time_temperature_display/src/network.cpp

#include "network.h"

#include <WiFi.h>
#include <time.h>

#include "config.h"
#include "rtc.h"

namespace {

bool g_synced = false;
uint32_t g_lastAttemptMs = 0;
uint32_t g_lastSyncMs = 0;
bool g_connecting = false;

void startConnect()
{
  Serial.printf("[net] connecting to %s\n", WIFI_SSID);
  WiFi.disconnect();
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  g_lastAttemptMs = millis();
  g_connecting = true;
}

}  // namespace

namespace network {

void begin()
{
  WiFi.mode(WIFI_STA);
  WiFi.setHostname(WIFI_HOSTNAME);
  WiFi.setAutoReconnect(true);
  WiFi.setSleep(true);  // the display is idle most of the time

  // Timezone is applied to the system clock regardless of connectivity, so the
  // RTC-derived time renders correctly offline.
  setenv("TZ", TIMEZONE_POSIX, 1);
  tzset();

  startConnect();
}

void loop()
{
  const uint32_t nowMs = millis();

  if (WiFi.status() == WL_CONNECTED) {
    if (g_connecting) {
      g_connecting = false;
      Serial.printf("[net] connected, ip=%s\n", WiFi.localIP().toString().c_str());
      syncTimeNow();
    }
    if (g_synced && nowMs - g_lastSyncMs >= NTP_RESYNC_MS) {
      syncTimeNow();
    }
    return;
  }

  // Not connected: retry, but never more often than WIFI_RETRY_MS.
  const uint32_t since = nowMs - g_lastAttemptMs;
  if (g_connecting && since < WIFI_CONNECT_TIMEOUT_MS) {
    return;
  }
  if (since >= WIFI_RETRY_MS || (g_connecting && since >= WIFI_CONNECT_TIMEOUT_MS)) {
    if (g_connecting) {
      Serial.println("[net] connect attempt timed out");
      g_connecting = false;
      g_lastAttemptMs = nowMs;  // hold off for WIFI_RETRY_MS before retrying
      return;
    }
    startConnect();
  }
}

bool isConnected()
{
  return WiFi.status() == WL_CONNECTED;
}

bool syncTimeNow()
{
  if (!isConnected()) {
    return false;
  }

  configTzTime(TIMEZONE_POSIX, NTP_SERVER_1, NTP_SERVER_2);

  // Wait briefly for the first SNTP response. A plausible year means the
  // system clock has been set from the network rather than left at the epoch.
  struct tm local = {};
  const uint32_t deadline = millis() + 10000UL;
  bool got = false;
  while (millis() < deadline) {
    if (getLocalTime(&local, 200) && local.tm_year + 1900 >= 2024) {
      got = true;
      break;
    }
    delay(100);
  }

  if (!got) {
    Serial.println("[net] NTP sync failed");
    return false;
  }

  // Persist UTC into the RTC so timekeeping survives the next outage.
  const time_t utcNow = time(nullptr);
  struct tm utc;
  gmtime_r(&utcNow, &utc);
  if (!rtc::setTime(utc)) {
    Serial.println("[net] NTP ok but RTC write failed");
  }

  g_synced = true;
  g_lastSyncMs = millis();
  Serial.printf("[net] time synced: %04d-%02d-%02d %02d:%02d local\n",
                local.tm_year + 1900, local.tm_mon + 1, local.tm_mday,
                local.tm_hour, local.tm_min);
  return true;
}

bool hasSyncedTime()
{
  return g_synced;
}

}  // namespace network