#include <stdio.h>
#include <stdint.h>
// Add your microcontroller's specific header file
// Add a header file for delay functions

// --- Pin Definitions (Adapt to your hardware - 8-bit LCD Mode) ---
#define LCD_RS_PIN   PD0
#define LCD_EN_PIN   PA13
#define LCD_D0_PIN   PB0
#define LCD_D1_PIN   PB1
#define LCD_D2_PIN   PB2
#define LCD_D3_PIN   PB3
#define LCD_D4_PIN   PB4
#define LCD_D5_PIN   PB5
#define LCD_D6_PIN   PB6
#define LCD_D7_PIN   PB7

#define BUTTON_PIN   PC13

#define BUTTON_PRESSED_LEVEL 0 // Adjust based on your wiring

// Keypad Row Pins
#define ROW1_PIN PD3
#define ROW2_PIN PA5
#define ROW3_PIN PA6
#define ROW4_PIN PA7

// Keypad Column Pins
#define COL1_PIN PC7
#define COL2_PIN PA9
#define COL3_PIN PA15
#define COL4_PIN PA10

// --- LCD Command Definitions ---
#define LCD_CLEAR           0x01
#define LCD_HOME            0x02
#define LCD_ENTRY_MODE_INC  0x06
#define LCD_CURSOR_OFF      0x0C
#define LCD_CURSOR_ON       0x0E
#define LCD_FUNCTION_8BIT   0x38 // For 8-bit interface, 2 lines, 5x8 font

// --- Global Variables ---
uint8_t display_on = 1;
uint8_t button_press_count = 0;
uint32_t last_press_time = 0;
char display_buffer[20 + 1]; // Buffer for 20 characters + null terminator
uint8_t buffer_index = 0;

// --- Function Prototypes ---
void initialize_ports(); // Configure GPIO pins
void lcd_init();
void lcd_command(unsigned char command);
void lcd_data(unsigned char data);
void lcd_string(char *str);
void lcd_display_buffer();
unsigned char keypad_scan();
uint8_t button_read_debounced();
uint8_t button_raw_read();
void delay_ms(uint16_t ms); // Implement your delay function
uint32_t get_time_ms();    // Implement a function to get current time in milliseconds

int main(void) {
    initialize_ports();
    lcd_init();
    lcd_string("Keypad Input:");

    while (1) {
        // Handle Button Press with Debouncing
        if (button_read_debounced()) {
            uint32_t current_time = get_time_ms();
            if (current_time - last_press_time < 3000) {
                button_press_count++;
                if (button_press_count >= 3) {
                    lcd_command(LCD_CLEAR);
                    for (int i = 0; i < 20; i++) {
                        display_buffer[i] = ' ';
                    }
                    display_buffer[20] = '\0';
                    buffer_index = 0;
                    button_press_count = 0;
                }
            } else {
                button_press_count = 1;
            }
            last_press_time = current_time;
            display_on = !display_on;
            if (display_on) {
                lcd_command(LCD_CURSOR_ON);
                lcd_display_buffer();
            } else {
                lcd_command(LCD_CURSOR_OFF);
                lcd_command(LCD_CLEAR); // Optionally clear when off
            }
        }

        // Handle Keypad Input and Display (if display is on)
        if (display_on) {
            unsigned char key = keypad_scan();
            if (key != '\0') {
                display_buffer[buffer_index % 20] = key;
                buffer_index++;
                lcd_command(LCD_CLEAR);
                lcd_string("Keypad Input:");
                // Display the rolling buffer
                for (int i = 0; i < 20; i++) {
                    lcd_data(display_buffer[(buffer_index - 20 + i + 20) % 20]);
                }
                delay_ms(200); // Simple delay for key press feedback
            }
        }

        delay_ms(10); // Small delay for the main loop
    }

    return 0;
}

// --- Implement your microcontroller's GPIO initialization here ---
void initialize_ports() {
    pinMode(LCD_RS_PIN, OUTPUT);
    pinMode(LCD_EN_PIN, OUTPUT);
    pinMode(LCD_D0_PIN, OUTPUT);
    pinMode(LCD_D1_PIN, OUTPUT);
    pinMode(LCD_D2_PIN, OUTPUT);
    pinMode(LCD_D3_PIN, OUTPUT);
    pinMode(LCD_D4_PIN, OUTPUT);
    pinMode(LCD_D5_PIN, OUTPUT);
    pinMode(LCD_D6_PIN, OUTPUT);
    pinMode(LCD_D7_PIN, OUTPUT);
    pinMode(BUTTON_PIN, INPUT_PULLUP);
    pinMode(ROW1_PIN, OUTPUT);
    pinMode(ROW2_PIN, OUTPUT);
    pinMode(ROW3_PIN, OUTPUT);
    pinMode(ROW4_PIN, OUTPUT);
    pinMode(COL1_PIN, INPUT_PULLUP);
    pinMode(COL2_PIN, INPUT_PULLUP);
    pinMode(COL3_PIN, INPUT_PULLUP);
    pinMode(COL4_PIN, INPUT_PULLUP);
}

// --- Implement LCD functions (8-bit Mode) ---
void lcd_init() {
    delay(50); // Initial delay

    lcd_command(0x38); // Function set: 8-bit interface, 2 lines, 5x8 font
    delay(5);
    lcd_command(0x38); // Function set again
    delay(1);
    lcd_command(0x38); // Function set a third time

    lcd_command(LCD_CURSOR_OFF); // Display control: Display ON, Cursor OFF, Blink OFF
    lcd_command(LCD_ENTRY_MODE_INC); // Entry mode set: Increment cursor, No display shift
    lcd_command(LCD_CLEAR); // Clear display
    delay(2);
}

void lcd_command(unsigned char command) {
    digitalWrite(LCD_RS_PIN, LOW);
    // Output the command to the 8 data lines
    digitalWrite(LCD_EN_PIN, HIGH);
    delay(1);
    digitalWrite(LCD_EN_PIN,LOW);
    delay(1);
}

void lcd_data(unsigned char data) {
    // Set RS HIGH for data
    // Output the data to the 8 data lines
    // Set EN HIGH, delay, set EN LOW
    delay_ms(1);
}

void lcd_string(char *str) {
    while (*str) {
        lcd_data(*str++);
    }
}

void lcd_display_buffer() {
    lcd_command(LCD_CLEAR);
    lcd_string("Keypad Input:");
    for (int i = 0; i < 20; i++) {
        lcd_data(display_buffer[i]);
    }
}

// --- Implement Keypad scanning function ---
unsigned char keypad_scan() {
    char keys[4][4] = {
        {'1', '2', '3', 'A'},
        {'4', '5', '6', 'B'},
        {'7', '8', '9', 'C'},
        {'*', '0', '#', 'D'}
    };

    // Set row pins as output, one at a time, low
    // Read column pins
    // Implement basic debouncing within the scan function
    // Return the pressed key or '\0' if none

    return '\0'; // Placeholder
}