ESP32 Weather Clock

#include <Arduino.h>
#include <SPI.h>
#include <WiFi.h>
#include <WiFiManager.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>
#include <Preferences.h>
#include <Adafruit_GFX.h>
#include <Adafruit_GC9A01A.h>
#include <time.h>

Adafruit_GC9A01A screen(9,8,11,10,12);
WiFiManager wm;
Preferences prefs;
WiFiManagerParameter latParam("lat","Zemepisna sirka (-90 az 90)","50.0755",16);
WiFiManagerParameter lonParam("lon","Zemepisna delka (-180 az 180)","14.4378",16);
WiFiManagerParameter townParam("town","Nazev obce (bez diakritiky)","Praha",40);
String town="Praha";
String lat="50.0755", lon="14.4378", previous;
bool screenOK=false, haveWeather=false, failed=false, requestWeather=true;
float temperature=0; int humidity=0, code=0;
uint32_t lastFetch=0, lastSuccess=0;

const char* condition(int c) {
  if(c==0) return "Jasno";
  if(c<=3) return "Oblacno";
  if(c==45 || c==48) return "Mlha";
  if(c>=95) return "Bourka";
  if((c>=71 && c<=77)||c==85||c==86) return "Snezeni";
  if((c>=51 && c<=67)||(c>=80 && c<=82)) return "Dest";
  return "Pocasi";
}
void saveLocation() {
  // Save the name independently of coordinate validation.
  String enteredTown=String(townParam.getValue()); enteredTown.trim();
  if(enteredTown=="Poloha" || enteredTown=="Nastavte obec") enteredTown="";
  town=enteredTown;
  prefs.putString("town",town);
  char *end;
  double a=strtod(latParam.getValue(),&end);
  if(end==latParam.getValue() || *end || !isfinite(a) || a < -90 || a>90) return;
  double b=strtod(lonParam.getValue(),&end);
  if(end==lonParam.getValue() || *end || !isfinite(b) || b < -180 || b>180) return;
  lat=String(a,5); lon=String(b,5);
  prefs.putString("lat",lat); prefs.putString("lon",lon);
  haveWeather=false; requestWeather=true;
}
void fetchWeather() {
  lastFetch=millis(); requestWeather=false;
  HTTPClient http;
  // Public weather data only: no credentials are sent to this HTTP endpoint.
  String url="http://api.open-meteo.com/v1/forecast?latitude="+lat+"&longitude="+lon+"&current=temperature_2m,relative_humidity_2m,weather_code";
  http.setConnectTimeout(4000); http.setTimeout(4000);
  failed=true;
  if(http.begin(url)) {
    int status=http.GET();
    if(status==200) {
      JsonDocument doc;
      if(!deserializeJson(doc,http.getString()) && doc["current"]["temperature_2m"].is<float>() && doc["current"]["weather_code"].is<int>()) {
        temperature=doc["current"]["temperature_2m"].as<float>();
        humidity=doc["current"]["relative_humidity_2m"].as<int>();
        code=doc["current"]["weather_code"].as<int>();
        haveWeather=true; failed=false; lastSuccess=millis();
      }
    }
    http.end();
  }
}
// Small off-screen buffers keep animation updates confined to the icon.
GFXcanvas16 face(240,240), icon(112,64);
const uint16_t BG=0x0843, CYAN=0x4E7F, WHITE=0xEF7D, MUTED=0x8494;
uint32_t animationAt=0;
unsigned animationFrame=0;
void centered(GFXcanvas16 &g,const String &text,int y,int size,uint16_t color) {
  g.setTextWrap(false); g.setTextSize(size); g.setTextColor(color);
  g.setCursor((g.width()-int(text.length())*6*size)/2,y); g.print(text);
}
void animateWeather() {
  if(!screenOK || millis()-animationAt<160) return;
  animationAt=millis(); unsigned f=animationFrame++;
  icon.fillScreen(BG);
  bool snow=(code>=71&&code<=77)||code==85||code==86;
  bool rain=(code>=51&&code<=67)||(code>=80&&code<=82)||code>=95;
  if(!haveWeather) {
    for(int i=0;i<8;i++) {
      float a=(i+f%8)*PI/4;
      icon.fillCircle(56+cosf(a)*18,30+sinf(a)*18,3,i==0?CYAN:MUTED);
    }
  } else {
    if(code<=2) {
      int x=code==0?56:38, y=26;
      for(int i=0;i<8;i++) {
        float a=i*PI/4+f*0.055f;
        icon.drawLine(x+cosf(a)*19,y+sinf(a)*19,x+cosf(a)*25,y+sinf(a)*25,0xFD20);
      }
      icon.fillCircle(x,y,14,0xFFE0);
      icon.fillCircle(x-4,y-4,5,0xFFF3);
    }
    if(code!=0) {
      int drift=int(sinf(f*0.12f)*4);
      uint16_t cloud=rain?0x9CF5:0xD6FC;
      icon.fillCircle(42+drift,25,12,cloud);
      icon.fillCircle(58+drift,19,17,cloud);
      icon.fillCircle(76+drift,29,12,cloud);
      icon.fillRoundRect(33+drift,26,55,17,8,cloud);
    }
    if(rain||snow) for(int i=0;i<5;i++) {
      int x=32+i*12, y=43+(f*3+i*7)%19;
      if(snow) {
        icon.drawLine(x-2,y,x+2,y,WHITE); icon.drawLine(x,y-2,x,y+2,WHITE);
      } else icon.drawLine(x,y,x-3,y+5,CYAN);
    }
    if(code==45||code==48) for(int i=0;i<3;i++) {
      int x=25+int(sinf(f*0.15f+i)*5);
      icon.drawFastHLine(x,46+i*6,60,MUTED);
    }
    if(code>=95 && f%12<3) {
      icon.fillTriangle(58,35,48,50,58,47,0xFFE0);
      icon.fillTriangle(55,45,64,43,52,61,0xFFE0);
    }
  }
  screen.drawRGBBitmap(64,112,icon.getBuffer(),112,64);
}
void draw() {
  time_t now=time(nullptr); struct tm local;
  char clockText[12]="--:--", dateText[24]="Cekam na cas";
  if(now>1700000000) {
    localtime_r(&now,&local);
    strftime(clockText,sizeof(clockText),"%H:%M",&local);
    strftime(dateText,sizeof(dateText),"%d.%m.%Y",&local);
  }
  bool connected=WiFi.status()==WL_CONNECTED;
  bool stale=failed || (haveWeather && millis()-lastSuccess>1800000UL);
  String weather=haveWeather ? String(temperature,1)+" C" : "--.- C";
  String state=!connected?"Hodiny-Setup":haveWeather?String(condition(code))+(stale?" *stare":""):"Cekam na pocasi";
  String frame=String(clockText)+dateText+weather+state+String(humidity)+town;
  if(frame!=previous && screenOK) {
    previous=frame;
    face.fillScreen(BG);
    face.drawCircle(120,120,118,0x19CC);
    face.drawCircle(120,120,115,0x19CC);
    for(int i=0;i<60;i++) {
      float a=i*PI/30-PI/2;
      int r=i%5==0?108:112;
      face.drawLine(120+cosf(a)*r,120+sinf(a)*r,120+cosf(a)*114,120+sinf(a)*114,i%5==0?CYAN:0x326D);
    }
    String label=town.isEmpty()?"Nastavte obec":town;
    if(label.length()>24) label=label.substring(0,21)+"...";
    centered(face,label,26,1,CYAN);
    centered(face,clockText,48,5,WHITE);
    centered(face,dateText,94,1,MUTED);
    centered(face,weather,178,3,WHITE);
    centered(face,connected?state:"WiFi: Hodiny-Setup",208,1,CYAN);
    centered(face,connected?(haveWeather?"Vlhkost "+String(humidity)+"%":"Open-Meteo"):"192.168.4.1",222,1,MUTED);
    screen.drawRGBBitmap(0,0,face.getBuffer(),240,240);
    animationAt=millis()-160;
  }
  animateWeather();
}
void setup() {
  Serial.begin(115200);
  pinMode(40,OUTPUT); digitalWrite(40,LOW);
  screen.begin(20000000); screen.setRotation(0);
  screen.fillScreen(0); screen.setTextWrap(false);
  digitalWrite(40,HIGH); screenOK=true;
  prefs.begin("weather",false);
  lat=prefs.getString("lat","50.0755"); lon=prefs.getString("lon","14.4378");
  town=prefs.isKey("town")?prefs.getString("town",""):"";
  town.trim();
  if(town=="Poloha") town="";
  townParam.setValue(town.c_str(),40);
  latParam.setValue(lat.c_str(),16); lonParam.setValue(lon.c_str(),16);
  WiFi.mode(WIFI_STA); WiFi.setAutoReconnect(true); WiFi.begin();
  wm.addParameter(&townParam); wm.addParameter(&latParam); wm.addParameter(&lonParam);
  wm.setSaveParamsCallback(saveLocation);
  wm.setConfigPortalBlocking(false);
  wm.startConfigPortal("Hodiny-Setup","Pocasi123");
  configTzTime("CET-1CEST,M3.5.0,M10.5.0/3","pool.ntp.org","time.nist.gov");
  draw();
}
void loop() {
  wm.process();
  if(WiFi.status()==WL_CONNECTED && (requestWeather || millis()-lastFetch >= (failed?60000UL:900000UL))) fetchWeather();
  draw(); delay(20);
}