/* ISC license. */

#include <stdlib.h>
#include <errno.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/sgetopt.h>
#include <skalibs/bytestr.h>
#include <skalibs/buffer.h>
#include <skalibs/strerr2.h>
#include <skalibs/stralloc.h>
#include <skalibs/genalloc.h>
#include <skalibs/djbunix.h>
#include <skalibs/skamisc.h>

#define USAGE "s6-sort [ -bcfru0 ]"

typedef int strncmp_t (char const *, unsigned int, char const *) ;
typedef strncmp_t *strncmp_t_ref ;
typedef int qsortcmp_t (void const *, void const *) ;
typedef qsortcmp_t *qsortcmp_t_ref ;

static int flagnoblanks = 0, flagreverse = 0, flaguniq = 0 ;

static int str_diffb_f (register char const *s1, register unsigned int n, register char const *s2)
{
  return str_diffb(s1, n, s2) ;
}

static strncmp_t_ref comp = &str_diffb_f ;

static int compit (register char const *s1, register unsigned int n1, register char const *s2, register unsigned int n2)
{
  register int r ;
  if (flagnoblanks)
  {
    while ((*s1 == ' ') || (*s1 == '\t')) (s1++, n1--) ;
    while ((*s2 == ' ') || (*s2 == '\t')) (s2++, n2--) ;
  }
  r = (*comp)(s1, n1 < n2 ? n1 : n2, s2) ;
  if (!r) r = n1 - n2 ;
  return flagreverse ? -r : r ;
}

static int sacmp (stralloc const *a, stralloc const *b)
{
  return compit(a->s, a->len - 1, b->s, b->len - 1) ;
}

static int slurplines (genalloc *lines, char sep)
{
  unsigned int i = 0 ;
  for (;; i++)
  {
    stralloc sa = STRALLOC_ZERO ;
    int r = skagetln(buffer_0, &sa, sep) ;
    if (!r) break ;
    if ((r < 0) && ((errno != EPIPE) || !stralloc_catb(&sa, &sep, 1)))
      return -1 ;
    stralloc_shrink(&sa) ;
    if (!genalloc_append(stralloc, lines, &sa)) return -1 ;
  }
  return (int)i ;
}

static void uniq (genalloc *lines)
{
  unsigned int len = genalloc_len(stralloc, lines) ;
  register stralloc *s = genalloc_s(stralloc, lines) ;
  register unsigned int i = 1 ;
  for (; i < len ; i++)
    if (!sacmp(s+i-1, s+i)) stralloc_free(s+i-1) ;
}

static int outputlines (stralloc const *s, unsigned int len)
{
  register unsigned int i = 0 ;
  for (; i < len ; i++)
    if (buffer_put(buffer_1, s[i].s, s[i].len) < 0) return 0 ;
  return buffer_flush(buffer_1) ;
}

static int check (stralloc const *s, unsigned int len)
{
  register unsigned int i = 1 ;
  for (; i < len ; i++)
    if (sacmp(s+i-1, s+i) >= !flaguniq) return 0 ;
  return 1 ;
}

int main (int argc, char const *const *argv)
{
  genalloc lines = GENALLOC_ZERO ; /* array of stralloc */
  char sep = '\n' ;
  int flagcheck = 0 ;
  PROG = "s6-sort" ;
  {
    subgetopt_t l = SUBGETOPT_ZERO ;
    for (;;)
    {
      register int opt = subgetopt_r(argc, argv, "bcfru0", &l) ;
      if (opt == -1) break ;
      switch (opt)
      {
        case 'b' : flagnoblanks = 1 ; break ;
        case 'c' : flagcheck = 1 ; break ;
        case 'f' : comp = &case_diffb ; break ;
        case 'r' : flagreverse = 1 ; break ;
        case 'u' : flaguniq = 1 ; break ;
        case '0' : sep = '\0' ; break ;
        default : strerr_dieusage(100, USAGE) ;
      }
    }
    argc -= l.ind ; argv += l.ind ;
  }

  if (slurplines(&lines, sep) < 0) strerr_diefu1sys(111, "read from stdin") ;
  if (flagcheck) return !check(genalloc_s(stralloc, &lines), genalloc_len(stralloc, &lines)) ;
  qsort(genalloc_s(stralloc, &lines), genalloc_len(stralloc, &lines), sizeof(stralloc), (qsortcmp_t_ref)&sacmp) ;
  if (flaguniq) uniq(&lines) ;
  if (!outputlines(genalloc_s(stralloc, &lines), genalloc_len(stralloc, &lines)))
    strerr_diefu1sys(111, "write to stdout") ;
  return 0 ;
}