; }
+uint32_t dataManager_dataVersion() { return s_dataVersion; }
+unsigned long dataManager_lastFetchMs() { return s_lastFetchMs; }

src/data/data_manager.h

@@ -0,0 +1,35 @@
+#pragma once
+#include <Arduino.h>
+#include "api/weather_api.h"
+#include "api/calendar_api.h"
+
+// Centralized async data manager for weather + calendar.
+//
+// A background FreeRTOS task fetches weather and calendar data every 10
+// minutes (or on manual trigger). Results are cached in memory and exposed
+// to the UI screens via thread-safe getters.
+//
+// Screens poll dataManager_dataVersion() in their tick_fn to detect changes
+// and re-render from cache. Navigation between screens never blocks on a
+// fetch — views always render instantly from whatever is cached.
+
+// Create the background task and trigger the initial fetch. Call once in setup().
+void dataManager_begin();
+
+// No-op for now (background task runs independently). Reserved for future use.
+void dataManager_tick();
+
+// Request a manual refresh (non-blocking). The background task picks this up
+// within ~1 second.
+void dataManager_triggerRefresh();
+
+// Thread-safe copy of the cached weather/calendar data into `out`.
+void dataManager_getWeather(WeatherData &out);
+void dataManager_getCalendar(CalendarData &out);
+
+// Status flags (safe to read from the main loop without a mutex).
+bool dataManager_isWeatherOk();
+bool dataManager_isCalendarOk();
+bool dataManager_isLoading();
+uint32_t dataManager_dataVersion();
+unsigned long dataManager_lastFetchMs();

src/main.cpp

@@ -4,6 +4,7 @@
 #include <secrets.h>
 #include <theme.h>
 #include "display/display_setup.h"
+#include "data/data_manager.h"
 #include "ui/screen_base.h"
 #include "ui/home_screen.h"
 #include "ui/weather_detail_screen.h"
@@ -53,6 +54,9 @@ void setup() {
     display_init();
     connectWifi();
 
+    // Start background data fetcher (weather + calendar every 10 min).
+    dataManager_begin();
+
     // Build all four screens and wire navigation callbacks.
     screens[(int)ScreenId::HOME]            = homeScreen_make();
     screens[(int)ScreenId::WEATHER_DETAIL]  = weatherDetailScreen_make();
@@ -73,6 +77,7 @@ void loop() {
     if (now - lastTickMs >= 5) {
         lastTickMs = now;
         display_loop();
+        dataManager_tick();
         screens[(int)current].tick();
 
         // Inactivity: return to home after 5 minutes without input.

src/ui/calendar_detail_screen.cpp

@@ -1,6 +1,6 @@
 #include "calendar_detail_screen.h"
 #include "ui/widgets/back_button.h"
-#include "api/calendar_api.h"
+#include "data/data_manager.h"
 #include <theme.h>
 #include <text_utils.h>
 #include <date_utils.h>
@@ -11,24 +11,28 @@ namespace {
 ScreenId (*g_navigate)(ScreenId) = nullptr;
 void on_back(lv_event_t *) { if (g_navigate) g_navigate(ScreenId::HOME); }
 
-CalendarData lastCalendar;
-bool ok = false;
 lv_obj_t *list = nullptr;
 
 void buildList() {
     if (!list) return;
     lv_obj_clean(list);
 
+    CalendarData c;
+    dataManager_getCalendar(c);
+    bool ok = dataManager_isCalendarOk();
+    bool loading = dataManager_isLoading();
+
     if (!ok) {
         lv_obj_t *lbl = lv_label_create(list);
-        lv_label_set_text(lbl, LV_SYMBOL_WARNING " Keine Verbindung");
-        lv_obj_set_style_text_color(lbl, Theme::accentError(), 0);
+        lv_label_set_text(lbl, loading ? LV_SYMBOL_REFRESH " Lade..."
+                                       : LV_SYMBOL_WARNING " Keine Verbindung");
+        lv_obj_set_style_text_color(lbl, loading ? Theme::textDim() : Theme::accentError(), 0);
         return;
     }
 
     // Columns (content width = 280 - 2*6 pad = 268), side by side like a table:
     //   date   72 px left (dim grey)  | time 56 px centered (grey) | summary (white, wraps)
-    for (const auto &ev : lastCalendar.events) {
+    for (const auto &ev : c.events) {
         lv_obj_t *row = lv_obj_create(list);
         lv_obj_set_size(row, 280, LV_SIZE_CONTENT);
         lv_obj_set_style_bg_opa(row, LV_OPA_TRANSP, 0);
@@ -78,13 +82,17 @@ void calendarDetailScreen_create(Screen &s) {
 }
 
 void calendarDetailScreen_refresh(Screen &) {
-    CalendarData c = fetchCalendar();
-    ok = c.valid;
-    if (c.valid) lastCalendar = c;
     buildList();
 }
 
-void calendarDetailScreen_tick(Screen &) {}
+void calendarDetailScreen_tick(Screen &) {
+    static uint32_t lastVersion = 0;
+    uint32_t v = dataManager_dataVersion();
+    if (v != lastVersion) {
+        lastVersion = v;
+        buildList();
+    }
+}
 
 Screen calendarDetailScreen_make() {
     Screen s;

src/ui/home_screen.cpp

@@ -1,8 +1,7 @@
 #include "home_screen.h"
 #include "ui/widgets/tile_button.h"
 #include "icons/icons.h"
-#include "api/weather_api.h"
-#include "api/calendar_api.h"
+#include "data/data_manager.h"
 #include <theme.h>
 #include <text_utils.h>
 #include <date_utils.h>
@@ -13,21 +12,9 @@ namespace {
 // --- navigation callback target (set by main.cpp) ---
 ScreenId (*g_navigate)(ScreenId) = nullptr;
 
-// Forward declarations (definitions below).
-void updateWidgets();
-void doFetch();
-
 void on_calendar_tile(lv_event_t *) { if (g_navigate) g_navigate(ScreenId::CALENDAR_DETAIL); }
 void on_mvg_tile(lv_event_t *) { if (g_navigate) g_navigate(ScreenId::MVG); }
 
-// --- cached data + refresh timer (ported from old home_screen.cpp) ---
-WeatherData lastWeather;
-CalendarData lastCalendar;
-bool weatherOk = false;
-bool calendarOk = false;
-unsigned long lastFetchMs = 0;
-const unsigned long REFRESH_INTERVAL_MS = 10UL * 60UL * 1000UL;
-
 // --- tile handles (value labels, for updating without rebuild) ---
 TileButton weatherTile{};
 TileButton calendarTile{};
@@ -43,45 +30,28 @@ void rebuildWeatherIcon(const String &symbol, const String &description) {
     lv_obj_align(weatherTile.icon, LV_ALIGN_CENTER, 0, -14);
 }
 
-void updateRainWarning() {
+void updateRainWarning(const WeatherData &w, bool ok) {
     if (rainWarningIcon) {
         lv_obj_del(rainWarningIcon);
         rainWarningIcon = nullptr;
     }
-    if (weatherOk && willRainSoon(lastWeather, 8)) {
+    if (ok && willRainSoon(w, 8)) {
         rainWarningIcon = Icons::createRainWarning(weatherTile.btn, 28);
         lv_obj_align(rainWarningIcon, LV_ALIGN_TOP_RIGHT, -4, 4);
     }
 }
 
-void doFetch() {
-    WeatherData w = fetchWeather();
-    weatherOk = w.valid;
-    if (w.valid) lastWeather = w;
-    CalendarData c = fetchCalendar();
-    calendarOk = c.valid;
-    if (c.valid) lastCalendar = c;
-    lastFetchMs = millis();
-}
-
 // Manual retry: tapping the weather tile when it is in error state triggers
-// a refresh instead of navigating away. Acts as the SPEC.md "retry per tap".
-void on_weather_tile(lv_event_t *e) {
-    if (!weatherOk) {
-        doFetch();
-        updateWidgets();
+// a background refresh instead of navigating away.
+void on_weather_tile(lv_event_t *) {
+    if (!dataManager_isWeatherOk()) {
+        dataManager_triggerRefresh();
         return;
     }
     if (g_navigate) g_navigate(ScreenId::WEATHER_DETAIL);
 }
 
-// --- formatting helpers (ported from old home_screen.cpp rendering) ---
-
-String weatherIconGlyph(const String &symbol) {
-    // Kept for fallback; real icons are drawn as canvas via rebuildWeatherIcon.
-    (void)symbol;
-    return LV_SYMBOL_IMAGE;
-}
+// --- formatting helpers ---
 
 String formatWeatherValue(const WeatherData &w) {
     if (!w.valid) return "Wetter n.a.";
@@ -96,9 +66,9 @@ String formatCalendarPreview(const CalendarData &c) {
     int shown = 0;
     for (const auto &ev : c.events) {
         if (shown >= 2) break;
-        if (shown > 0) s += "\n\n";
-        s += DateUtils::formatShortDE(ev.startAt, ev.allDay);
-        s += "\n" + sanitizeGermanText(ev.summary.substring(0, 22));
+        if (shown > 0) s += "\n";
+        s += sanitizeGermanText(ev.summary.substring(0, 22));
+        s += "\n" + DateUtils::formatShortDE(ev.startAt, ev.allDay);
         ++shown;
     }
     if (s.length() == 0) s = "Keine Termine";
@@ -107,12 +77,38 @@ String formatCalendarPreview(const CalendarData &c) {
 
 void updateWidgets() {
     if (!widgetsBuilt) return;
-    rebuildWeatherIcon(lastWeather.current.symbol, lastWeather.current.description);
-    updateRainWarning();
-    tile_button_set_value(weatherTile, formatWeatherValue(lastWeather).c_str());
+
+    WeatherData w;
+    CalendarData c;
+    dataManager_getWeather(w);
+    dataManager_getCalendar(c);
+    bool weatherOk = dataManager_isWeatherOk();
+    bool calendarOk = dataManager_isCalendarOk();
+    bool loading = dataManager_isLoading();
+
+    // Weather tile
+    if (weatherOk) {
+        rebuildWeatherIcon(w.current.symbol, w.current.description);
+        updateRainWarning(w, true);
+        tile_button_set_value(weatherTile, formatWeatherValue(w).c_str());
+    } else if (loading) {
+        tile_button_set_value(weatherTile, "Lade...");
+    } else {
+        tile_button_set_value(weatherTile, "Wetter n.a.");
+    }
     lv_obj_align(weatherTile.value, LV_ALIGN_CENTER, 0, 50);
-    tile_button_set_value(calendarTile, formatCalendarPreview(lastCalendar).c_str());
+
+    // Calendar tile
+    if (calendarOk) {
+        tile_button_set_value(calendarTile, formatCalendarPreview(c).c_str());
+    } else if (loading) {
+        tile_button_set_value(calendarTile, "Lade...");
+    } else {
+        tile_button_set_value(calendarTile, "Kalender n.a.");
+    }
     tile_button_set_icon(calendarTile, LV_SYMBOL_FILE);
+
+    // MVG tile
     tile_button_set_value(mvgTile, "Abfahrten");
 }
 
@@ -148,13 +144,14 @@ void homeScreen_create(Screen &s) {
 }
 
 void homeScreen_refresh(Screen &) {
-    doFetch();
     updateWidgets();
 }
 
 void homeScreen_tick(Screen &) {
-    if (lastFetchMs == 0 || millis() - lastFetchMs >= REFRESH_INTERVAL_MS) {
-        doFetch();
+    static uint32_t lastVersion = 0;
+    uint32_t v = dataManager_dataVersion();
+    if (v != lastVersion) {
+        lastVersion = v;
         updateWidgets();
     }
 }
@@ -166,4 +163,3 @@ Screen homeScreen_make() {
     s.tick_fn    = homeScreen_tick;
     return s;
 }
-

src/ui/weather_detail_screen.cpp

@@ -1,6 +1,6 @@
 #include "weather_detail_screen.h"
 #include "ui/widgets/back_button.h"
-#include "api/weather_api.h"
+#include "data/data_manager.h"
 #include "icons/icons.h"
 #include <theme.h>
 #include <text_utils.h>
@@ -11,18 +11,22 @@ namespace {
 ScreenId (*g_navigate)(ScreenId) = nullptr;
 void on_back(lv_event_t *) { if (g_navigate) g_navigate(ScreenId::HOME); }
 
-WeatherData lastWeather;
-bool ok = false;
 lv_obj_t *list = nullptr;
 
 void buildList() {
     if (!list) return;
     lv_obj_clean(list);
 
+    WeatherData w;
+    dataManager_getWeather(w);
+    bool ok = dataManager_isWeatherOk();
+    bool loading = dataManager_isLoading();
+
     if (!ok) {
         lv_obj_t *lbl = lv_label_create(list);
-        lv_label_set_text(lbl, LV_SYMBOL_WARNING " Keine Verbindung");
-        lv_obj_set_style_text_color(lbl, Theme::accentError(), 0);
+        lv_label_set_text(lbl, loading ? LV_SYMBOL_REFRESH " Lade..."
+                                       : LV_SYMBOL_WARNING " Keine Verbindung");
+        lv_obj_set_style_text_color(lbl, loading ? Theme::textDim() : Theme::accentError(), 0);
         return;
     }
 
@@ -39,7 +43,7 @@ void buildList() {
     lv_obj_set_style_line_color(header_line, Theme::textDim(), 0);
     lv_obj_set_style_line_width(header_line, 1, 0);
 
-    for (const auto &fe : lastWeather.forecast) {
+    for (const auto &fe : w.forecast) {
         lv_obj_t *row = lv_obj_create(list);
         lv_obj_set_size(row, 280, 30);
         lv_obj_set_style_bg_opa(row, LV_OPA_TRANSP, 0);
@@ -105,13 +109,17 @@ void weatherDetailScreen_create(Screen &s) {
 }
 
 void weatherDetailScreen_refresh(Screen &) {
-    WeatherData w = fetchWeather();
-    ok = w.valid;
-    if (w.valid) lastWeather = w;
     buildList();
 }
 
-void weatherDetailScreen_tick(Screen &) {}
+void weatherDetailScreen_tick(Screen &) {
+    static uint32_t lastVersion = 0;
+    uint32_t v = dataManager_dataVersion();
+    if (v != lastVersion) {
+        lastVersion = v;
+        buildList();
+    }
+}
 
 Screen weatherDetailScreen_make() {
     Screen s;