Implement Improv via Serial component (#2423)

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

esphome/components/improv_serial/improv_serial_component.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#include "esphome/components/improv/improv.h"
+#include "esphome/components/wifi/wifi_component.h"
+#include "esphome/core/component.h"
+#include "esphome/core/defines.h"
+#include "esphome/core/helpers.h"
+
+#ifdef USE_ARDUINO
+#include <HardwareSerial.h>
+#endif
+#ifdef USE_ESP_IDF
+#include <driver/uart.h>
+#endif
+
+namespace esphome {
+namespace improv_serial {
+
+enum ImprovSerialType : uint8_t {
+  TYPE_CURRENT_STATE = 0x01,
+  TYPE_ERROR_STATE = 0x02,
+  TYPE_RPC = 0x03,
+  TYPE_RPC_RESPONSE = 0x04
+};
+
+static const uint8_t IMPROV_SERIAL_VERSION = 1;
+
+class ImprovSerialComponent : public Component {
+ public:
+  void setup() override;
+  void loop() override;
+  void dump_config() override;
+
+  float get_setup_priority() const override { return setup_priority::HARDWARE; }
+
+ protected:
+  bool parse_improv_serial_byte_(uint8_t byte);
+  bool parse_improv_payload_(improv::ImprovCommand &command);
+
+  void set_state_(improv::State state);
+  void set_error_(improv::Error error);
+  void send_response_(std::vector<uint8_t> &response);
+  void on_wifi_connect_timeout_();
+
+  std::vector<uint8_t> build_rpc_settings_response_(improv::Command command);
+  std::vector<uint8_t> build_version_info_();
+
+  int available_();
+  uint8_t read_byte_();
+  void write_data_(std::vector<uint8_t> &data);
+
+#ifdef USE_ARDUINO
+  HardwareSerial *hw_serial_{nullptr};
+#endif
+#ifdef USE_ESP_IDF
+  uart_port_t uart_num_;
+#endif
+
+  std::vector<uint8_t> rx_buffer_;
+  uint32_t last_read_byte_{0};
+  wifi::WiFiAP connecting_sta_;
+  improv::State state_{improv::STATE_AUTHORIZED};
+};
+
+extern ImprovSerialComponent
+    *global_improv_serial_component;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+
+}  // namespace improv_serial
+}  // namespace esphome