#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>

#define DEFAULT_FILE        "input.txt"
#define STRBUF_LEN          200
#define NUM_CARDS           202
#define WINNING_NUM_SIZE    10
#define HOLDING_NUM_SIZE    25
#define ISDIGIT(X)      (X >= '0' && X <= '9')

void parse_nums(char *str, uint8_t *nums, uint8_t len)
{
    uint8_t i = 0;
    uint8_t digit_idx = 0;
    char c;
    uint8_t num = 0;

    for (i = 0; i < len; i++)
    {
        num = 0;
        digit_idx = (i * 3);
        c = str[digit_idx];
        if (ISDIGIT(c)) num = (c - '0') * 10;
        num += str[digit_idx + 1] - '0';
        nums[i] = num;
    }
}

void parse_line(char *str, uint8_t *winning_nums, uint8_t *holding_nums)
{
    while (*str != ':') str++;
    str += 2;
    parse_nums(str, winning_nums, WINNING_NUM_SIZE);

    while (*str != '|') str++;
    str += 2;
    parse_nums(str, holding_nums, HOLDING_NUM_SIZE);
}

bool num_in_set(uint8_t num, uint8_t *set, uint8_t len)
{
    uint8_t i = 0;
    for (i = 0; i < len; i++)
    {
        if (num == set[i]) return true;
    }

    return false;
}

uint32_t calculate_points(uint8_t *winning_nums, uint8_t *holding_nums)
{
    uint32_t points = 0;
    uint8_t i = 0;
    for (i = 0; i < HOLDING_NUM_SIZE; i++)
    {
        if (num_in_set(holding_nums[i], winning_nums, WINNING_NUM_SIZE)) points++;
    }

    return points;
}

int main(int argc, char **argv)
{
    // Get filename as an argument, defaults to "input.txt"
    char *path = (argc > 1) ? argv[1] : DEFAULT_FILE;

    if (!path)
    {
        printf("Requires input file.\n");
        return 1;
    }

    FILE *file = fopen(path, "r");

    if (!file)
    {
        printf("Could not find file.");
        return 1;
    }

    char strbuf[STRBUF_LEN] = {0};
    uint8_t winning_nums[WINNING_NUM_SIZE] = {0};
    uint8_t holding_nums[HOLDING_NUM_SIZE] = {0};
    uint64_t points = 0;
    uint64_t card_copies[NUM_CARDS] = { [0 ... NUM_CARDS-1] = 1 };
    uint8_t i = 0;
    uint8_t copyidx = 0;
    uint8_t cardidx = 0;

    for (cardidx = 0; cardidx < NUM_CARDS; cardidx++)
    {
        fgets(strbuf, STRBUF_LEN, file);
        if (strbuf[0] == '\n') break;
        parse_line(strbuf, winning_nums, holding_nums);
        points = calculate_points(winning_nums, holding_nums);
        for (i = 0; i < points; i++)
        {
            // Add copy of card for every point
            if (cardidx + i < NUM_CARDS)
                card_copies[cardidx + i + 1] = card_copies[cardidx + i + 1] + card_copies[cardidx];
            else
                break;
        }
    }

    points = 0;
    for (i = 0; i < NUM_CARDS; i++)
    {
        points += card_copies[i];
    }

    printf("Total cards: %d", points);

    return 0;
}