# ==========================================
# Semester 1 Project: Smart Entry System
# ESP32 Board 2: UART Receiver & LCD Display
# ==========================================

from machine import Pin, I2C, UART
import time
from machine_i2c_lcd import I2cLcd

# --- I2C LCD Configuration ---
i2c_bus = I2C(0, scl=Pin(22), sda=Pin(21))
i2c_devices = i2c_bus.scan()

if not i2c_devices:
    raise RuntimeError("No I2C devices found. Check wiring!")

lcd_display = I2cLcd(i2c_bus, i2c_devices[0], 2, 16)

# --- UART Configuration ---
# Important wiring note: Ensure TX on board 1 is connected to RX on board 2 and vice versa.
uart_conn = UART(1, baudrate=9600, tx=Pin(17), rx=Pin(16), timeout=1000, timeout_char=100)

# --- Display Functions ---
def display_sensor_data(temp, humidity, object_near, door_state, gas_leak):
    lcd_display.clear() # Clear the display for new data
    
    # Top Priority: Gas leak warning
    if gas_leak == 1:
        lcd_display.move_to(1, 0)
        lcd_display.putstr("!! GAS LEAK !!")
        lcd_display.move_to(1, 1)
        lcd_display.putstr("Evacuate Area!") # Additional warning message
    else:
        # Normal State: Display temp, humidity, and door status
        
        # First line (Temperature & Humidity)
        line1_text = "T:{:.1f}C H:{:.0f}%".format(temp, humidity)
        lcd_display.move_to(0, 0)
        lcd_display.putstr(line1_text)

        # Second line (Door Status)
        if door_state == 1:
            door_text = "Door: Open" 
        else:
            door_text = "Door: Closed"
            
        lcd_display.move_to(0, 1)
        lcd_display.putstr(door_text)

def display_waiting_screen():
    lcd_display.clear()
    lcd_display.move_to(2, 0)
    lcd_display.putstr("Waiting Data")
    lcd_display.move_to(5, 1)
    lcd_display.putstr("(^_^)")

# --- System Initialization ---
display_waiting_screen()
previous_data_tuple = None
uart_data_buffer = bytearray()

print("Board 2 is ready and waiting for UART data...")

# ==========================================
# --- Main Loop ---
# ==========================================

while True:
    if uart_conn.any():
        uart_chunk = uart_conn.readline()
        if uart_chunk:
            uart_data_buffer.extend(uart_chunk)
            
            # Process data line by line to prevent data overlap/crashes
            while b"\n" in uart_data_buffer:
                # Extract one complete line
                line, _, remainder = uart_data_buffer.partition(b"\n")
                uart_data_buffer = bytearray(remainder)

                try:
                    csv_data = line.decode("utf-8", "ignore").strip()
                except UnicodeError:
                    print("Ignoring invalid UART bytes")
                    continue

                if not csv_data:
                    continue

                print("Received:", csv_data)
                data_parts = csv_data.split(",")

                # Ensure the message contains exactly 5 values
                if len(data_parts) != 5:
                    print("Invalid message format:", csv_data)
                    continue

                # Extra protection (try/except) in case corrupted data is received (e.g., letters instead of numbers)
                try:
                    current_temp = float(data_parts[0])
                    current_humidity = float(data_parts[1])
                    numeric_object_near = int(data_parts[2])
                    numeric_door_state = int(data_parts[3])
                    numeric_gas_leak = int(data_parts[4])
                    
                    # Group current readings for comparison
                    current_data_tuple = (
                        current_temp,
                        current_humidity,
                        numeric_object_near,
                        numeric_door_state,
                        numeric_gas_leak
                    )
                    
                    # Update the LCD *only* if the data has changed (prevents screen flickering)
                    if current_data_tuple != previous_data_tuple:
                        display_sensor_data(
                            current_temp, 
                            current_humidity, 
                            numeric_object_near, 
                            numeric_door_state, 
                            numeric_gas_leak
                        )
                        print("Object State (Near):", numeric_object_near)
                        previous_data_tuple = current_data_tuple
                        
                except ValueError:
                    print("Data conversion error. Waiting for clean data...")
                    
    time.sleep_ms(20)