#include <avr/io.h>
#include <util/delay.h>
#include <string.h>

// Define pins for LED
#define LED_PIN PB0

// Define keypad connections
#define KEYPAD_PORT PORTD
#define KEYPAD_DDR DDRD
#define KEYPAD_PIN PIND

// Password definition
const char password[] = "1234";
char entered_password[5];

void keypad_init();
char keypad_getkey();
void check_password();
void lock_open();
void lock_close();

int main(void) {
    // Initialize peripherals
    keypad_init();
    DDRB |= (1 << LED_PIN); // Set LED pin as output

    while (1) {
        check_password();
    }
}

void keypad_init() {
    KEYPAD_DDR = 0xF0; // Rows as outputs, Columns as inputs
    KEYPAD_PORT = 0x0F; // Enable pull-ups on columns
}

char keypad_getkey() {
    for (uint8_t row = 0; row < 4; row++) {
        KEYPAD_PORT = ~(1 << (row + 4)); // Ground one row
        _delay_ms(10);
        for (uint8_t col = 0; col < 4; col++) {
            if (!(KEYPAD_PIN & (1 << col))) {
                while (!(KEYPAD_PIN & (1 << col))); // Wait for release
                return (row * 4 + col) + '0'; // Return key value
            }
        }
    }
    return '\0'; // No key pressed
}

void check_password() {
    uint8_t index = 0;
    char key;

    // Collect password
    while (index < 4) {
        key = keypad_getkey();
        if (key != '\0') {
            entered_password[index++] = key;
        }
    }
    entered_password[index] = '\0';

    // Verify password
    if (strcmp(entered_password, password) == 0) {
        lock_open();
    } else {
        lock_close();
    }
}

void lock_open() {
    PORTB |= (1 << LED_PIN); // Turn on LED
    _delay_ms(3000);         // Hold for 3 seconds
    PORTB &= ~(1 << LED_PIN);// Turn off LED
}

void lock_close() {
    // Blink LED for failure
    for (uint8_t i = 0; i < 3; i++) {
        PORTB |= (1 << LED_PIN);
        _delay_ms(200);
        PORTB &= ~(1 << LED_PIN);
        _delay_ms(200);
    }
}