/*
 *  WOKWI SIMULATION — Arduino Nano
 *  Matches Fritzing schematic pin-for-pin.
 *
 *  Buzzer MOSFET Gate: D6 (via 220Ω)
 *  SD CS:   D10
 *  SD MOSI: D11 (DI on SparkFun board)
 *  SD MISO: D12 (DO on SparkFun board)
 *  SD SCK:  D13
 *
 *  In Wokwi:
 *    1. New Project → Arduino Nano
 *    2. Paste this code
 *    3. Add components: buzzer, MOSFET, resistor, SD card
 *    4. Wire them up (or paste the diagram.json)
 *    5. Hit Play
 */

#include <SPI.h>
#include <SD.h>

const int PIN_BUZZER = 6;
const int PIN_SD_CS  = 10;

void playTone(int pin, unsigned int freq, unsigned long ms) {
  unsigned long halfPeriod = 500000UL / freq;
  unsigned long endTime = millis() + ms;
  while (millis() < endTime) {
    digitalWrite(pin, HIGH);
    delayMicroseconds(halfPeriod);
    digitalWrite(pin, LOW);
    delayMicroseconds(halfPeriod);
  }
  digitalWrite(pin, LOW);
}

void beepOK() {
  playTone(PIN_BUZZER, 2000, 100);
  delay(80);
  playTone(PIN_BUZZER, 2500, 100);
}

void beepFail() {
  playTone(PIN_BUZZER, 400, 500);
}

void beepStartup() {
  playTone(PIN_BUZZER, 800, 80);
  delay(50);
  playTone(PIN_BUZZER, 1200, 80);
  delay(50);
  playTone(PIN_BUZZER, 1600, 120);
}

// ── Tests ──

bool testBuzzer() {
  Serial.println("\n=== TEST 1: Buzzer + MOSFET ===");
  Serial.println("  Toggling MOSFET on D6...");

  // DC click test
  digitalWrite(PIN_BUZZER, HIGH);
  delay(200);
  digitalWrite(PIN_BUZZER, LOW);
  delay(200);

  Serial.println("  Playing tones...");
  beepStartup();
  delay(200);
  playTone(PIN_BUZZER, 1000, 300);

  Serial.println("  PASS - Buzzer test complete");
  return true;
}

bool testSD() {
  Serial.println("\n=== TEST 2: SD Card (SPI) ===");
  Serial.println("  CS=D10, MOSI=D11, MISO=D12, SCK=D13");
  Serial.println("  Initializing...");

  if (!SD.begin(PIN_SD_CS)) {
    Serial.println("  FAIL - SD card not detected!");
    Serial.println("  Check: card inserted? wires correct?");
    return false;
  }
  Serial.println("  SD card OK!");

  // Write
  if (SD.exists("test.txt")) SD.remove("test.txt");
  File f = SD.open("test.txt", FILE_WRITE);
  if (!f) {
    Serial.println("  FAIL - can't create file!");
    return false;
  }
  f.println("Hello from simulation!");
  f.println("All connections verified.");
  f.print("Boot time: ");
  f.print(millis());
  f.println(" ms");
  f.close();
  Serial.println("  Wrote test.txt");

  // Read back
  f = SD.open("test.txt");
  if (!f) {
    Serial.println("  FAIL - can't read file!");
    return false;
  }
  Serial.println("  --- File contents ---");
  while (f.available()) {
    Serial.write(f.read());
  }
  Serial.println("  --- End ---");
  f.close();

  Serial.println("  PASS - SD read/write working!");
  return true;
}

// ── Setup ──

void setup() {
  Serial.begin(115200);
  delay(1000);

  pinMode(PIN_BUZZER, OUTPUT);
  digitalWrite(PIN_BUZZER, LOW);

  Serial.println("========================================");
  Serial.println("  CIRCUIT TEST - Arduino Nano");
  Serial.println("  SD Card + MOSFET Buzzer");
  Serial.println("========================================");

  bool bz = testBuzzer();
  delay(500);
  bool sd = testSD();
  delay(500);

  Serial.println("\n========== RESULTS ==========");
  Serial.println("  Buzzer: " + String(bz ? "PASS" : "FAIL"));
  Serial.println("  SD:     " + String(sd ? "PASS" : "FAIL"));
  Serial.println("=============================");

  if (bz && sd) {
    Serial.println("  ALL TESTS PASSED!");
    beepOK();
  } else {
    Serial.println("  SOME TESTS FAILED");
    beepFail();
  }

  Serial.println("\n  Logging to SD every 5 sec...\n");
}

// ── Loop ──

unsigned long lastLog = 0;
int count = 0;

void loop() {
  if (millis() - lastLog >= 5000) {
    lastLog = millis();
    count++;

    File log = SD.open("log.csv", FILE_WRITE);
    if (log) {
      if (count == 1) log.println("entry,ms,sec");
      log.print(count);
      log.print(",");
      log.print(millis());
      log.print(",");
      log.println(millis() / 1000);
      log.close();

      Serial.println("[LOG #" + String(count) + "] " +
                     String(millis() / 1000) + "s uptime");
      playTone(PIN_BUZZER, 1800, 50);
    }
  }
}