/*
  ESP32-C3 Super Mini + 2.13" E-Paper (250x122, SSD1680) — 10-in-1 Project Firmware
  Arvind Patil / AI Centre Nandurbar

  Library: GxEPD2  (Jean-Marc Zingg)  -> Install "GxEPD2" via Library Manager
  Display: GDEY0213B74 / DEPG0213BN  (SSD1680, 250x122, B/W)

  Wiring (ESP32-C3 Super Mini):
    EPD CS   -> GPIO 7
    EPD DC   -> GPIO 2
    EPD RST  -> GPIO 3
    EPD BUSY -> GPIO 5
    EPD CLK  -> GPIO 4  (SPI SCK, custom via SPI.begin)
    EPD DIN  -> GPIO 6  (SPI MOSI, custom via SPI.begin)
    EPD GND  -> GND
    EPD VCC  -> 3V3
  Note: C3 Super Mini has no free hardware MISO pin needed for e-paper
  (write-only display), so SPI.begin(SCK, -1, MOSI, CS) is used.

  BOOT button (onboard, GPIO9): short press = next mode (partial refresh cycle)
                                long press (>800ms) = force full refresh
  GPIO9 is a strapping pin — only read after boot completes, never driven low
  externally at power-on, which is safe here since it is only used as an input.

  Modes: 0 Weather  1 Clock  2 To-Do  3 Quote  4 Timetable
         5 Price Tag 6 Plant Monitor 7 Business Card 8 Ticker 9 System
*/

#include <SPI.h>
#include <GxEPD2_BW.h>
#include <Fonts/FreeMonoBold9pt7b.h>
#include <Fonts/FreeMono9pt7b.h>
#include <Fonts/FreeMonoBold12pt7b.h>
#include <WiFi.h>
#include <time.h>

#define CS_PIN   7
#define DC_PIN   2
#define RST_PIN  3
#define BUSY_PIN 5
#define SCK_PIN  4
#define MOSI_PIN 6
#define BOOT_BTN 9

GxEPD2_BW<GxEPD2_213_B74, GxEPD2_213_B74::HEIGHT> display(
  GxEPD2_213_B74(CS_PIN, DC_PIN, RST_PIN, BUSY_PIN));

const char* WIFI_SSID = "Airtel_arvi_6035";
const char* WIFI_PASS = "air26289";
const long  GMT_OFFSET_SEC = 5.5 * 3600;   // IST

int mode = 0;
const int MODE_COUNT = 10;
unsigned long lastPress = 0;
unsigned long pressStart = 0;
bool btnDown = false;

void setup() {
  Serial.begin(115200);
  pinMode(BOOT_BTN, INPUT_PULLUP);

  SPI.begin(SCK_PIN, -1 /* MISO unused */, MOSI_PIN, CS_PIN);
  display.init(115200);
  display.setRotation(1);          // landscape, 250x122
  display.setTextColor(GxEPD_BLACK);

  WiFi.begin(WIFI_SSID, WIFI_PASS);
  unsigned long t0 = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - t0 < 8000) { delay(200); }
  if (WiFi.status() == WL_CONNECTED) {
    configTime(GMT_OFFSET_SEC, 0, "pool.ntp.org", "time.google.com");
  }

  drawMode(mode, true);
}

void loop() {
  bool pressed = (digitalRead(BOOT_BTN) == LOW);
  if (pressed && !btnDown) { btnDown = true; pressStart = millis(); }
  if (!pressed && btnDown) {
    btnDown = false;
    unsigned long held = millis() - pressStart;
    if (held > 800) {
      drawMode(mode, true);                 // long press -> full refresh, same mode
    } else {
      mode = (mode + 1) % MODE_COUNT;
      drawMode(mode, mode == 0);            // full refresh only when wrapping to mode 0
    }
  }
  delay(20);
}

// ---- helpers -------------------------------------------------
void hline(int x1, int y, int x2) { display.drawLine(x1, y, x2, y, GxEPD_BLACK); }

void drawFrame() {
  display.drawRect(0, 0, display.width(), display.height(), GxEPD_BLACK);
}

void getTimeParts(char *hhmm, char *datestr) {
  struct tm ti;
  if (getLocalTime(&ti)) {
    sprintf(hhmm, "%02d:%02d", ti.tm_hour, ti.tm_min);
    strftime(datestr, 24, "%a %d %b %Y", &ti);
  } else {
    strcpy(hhmm, "--:--");
    strcpy(datestr, "no NTP sync");
  }
}

// ---- mode renderers -------------------------------------------
void modeWeather() {
  display.setFont(&FreeMonoBold12pt7b);
  display.setCursor(6, 20); display.print("NANDURBAR");
  display.setFont(&FreeMono9pt7b);
  display.setCursor(6, 34); display.print("26 Aug 2026");
  hline(4, 40, 246);
  display.drawCircle(35, 68, 14, GxEPD_BLACK);
  display.setFont(&FreeMonoBold12pt7b);
  display.setCursor(70, 68); display.print("34C");
  display.setFont(&FreeMono9pt7b);
  display.setCursor(70, 84); display.print("Clear Sky");
  hline(4, 96, 246);
  display.setCursor(6, 112); display.print("Hum 41%   Wind 9km/h");
}

void modeClock() {
  char hhmm[8], datestr[24];
  getTimeParts(hhmm, datestr);
  display.setFont(&FreeMonoBold12pt7b);
  int16_t x1,y1; uint16_t w,h;
  display.getTextBounds(hhmm, 0,0,&x1,&y1,&w,&h);
  display.setCursor((display.width()-w)/2, 55); display.print(hhmm);
  display.setFont(&FreeMono9pt7b);
  display.getTextBounds(datestr, 0,0,&x1,&y1,&w,&h);
  display.setCursor((display.width()-w)/2, 78); display.print(datestr);
  hline(4, 100, 246);
  display.setCursor(6, 116); display.print("IST  NTP synced");
}

void modeTodo() {
  display.setFont(&FreeMonoBold9pt7b);
  display.setCursor(6, 16); display.print("TODAY");
  hline(4, 22, 246);
  display.setFont(&FreeMono9pt7b);
  const char* items[] = {"[x] Print worksheets", "[ ] ESP32 lab setup",
                          "[ ] Call parent-fees", "[ ] Update blog"};
  for (int i = 0; i < 4; i++) { display.setCursor(8, 40 + i*18); display.print(items[i]); }
}

void modeQuote() {
  display.setFont(&FreeMono9pt7b);
  const char* l1 = "Small daily improvements";
  const char* l2 = "compound into staggering";
  const char* l3 = "results.  -- James Clear";
  display.setCursor(10, 40); display.print(l1);
  display.setCursor(10, 60); display.print(l2);
  display.setCursor(10, 80); display.print(l3);
  hline(4, 100, 246);
  display.setCursor(6, 116); display.print("AI Centre Nandurbar");
}

void modeTimetable() {
  display.setFont(&FreeMonoBold9pt7b);
  display.setCursor(6, 16); display.print("BUS STAND");
  hline(4, 20, 246);
  display.setFont(&FreeMono9pt7b);
  display.setCursor(6, 36); display.print("17:05 Dhule   OnTime");
  display.setCursor(6, 54); display.print("17:40 Shirpur Delay10");
  display.setCursor(6, 72); display.print("18:15 Jalgaon OnTime");
  hline(4, 92, 246);
  display.setCursor(6, 112); display.print("Updated 14:22");
}

void modePriceTag() {
  display.setFont(&FreeMonoBold9pt7b);
  display.setCursor(6, 18); display.print("Basmati Rice 5kg");
  hline(4, 24, 246);
  display.setFont(&FreeMonoBold12pt7b);
  display.setCursor(20, 78); display.print("Rs 449");
  display.setFont(&FreeMono9pt7b);
  display.setCursor(150, 55); display.print("MRP 520");
  display.setCursor(150, 72); display.print("Save 14%");
  hline(4, 96, 246);
  display.setCursor(6, 116); display.print("SKU RC-5049");
}

void modePlant(float moisture, float lux, float temp, float hum) {
  display.setFont(&FreeMonoBold9pt7b);
  display.setCursor(6, 16); display.print("TULSI - POT 2");
  hline(4, 22, 246);
  display.setFont(&FreeMono9pt7b);
  display.setCursor(6, 40); display.printf("Moisture %.0f%%", moisture);
  display.drawRect(150, 30, 80, 12, GxEPD_BLACK);
  display.fillRect(150, 30, (int)(80*moisture/100.0), 12, GxEPD_BLACK);
  display.setCursor(6, 62); display.printf("Temp %.1fC  Hum %.0f%%", temp, hum);
  hline(4, 92, 246);
  display.setCursor(6, 112); display.print(moisture > 40 ? "Status: Healthy" : "Status: Water soon");
}

void modeCard() {
  display.setFont(&FreeMonoBold12pt7b);
  display.setCursor(6, 24); display.print("ARVIND PATIL");
  display.setFont(&FreeMono9pt7b);
  display.setCursor(6, 40); display.print("Founder, AI Centre Nandurbar");
  hline(4, 48, 246);
  display.setCursor(6, 64); display.print("AI Literacy / EdTech / ESP32");
  display.setCursor(6, 78); display.print("Nandurbar, Maharashtra");
  display.drawRect(190, 58, 50, 50, GxEPD_BLACK);
}

void modeTicker() {
  display.setFont(&FreeMonoBold9pt7b);
  display.setCursor(6, 16); display.print("MARKET WATCH");
  hline(4, 22, 246);
  display.setFont(&FreeMono9pt7b);
  display.setCursor(6, 40); display.print("NIFTY   24812  +0.6%");
  display.setCursor(6, 60); display.print("SENSEX  81240  +0.4%");
  display.setCursor(6, 80); display.print("BTC     61900  -1.2%");
  hline(4, 92, 246);
  display.setCursor(6, 112); display.print("as of 14:22 IST");
}

void modeSystem() {
  display.setFont(&FreeMonoBold9pt7b);
  display.setCursor(6, 16); display.print("SYSTEM STATUS");
  hline(4, 22, 246);
  display.setFont(&FreeMono9pt7b);
  display.setCursor(6, 38); display.printf("WiFi RSSI %ddBm", WiFi.RSSI());
  display.setCursor(6, 54); display.printf("Uptime %lus", millis()/1000);
  display.setCursor(6, 70); display.printf("Free Heap %uKB", ESP.getFreeHeap()/1024);
  hline(4, 90, 246);
  display.setCursor(6, 112); display.print("Deep-sleep next: 30s");
}

// ---- dispatcher -------------------------------------------------
void drawMode(int m, bool full) {
  display.setFullWindow();
  display.firstPage();
  do {
    display.fillScreen(GxEPD_WHITE);
    switch (m) {
      case 0: modeWeather(); break;
      case 1: modeClock(); break;
      case 2: modeTodo(); break;
      case 3: modeQuote(); break;
      case 4: modeTimetable(); break;
      case 5: modePriceTag(); break;
      case 6: modePlant(62.0, 780.0, 29.4, 55.0); break;
      case 7: modeCard(); break;
      case 8: modeTicker(); break;
      case 9: modeSystem(); break;
    }
    drawFrame();
  } while (display.nextPage());
  // Note: GxEPD2 handles partial vs full internally per-driver;
  // for true partial refresh use display.setPartialWindow(x,y,w,h)
  // around the specific region that changed (e.g. clock digits).
}