/*
  Session 4 — Local storage without an SD card: EEPROM ring log (Arduino Uno / Tinkercad)
  Logs temperature (TMP36 A0) + soil moisture (A1) every LOG_EVERY_MS into the 1 KB EEPROM.
  Each record = 4 bytes: int16 temp*10, uint8 soil%, uint8 sequence. 250 records fit.
  Commands from the Serial Monitor:  d = dump CSV,  c = clear
  (Real hardware with SD + deep sleep: s04_sd_logger_esp32)
*/
#include <EEPROM.h>

const unsigned long LOG_EVERY_MS = 5000;   // use 15 min (900000) in the field
const int REC_SIZE = 4;
const int MAX_REC = (1024 - 2) / REC_SIZE; // first 2 bytes store the write index
unsigned long lastLog = 0;

int readIndex() { int i; EEPROM.get(0, i); return (i < 0 || i >= MAX_REC) ? 0 : i; }

void writeRecord(int16_t temp10, uint8_t soil, uint8_t seq) {
  int i = readIndex();
  int addr = 2 + i * REC_SIZE;
  EEPROM.put(addr, temp10);               // EEPROM.put only writes changed bytes (saves wear)
  EEPROM.update(addr + 2, soil);
  EEPROM.update(addr + 3, seq);
  EEPROM.put(0, (i + 1) % MAX_REC);
}

void dump() {
  Serial.println(F("record,temp_c,soil_pct,seq"));
  for (int i = 0; i < MAX_REC; i++) {
    int addr = 2 + i * REC_SIZE;
    int16_t t; EEPROM.get(addr, t);
    uint8_t s = EEPROM.read(addr + 2), q = EEPROM.read(addr + 3);
    if (s == 255) continue;               // empty (erased EEPROM = 0xFF)
    Serial.print(i); Serial.print(','); Serial.print(t / 10.0, 1);
    Serial.print(','); Serial.print(s); Serial.print(','); Serial.println(q);
  }
}

void setup() {
  Serial.begin(9600);
  Serial.println(F("EEPROM logger. Send 'd' to dump, 'c' to clear."));
}

void loop() {
  if (Serial.available()) {
    char c = Serial.read();
    if (c == 'd') dump();
    if (c == 'c') { for (int i = 0; i < 1024; i++) EEPROM.update(i, 255); EEPROM.put(0, 0); Serial.println(F("cleared")); }
  }
  if (millis() - lastLog >= LOG_EVERY_MS) {
    lastLog = millis();
    float t = (analogRead(A0) * 5.0 / 1023.0 - 0.5) * 100.0;
    uint8_t soil = constrain(map(analogRead(A1), 0, 876, 0, 100), 0, 100);
    static uint8_t seq = 0;
    writeRecord((int16_t)(t * 10), soil, seq++);
    Serial.print(F("logged #")); Serial.print(readIndex()); Serial.print(F(" t=")); Serial.print(t, 1);
    Serial.print(F(" soil=")); Serial.println(soil);
  }
}