#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#include "../../lib/aoc.h"

typedef struct Rule {
  int first;
  int last;
} Rule;

typedef struct Rules {
  Rule rule[1200];
  int length;
} Rules;

typedef struct Update {
  int page[100];
  int length;
} Update;

bool valid_rule(Rule *rule, Update *update) {
  int first = -1, last = -1;
  for (int i = 0; i < update->length; i++) {
    if (rule->first == update->page[i]) first = i;
    if (rule->last == update->page[i]) last = i;
    if (first != -1 && last != -1) return first < last;
  }

  return true;
}

bool valid_update(Rules *rules, Update *update) {
  for (int i = 0; i < rules->length; i++) {
    if (!valid_rule(&(rules->rule[i]), update)) return false;
  }
  return true;
}

int middle_page_number(Update *update) {
  return update->page[update->length / 2];
}

void reorder_update(Rules *rules, Update *update) {
  bool dirty = true;
  while (dirty) {
    dirty = false;
    for (int i = 0; i < update->length - 1; i++) {
      for (int j = 0; j < rules->length; j++) {
	Rule rule = rules->rule[j];
	if (update->page[i] == rule.last && update->page[i + 1] == rule.first) {
	  dirty = true;
	  update->page[i] = rule.first;
	  update->page[i + 1] = rule.last;
	  break;
	}
      }
    }
  }
}

int main() {
  char *line;

  int sum = 0;
  int reorder_sum = 0;

  Rules rules;
  int first, last;

  Update update;
  char *update_element;

  bool scanning_rules = true;
  while ((line = aoc_read_line()) != NULL) {
    if (scanning_rules) {
      if (strlen(line) == 0) scanning_rules = false;
      else {
	sscanf(line, "%d|%d", &first, &last);
	rules.rule[rules.length].first = first;
	rules.rule[rules.length].last = last;
	rules.length++;
      }
    } else {
      update.length = 0;
      update_element = strtok(line, ",");
      while(update_element != NULL) {
	update.page[update.length++] = atoi(update_element);
	update_element = strtok(NULL, ",");
      }
      if (valid_update(&rules, &update)) sum += middle_page_number(&update);
      else {
	reorder_update(&rules, &update);
	reorder_sum += middle_page_number(&update);
      }
    }
  }

  printf("Part 1: %d\n", sum);
  printf("Part 2: %d\n", reorder_sum);

  aoc_free();
  return 0;
}