Improv - BLE WiFi provisioning (#1807)

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>

esphome/components/esp32_ble/ble_descriptor.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include "ble_uuid.h"
+
+#ifdef ARDUINO_ARCH_ESP32
+
+#include <esp_gatt_defs.h>
+#include <esp_gatts_api.h>
+
+namespace esphome {
+namespace esp32_ble {
+
+class BLECharacteristic;
+
+class BLEDescriptor {
+ public:
+  BLEDescriptor(ESPBTUUID uuid, uint16_t max_len = 100);
+  virtual ~BLEDescriptor();
+  bool do_create(BLECharacteristic *characteristic);
+
+  void set_value(const std::string value);
+  void set_value(uint8_t *data, size_t length);
+
+  void gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt_if_t gatts_if, esp_ble_gatts_cb_param_t *param);
+
+ protected:
+  BLECharacteristic *characteristic_{nullptr};
+  ESPBTUUID uuid_;
+  uint16_t handle_{0xFFFF};
+  SemaphoreHandle_t create_lock_;
+
+  esp_attr_value_t value_;
+
+  esp_gatt_perm_t permissions_ = ESP_GATT_PERM_READ | ESP_GATT_PERM_WRITE;
+};
+
+}  // namespace esp32_ble
+}  // namespace esphome
+
+#endif