import machine
import utime
import onewire
import ds18x20
from lcd_parallel import LCD

# ── Sensor ───────────────────────────────────────
ow  = onewire.OneWire(machine.Pin(2))
ds  = ds18x20.DS18X20(ow)
rom = None

def init_sensor():
    global rom
    try:
        roms = ds.scan()
        if roms:
            rom = roms[0]
            return True
    except Exception:
        pass
    return False

# ── LCD (Parallel 4-bit) ─────────────────────────
lcd = LCD(7, 8, 9, 10, 11, 12)

# ── Button ───────────────────────────────────────
button = machine.Pin(15, machine.Pin.IN, machine.Pin.PULL_UP)

# ── Variables ────────────────────────────────────
mode      = 0        # 0=Celsius 1=Fahrenheit 2=Kelvin 3=MIN/MAX
temp_c    = 25.0     # default starting temperature
min_c     = 25.0     # ← start at default temp (not 999)
max_c     = 25.0     # ← start at default temp (not -999)
min_set   = False    # ← track if real reading received
DEGREE    = chr(223)

# ── Conversion Functions ─────────────────────────
def c_to_f(c):
    return c * 9 / 5 + 32

def c_to_k(c):
    return c + 273.15

# ── Display Function ─────────────────────────────
def update_display():
    lcd.clear()

    if mode == 0:
        # ── Celsius ──────────────────────────────
        lcd.move_to(0, 0)
        lcd.putstr("Temp:{:.1f}{}C  ".format(temp_c, DEGREE))
        lcd.move_to(0, 1)
        lcd.putstr("Mode: Celsius   ")

    elif mode == 1:
        # ── Fahrenheit ───────────────────────────
        lcd.move_to(0, 0)
        lcd.putstr("Temp:{:.1f}{}F  ".format(c_to_f(temp_c), DEGREE))
        lcd.move_to(0, 1)
        lcd.putstr("Mode:Fahrenheit ")

    elif mode == 2:
        # ── Kelvin ───────────────────────────────
        lcd.move_to(0, 0)
        lcd.putstr("Temp:{:.1f}K   ".format(c_to_k(temp_c)))
        lcd.move_to(0, 1)
        lcd.putstr("Mode: Kelvin    ")

    else:
        # ── MIN / MAX ────────────────────────────
        if not min_set:
            # no real reading yet
            lcd.move_to(0, 0)
            lcd.putstr("MIN: --.-{}C    ".format(DEGREE))
            lcd.move_to(0, 1)
            lcd.putstr("MAX: --.-{}C    ".format(DEGREE))
        else:
            lcd.move_to(0, 0)
            lcd.putstr("MIN:{:.1f}{}C   ".format(min_c, DEGREE))
            lcd.move_to(0, 1)
            lcd.putstr("MAX:{:.1f}{}C   ".format(max_c, DEGREE))

# ── Safe Sensor Read ─────────────────────────────
def read_sensor():
    global temp_c, min_c, max_c, min_set
    try:
        t = ds.read_temp(rom)
        # ✅ validate reading (ignore garbage values)
        if -55 <= t <= 125:
            temp_c = t
            if not min_set:
                min_c   = t
                max_c   = t
                min_set = True
            else:
                if t < min_c: min_c = t
                if t > max_c: max_c = t
            return True
    except Exception:
        # ✅ CRC error caught here — skip bad reading
        pass
    return False

# ── Splash Screen ────────────────────────────────
lcd.clear()
lcd.move_to(0, 0)
lcd.putstr("  Thermometer  ")
lcd.move_to(0, 1)
lcd.putstr(" ANBU ARASAN V ")
utime.sleep(2)

lcd.clear()
lcd.move_to(0, 0)
lcd.putstr(" ID:2403917711 ")
lcd.move_to(0, 1)
lcd.putstr("    521002     ")
utime.sleep(2)
lcd.clear()

# ── Init Sensor ──────────────────────────────────
if not init_sensor():
    lcd.clear()
    lcd.move_to(0, 0)
    lcd.putstr("Sensor Error!  ")
    lcd.move_to(0, 1)
    lcd.putstr("Check Wiring.. ")
    utime.sleep(3)
    init_sensor()

if rom:
    ds.convert_temp()

# ── Timing ───────────────────────────────────────
conversion_start = utime.ticks_ms()
CONVERSION_MS    = 1000     # ← increased to 1 second (reduces CRC errors)

update_display()

# ── Main Loop ────────────────────────────────────
while True:
    now = utime.ticks_ms()

    # ✅ Button Check
    if button.value() == 0:
        utime.sleep_ms(50)
        if button.value() == 0:
            mode = (mode + 1) % 4
            update_display()
            while button.value() == 0:
                utime.sleep_ms(10)

    # ✅ Sensor Read Every 1000ms
    if utime.ticks_diff(now, conversion_start) >= CONVERSION_MS:
        if rom:
            read_sensor()        # ← safe read with CRC protection
            update_display()
            try:
                ds.convert_temp()
            except Exception:
                pass
            conversion_start = now
        else:
            init_sensor()

    utime.sleep_ms(10)