Add select entities and implement template select (#2067)

Co-authored-by: Otto Winter <otto@otto-winter.com>

esphome/components/select/select.h

@@ -0,0 +1,87 @@
+#pragma once
+
+#include <set>
+#include <utility>
+#include "esphome/core/component.h"
+#include "esphome/core/helpers.h"
+
+namespace esphome {
+namespace select {
+
+#define LOG_SELECT(prefix, type, obj) \
+  if ((obj) != nullptr) { \
+    ESP_LOGCONFIG(TAG, "%s%s '%s'", prefix, type, (obj)->get_name().c_str()); \
+    if (!(obj)->traits.get_icon().empty()) { \
+      ESP_LOGCONFIG(TAG, "%s  Icon: '%s'", prefix, (obj)->traits.get_icon().c_str()); \
+    } \
+  }
+
+class Select;
+
+class SelectCall {
+ public:
+  explicit SelectCall(Select *parent) : parent_(parent) {}
+  void perform();
+
+  SelectCall &set_option(const std::string &option) {
+    option_ = option;
+    return *this;
+  }
+  const optional<std::string> &get_option() const { return option_; }
+
+ protected:
+  Select *const parent_;
+  optional<std::string> option_;
+};
+
+class SelectTraits {
+ public:
+  void set_options(std::vector<std::string> options) { this->options_ = std::move(options); }
+  const std::vector<std::string> get_options() const { return this->options_; }
+  void set_icon(std::string icon) { icon_ = std::move(icon); }
+  const std::string &get_icon() const { return icon_; }
+
+ protected:
+  std::vector<std::string> options_;
+  std::string icon_;
+};
+
+/** Base-class for all selects.
+ *
+ * A select can use publish_state to send out a new value.
+ */
+class Select : public Nameable {
+ public:
+  std::string state;
+
+  void publish_state(const std::string &state);
+
+  SelectCall make_call() { return SelectCall(this); }
+  void set(const std::string &value) { make_call().set_option(value).perform(); }
+
+  void add_on_state_callback(std::function<void(std::string)> &&callback);
+
+  SelectTraits traits;
+
+  /// Return whether this select has gotten a full state yet.
+  bool has_state() const { return has_state_; }
+
+ protected:
+  friend class SelectCall;
+
+  /** Set the value of the select, this is a virtual method that each select integration must implement.
+   *
+   * This method is called by the SelectCall.
+   *
+   * @param value The value as validated by the SelectCall.
+   */
+  virtual void control(const std::string &value) = 0;
+
+  uint32_t hash_base() override;
+
+  CallbackManager<void(std::string)> state_callback_;
+  bool has_state_{false};
+};
+
+}  // namespace select
+}  // namespace esphome