#include "net.h"

#include <WiFi.h>
#include <esp_sntp.h>
#include <sys/time.h>

#include "settings.h"

namespace {

bool synced = false;
bool wasConnected = false;

// The device cannot be running before its own firmware was compiled, so the build
// timestamp is a safe floor. Certificate validity checks fail against 1970, and this
// makes them pass before SNTP has answered. mktime reads it as UTC while the build
// machine wrote local time; a few hours of error is irrelevant for a lower bound.
time_t buildTime() {
  static const char months[] = "JanFebMarAprMayJunJulAugSepOctNovDec";
  char month[4] = {__DATE__[0], __DATE__[1], __DATE__[2], '\0'};
  const char* found = strstr(months, month);
  struct tm parts = {};
  parts.tm_mon = found ? (found - months) / 3 : 0;
  parts.tm_mday = atoi(__DATE__ + 4);
  parts.tm_year = atoi(__DATE__ + 7) - 1900;
  parts.tm_hour = atoi(__TIME__);
  parts.tm_min = atoi(__TIME__ + 3);
  parts.tm_sec = atoi(__TIME__ + 6);
  return mktime(&parts);
}

// Latched, because sntp_get_sync_status() reports COMPLETED only briefly before
// resetting to wait for the next cycle; polling it would flap.
void onTimeSync(struct timeval*) {
  synced = true;
  Serial.printf("[net] clock synced: %lu\n", (unsigned long)time(nullptr));
}

}  // namespace

void net::applyTimezone() {
  setenv("TZ", settings.timezone.c_str(), 1);
  tzset();
}

void net::begin() {
  applyTimezone();
  time_t floor = buildTime();
  if (time(nullptr) < floor) {
    struct timeval seed = {.tv_sec = floor, .tv_usec = 0};
    settimeofday(&seed, nullptr);
  }

  sntp_set_time_sync_notification_cb(onTimeSync);

  WiFi.persistent(false);
  if (settings.wifiSsid.length()) {
    WiFi.mode(WIFI_STA);
    WiFi.begin(settings.wifiSsid.c_str(), settings.wifiPassword.c_str());
  }
}

void net::loop() {
  bool connected = WiFi.status() == WL_CONNECTED;
  if (connected == wasConnected) return;
  wasConnected = connected;
  if (!connected) return;

  // Started per join rather than once at boot: a fresh lease may hand us a different
  // NTP server, and the daemon re-syncs on its own hourly from here.
  sntp_servermode_dhcp(1);
  configTime(0, 0, "pool.ntp.org", "time.nist.gov");  // UTC; the UI decides how to show it
  Serial.println("[net] wifi up, sntp started");
}

bool net::clockSynced() { return synced; }