/*
 * ============================================================
 *  Tishvi OLED 1.3" 128×64 Display (SH1106) — Sample Sketch
 *  guide.tishvi.com
 * ============================================================
 *  Wiring (I2C — 4 wires):
 *    OLED GND → Arduino GND
 *    OLED VCC → Arduino 5V
 *    OLED SCL → Arduino A5
 *    OLED SDA → Arduino A4
 *
 *  I2C Address : 0x3C  (pre-configured — no hardware change needed)
 *  Controller  : SH1106  (NOT SSD1306 — different chip, different library)
 *
 *  ⚠ IMPORTANT — Library Required:
 *    Install "U8g2" by oliver via Arduino IDE Library Manager.
 *    Search: U8g2  →  Install by "oliver"
 *    Do NOT use Adafruit SSD1306 — it will not align correctly on SH1106.
 *
 *  What this sketch does:
 *    1. Shows a Tishvi welcome screen with a border for 2.5 seconds
 *    2. Transitions to a live uptime counter (updates every second)
 *    3. Draws a horizontal separator line and a small footer
 *    4. Demonstrates: clearBuffer, setFont, drawStr, drawLine, sendBuffer
 *
 *  U8g2 key pattern:
 *    u8g2.clearBuffer();   // clear RAM buffer
 *    // ... all draw calls go here ...
 *    u8g2.sendBuffer();    // push buffer → display
 * ============================================================
 */

#include <Arduino.h>
#include <U8g2lib.h>
#include <Wire.h>

// ── Display Constructor ──────────────────────────────────────
// SH1106 · 128×64 · I2C · Hardware I2C pins (A4=SDA, A5=SCL)
// _F_ = full framebuffer (requires ~1KB RAM — fine on UNO R3)
U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset= */ U8X8_PIN_NONE);

// ── Variables ────────────────────────────────────────────────
unsigned long lastUpdate = 0;
unsigned long counter    = 0;

// ── Helper: print zero-padded 2-digit number ─────────────────
void printPadded(uint8_t x, uint8_t y, int val) {
  char buf[3];
  sprintf(buf, "%02d", val);
  u8g2.drawStr(x, y, buf);
}

void setup() {
  Serial.begin(9600);

  // Initialise display
  u8g2.begin();
  Serial.println("Tishvi 1.3\" OLED (SH1106) — Ready");

  // ── Welcome Screen ─────────────────────────────────────────
  u8g2.clearBuffer();

  // Outer border
  u8g2.drawFrame(0, 0, 128, 64);

  // Title — large font
  u8g2.setFont(u8g2_font_logisoso16_tr);
  u8g2.drawStr(18, 26, "TISHVI");

  // Subtitle — small font
  u8g2.setFont(u8g2_font_6x10_tr);
  u8g2.drawStr(22, 42, "1.3\" OLED Ready");
  u8g2.drawStr(10, 57, "guide.tishvi.com");

  u8g2.sendBuffer();
  delay(2500);
}

void loop() {
  // Update display every second
  if (millis() - lastUpdate >= 1000) {
    lastUpdate = millis();

    unsigned long totalSec = millis() / 1000;
    int hours   = totalSec / 3600;
    int minutes = (totalSec % 3600) / 60;
    int seconds = totalSec % 60;

    u8g2.clearBuffer();

    // ── Header ─────────────────────────────────────────────
    u8g2.setFont(u8g2_font_6x10_tr);
    u8g2.drawStr(10, 10, "Tishvi SH1106 Demo");
    u8g2.drawHLine(0, 13, 128);   // separator line

    // ── Counter label ───────────────────────────────────────
    u8g2.setFont(u8g2_font_6x10_tr);
    u8g2.drawStr(0, 28, "Uptime:");

    // ── HH:MM:SS — large font ───────────────────────────────
    u8g2.setFont(u8g2_font_logisoso16_tr);
    char timeBuf[9];
    sprintf(timeBuf, "%02d:%02d:%02d", hours, minutes, seconds);
    u8g2.drawStr(4, 50, timeBuf);

    // ── Footer ──────────────────────────────────────────────
    u8g2.drawHLine(0, 53, 128);
    u8g2.setFont(u8g2_font_5x7_tr);
    u8g2.drawStr(20, 62, "128x64  SH1106  I2C");

    u8g2.sendBuffer();

    // Log to Serial Monitor
    Serial.print("Uptime: ");
    Serial.println(timeBuf);

    counter++;
  }
}