Add Captive Portal (#624)

* WIP: Captive Portal

* Updates

* Updates

* Lint

* Fixes

esphome/components/web_server_base/web_server_base.h

@@ -0,0 +1,76 @@
+#pragma once
+
+#include "esphome/core/component.h"
+
+#include <ESPAsyncWebServer.h>
+
+namespace esphome {
+namespace web_server_base {
+
+class WebServerBase : public Component {
+ public:
+  void init() {
+    if (this->initialized_) {
+      this->initialized_++;
+      return;
+    }
+    this->server_ = new AsyncWebServer(this->port_);
+    this->server_->begin();
+
+    for (auto *handler : this->handlers_)
+      this->server_->addHandler(handler);
+
+    this->initialized_++;
+  }
+  void deinit() {
+    this->initialized_--;
+    if (this->initialized_ == 0) {
+      delete this->server_;
+      this->server_ = nullptr;
+    }
+  }
+  AsyncWebServer *get_server() const { return server_; }
+  float get_setup_priority() const override;
+
+  void add_handler(AsyncWebHandler *handler) {
+    // remove all handlers
+
+    this->handlers_.push_back(handler);
+    if (this->server_ != nullptr)
+      this->server_->addHandler(handler);
+  }
+
+  void add_ota_handler();
+
+  void set_port(uint16_t port) { port_ = port; }
+  uint16_t get_port() const { return port_; }
+
+ protected:
+  friend class OTARequestHandler;
+
+  int initialized_{0};
+  uint16_t port_{80};
+  AsyncWebServer *server_{nullptr};
+  std::vector<AsyncWebHandler *> handlers_;
+};
+
+class OTARequestHandler : public AsyncWebHandler {
+ public:
+  OTARequestHandler(WebServerBase *parent) : parent_(parent) {}
+  void handleRequest(AsyncWebServerRequest *request) override;
+  void handleUpload(AsyncWebServerRequest *request, const String &filename, size_t index, uint8_t *data, size_t len,
+                    bool final) override;
+  bool canHandle(AsyncWebServerRequest *request) override {
+    return request->url() == "/update" && request->method() == HTTP_POST;
+  }
+
+  bool isRequestHandlerTrivial() override { return false; }
+
+ protected:
+  uint32_t last_ota_progress_{0};
+  uint32_t ota_read_length_{0};
+  WebServerBase *parent_;
+};
+
+}  // namespace web_server_base
+}  // namespace esphome