From a21acebdb447ec29a2a720df133ae4012ca3e846 Mon Sep 17 00:00:00 2001
From: Theo Arends <11044339+arendst@users.noreply.github.com>
Date: Wed, 13 Jan 2021 13:51:49 +0100
Subject: [PATCH] Add support for Last Known Good Settings

---
 tasmota/settings.ino        | 16 ++++++++++++----
 tasmota/support_tasmota.ino |  9 +++++++++
 tasmota/tasmota_globals.h   |  5 +++--
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/tasmota/settings.ino b/tasmota/settings.ino
index d61f66743..b2d438df6 100644
--- a/tasmota/settings.ino
+++ b/tasmota/settings.ino
@@ -540,7 +540,7 @@ void SettingsSave(uint8_t rotate)
 #ifdef ESP8266
 #ifdef USE_UFILESYS
     TfsSaveFile(TASM_FILE_SETTINGS, (const uint8_t*)&Settings, sizeof(Settings));
-#endif
+#endif  // USE_UFILESYS
     if (ESP.flashEraseSector(settings_location)) {
       ESP.flashWrite(settings_location * SPI_FLASH_SEC_SIZE, (uint32*)&Settings, sizeof(Settings));
     }
@@ -578,7 +578,7 @@ void SettingsLoad(void) {
     flash_location = 1;
     slot = 0;
   }
-#endif
+#endif  // USE_UFILESYS
   while (slot <= max_slots) {                                  // Read all config pages in search of valid and latest
     if (slot > 0) {
       flash_location = (1 == slot) ? FLASH_EEPROM_START : (2 == slot) ? SETTINGS_LOCATION : flash_location -1;
@@ -602,7 +602,7 @@ void SettingsLoad(void) {
       TfsLoadFile(TASM_FILE_SETTINGS, (uint8_t*)&Settings, sizeof(Settings));
       AddLog_P(LOG_LEVEL_NONE, PSTR(D_LOG_CONFIG "Loaded from File, " D_COUNT " %lu"), Settings.save_flag);
     } else
-#endif
+#endif  // USE_UFILESYS
     {
       ESP.flashRead(settings_location * SPI_FLASH_SEC_SIZE, (uint32*)&Settings, sizeof(Settings));
       AddLog_P(LOG_LEVEL_NONE, PSTR(D_LOG_CONFIG D_LOADED_FROM_FLASH_AT " %X, " D_COUNT " %lu"), settings_location, Settings.save_flag);
@@ -617,7 +617,15 @@ void SettingsLoad(void) {
 
 #ifndef FIRMWARE_MINIMAL
   if ((0 == settings_location) || (Settings.cfg_holder != (uint16_t)CFG_HOLDER)) {  // Init defaults if cfg_holder differs from user settings in my_user_config.h
-    SettingsDefault();
+#ifdef USE_UFILESYS
+    if (TfsLoadFile(TASM_FILE_SETTINGS_LKG, (uint8_t*)&Settings, sizeof(Settings)) && (Settings.cfg_crc32 == GetSettingsCrc32())) {
+      settings_location = 1;
+      AddLog_P(LOG_LEVEL_NONE, PSTR(D_LOG_CONFIG "Loaded from LKG File, " D_COUNT " %lu"), Settings.save_flag);
+    } else
+#endif  // USE_UFILESYS
+    {
+      SettingsDefault();
+    }
   }
   settings_crc32 = GetSettingsCrc32();
 #endif  // FIRMWARE_MINIMAL
diff --git a/tasmota/support_tasmota.ino b/tasmota/support_tasmota.ino
index a6e0b2104..3ac17a490 100644
--- a/tasmota/support_tasmota.ino
+++ b/tasmota/support_tasmota.ino
@@ -886,6 +886,15 @@ void PerformEverySecond(void)
     ESP_getSketchSize();             // Init sketchsize as it can take up to 2 seconds
   }
 #endif
+
+#ifdef USE_UFILESYS
+  static bool settings_lkg = false;  // Settings saved as Last Known Good
+  // Copy Settings as Last Known Good if no changes have been saved since 30 minutes
+  if (!settings_lkg && (UtcTime() > START_VALID_TIME) && (Settings.cfg_timestamp < UtcTime() - (30 * 60))) {
+    TfsSaveFile(TASM_FILE_SETTINGS_LKG, (const uint8_t*)&Settings, sizeof(Settings));
+    settings_lkg = true;
+  }
+#endif
 }
 
 /*-------------------------------------------------------------------------------------------*\
diff --git a/tasmota/tasmota_globals.h b/tasmota/tasmota_globals.h
index 330a1a87e..4524410dd 100644
--- a/tasmota/tasmota_globals.h
+++ b/tasmota/tasmota_globals.h
@@ -225,8 +225,9 @@ const uint16_t LOG_BUFFER_SIZE = 4000;         // Max number of characters in lo
   #error "Arduino ESP8266 Core versions before 2.7.1 are not supported"
 #endif
 
-#define TASM_FILE_SETTINGS          "/.settings"
-#define TASM_FILE_ZIGBEE            "/zb"
+#define TASM_FILE_SETTINGS          "/.settings"       // Settings binary blob
+#define TASM_FILE_SETTINGS_LKG      "/.settings.lkg"   // Last Known Good Settings binary blob
+#define TASM_FILE_ZIGBEE            "/zb"              // Zigbee settings blob as used by CC2530 on ESP32
 
 #ifndef MQTT_MAX_PACKET_SIZE
 #define MQTT_MAX_PACKET_SIZE        1200       // Bytes