/* aoc-c.c: Advent of Code 2021, day 14 parts 1 & 2
 *
 * Copyright (C) 2021 Bruno Raoult ("br")
 * Licensed under the GNU General Public License v3.0 or later.
 * Some rights reserved. See COPYING.
 *
 * You should have received a copy of the GNU General Public License along with this
 * program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
 *
 * SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <malloc.h>
#include <stdint.h>

#include "debug.h"
#include "bits.h"

#define NPOLYMERS   10                     /* max number of polymers */

/* possible 10 letters: B, C, F, H, K, N, O, P, S, V, reduced to 10 integers */
static int cindex[] =  {
    ['B'] = 0, ['C'] = 1, ['F'] = 2, ['H'] = 3, ['K'] = 4,
    ['N'] = 5, ['O'] = 6, ['P'] = 7, ['S'] = 8, ['V'] = 9
};
static int rev_index[] =  {
    'B', 'C', 'F', 'H', 'K', 'N', 'O', 'P', 'S', 'V'
};

#define INDEX(c) cindex[(int)c]

static u64 polymers[NPOLYMERS][NPOLYMERS];
static u64 rules[NPOLYMERS][NPOLYMERS];

#define MAX_SIZE 10000
char seq[MAX_SIZE], seq2[MAX_SIZE];
int nseq;

//int rules[NPOLYMERS * NPOLYMERS];
int nrules;

u64 count[NPOLYMERS] = {0};

static void print_polymers(int step)
{
    //log(3, "   B C F C D E F G H I J K")
    log_f(3, "polymers(%d):\n  ", step);
    for (int i = 0; i < NPOLYMERS; ++i) {
        log(3, "%10c", rev_index[i]);
    }
    for (int i = 0; i < NPOLYMERS; ++i) {
        log(3, "\n%c ", rev_index[i]);
        for (int j = 0; j < NPOLYMERS; ++j) {
            if (polymers[i][j])
                log(3, "%10lu", polymers[i][j]);
            else
                log(3, "%10s", "");
        }
    }
    log(3, "\n");
}
static void print_rules()
{
    //log(3, "   B C F C D E F G H I J K")
    log_f(3, "rules:\n  ");
    for (int i = 0; i < NPOLYMERS; ++i) {
        log(3, "%10c", rev_index[i]);
    }
    for (int i = 0; i < NPOLYMERS; ++i) {
        log(3, "\n%c ", rev_index[i]);
        for (int j = 0; j < NPOLYMERS; ++j) {
            log(3, "%10c", rules[i][j]? rules[i][j]: ' ');
        }
    }
    log(3, "\n");
}
static void print_count()
{
    //log(3, "   B C F C D E F G H I J K")
    log_f(3, "count:\n  ");
    for (int i = 0; i < NPOLYMERS; ++i) {
        log(3, "%1c=%d ", rev_index[i], count[i]);
    }
    log(3, "\n");
}

/* read data and create graph.
 */
static int read_input()
{
    ssize_t len;
    size_t alloc = 0;
    char *buf;
    char x, y, z;

    nseq = getline(&buf, &alloc, stdin) - 1;
    print_polymers(0);
    buf[nseq] = 0;
    count[INDEX(*buf)]++;
    count[INDEX(*(buf + nseq - 1))]++;
    print_count();
    for (int i = 0; i < nseq - 1; ++i) {
        polymers[INDEX(buf[i])][INDEX(buf[i+1])]++;
    }
    log(3, "buf=[%s]\n", buf);
    print_polymers(0);
    strcpy(seq, buf);
    printf("str = %d [%s]\n", nseq, seq);
    printf("empt = %ld\n", getline(&buf, &alloc, stdin));


    /* get rules */
    while ((len = getline(&buf, &alloc, stdin)) >= 0) {
        if (sscanf(buf, "%c%c -> %c", &x, &y, &z) == 3)
            rules[INDEX(x)][INDEX(y)] = z;
        nrules++;
    }
    free(buf);
    print_rules();
    return nrules;
}

static u64 diff()
{
    u64 min = UINT64_MAX, max = 0;

    //for (unsigned i = 0; i < NPOLYMERS; ++i)
    //    for (unsigned i = 0; i < NPOLYMERS; ++i)
    //        log(5, "count[%c%c]=%d\n", rev_index[i] i + 'A', count[i]);
    for (int i = 0; i < NPOLYMERS; ++i) {
        for (int j = 0; j < NPOLYMERS; ++j) {
            count[i] += polymers[i][j];
            count[j] += polymers[i][j];
        }
    }
    print_count();
    for (int i = 0; i < NPOLYMERS; ++i) {
        if (count[i] && count[i] < min)
            min = count[i];
        if (count[i] > max)
            max = count[i];
    }
    log(3, "min = %lu max=%lu\n", min, max);
    return (max - min) / 2;
}

static u64 part1(int steps)
{
    //int step;
    read_input();
    for (int step = 0; step < steps; ++step) {
        int new;
        u64 new_polymers[NPOLYMERS][NPOLYMERS];

        memset(new_polymers, 0, sizeof(new_polymers));
        for (int i = 0; i < NPOLYMERS; ++i) {
            for (int j = 0; j < NPOLYMERS; ++j) {
                new = INDEX(rules[i][j]);
                new_polymers[i][new] += polymers[i][j];
                new_polymers[new][j] += polymers[i][j];
            }
        }
        memcpy(polymers, new_polymers, sizeof(polymers));
        print_polymers(step);
    }
    return diff();
    //print_polymers(step);
}

static u64 doit(int part)
{
    //read_input();
    return part == 1? part1(10): part1(40);
}

static int usage(char *prg)
{
    fprintf(stderr, "Usage: %s [-d debug_level] [-p part]\n", prg);
    return 1;
}

int main(int ac, char **av)
{
    int opt, part = 1;

    while ((opt = getopt(ac, av, "d:p:")) != -1) {
        switch (opt) {
            case 'd':
                debug_level_set(atoi(optarg));
                break;
            case 'p':                             /* 1 or 2 */
                part = atoi(optarg);
                if (part < 1 || part > 2)
                    return usage(*av);
                break;
            default:
                return usage(*av);
        }
    }
    if (optind < ac)
        return usage(*av);

    printf("%s : res=%lu\n", *av, doit(part));
    exit (0);
}