Refactor the increasingly complex wifi code into its own header, update some docs.

wifi.h

@@ -0,0 +1,60 @@
+#include <ESP8266WiFi.h>
+#include <ESP8266HTTPClient.h>
+//#include <WifiClientSecureBearSSL.h>
+#include <bearssl.h>
+#include <FS.h>
+
+HTTPClient client;
+BearSSL::WifiClientSecure *transport;
+BearSSL::X509List cert_list;
+
+void init_wifi() {
+  transport = new WifiClientSecure();
+
+  Serial.println("Attempting to (re)connect to wifi");
+  WiFi.disconnect();
+  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
+  int elapsed = 0;
+  while (WiFi.status() != WL_CONNECTED) {
+      Serial.print("Wifi connecting for ");
+      Serial.print(elapsed);
+      Serial.println(" seconds");
+      elapsed++;
+      delay(1000);
+  }
+
+  Serial.println("Wifi connected");
+  
+  sync_time();
+  load_ca_cert();
+}
+
+void load_ca_cert() {
+  // read cert from file
+  if (!SPIFFS.begin()) {
+    Serial.println("Failed to mount file system.");
+    return
+  }
+
+  File cert = SPIFFS.open("/ca_cert.pem", "r");
+  if (!cert) {
+    Serial.println("Couldn't open cert file.");
+    return;
+  }
+
+  cert_list.append(strdup(cert.readString().c_str()));
+  netClient->setTrustAnchors(&certList);
+}
+
+void sync_time() {
+  // sync time
+  Serial.print("Syncing time");
+  configTime(8 * 3600, 0, "pool.ntp.org", "time.nist.gov");
+  time_t now = time(nullptr);
+  while (now < 8 * 3600 * 2) {
+    delay(500);
+    Serial.print(".");
+    now = time(nullptr);
+  }
+  Serial.println("");
+}