#include "buff.h"
#include <regex.h>

line_t* __search_pos(int addr){
  
  int i;
  line_t *cur = b_start;
  for(i=1; i<addr; i++){
    cur = cur -> next;
  }
  return cur;
}

int __get_lines(FILE *fin, line_t **first, line_t **last, int *tot){

  char buff[4096];
  int n,s, num_alloc=0;
  line_t *l;
  
  n = 0;
  *tot = 0;
  *first = *last = NULL;
  while(feof(fin) == 0){
    if (!fgets(buff, 4095, fin)) break;
    if (*buff == '.')
      break;
    s = strlen(buff) + 1;
    *tot += s -1;
    l = malloc(sizeof(line_t));
    l->c = malloc(s * sizeof(char));
    num_alloc++;
    memcpy(l->c, buff, s);
    l->s = s;
    if (*first == NULL){
      *first = *last = l;
      (*first) -> next = (*last) -> next = NULL;
      (*first) -> prev = (*last) -> prev = NULL;
    }
    
    else{
      (*last) -> next = l;
      l->prev = *last;
      l->next = NULL;
      *last = l;
    }
    n++;
  }
  fprintf(stderr, "    >>>> get_lines: num_alloc: %d\n", num_alloc);
  return n;
}

int read_file(){

  FILE *fin;
  int tot;

  fprintf(stderr, "   >>> reading file: %s\n", fname);
  
  if (!(fin = fopen(fname, "r"))){
    return -1;
  }

  if (b_start){
    addr1=num, addr2=1;
    delete_lines();
  }
  num = pos = __get_lines(fin, &b_start, &b_end, &tot);
  fprintf (stderr, "    >>>> read_file: pos: %d num: %d\n", pos, num);
  cur = b_end;
  fclose(fin);
  printf("%d\n", tot);
  return 0;
}


void print_cur_line(char lineno){
  
  if (!b_start){
    E;
    return;
  }
  
  if (lineno)
    printf("%d\t", pos);
  printf("%s", cur->c);
}
  
void print_lines(char lineno){

  line_t *p;
  int i=0;
  p = b_start;

  
  fprintf(stderr, ">>> *** addr1: %d addr2: %d ***\n", addr1, addr2);
  for (i=1; i<addr2; i++) p = p->next;
  pos = i;
  cur = p;
  while(pos++ < addr1){
    if (lineno)
      printf("%d\t", pos);
    printf("%s", cur->c);
    cur = cur->next;
  }
  if (lineno)
    printf("%d\t", pos);
  printf("%s", cur->c);
}

int move_to_line(int addr, char print){

  fprintf(stderr, " >>>> move_to_line: addr: %d pos: %d\n", addr, pos);
  
  if (addr > num)
    return -1;
  else if (addr >= 0){
    pos = addr;
    cur = __search_pos(pos);
    if (print)
      print_cur_line(0);
  }
  return pos;
}

void print_lineno(){
  printf("%d\n", addr1);
}

int move_forward(int n){

  if (pos + n > num){
    E;
    return -1;
  }
  while(n-- > 0){
    cur = cur->next;
  }
  pos += n;
  return 0;
}

int move_backward(int n){

  if (pos - n < 1){
    E;
    return -1;
  }
  while(n-- >0){
    cur = cur->prev;
  }
  pos -= n;
  return 0;
}



/* add lines after pos */
void append_lines(){

  int n, tot;
  line_t *first, *last;

  first = last = NULL;
  n = __get_lines(stdin, &first, &last, &tot);
  
  if (addr1 == 0){
    fprintf(stderr, "  >>> append (zero): pos: %d n:%d\n", pos, n);
    last->next = b_start;
    if (b_start)
      b_start -> prev = last;
    b_start = first;
    num += n;
    move_to_line(n,0);
  }
  else{
    fprintf(stderr, "  >>> append (non-zero): pos: %d n:%d\n", pos, n);
    last -> next = cur -> next;
    cur->next = first;
    first->prev = cur;
    num += n;
    //move_forward(n);
    pos += n;
    cur = last;
  }
}

void insert_lines(){

  int n, tot;
  line_t *first, *last;

  first = last = NULL;
  n = __get_lines(stdin, &first, &last, &tot);

  if (addr1 == 0){
    fprintf(stderr, "  >>> insert (zero): pos: %d n:%d\n", pos, n);
    last->next = b_start;
    b_start -> prev = last;
    b_start = first;
    num += n;
    move_to_line(n,0);
  }
  else{
    fprintf(stderr, "  >>> insert (non-zero): pos: %d n:%d\n", pos, n);
    
    cur -> prev -> next = first;
    first -> prev = cur -> prev;
    last -> next = cur;
    num += n;
    pos-- ;
    cur = last;
  }
}


void delete_lines(){

  line_t *handle;
  int num_free = 0;
  
  if (addr1 == -1){
    addr1 = pos;
  }
  if (addr2 == -1){
    addr2 = addr1;
  }

  if (addr1 < addr2){
    return;
  }

  
  move_to_line(addr2,0);
  fprintf(stderr, "    >>> delete: addr1: %d addr2: %d pos: %d\n", addr1, addr2, pos);

  if (addr2 <= 1){ /* we are deleting the first line */
    while(pos <= addr1){
      pos ++;
      free(cur->c);
      num_free++;
      if (cur -> next){
        cur = cur -> next;
        free(cur -> prev);
      }
      else {
        free(cur);
        cur = NULL;
        break;
      }
    }

    fprintf(stderr, "    >>>> delete_lines: num_free: %d\n", num_free);
    
    /* free(b_start); */
    b_start = cur;
    if (cur){
      pos = 1;
      cur = b_start;
    }
    else
      pos = 0;
  }
  else{
    handle = cur->prev;
    while(pos < addr1){
      free(cur->c);
      cur = cur -> next;
      free(cur->prev);
      pos ++;
    }
    handle->next = cur -> next;
    free(cur->c);
    free(cur);
    if (handle -> next){
      pos = addr2 ;
      cur = handle->next;
    }
    else{
      pos = addr2 - 1;
      cur = handle;
    }
  }
  num -= addr1 - addr2 + 1;  
}


void change_lines(){
  delete_lines();
  addr2 = addr1 =pos;
  append_lines();
}



int write_lines(){
  FILE *fout;
  line_t *l;
  int tot=0;
  
  if (! (fout = fopen(fname, "w+"))){
    return -1;
  }

  l = b_start;
  while(l){
    tot += fprintf(fout, "%s", l->c);
    l = l->next;
  }
  fclose(fout);
  printf("%d\n", tot);
  return 0;
}

/* match either forward (bw=0) or backward (bw=1)*/
int match(char **c, char bw){
  
  char sep = **c, *tmp;
  line_t *ptr;
  regex_t re;
  int l;

  if (bw)
    tmp = strtok(*c, "?\n");
  else
    tmp = strtok(*c, "/\n");
  fprintf(stderr, "  >>>> string to match: \"%s\" bw: %d\n", tmp, bw);
  if (!tmp)
    return -1;

  if (regcomp(&re, tmp, REG_EXTENDED)){
    return -1;
  }
  *c += strlen(tmp);
  l = pos;
  ptr = cur;
  do {
    fprintf(stderr, ".");
    if (bw){
      ptr = ptr->prev;
      l = (l-1 + num) % num;
      if (!ptr){
        /* FIXME: if we keep b_end updated we can avoid this search */
        ptr = __search_pos(num);
        l = num;
      }
    }
    else{
      ptr = ptr->next;
      l = (l+1) % num;
      if (! ptr){
        ptr = b_start;
        l = 1;
      }
    }
    if (!l) l = num;
    if (!regexec(&re, (char *) ptr->c , (size_t) 0, NULL, 0)){
      regfree(&re);
      return l;
    }
    fprintf(stderr, "     %d\n", l);
  } while(l != pos);
  fprintf(stderr, "    >>>> match: returning\n");
  regfree(&re);
  return -1;
}