#include <avr/io.h>
#include <avr/interrupt.h>

#define FOSC 16000000 // Clock Speed
#define BAUD 9600
#define MYUBRR (FOSC/16/BAUD-1)

static long holdrand = 1L;
static volatile uint8_t MilisFlag; 
static uint32_t milis;
static uint8_t UCounter;
static uint32_t globalMilis; 

int main(void) {
    uint8_t randomSec;
    char str[10];
    
    // Initializations
    UCounter = 0;
    milis = 0;
    gpio_ini();
    uart_ini(MYUBRR);
    Timer2_Ini();
    uart_puts("Ingrese una tecla para iniciar\n");
    uart_getchar();
    srand(globalMilis);
    
    while (1) {
    uart_puts("Advertencia\n");
    uart_puts("Iniciando programa...");
        // Generate random delay
        randomSec = getRandomNumber();
        uart_itoa(randomSec, str, 10);
        uart_puts(str);
        uart_putchar('\n');

        for (uint8_t counter = 0; counter < randomSec; counter++) {
            secondDelay();
            uart_itoa(counter + 1, str, 10);
            uart_puts(str);
            uart_putchar('\n');
            milis = 0;
        }

        globalMilis = 0;
        led_On_Off(1);
        
        while ((PINA >> PA3) & 1)
            ;

        uart_itoa(globalMilis, str, 10);
        uart_puts(str);
        uart_putchar('.');
        uart_itoa(UCounter, str, 10);
        uart_puts(str);
        uart_puts(" ms");
        uart_putchar('\n');
        
        randomSec = 2;

        for (uint8_t counter = 0; counter < randomSec; counter++) 
        {
          if (globalMilis > 1000) 
              {
                led_On_Off(2);
                secondDelay();
                uart_itoa(counter + 1, str, 10);
                uart_puts(str);
                uart_putchar('\n');
                milis = 0;
                led_On_Off(3);
              }  
        }
        
        Msdelay();
        milis++;
    }

    return 0;
}

// Function implementations
void srand(unsigned int seed) {
    holdrand = (long)seed;
}

int rand(void) {
    return (((holdrand = holdrand * 214013L + 2531011L) >> 16) & 0x7fff);
}

uint16_t getRandomNumber(void) {
    uint16_t number = rand() & 0xf;

    if (number > 10) {
        number = 10;
    } else if (number < 1) {
        number = 1;
    }

    return number;
}

void uart_ini(int ubrr) {
    UBRR0L = ubrr;
    UBRR0H = (ubrr >> 8);
    UCSR0B = (1 << RXEN0) | (1 << TXEN0);
    UCSR0C = (3 << UCSZ00);
}

void uart_putchar(unsigned char data) {
    while (!(UCSR0A & (1 << UDRE0)))
        ;
    UDR0 = data;
}

void uart_puts(char *str) {
    while (*str != '\0') {
        uart_putchar(*str++);
    }
}

unsigned char uart_getchar(void) {
    while (!(UCSR0A & (1 << RXC0)))
        ;
    return UDR0;
}

void uart_itoa(uint32_t num, char* str, uint8_t base) {
    uint8_t i = 0;
    uint8_t is_negative = 0;

    if (num == 0) {
        str[i++] = '0';
        str[i] = '\0';
        return;
    }

    if (num < 0 && base == 10) {
        is_negative = 1;
        num = -num;
    }

    while (num != 0) {
        int rem = num % base;
        str[i++] = (rem > 9) ? (rem - 10) + 'A' : rem + '0';
        num = num / base;
    }

    if (is_negative) {
        str[i++] = '-';
    }

    uint16_t start = 0;
    uint16_t end = i - 1;
    while (start < end) {
        char temp = str[start];
        str[start] = str[end];
        str[end] = temp;
        start++;
        end--;
    }

    str[i] = '\0';
}

void gpio_ini(void) {
    DDRA = (1 << PA0) | (1 << PA1) | (1 << PA2);
    PORTA = 0;
    PORTA |= (1 << PA3);
}

void Timer2_Ini(void) {
    TCNT2 = 0;
    TCCR2A = 2 << WGM20;
    OCR2A = 25 - 1;
    TCCR2B = 0x04;
    TIMSK2 = 1 << OCIE2A;
    sei();
}

uint8_t Timer2_MilisFlag(void) {
    if (MilisFlag) {
        MilisFlag = 0;
        return 1;
    } else {
        return 0;
    }
}

ISR(TIMER2_COMPA_vect) {
    TCNT2 = 0;
    UCounter++;
    if (UCounter == 10) {
        globalMilis++;
        UCounter = 0;
        MilisFlag = 1;
    }
}

void Msdelay(void) {
    while (!Timer2_MilisFlag())
        ;
}

void secondDelay(void) {
    while (milis < 1000) {
        Msdelay();
        milis++;
    }
    milis = 0;
}

void led_On_Off(uint8_t state) {
    if (state == 1) {
        PORTA |= (1 << PA1);
        PORTA &= ~(1 << PA2);
    } else if (state == 2) {
        PORTA |= (1 << PA2);
        PORTA &= ~(1 << PA1);
    } else if (state == 3) {
        PORTA &= ~(1 << PA1);
        PORTA &= ~(1 << PA2);
    }
}