from machine import Pin, UART, I2C
import time

# ==========================================
# HARDWARE & INLINE LCD INITIALIZATION
# ==========================================
I2C_ADDR = 0x27
i2c = I2C(0, sda=Pin(22), scl=Pin(21), freq=400000)

class InlineLCD:
    def __init__(self, i2c, addr=0x27):
        self.i2c = i2c
        self.addr = addr
        self.backlight = 0x08
        time.sleep_ms(20)
        for val in [0x33, 0x32, 0x28, 0x0C, 0x06, 0x01]:
            self.write_cmd(val)
            time.sleep_ms(5)

    def write_cmd(self, cmd):
        b1 = (cmd & 0xF0) | self.backlight
        b2 = ((cmd << 4) & 0xF0) | self.backlight
        self.i2c.writeto(self.addr, bytes([b1 | 0x04, b1, b2 | 0x04, b2]))

    def write_data(self, data):
        b1 = (data & 0xF0) | self.backlight | 0x01
        b2 = ((data << 4) & 0xF0) | self.backlight | 0x01
        self.i2c.writeto(self.addr, bytes([b1 | 0x04, b1, b2 | 0x04, b2]))

    def clear(self):
        self.write_cmd(0x01)
        time.sleep_ms(2)

    def move_to(self, x, y):
        """Moves cursor to explicit column (x) and row (y)."""
        addr = x & 0x3F
        if y == 1:
            addr += 0x40
        self.write_cmd(0x80 | addr)

    def putstr(self, string):
        for char in string:
            if char == '\n':
                self.move_to(0, 1)
            else:
                self.write_data(ord(char))
                
    def show_reading_format(self, temp, hum, door, gas_val):
        """Clean formatting matching your preferred style."""
        self.clear()
        if gas_val == 0:
            self.move_to(0, 0)
            self.putstr("GAS ALERT!")
            self.move_to(0, 1)
            self.putstr("Ventilate NOW")
        else:
            self.move_to(0, 0)
            self.putstr(f"T:{temp:.1f}C H:{hum:.1f}%")
            self.move_to(0, 1)
            self.putstr(f"Door: {door}")

lcd = InlineLCD(i2c, I2C_ADDR)
uart = UART(1, baudrate=9600, tx=Pin(17), rx=Pin(16))

# ==========================================
# DISPLAY FUNCTIONS
# ==========================================
def show_waiting():
    """Initial boot screen while waiting for UART stream."""
    lcd.clear()
    lcd.move_to(0, 0)
    lcd.putstr("Waiting for data")
    lcd.move_to(6, 1)
    lcd.putstr("(^_^)")

def process_uart_data(rx_buffer, last_payload):
    if uart.any():
        raw_bytes = uart.read()
        if raw_bytes:
            rx_buffer += raw_bytes.decode('utf-8', 'ignore')

        while "\n" in rx_buffer:
            line, rx_buffer = rx_buffer.split("\n", 1)
            line = line.strip().strip(',')
            if line:
                parts = [p.strip() for p in line.split(',')]
                if len(parts) >= 4:
                    try:
                        temp = float(parts[0]) if parts[0] else 25.0
                        hum = float(parts[1]) if parts[1] else 0.0
                        door = parts[3]
                        gas_val = int(parts[4]) if len(parts) >= 5 and parts[4].isdigit() else 1
                        
                        current_payload = (temp, hum, door, gas_val)
                        
                        # Only update if data changed (stops flickering)
                        if current_payload != last_payload:
                            lcd.show_reading_format(temp, hum, door, gas_val)
                            last_payload = current_payload
                            
                    except Exception as e:
                        print("Parse error:", e)

    return rx_buffer, last_payload

# ==========================================
# MAIN LOOP
# ==========================================
def main():
    show_waiting()
    time.sleep(1)

    rx_buffer = ""
    last_payload = None
    
    while True:
        rx_buffer, last_payload = process_uart_data(rx_buffer, last_payload)
        time.sleep(0.01)

if __name__ == "__main__":
    main()