#include <Arduino.h>
#include <Wire.h>
#include <SoftwareSerial.h>
#include <DFRobotDFPlayerMini.h>
#include <Adafruit_SGP40.h>
#include <WiFi.h>
#include <WebServer.h>

const char* WIFI_SSID     = "SSID";
const char* WIFI_PASSWORD = "PASS";

#define LED_PIN 0
#define DF_RX 7
#define DF_TX 8
#define SGP40_SDA 4
#define SGP40_SCL 5
#define LED_IDLE 20
#define LED_PEAK 80

const uint16_t TRACK_MS[] = {
0, 4000, 5000, 4000, 4000, 2000, 2000, 3000, 1000, 2000, 2000, 10000, 10000, 9000, 15000, 0, 0, 1000, 1000
};

#define INTERVAL_07 30000UL
#define INTERVAL_VOC 60000UL
#define INTERVAL_10 300000UL
#define INTERVAL_11 600000UL
#define SENSOR_RETRY 30000UL
#define VOC_GOOD_MAX 100
#define VOC_MODERATE_MAX 200

SoftwareSerial      mySerial(7, 8); // RX, TX
DFRobotDFPlayerMini player;
Adafruit_SGP40      sgp;
WebServer           server(80);

bool     sensorOK      = false;
bool     sensorWasLost = false;
bool     goodAlt       = false;
bool     modAlt        = false;
bool     elevAlt       = false;
uint16_t vocRaw        = 0;
uint16_t vocSmooth     = 0;
unsigned long bootTime = 0;
unsigned long lastTime07      = 0;
unsigned long lastTimeVOC     = 0;
unsigned long lastTime10      = 0;
unsigned long lastTime11      = 0;
unsigned long lastSensorRetry = 0;

//WEB APP HTML (Stored in PROGMEM to save RAM)
const char HTML_PAGE[] PROGMEM = R"rawhtml(

)rawhtml";

void handleRoot() { server.send(200, "text/html", HTML_PAGE); }

void handleVOC() {
unsigned long uptime = (millis() - bootTime) / 1000;
String json = "{\"voc\":";
json += vocRaw;
json += ",\"smooth\":";
json += vocSmooth;
json += ",\"uptime\":";
json += uptime;
json += "}";
server.send(200, "application/json", json);
}

void handleNotFound() { server.send(404, "text/plain", "Not found"); }

void ledIdle() { analogWrite(LED_PIN, LED_IDLE); }

void ledFade(uint8_t from, uint8_t to, uint32_t ms) {
const int steps = 200;
int32_t  delta     = (int32_t)to - (int32_t)from;
uint32_t stepDelay = ms / steps;
for (int i = 0; i <= steps; i++) {
analogWrite(LED_PIN, (uint8_t)(from + (delta * i) / steps));
delay(stepDelay);
server.handleClient();  // keep web server alive during fades
}
}

void ledBreatheForMs(uint32_t totalMs) {
const uint32_t BREATH_CYCLE = 2000;
uint32_t start = millis();
while (millis() - start < totalMs) {
uint32_t elapsed = millis() - start;
float t      = (float)(elapsed % BREATH_CYCLE) / (float)BREATH_CYCLE;
float norm   = sin(t * PI);
float bright = LED_IDLE + norm * (LED_PEAK - LED_IDLE);
analogWrite(LED_PIN, (uint8_t)bright);
delay(10);
server.handleClient();
}
ledIdle();
}

void playBlocking(uint8_t track) {
Serial.print(F("[PLAY] ")); Serial.println(track);
player.play(track);
delay(800);
uint32_t remaining = (TRACK_MS[track] > 800) ? TRACK_MS[track] - 800 : 0;
if (remaining > 0) ledBreatheForMs(remaining);
delay(200);
ledIdle();
}

bool initSensor() {
if (sgp.begin()) {
sensorOK = true;
Serial.println(F("[SGP40] ready"));
return true;
}
sensorOK = false;
Serial.println(F("[SGP40] not found"));
return false;
}

void pollVOC() {
uint16_t raw = sgp.measureVocIndex();
if (raw > 0) {
vocRaw    = raw;
vocSmooth = (vocSmooth == 0) ? raw
: (uint16_t)((vocSmooth * 7 + raw) / 8);
}
}

void reportVOC() {
Serial.print(F("[REPORT] VOC=")); Serial.println(vocSmooth);
if (vocSmooth <= VOC_GOOD_MAX) {
playBlocking(goodAlt ? 2 : 1);
goodAlt = !goodAlt;
} else if (vocSmooth <= VOC_MODERATE_MAX) {
playBlocking(modAlt ? 4 : 3);
modAlt = !modAlt;
} else {
playBlocking(elevAlt ? 6 : 5);
elevAlt = !elevAlt;
}
}

void setup() {
Serial.begin(9600);
pinMode(LED_PIN, OUTPUT);
analogWrite(LED_PIN, 0);
mySerial.begin(9600);
if (!player.begin(mySerial)) {
Serial.println(F("DFPlayer Mini not found"));
while (true) {
ledFade(0, LED_PEAK, 500);
ledFade(LED_PEAK, 0, 500);
}
}
player.volume(25);
delay(3000);
Wire.setSDA(SGP40_SDA);
Wire.setSCL(SGP40_SCL);
Wire.begin();
initSensor();
Serial.print(F("[WiFi] connecting to "));
Serial.println(WIFI_SSID);
WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
int attempts = 0;
while (WiFi.status() != WL_CONNECTED && attempts < 30) {
delay(500);
Serial.print(".");
attempts++;
}
if (WiFi.status() == WL_CONNECTED) {
Serial.println();
Serial.print(F("[WiFi] connected! IP: "));
Serial.println(WiFi.localIP());
} else {
Serial.println(F("[WiFi] failed — running without web server"));
}
server.on("/",    handleRoot);
server.on("/voc", handleVOC);
server.onNotFound(handleNotFound);
server.begin();
Serial.println(F("[HTTP] server started"));
bootTime = millis();
ledFade(0, LED_PEAK, 10000);
ledIdle();
playBlocking(14);
delay(2000);
playBlocking(7);
uint32_t warmStart = millis();
while (millis() - warmStart < 27000UL) {
pollVOC();
server.handleClient();
ledIdle();
delay(500);
}
reportVOC();
unsigned long now = millis();
lastTime07 = lastTimeVOC = lastTime10 = lastTime11 = lastSensorRetry = now;
Serial.println(F("[BOOT] done"));
}

void loop() {
server.handleClient();
unsigned long now = millis();
if (!sensorOK) {
if (!sensorWasLost) {
sensorWasLost = true;
playBlocking(12);
lastSensorRetry = millis();
}
if (millis() - lastSensorRetry >= SENSOR_RETRY) {
lastSensorRetry = millis();
if (initSensor()) {
sensorWasLost = false;
playBlocking(13);
unsigned long t = millis();
lastTime07 = t; lastTimeVOC = t;
lastTime10 = t; lastTime11  = t;
}
}
ledIdle();
delay(200);
return;
}
pollVOC();
bool vocDue = (now - lastTimeVOC >= INTERVAL_VOC);
bool t10Due = (now - lastTime10  >= INTERVAL_10);
bool t11Due = (now - lastTime11  >= INTERVAL_11);
bool t07Due = (now - lastTime07  >= INTERVAL_07);
if (vocDue) {
reportVOC();
lastTimeVOC = millis();
} else if (t10Due) {
playBlocking(10);
lastTime10 = millis();
} else if (t11Due) {
playBlocking(11);
lastTime11 = millis();
} else if (t07Due) {
playBlocking(7);
lastTime07 = millis();
} else {
ledIdle();
delay(200);
}
}