Smart Infrastructure Monitoring Box

// Bare ESP32-D0WD-V3 PCB: external 4 MB flash, 40 MHz crystal.
// SHT31-DIS at 0x44; SDA=GPIO21 (U1 pad42), SCL=GPIO22 (U1 pad39).
#include <Arduino.h>
#include <WiFi.h>
#include <WebServer.h>
#include <HTTPClient.h>
#include <WiFiClientSecure.h>
#include <Wire.h>
#include <Adafruit_SHT31.h>
#include <time.h>
// Set these before Deploy. Use a dedicated monitoring Wi-Fi network.
const char* SSID="YOUR_WIFI";
const char* PASSWORD="YOUR_WIFI_PASSWORD";
const char* DASH_PASSWORD="CHANGE_THIS_PASSWORD";
const char* WEBHOOK=""; // HTTPS endpoint accepting JSON {"text":"..."}
const char* WEBHOOK_CA=""; // PEM root CA for webhook host; never bypass TLS validation.
const char* BEARER="";
const char* UPS_URL=""; // Optional trusted LAN HTTP gateway: 200 + ONLINE or ONBATT
struct Target {const char* name; const char* host; uint16_t port; bool known=false,up=false; uint8_t failures=0; uint32_t downAt=0; uint64_t downtime=0; int latency=-1;};
// Replace empty hosts with local IPs. TCP reachability is not CPU/port/SNMP health.
Target targets[]={{"Internet A","1.1.1.1",443},{"Internet B","8.8.8.8",443},{"Router","",80},{"Switch","",443},{"Server","",443},{"Firewall","",443}};
WebServer server(80);
Adafruit_SHT31 sensor;
float temp=NAN, humidity=NAN;
String events[40]; unsigned eventIndex=0;
String pending[24]; unsigned qhead=0,qcount=0; uint32_t dropped=0;
uint32_t lastPoll=0,lastSend=0; bool sensorOK=false; int environmentState=-1, internetState=-1; String upsState="disabled";
String stamp(){time_t now=time(nullptr); if(now<1700000000) return String("uptime ")+String(millis()/1000)+"s"; char b[32]; struct tm t; gmtime_r(&now,&t); strftime(b,sizeof(b),"%Y-%m-%dT%H:%M:%SZ",&t); return b;}
String escape(String s){s.replace("\\","\\\\");s.replace("\"","\\\"");s.replace("\n","\\n");s.replace("\r","");return s;}
void event(String text){String line=stamp()+" "+text; Serial.println(line); events[eventIndex++%40]=line; if(!strlen(WEBHOOK))return; if(qcount==24){qhead=(qhead+1)%24;qcount--;dropped++;} pending[(qhead+qcount++)%24]=line;}
bool auth(){if(server.authenticate("admin",DASH_PASSWORD))return true;server.requestAuthentication();return false;}
void dashboard(){if(!auth())return; String s="Smart IT Monitor\n\n"; s+="Wi-Fi: "+String(WiFi.status()==WL_CONNECTED?"connected":"offline")+"\n"; s+="Temperature C: "+String(temp)+" | Humidity %: "+String(humidity)+"\n";
 for(auto &t:targets){if(!strlen(t.host))continue; uint64_t dt=t.downtime+((t.known&&!t.up)?uint32_t(millis()-t.downAt)/1000:0); s+=String(t.name)+": "+(!t.known?"pending":t.up?"UP":"DOWN")+" | TCP connect ms="+String(t.latency)+" | downtime seconds="+String((unsigned long)dt)+"\n";}
 s+="UPS: "+upsState+"\nQueued alerts: "+String(qcount)+" | discarded: "+String(dropped)+"\n\nRecent events (RAM only):\n"; unsigned n=eventIndex<40?eventIndex:40; for(unsigned i=0;i<n;i++)s+=events[(eventIndex-n+i)%40]+"\n"; server.sendHeader("Cache-Control","no-store");server.send(200,"text/plain",s);}
void probe(Target &t){if(!strlen(t.host))return; WiFiClient c; uint32_t start=millis(); bool ok=WiFi.status()==WL_CONNECTED && c.connect(t.host,t.port,700);t.latency=ok?int(millis()-start):-1;c.stop(); if(ok)t.failures=0;else if(t.failures<3)t.failures++; if(!ok&&t.failures<3)return;
 if(!t.known||t.up!=ok){if(t.known&&!t.up)t.downtime+=uint32_t(millis()-t.downAt)/1000;t.known=true;t.up=ok;if(!ok)t.downAt=millis();event(String(t.name)+(ok?" UP":" DOWN (3 failed checks)"));}}
void poll(){for(auto &t:targets){probe(t);server.handleClient();}
 if(targets[0].known&&targets[1].known){int state=targets[0].up||targets[1].up; if(state!=internetState){internetState=state;event(state?"Internet reachable":"Internet unavailable: both external TCP probes failed");}}
 if(!sensorOK)sensorOK=sensor.begin(0x44); temp=sensorOK?sensor.readTemperature():NAN;humidity=sensorOK?sensor.readHumidity():NAN;
 int e=(!isfinite(temp)||!isfinite(humidity))?2:(temp>=35||humidity>=70||humidity<=20)?1:0;
 if(e!=environmentState){environmentState=e;event(e==2?"Environment sensor fault":e==1?"Environment outside limits (35C, 20-70% RH)":"Environment normal");} if(e==2)sensorOK=false;
 if(strlen(UPS_URL)&&WiFi.status()==WL_CONNECTED){HTTPClient h;h.setTimeout(1500);String next="gateway unavailable";if(h.begin(UPS_URL)){int code=h.GET();if(code==200){String b=h.getString();b.trim();next=(b=="ONLINE"||b=="ONBATT")?b:"invalid gateway response";}h.end();}if(next!=upsState){upsState=next;event("UPS "+next);}}
}
void sendAlert(){if(!qcount||WiFi.status()!=WL_CONNECTED||!strlen(WEBHOOK_CA)||!String(WEBHOOK).startsWith("https://"))return; if(time(nullptr)<1700000000)return;
 WiFiClientSecure c;c.setCACert(WEBHOOK_CA);HTTPClient h;h.setTimeout(2500); if(h.begin(c,WEBHOOK)){h.addHeader("Content-Type","application/json");if(strlen(BEARER))h.addHeader("Authorization",String("Bearer ")+BEARER);int code=h.POST(String("{\"text\":\"")+escape(pending[qhead])+"\"}");if(code>=200&&code<300){qhead=(qhead+1)%24;qcount--;}h.end();}}
void setup(){Serial.begin(115200);Wire.begin(21,22);sensorOK=sensor.begin(0x44);WiFi.mode(WIFI_STA);WiFi.setAutoReconnect(true);WiFi.begin(SSID,PASSWORD);configTime(0,0,"pool.ntp.org","time.google.com"); server.on("/",dashboard);server.begin(); event("Monitor started; outage history resets on restart");lastPoll=millis()-30000;}
void loop(){server.handleClient();static bool connected=false;bool now=WiFi.status()==WL_CONNECTED;if(now!=connected){connected=now;event(now?String("Wi-Fi connected; dashboard http://")+WiFi.localIP().toString():"Wi-Fi lost; remote alerts queued");} if(uint32_t(millis()-lastPoll)>=30000){lastPoll=millis();poll();}if(uint32_t(millis()-lastSend)>=10000){lastSend=millis();sendAlert();}delay(2);}