Settings placeholder substitution (#164)

* Use text formatting for default factory values to produce dynamic names.
Header files contains duplicates of factory values defined in factory_settings.ini Removed them to simplify the code.

* Use text formatting for default factory values to produce dynamic names.
Header files contains duplicates of factory values defined in factory_settings.ini Removed them to simplify the code.

* Configured the WiFi host name to contain the device id by default

* Removed possibility to use placeholders for FACTORY_WIFI_SSID factory setting.

* Update README.md

Updated documentation

* Use text formatting for default factory values to produce dynamic names.
Header files contains duplicates of factory values defined in factory_settings.ini Removed them to simplify the code.

* Configured the WiFi host name to contain the device id by default

* Removed possibility to use placeholders for FACTORY_WIFI_SSID factory setting.

* Added a space to the end of the file to comply project code style

* fix typos
clang formatting
use 2 spaces in ini files
use ${platform}-${chip_id} for hostname
put chip id in brackets in AP SSID

* restore (and update) factory setting ifndefs

- this is so src can be built without an exaustive set build-time defines
- standardize ordering of defines: factory settings, paths, config

* format and modify comment

* escape spaces in pio defines
experiment with removing $'s from our format strings (they are being substituted with empty values by pio)

* fix formatting in readme
rename FactoryValue to SettingValue, put in own header
give example of direct usage of FactorySetting::format in README.md

* auto format

* use hash to delimit placeholders

* fix factory_settings.ini

* remove flash string helpers

* format ini file

* use MAC address instead of chip id for properly unique identifier

* use lower case hex encoding for unique id
use chip id and unique id for more secure secret

* fix comment

* Use random values for JWT secret
Arduino uses the ESP random number generator for "true random" numbers on both esp32 and esp8266
This makes a better JWT secret and may be useful for other factory defaults too
In addition a modification has been made to force the FSPersistance to save the file if applying defaults

* Don't use spaces in default AP SSID

* restore helpful comment in factory_settings.ini
fix default defines

Co-authored-by: kasedy <kasedy@gmail.com>

lib/framework/WiFiSettingsService.h

@@ -1,15 +1,12 @@
 #ifndef WiFiSettingsService_h
 #define WiFiSettingsService_h
 
+#include <SettingValue.h>
 #include <StatefulService.h>
 #include <FSPersistence.h>
 #include <HttpEndpoint.h>
 #include <JsonUtils.h>
 
-#define WIFI_SETTINGS_FILE "/config/wifiSettings.json"
-#define WIFI_SETTINGS_SERVICE_PATH "/rest/wifiSettings"
-#define WIFI_RECONNECTION_DELAY 1000 * 30
-
 #ifndef FACTORY_WIFI_SSID
 #define FACTORY_WIFI_SSID ""
 #endif
@@ -19,9 +16,14 @@
 #endif
 
 #ifndef FACTORY_WIFI_HOSTNAME
-#define FACTORY_WIFI_HOSTNAME ESPUtils::defaultDeviceValue("esp-react-")
+#define FACTORY_WIFI_HOSTNAME "#{platform}-#{unique_id}"
 #endif
 
+#define WIFI_SETTINGS_FILE "/config/wifiSettings.json"
+#define WIFI_SETTINGS_SERVICE_PATH "/rest/wifiSettings"
+
+#define WIFI_RECONNECTION_DELAY 1000 * 30
+
 class WiFiSettings {
  public:
   // core wifi configuration
@@ -55,7 +57,7 @@ class WiFiSettings {
   static StateUpdateResult update(JsonObject& root, WiFiSettings& settings) {
     settings.ssid = root["ssid"] | FACTORY_WIFI_SSID;
     settings.password = root["password"] | FACTORY_WIFI_PASSWORD;
-    settings.hostname = root["hostname"] | FACTORY_WIFI_HOSTNAME;
+    settings.hostname = root["hostname"] | SettingValue::format(FACTORY_WIFI_HOSTNAME);
     settings.staticIPConfig = root["static_ip_config"] | false;
 
     // extended settings