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

struct unite_enseignement {
  char identifiant[10 + 1];
  char nom[200 + 1];
  int credits;
  char responsable[60 + 1];
  struct unite_enseignement *prerequis[5];
  struct unite_enseignement *corequis[5];
};

void encoder_ue(void);
void print_prerequis(struct unite_enseignement *ue);
void ajouter_prerequis(struct unite_enseignement *ue1, struct unite_enseignement *ue2);

/**
 * Renvoie l'index du premier élément libre ou length si tab est plein.
 */
static int premier_libre(struct unite_enseignement *tab[], int length) {
  for (int i = 0; i < length; i++) {
    if (tab[i] == NULL)
      return i;
  }
  return length;
}

int main() { encoder_ue(); }

void encoder_ue() {
  struct unite_enseignement u;
  strcpy(u.identifiant, "AAA-1");
  strcpy(u.nom, "unite_enseignement 1");
  u.credits = 20;
  strcpy(u.responsable, "responsable 1");
  for(int i = 0; i < 5; i++) {
    u.corequis[i] = NULL;
    u.prerequis[i] = NULL;
  }

  struct unite_enseignement u2;
  strcpy(u2.identifiant, "BBB-2");
  strcpy(u2.nom, "unite_enseignement 2");
  u2.credits = 30;
  strcpy(u2.responsable, "responsable 2");
  for(int i = 0; i < 5; i++) {
    u2.corequis[i] = NULL;
    u2.prerequis[i] = NULL;
  }

  print_prerequis(&u2);

  ajouter_prerequis(&u, &u2);

  print_prerequis(&u2);
}

void print_prerequis(struct unite_enseignement *ue) {
  printf("--------- Prérequis de %s ---------\n", ue->nom);
  int max_index = premier_libre(ue->prerequis, 5);
  if (max_index == 0) {
    printf("Aucune.\n");
  } else {
    for (int i = 0; i < max_index; i++) {
      struct unite_enseignement *pr = ue->prerequis[i];
      printf("%d) %s (%dc)\n", i, pr->nom, pr->credits);
    }
  }
}

void ajouter_prerequis(struct unite_enseignement *ue1, struct unite_enseignement *ue2) {
  if (ue1 == NULL || ue2 == NULL) {
    return;
  }

  int first_null = premier_libre(ue2->prerequis, 5);

  if (first_null == 5) {
    return;
  }

  ue2->prerequis[first_null] = ue1;
}