#include <stdlib.h>
#include <stdio.h>
#include "expression.h"


struct li_production_t * li_production_alloc(size_t seq_len) {
  struct li_production_t *prod = malloc(sizeof(struct li_production_t));
  if (prod == NULL) {
    fprintf(stderr, "failed to allocate production rule\n");
    return NULL;
  }
  prod->seq = malloc(seq_len * sizeof(int));
  if (prod->seq == NULL) {
    fprintf(stderr, "failed to allocate production sequence buffer\n");
    free(prod);
    return NULL;
  }
  prod->seq_len = seq_len;
  prod->next = NULL;
  return prod;
}


void li_production_free(struct li_production_t *prod) {
  if (prod != NULL) {
    li_production_free(prod->next);
    free(prod->seq);
    free(prod);
  }
}


struct li_production_rule_t * li_prod_rule_alloc() {
  struct li_production_rule_t *rule = malloc(sizeof(struct li_production_rule_t));
  if (rule == NULL) {
    fprintf(stderr, "failed to allocate production rule\n");
    return NULL;
}
  rule->num_productions = 0;
  rule->head = NULL;
  return rule;
}


void li_prod_rule_free(struct li_production_rule_t *rule) {
  if (rule != NULL) {
    li_production_free(rule->head);
    free(rule);
  }
}


int li_prod_rule_add(
  struct li_production_rule_t *rule, size_t seq_len, int *seq
) {
  struct li_production_t *prod = li_production_alloc(seq_len);
  if (prod == NULL) {
    return 1;
  }
  memcpy(prod->seq, seq, seq_len*sizeof(int));
  prod->next = rule->head;
  rule->head = prod;
  rule->num_productions += 1;
  return 0;
}


li_grammar_t * li_grammar_alloc(size_t num_nonterminal) {
  li_grammar_t *grammar = malloc(sizeof(li_grammar_t));
  if (grammar == NULL) {
    fprintf(stderr, "failed to allocate grammar\n");
    return NULL;
  }
  grammar->rules = malloc(num_nonterminal * sizeof(struct li_production_rule_t));
  if (grammar->rules == NULL) {
    fprintf(stderr, "failed to allocate grammar rules buffer\n");
    free(grammar);
    return NULL;
  }
  for (size_t i=0; i<num_nonterminal; i++) {
    grammar->rules[i].num_productions = 0;
    grammar->rules[i].head = NULL;
  }
  grammar->num_nonterminal = NULL;
  return grammar;
}


void li_grammar_free(li_grammar_t *grammar) {
  if (grammar != NULL) {
    for (size_t i=0; i<grammar->num_nonterminal; i++) {
      li_production_free(grammar->rules[i].head);
    }
    free(grammar->rules);
    free(grammar);
  }
}


int li_grammar_rule_add(
  li_grammar_t *grammar, int nonterminal, size_t seq_len, int *seq
) {
  if (nonterminal < 0 || nonterminal >= grammar->num_nonterminal) {
    return 2;
  }
  return li_prod_rule_add(grammar->rules + nonterminal, seq_len, seq);
}