Implement teardown contract for ESPDate

README.md

@@ -22,7 +22,8 @@ ESPDate is a tiny C++17 helper for ESP32 projects that makes working with dates
 - **Optional NTP bootstrap**: call `init` with `ESPDateConfig` containing both `timeZone` and `ntpServer` to set TZ and start SNTP after Arduino/WiFi is ready.
 - **NTP sync callback + manual re-sync**: register `setNtpSyncCallback(...)` with a function, lambda, or `std::bind`, call `syncNTP()` anytime to trigger an immediate refresh, and optionally override SNTP interval via `ntpSyncIntervalMs` / `setNtpSyncIntervalMs(...)`.
 - **Optional PSRAM-backed config/state buffers**: `ESPDateConfig::usePSRAMBuffers` routes ESPDate-owned text state (timezone/NTP/scoped TZ restore buffers) through `ESPBufferManager` with automatic fallback.
-- **Explicit lifecycle cleanup**: `deinit()` unregisters ESPDate-owned SNTP callback hooks; the destructor calls it automatically.
+- **Explicit lifecycle cleanup**: `deinit()` unregisters ESPDate-owned SNTP callback hooks, clears runtime config buffers, and is safe to call repeatedly; the destructor calls it automatically.
+- **Init-state introspection**: `isInitialized()` reports whether `init(...)` has been called without a matching `deinit()`.
 - **Last sync tracking**: `hasLastNtpSync()` / `lastNtpSync()` expose the latest SNTP sync timestamp kept inside `ESPDate`.
 - **Last sync string helpers**: `lastNtpSyncStringLocal/Utc` provide direct formatting helpers for `lastNtpSync`.
 - **Local breakdown helpers**: `nowLocal()` / `toLocal()` surface the broken-out local time (with UTC offset) for quick DST/debug checks; feed sunrise/sunset results into `toLocal` to read them in local time.
@@ -118,6 +119,20 @@ void setup() {
     std::string utcString = date.nowUtcString();
     Serial.printf("UTC now (string): %s\n", utcString.c_str());
 }
+
+void loop() {
+    // Example teardown path (mode switch / OTA / feature shutdown).
+    static bool released = false;
+    if (!released && millis() > 60000UL) {
+        if (date.isInitialized()) {
+            date.deinit();
+        }
+        if (solar.isInitialized()) {
+            solar.deinit();
+        }
+        released = true;
+    }
+}
 ```
 
 ### Working With Local Time (UI) vs UTC (storage/logic)
@@ -186,6 +201,7 @@ public:
     ~ESPDate();
     void init(const ESPDateConfig &config);
     void deinit();
+    bool isInitialized() const;
     void setNtpSyncCallback(NtpSyncCallback callback);
     template <typename Callable>
     void setNtpSyncCallback(Callable&& callback); // capturing lambda/std::bind/functor

examples/basic_date/basic_date.ino

@@ -3,6 +3,7 @@
 #include <functional>
 
 ESPDate date;
+bool releasedDateResources = false;
 
 class SyncObserver {
  public:
@@ -95,5 +96,10 @@ void setup() {
 }
 
 void loop() {
-  // Intentionally empty.
+  // Demonstrate explicit teardown in long-running sketches.
+  if (!releasedDateResources && millis() > 60000UL && date.isInitialized()) {
+    date.deinit();
+    releasedDateResources = true;
+    Serial.println("ESPDate deinitialized.");
+  }
 }

src/esp_date/date.cpp

@@ -191,9 +191,17 @@ ESPDate::~ESPDate() {
 void ESPDate::deinit() {
   ntpSyncCallback_ = nullptr;
   ntpSyncCallbackCallable_ = NtpSyncCallable{};
-  usePSRAMBuffers_ = false;
   hasLastNtpSync_ = false;
   lastNtpSync_ = DateTime{};
+  hasLocation_ = false;
+  latitude_ = 0.0f;
+  longitude_ = 0.0f;
+  ntpSyncIntervalMs_ = 0;
+  const bool usePSRAM = usePSRAMBuffers_;
+  timeZone_ = DateString(DateAllocator<char>(usePSRAM));
+  ntpServer_ = DateString(DateAllocator<char>(usePSRAM));
+  usePSRAMBuffers_ = false;
+  initialized_ = false;
 
   if (activeNtpSyncOwner_ == this) {
     activeNtpSyncOwner_ = nullptr;
@@ -229,6 +237,7 @@ void ESPDate::init(const ESPDateConfig& config) {
     setenv("TZ", timeZone_.c_str(), 1);
     tzset();
   }
+  initialized_ = true;
 }
 
 void ESPDate::setNtpSyncCallback(NtpSyncCallback callback) {

src/esp_date/date.h

@@ -79,6 +79,9 @@ class ESPDate {
   ~ESPDate();
   void init(const ESPDateConfig& config);
   void deinit();
+  bool isInitialized() const {
+    return initialized_;
+  }
   // Optional SNTP sync notification. Pass nullptr to clear.
   void setNtpSyncCallback(NtpSyncCallback callback);
   // Accepts capturing lambdas / std::bind / functors.
@@ -298,4 +301,5 @@ class ESPDate {
   static NtpSyncCallable activeNtpSyncCallbackCallable_;
   static ESPDate* activeNtpSyncOwner_;
   bool hasLocation_ = false;
+  bool initialized_ = false;
 };

test/test_esp_date/test_esp_date.cpp

@@ -11,6 +11,42 @@ ESPDate date;
 static const float kBudapestLat = 47.4979f;
 static const float kBudapestLon = 19.0402f;
 
+static void test_deinit_is_safe_before_init() {
+    ESPDate monitor;
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+}
+
+static void test_deinit_is_idempotent() {
+    ESPDate monitor;
+    monitor.init(ESPDateConfig{0.0f, 0.0f, "UTC0", nullptr});
+    TEST_ASSERT_TRUE(monitor.isInitialized());
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+}
+
+static void test_reinit_after_deinit() {
+    ESPDate monitor;
+    monitor.init(ESPDateConfig{0.0f, 0.0f, "UTC0", nullptr});
+    TEST_ASSERT_TRUE(monitor.isInitialized());
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+
+    monitor.init(ESPDateConfig{kBudapestLat, kBudapestLon, "CET-1CEST,M3.5.0/2,M10.5.0/3", nullptr});
+    TEST_ASSERT_TRUE(monitor.isInitialized());
+    TEST_ASSERT_TRUE(monitor.sunrise(monitor.fromUtc(2024, 6, 1)).ok);
+
+    monitor.deinit();
+    TEST_ASSERT_FALSE(monitor.isInitialized());
+}
+
 static void test_add_days_and_differences() {
     DateTime base = date.fromUnixSeconds(1704067200);  // 2024-01-01T00:00:00Z
     DateTime plus = date.addDays(base, 1);
@@ -331,6 +367,9 @@ void setup() {
     tzset();
     delay(2000);
     UNITY_BEGIN();
+    RUN_TEST(test_deinit_is_safe_before_init);
+    RUN_TEST(test_deinit_is_idempotent);
+    RUN_TEST(test_reinit_after_deinit);
     RUN_TEST(test_add_days_and_differences);
     RUN_TEST(test_add_months_clamps_day_in_leap_year);
     RUN_TEST(test_start_and_end_of_day_utc);