AI API Reliability Sentinel

#include <Arduino.h>

#define TFT_DC 14
#define TFT_RST 15
#define TFT_BL 16
#define BUTTON_PIN 4
/* AI/API Sentinel v0.1.0 — portable ESP32-S3 Arduino foundation.
 * Intentionally bounded: 4 monitor definitions and 12 retained results each.
 * Secrets are stored locally in ESP32 NVS; never printed or returned unmasked.
 */
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <HTTPClient.h>
#include <WebServer.h>
#include <WiFiManager.h>
#include <Preferences.h>
#include <ArduinoJson.h>
#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ST7789.h>


// Hoisted type definitions
enum State : uint8_t { HEALTHY, WARNING, FAILED, TIMEOUT, AUTH_ERROR, RATE_LIMITED, VALIDATION_FAILED, NETWORK_ERROR, UNKNOWN };

struct Result { uint32_t at=0, ms=0; int status=0; State state=UNKNOWN; String message="Not tested"; };

struct Monitor {
  String id, name, provider, endpoint, method, headers, body, requiredFields, keyword;
  int expectedStatus=200; uint32_t intervalS=DEFAULT_INTERVAL_S, timeoutMs=DEFAULT_TIMEOUT_MS, warnMs=2000, criticalMs=5000;
  bool enabled=true; uint8_t failures=0, consecutiveFailures=0; uint32_t lastRun=0;
  Result history[HISTORY_PER_MONITOR]; uint8_t historyCount=0;
};


// Forward declarations
String safeText(const String &s, size_t maxLen);
bool online();
void logLine(const char *tag, const String &s);
void addHistory(Monitor &m, Result r);
State currentState(const Monitor &m);
void saveMonitors();
void loadMonitors();
void defaultMonitor();
bool hasField(JsonVariantConst root, String path);
void runMonitor(Monitor &m);
void drawDashboard();
void sendJson(int code, JsonDocument &d);
void monitorJson(JsonObject o, const Monitor &m, bool detail);
int findMonitor(const String&id);
bool applyMonitor(Monitor &m, JsonObject o, bool create);
void setupWeb();
void connectWiFi();

constexpr char FW_VERSION[] = "0.1.0";
constexpr uint8_t MAX_MONITORS = 4, HISTORY_PER_MONITOR = 12;
constexpr uint32_t DEFAULT_INTERVAL_S = 300, DEFAULT_TIMEOUT_MS = 15000;
constexpr int TFT_CS=10, TFT_DC=14, TFT_RST=15, TFT_BL=16, BUTTON_PIN=4;
Adafruit_ST7789 tft(TFT_CS, TFT_DC, TFT_RST);
WebServer server(80); Preferences prefs;


const char *stateName(State s) { const char *n[]={"HEALTHY","WARNING","FAILED","TIMEOUT","AUTH_ERROR","RATE_LIMITED","VALIDATION_FAILED","NETWORK_ERROR","UNKNOWN"}; return n[s]; }



Monitor monitors[MAX_MONITORS]; uint8_t monitorCount=0; bool portalStarted=false; uint32_t lastDisplay=0, startedAt=0;

String safeText(const String &s, size_t maxLen=240) { String o=s; o.replace("\r",""); o.replace("\n",""); return o.substring(0, min(o.length(),maxLen)); }
bool online() { return WiFi.status()==WL_CONNECTED; }
void logLine(const char *tag, const String &s) { Serial.printf("[%s] %s\n", tag, s.c_str()); }

void addHistory(Monitor &m, Result r) { if (m.historyCount < HISTORY_PER_MONITOR) m.history[m.historyCount++]=r; else { for(uint8_t i=1;i<HISTORY_PER_MONITOR;i++) m.history[i-1]=m.history[i]; m.history[HISTORY_PER_MONITOR-1]=r; } }
State currentState(const Monitor &m) { return m.historyCount ? m.history[m.historyCount-1].state : UNKNOWN; }

void saveMonitors() {
  DynamicJsonDocument d(8192); JsonArray a=d.to<JsonArray>();
  for(uint8_t i=0;i<monitorCount;i++) { Monitor &m=monitors[i]; JsonObject o=a.createNestedObject();
    o["id"]=m.id; o["name"]=m.name; o["provider"]=m.provider; o["endpoint"]=m.endpoint; o["method"]=m.method; o["headers"]=m.headers; o["body"]=m.body; o["requiredFields"]=m.requiredFields; o["keyword"]=m.keyword; o["expectedStatus"]=m.expectedStatus; o["intervalS"]=m.intervalS; o["timeoutMs"]=m.timeoutMs; o["warnMs"]=m.warnMs; o["criticalMs"]=m.criticalMs; o["enabled"]=m.enabled;
  }
  String out; serializeJson(d,out); prefs.putString("monitors",out);
}
void loadMonitors() {
  String raw=prefs.getString("monitors",""); if(!raw.length()) return; DynamicJsonDocument d(8192); if(deserializeJson(d,raw)) return;
  for(JsonObject o:d.as<JsonArray>()) { if(monitorCount>=MAX_MONITORS) break; Monitor &m=monitors[monitorCount++]; m.id=o["id"]|String("m"+String(monitorCount)); m.name=o["name"]|"Monitor"; m.provider=o["provider"]|"Generic REST"; m.endpoint=o["endpoint"]|""; m.method=o["method"]|"GET"; m.headers=o["headers"]|""; m.body=o["body"]|""; m.requiredFields=o["requiredFields"]|""; m.keyword=o["keyword"]|""; m.expectedStatus=o["expectedStatus"]|200; m.intervalS=o["intervalS"]|DEFAULT_INTERVAL_S; m.timeoutMs=o["timeoutMs"]|DEFAULT_TIMEOUT_MS; m.warnMs=o["warnMs"]|2000; m.criticalMs=o["criticalMs"]|5000; m.enabled=o["enabled"]|true; }
}
void defaultMonitor() { if(monitorCount) return; Monitor &m=monitors[monitorCount++]; m.id="example"; m.name="Example API"; m.provider="Generic REST"; m.endpoint="https://example.com/health"; m.method="GET"; m.expectedStatus=200; m.intervalS=300; m.requiredFields=""; saveMonitors(); }

bool hasField(JsonVariantConst root, String path) { JsonVariantConst v=root; int start=0; while(start<(int)path.length()) { int dot=path.indexOf('.',start); String key=path.substring(start,dot<0?path.length():dot); v=v[key]; if(v.isNull()) return false; if(dot<0) break; start=dot+1; } return !v.isNull(); }
void runMonitor(Monitor &m) {
  Result r; r.at=millis()/1000; uint32_t begin=millis();
  if(!online()) { r.state=NETWORK_ERROR; r.message="Local Wi-Fi is offline"; addHistory(m,r); return; }
  if(!m.endpoint.startsWith("https://") && !m.endpoint.startsWith("http://")) { r.state=VALIDATION_FAILED; r.message="Endpoint must begin http:// or https://"; addHistory(m,r); return; }
  WiFiClientSecure secure; secure.setInsecure(); // Trust-store provisioning is a future production extension.
  HTTPClient http; http.setConnectTimeout(m.timeoutMs); http.setTimeout(m.timeoutMs);
  if(!http.begin(secure,m.endpoint)) { r.state=NETWORK_ERROR; r.message="Could not start HTTP client"; addHistory(m,r); return; }
  int pos=0; while(pos<(int)m.headers.length()) { int nl=m.headers.indexOf('\n',pos); String line=m.headers.substring(pos,nl<0?m.headers.length():nl); int colon=line.indexOf(':'); if(colon>0) http.addHeader(line.substring(0,colon),line.substring(colon+1)); if(nl<0) break; pos=nl+1; }
  int code = m.method=="POST" ? http.POST(m.body) : (m.method=="PUT" ? http.PUT(m.body) : http.GET());
  r.ms=millis()-begin; r.status=code;
  if(code<=0) { r.state=(code==HTTPC_ERROR_CONNECTION_REFUSED||code==HTTPC_ERROR_CONNECTION_LOST)?NETWORK_ERROR:TIMEOUT; r.message="HTTP client error "+String(code); http.end(); addHistory(m,r); m.consecutiveFailures++; m.failures++; return; }
  String payload=http.getString(); http.end();
  if(code==401||code==403) { r.state=AUTH_ERROR; r.message="Authentication rejected (HTTP "+String(code)+")"; }
  else if(code==429) { r.state=RATE_LIMITED; r.message="Rate limited (HTTP 429)"; }
  else if(code!=m.expectedStatus) { r.state=FAILED; r.message="Expected HTTP "+String(m.expectedStatus)+", got "+String(code); }
  else {
    r.state=HEALTHY; r.message="HTTP "+String(code)+"";
    if(m.requiredFields.length()) { DynamicJsonDocument d(4096); DeserializationError e=deserializeJson(d,payload); if(e) {r.state=VALIDATION_FAILED; r.message="Expected JSON but response was invalid";} else { int p=0; while(p<(int)m.requiredFields.length()) { int c=m.requiredFields.indexOf(',',p); String field=m.requiredFields.substring(p,c<0?m.requiredFields.length():c); field.trim(); if(field.length()&&!hasField(d.as<JsonVariantConst>(),field)){r.state=VALIDATION_FAILED;r.message="Missing field: "+field;break;} if(c<0)break;p=c+1; } } }
    if(r.state==HEALTHY && m.keyword.length() && payload.indexOf(m.keyword)<0) { r.state=VALIDATION_FAILED; r.message="Expected text was not found"; }
    if(r.state==HEALTHY && r.ms>=m.criticalMs) {r.state=WARNING;r.message="Critical latency threshold exceeded";} else if(r.state==HEALTHY && r.ms>=m.warnMs) {r.state=WARNING;r.message="Latency warning threshold exceeded";}
  }
  if(r.state==HEALTHY||r.state==WARNING) { if(m.consecutiveFailures) logLine("RECOVERY",m.name+" recovered"); m.consecutiveFailures=0; } else {m.consecutiveFailures++;m.failures++;}
  addHistory(m,r); logLine("TEST",m.name+" "+stateName(r.state)+" "+String(r.ms)+"ms: "+r.message);
}

void drawDashboard() {
  if(millis()-lastDisplay<1000) return; lastDisplay=millis(); tft.fillScreen(ST77XX_BLACK); tft.setTextWrap(false);
  tft.setTextColor(ST77XX_CYAN); tft.setTextSize(2); tft.setCursor(8,8); tft.print("AI/API SENTINEL");
  tft.setTextSize(1); tft.setTextColor(ST77XX_WHITE); tft.setCursor(8,35); tft.printf("Firmware v%s",FW_VERSION);
  tft.setCursor(8,52); tft.setTextColor(online()?ST77XX_GREEN:ST77XX_RED); tft.printf("Wi-Fi: %s",online()?"OK":"OFFLINE");
  tft.setTextColor(ST77XX_WHITE); tft.setCursor(8,72); tft.print("SERVICES");
  for(uint8_t i=0;i<monitorCount && i<6;i++) { State s=currentState(monitors[i]); uint16_t col=(s==HEALTHY?ST77XX_GREEN:(s==WARNING?ST77XX_YELLOW:ST77XX_RED)); tft.setTextColor(col); tft.setCursor(10,90+i*22); tft.print("● "); tft.print(monitors[i].name.substring(0,17)); tft.setCursor(205,90+i*22); tft.print(stateName(s)); }
  tft.setTextColor(ST77XX_WHITE); tft.setCursor(8,225); tft.printf("IP: %s",online()?WiFi.localIP().toString().c_str():"configure via AP");
}

void sendJson(int code, JsonDocument &d) { String out; serializeJson(d,out); server.sendHeader("Cache-Control","no-store"); server.send(code,"application/json",out); }
void monitorJson(JsonObject o, const Monitor &m, bool detail=false) { o["id"]=m.id;o["name"]=m.name;o["provider"]=m.provider;o["endpoint"]=m.endpoint;o["method"]=m.method;o["expectedStatus"]=m.expectedStatus;o["intervalS"]=m.intervalS;o["timeoutMs"]=m.timeoutMs;o["warnMs"]=m.warnMs;o["criticalMs"]=m.criticalMs;o["enabled"]=m.enabled;o["state"]=stateName(currentState(m));o["failures"]=m.failures;o["consecutiveFailures"]=m.consecutiveFailures; if(m.historyCount){Result&r=m.history[m.historyCount-1];o["lastMs"]=r.ms;o["lastStatus"]=r.status;o["message"]=r.message;} if(detail){o["headersMasked"]=m.headers.length()?"Configured (not returned)":"";o["bodyConfigured"]=m.body.length()>0;o["requiredFields"]=m.requiredFields;o["keyword"]=m.keyword;} }
int findMonitor(const String&id){for(uint8_t i=0;i<monitorCount;i++)if(monitors[i].id==id)return i;return -1;}
bool applyMonitor(Monitor &m, JsonObject o, bool create) { String endpoint=o["endpoint"]|m.endpoint; if(!endpoint.startsWith("http://")&&!endpoint.startsWith("https://")) return false; m.name=safeText(o["name"]|m.name,32);m.provider=safeText(o["provider"]|m.provider,24);m.endpoint=endpoint;m.method=(o["method"]|m.method);m.method.toUpperCase(); if(m.method!="GET"&&m.method!="POST"&&m.method!="PUT")return false; if(o.containsKey("headers"))m.headers=safeText(o["headers"].as<String>(),512);if(o.containsKey("body"))m.body=o["body"].as<String>();m.requiredFields=safeText(o["requiredFields"]|m.requiredFields,180);m.keyword=safeText(o["keyword"]|m.keyword,120);m.expectedStatus=constrain(o["expectedStatus"]|m.expectedStatus,100,599);m.intervalS=constrain(o["intervalS"]|m.intervalS,30,86400);m.timeoutMs=constrain(o["timeoutMs"]|m.timeoutMs,1000,30000);m.warnMs=constrain(o["warnMs"]|m.warnMs,100,30000);m.criticalMs=constrain(o["criticalMs"]|m.criticalMs,m.warnMs,60000);m.enabled=o["enabled"]|m.enabled;return true; }

const char INDEX_HTML[] PROGMEM=R"HTML(<!doctype html><html><head><meta name=viewport content="width=device-width,initial-scale=1"><title>AI/API Sentinel</title><style>body{font:16px system-ui;margin:20px;background:#10151d;color:#e6edf3;max-width:900px}h1{color:#5eead4}.card{background:#19212c;border-radius:10px;padding:14px;margin:10px 0}.ok{color:#4ade80}.bad{color:#fb7185}.warn{color:#facc15}button{padding:9px;margin:4px}small{color:#9ca3af}</style></head><body><h1>AI/API Sentinel</h1><div id=sys class=card>Loading...</div><h2>Monitors</h2><div id=mon></div><p><button onclick="location='/api/restart'">Restart device</button> <button onclick="location='/api/reset'">Reset Wi-Fi and configuration</button></p><small>This local interface is unauthenticated. Keep it on a trusted LAN.</small><script>async function load(){let s=await(await fetch('/api/status')).json();sys.innerHTML=`<b>${s.device}</b> · Wi-Fi: <span class=${s.wifi?'ok':'bad'}>${s.wifi?'OK':'OFFLINE'}</span><br>IP: ${s.ip} · Uptime: ${s.uptime}s · Free heap: ${s.heap}`;let a=await(await fetch('/api/monitors')).json();mon.innerHTML=a.map(x=>`<div class=card><b>${x.name}</b> <span class=${x.state==='HEALTHY'?'ok':x.state==='WARNING'?'warn':'bad'}>${x.state}</span><br><small>${x.provider} · ${x.lastMs||'-'} ms · ${x.message||'Not tested'}</small><br><button onclick="fetch('/api/monitors/'+x.id+'/test',{method:'POST'}).then(load)">Test now</button></div>`).join('')}load();setInterval(load,5000)</script></body></html>)HTML";
void setupWeb() {
 server.on("/",[](){server.send_P(200,"text/html",INDEX_HTML);});
 server.on("/api/status",[](){DynamicJsonDocument d(1024);d["device"]=prefs.getString("device","AI/API Sentinel");d["version"]=FW_VERSION;d["wifi"]=online();d["ip"]=online()?WiFi.localIP().toString():"";d["uptime"]=millis()/1000;d["heap"]=ESP.getFreeHeap();d["monitors"]=monitorCount;sendJson(200,d);});
 server.on("/api/monitors",HTTP_GET,[](){DynamicJsonDocument d(4096);JsonArray a=d.to<JsonArray>();for(uint8_t i=0;i<monitorCount;i++)monitorJson(a.createNestedObject(),monitors[i]);sendJson(200,d);});
 server.on("/api/system",[](){DynamicJsonDocument d(1024);d["firmware"]=FW_VERSION;d["chip"]=ESP.getChipModel();d["heap"]=ESP.getFreeHeap();d["uptimeSeconds"]=millis()/1000;d["rssi"]=online()?WiFi.RSSI():0;sendJson(200,d);});
 server.on("/api/config",HTTP_GET,[](){DynamicJsonDocument d(512);d["deviceName"]=prefs.getString("device","AI/API Sentinel");d["wifiConfigured"]=online();d["monitorLimit"]=MAX_MONITORS;sendJson(200,d);});
 server.on("/api/config",HTTP_POST,[](){DynamicJsonDocument in(512),out(256);if(deserializeJson(in,server.arg("plain"))){server.send(400,"application/json","{\"error\":\"invalid JSON\"}");return;}String n=safeText(in["deviceName"]|"",32);if(n.length())prefs.putString("device",n);out["ok"]=true;sendJson(200,out);});
 server.on("/api/restart",HTTP_GET,[](){server.send(202,"application/json","{\"restarting\":true}");delay(200);ESP.restart();});
 server.on("/api/reset",HTTP_GET,[](){server.send(202,"application/json","{\"resetting\":true}");delay(200);prefs.clear();WiFiManager().resetSettings();ESP.restart();});
 server.onNotFound([](){String u=server.uri(); if(!u.startsWith("/api/monitors/")){server.send(404,"application/json","{\"error\":\"not found\"}");return;} String tail=u.substring(14); bool test=tail.endsWith("/test");if(test)tail=tail.substring(0,tail.length()-5);int i=findMonitor(tail);if(i<0){server.send(404,"application/json","{\"error\":\"unknown monitor\"}");return;}if(test&&server.method()==HTTP_POST){runMonitor(monitors[i]);DynamicJsonDocument d(1024);monitorJson(d.to<JsonObject>(),monitors[i],true);sendJson(200,d);return;}if(server.method()==HTTP_GET){DynamicJsonDocument d(2048);JsonObject o=d.to<JsonObject>();monitorJson(o,monitors[i],true);JsonArray h=o.createNestedArray("history");for(uint8_t k=0;k<monitors[i].historyCount;k++){Result&r=monitors[i].history[k];JsonObject x=h.createNestedObject();x["at"]=r.at;x["ms"]=r.ms;x["status"]=r.status;x["state"]=stateName(r.state);x["message"]=r.message;}sendJson(200,d);return;}if(server.method()==HTTP_DELETE){for(uint8_t k=i+1;k<monitorCount;k++)monitors[k-1]=monitors[k];monitorCount--;saveMonitors();server.send(204);return;}if(server.method()==HTTP_POST||server.method()==HTTP_PUT){DynamicJsonDocument in(2048);if(deserializeJson(in,server.arg("plain"))||!applyMonitor(monitors[i],in.as<JsonObject>(),false)){server.send(400,"application/json","{\"error\":\"invalid monitor\"}");return;}saveMonitors();server.send(200,"application/json","{\"ok\":true}");return;}server.send(405,"application/json","{\"error\":\"method not allowed\"}");});
 server.on("/api/monitors",HTTP_POST,[](){if(monitorCount>=MAX_MONITORS){server.send(409,"application/json","{\"error\":\"monitor limit reached\"}");return;}DynamicJsonDocument in(2048);if(deserializeJson(in,server.arg("plain"))){server.send(400,"application/json","{\"error\":\"invalid JSON\"}");return;}Monitor m;m.id="m"+String(millis());if(!applyMonitor(m,in.as<JsonObject>(),true)){server.send(400,"application/json","{\"error\":\"invalid monitor\"}");return;}monitors[monitorCount++]=m;saveMonitors();server.send(201,"application/json","{\"ok\":true}");});
 server.begin();
}
void connectWiFi() { WiFiManager wm; wm.setConfigPortalTimeout(180); wm.setConnectTimeout(15); wm.setDarkMode(true); if(!wm.autoConnect("AI-API-Sentinel","configure-sentinel")){logLine("WIFI","Offline mode; hold button to reopen configuration");}else logLine("WIFI","Connected: "+WiFi.localIP().toString()); }
void setup(){Serial.begin(115200);delay(200);logLine("SYSTEM","AI/API Sentinel booting");startedAt=millis();pinMode(BUTTON_PIN,INPUT_PULLUP);pinMode(TFT_BL,OUTPUT);digitalWrite(TFT_BL,HIGH);SPI.begin(12,-1,11,TFT_CS);tft.init(240,320);tft.setRotation(1);tft.fillScreen(ST77XX_BLACK);prefs.begin("sentinel",false);loadMonitors();defaultMonitor();connectWiFi();setupWeb();}
void loop(){server.handleClient(); if(WiFi.status()!=WL_CONNECTED && millis()>30000) WiFi.reconnect(); if(!digitalRead(BUTTON_PIN)){delay(30);if(!digitalRead(BUTTON_PIN)){WiFiManager wm;wm.startConfigPortal("AI-API-Sentinel","configure-sentinel");}} for(uint8_t i=0;i<monitorCount;i++){Monitor&m=monitors[i];if(m.enabled && millis()-m.lastRun>=m.intervalS*1000UL){m.lastRun=millis();runMonitor(m);}}drawDashboard();delay(5);}