/* seq - print sequence of numbers to standard output.
   Copyright (C) 1994-2008 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Written by Ulrich Drepper.  */

#include <config.h>
#include <getopt.h>
#include <stdio.h>
#include <sys/types.h>
#include <math.h>
#include <float.h>

#include "system.h"
#include "c-strtod.h"
#include "error.h"
#include "quote.h"
#include "xstrtod.h"

/* Roll our own isfinite rather than using <math.h>, so that we don't
   have to worry about linking -lm just for isfinite.  */
#ifndef isfinite
# define isfinite(x) ((x) * 0 == 0)
#endif

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "seq"

#define AUTHORS proper_name ("Ulrich Drepper")

/* If true print all number with equal width.  */
static bool equal_width;

/* The string used to separate two numbers.  */
static char const *separator;

/* The string output after all numbers have been output.
   Usually "\n" or "\0".  */
/* FIXME: make this an option.  */
static char const terminator[] = "\n";

static struct option const long_options[] =
{
  { "equal-width", no_argument, NULL, 'w'},
  { "format", required_argument, NULL, 'f'},
  { "separator", required_argument, NULL, 's'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  { NULL, 0, NULL, 0}
};

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
	     program_name);
  else
    {
      printf (_("\
Usage: %s [OPTION]... LAST\n\
  or:  %s [OPTION]... FIRST LAST\n\
  or:  %s [OPTION]... FIRST INCREMENT LAST\n\
"), program_name, program_name, program_name);
      fputs (_("\
Print numbers from FIRST to LAST, in steps of INCREMENT.\n\
\n\
  -f, --format=FORMAT      use printf style floating-point FORMAT\n\
  -s, --separator=STRING   use STRING to separate numbers (default: \\n)\n\
  -w, --equal-width        equalize width by padding with leading zeroes\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      fputs (_("\
\n\
If FIRST or INCREMENT is omitted, it defaults to 1.  That is, an\n\
omitted INCREMENT defaults to 1 even when LAST is smaller than FIRST.\n\
FIRST, INCREMENT, and LAST are interpreted as floating point values.\n\
INCREMENT is usually positive if FIRST is smaller than LAST, and\n\
INCREMENT is usually negative if FIRST is greater than LAST.\n\
"), stdout);
      fputs (_("\
FORMAT must be suitable for printing one argument of type `double';\n\
it defaults to %.PRECf if FIRST, INCREMENT, and LAST are all fixed point\n\
decimal numbers with maximum precision PREC, and to %g otherwise.\n\
"), stdout);
      emit_bug_reporting_address ();
    }
  exit (status);
}

/* A command-line operand.  */
struct operand
{
  /* Its value, converted to 'long double'.  */
  long double value;

  /* Its print width, if it were printed out in a form similar to its
     input form.  An input like "-.1" is treated like "-0.1", and an
     input like "1." is treated like "1", but otherwise widths are
     left alone.  */
  size_t width;

  /* Number of digits after the decimal point, or INT_MAX if the
     number can't easily be expressed as a fixed-point number.  */
  int precision;
};
typedef struct operand operand;

/* Description of what a number-generating format will generate.  */
struct layout
{
  /* Number of bytes before and after the number.  */
  size_t prefix_len;
  size_t suffix_len;
};

/* Read a long double value from the command line.
   Return if the string is correct else signal error.  */

static operand
scan_arg (const char *arg)
{
  operand ret;

  if (! xstrtold (arg, NULL, &ret.value, c_strtold))
    {
      error (0, 0, _("invalid floating point argument: %s"), arg);
      usage (EXIT_FAILURE);
    }

  /* We don't output spaces or '+' so don't include in width */
  while (isspace (to_uchar (*arg)) || *arg == '+')
    arg++;

  ret.width = strlen (arg);
  ret.precision = INT_MAX;

  if (! arg[strcspn (arg, "xX")] && isfinite (ret.value))
    {
      char const *decimal_point = strchr (arg, '.');
      if (! decimal_point)
	ret.precision = 0;
      else
	{
	  size_t fraction_len = strcspn (decimal_point + 1, "eE");
	  if (fraction_len <= INT_MAX)
	    ret.precision = fraction_len;
	  ret.width += (fraction_len == 0                      /* #.  -> #   */
			? -1
			: (decimal_point == arg                /* .#  -> 0.# */
			   || ! ISDIGIT (decimal_point[-1]))); /* -.# -> 0.# */
	}
      char const *e = strchr (arg, 'e');
      if (! e)
	e = strchr (arg, 'E');
      if (e)
	{
	  long exponent = strtol (e + 1, NULL, 10);
	  ret.precision += exponent < 0 ? -exponent : 0;
	}
    }

  return ret;
}

/* Validate the format, FMT.  Print a diagnostic and exit
   if there is not exactly one %-directive.  */

static void
validate_format (char const *fmt)
{
  unsigned int n_directives = 0;
  char const *p;

  for (p = fmt; *p; p++)
    {
      if (p[0] == '%' && p[1] != '%' && p[1] != '\0')
	{
	  ++n_directives;
	  ++p;
	}
    }
  if (n_directives == 0)
    {
      error (0, 0, _("no %% directive in format string %s"), quote (fmt));
      usage (EXIT_FAILURE);
    }
  else if (1 < n_directives)
    error (EXIT_FAILURE, 0, _("too many %% directives in format string %s"),
	   quote (fmt));
}

/* If FORMAT is a valid printf format for a double argument, return
   its long double equivalent, possibly allocated from dynamic
   storage, and store into *LAYOUT a description of the output layout;
   otherwise, return NULL.  */

static char const *
long_double_format (char const *fmt, struct layout *layout)
{
  size_t i;
  size_t prefix_len = 0;
  size_t suffix_len = 0;
  size_t length_modifier_offset;
  bool has_L;

  for (i = 0; ! (fmt[i] == '%' && fmt[i + 1] != '%'); i += (fmt[i] == '%') + 1)
    if (fmt[i])
      prefix_len++;
    else
      return NULL;

  i++;
  i += strspn (fmt + i, "-+#0 '");
  i += strspn (fmt + i, "0123456789");
  if (fmt[i] == '.')
    {
      i++;
      i += strspn (fmt + i, "0123456789");
    }

  length_modifier_offset = i;
  has_L = (fmt[i] == 'L');
  i += has_L;
  /* In a valid format string, fmt[i] must be one of these specifiers.  */
  if (fmt[i] == '\0' || ! strchr ("efgaEFGA", fmt[i]))
    return NULL;

  for (i++; ! (fmt[i] == '%' && fmt[i + 1] != '%'); i += (fmt[i] == '%') + 1)
    if (fmt[i])
      suffix_len++;
    else
      {
	size_t format_size = i + 1;
	char *ldfmt = xmalloc (format_size + 1);
	memcpy (ldfmt, fmt, length_modifier_offset);
	ldfmt[length_modifier_offset] = 'L';
	strcpy (ldfmt + length_modifier_offset + 1,
		fmt + length_modifier_offset + has_L);
	layout->prefix_len = prefix_len;
	layout->suffix_len = suffix_len;
	return ldfmt;
      }

  return NULL;
}

/* Return the absolute relative difference from x to y.  */
static double
abs_rel_diff (double x, double y)
{
  double s = (y == 0.0 ? 1 : y);
  return fabs ((y - x) / s);
}

/* Actually print the sequence of numbers in the specified range, with the
   given or default stepping and format.  */

static void
print_numbers (char const *fmt, struct layout layout,
	       long double first, long double step, long double last)
{
  bool out_of_range = (step < 0 ? first < last : last < first);

  if (! out_of_range)
    {
      long double x = first;
      long double i;

      for (i = 1; ; i++)
	{
	  long double x0 = x;
	  printf (fmt, x);
	  if (out_of_range)
	    break;
	  x = first + i * step;
	  out_of_range = (step < 0 ? x < last : last < x);

	  if (out_of_range)
	    {
	      /* If the number just past LAST prints as a value equal
		 to LAST, and prints differently from the previous
		 number, then print the number.  This avoids problems
		 with rounding.  For example, with the x86 it causes
		 "seq 0 0.000001 0.000003" to print 0.000003 instead
		 of stopping at 0.000002.  */

	      bool print_extra_number = false;
	      long double x_val;
	      char *x_str;
	      int x_strlen = asprintf (&x_str, fmt, x);
	      if (x_strlen < 0)
		xalloc_die ();
	      x_str[x_strlen - layout.suffix_len] = '\0';

	      if (xstrtold (x_str + layout.prefix_len, NULL, &x_val, strtold)
		  && abs_rel_diff (x_val, last) < DBL_EPSILON)
		{
		  char *x0_str = NULL;
		  if (asprintf (&x0_str, fmt, x0) < 0)
		    xalloc_die ();
		  print_extra_number = !STREQ (x0_str, x_str);
		  free (x0_str);
		}

	      free (x_str);
	      if (! print_extra_number)
		break;
	    }

	  fputs (separator, stdout);
	}

      fputs (terminator, stdout);
    }
}

/* Return the default format given FIRST, STEP, and LAST.  */
static char const *
get_default_format (operand first, operand step, operand last)
{
  static char format_buf[sizeof "%0.Lf" + 2 * INT_STRLEN_BOUND (int)];

  int prec = MAX (first.precision, step.precision);

  if (prec != INT_MAX && last.precision != INT_MAX)
    {
      if (equal_width)
	{
	  /* increase first_width by any increased precision in step */
	  size_t first_width = first.width + (prec - first.precision);
	  /* adjust last_width to use precision from first/step */
	  size_t last_width = last.width + (prec - last.precision);
	  if (last.precision && prec == 0)
	    last_width--;  /* don't include space for '.' */
	  size_t width = MAX (first_width, last_width);
	  if (width <= INT_MAX)
	    {
	      int w = width;
	      sprintf (format_buf, "%%0%d.%dLf", w, prec);
	      return format_buf;
	    }
	}
      else
	{
	  sprintf (format_buf, "%%.%dLf", prec);
	  return format_buf;
	}
    }

  return "%Lg";
}

int
main (int argc, char **argv)
{
  int optc;
  operand first = { 1, 1, 0 };
  operand step = { 1, 1, 0 };
  operand last;
  struct layout layout = { 0, 0 };

  /* The printf(3) format used for output.  */
  char const *format_str = NULL;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  equal_width = false;
  separator = "\n";

  /* We have to handle negative numbers in the command line but this
     conflicts with the command line arguments.  So explicitly check first
     whether the next argument looks like a negative number.  */
  while (optind < argc)
    {
      if (argv[optind][0] == '-'
	  && ((optc = argv[optind][1]) == '.' || ISDIGIT (optc)))
	{
	  /* means negative number */
	  break;
	}

      optc = getopt_long (argc, argv, "+f:s:w", long_options, NULL);
      if (optc == -1)
	break;

      switch (optc)
	{
	case 'f':
	  format_str = optarg;
	  break;

	case 's':
	  separator = optarg;
	  break;

	case 'w':
	  equal_width = true;
	  break;

	case_GETOPT_HELP_CHAR;

	case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);

	default:
	  usage (EXIT_FAILURE);
	}
    }

  if (argc - optind < 1)
    {
      error (0, 0, _("missing operand"));
      usage (EXIT_FAILURE);
    }

  if (3 < argc - optind)
    {
      error (0, 0, _("extra operand %s"), quote (argv[optind + 3]));
      usage (EXIT_FAILURE);
    }

  if (format_str)
    {
      validate_format (format_str);
      char const *f = long_double_format (format_str, &layout);
      if (! f)
	{
	  error (0, 0, _("invalid format string: %s"), quote (format_str));
	  usage (EXIT_FAILURE);
	}
      format_str = f;
    }

  last = scan_arg (argv[optind++]);

  if (optind < argc)
    {
      first = last;
      last = scan_arg (argv[optind++]);

      if (optind < argc)
	{
	  step = last;
	  last = scan_arg (argv[optind++]);
	}
    }

  if (format_str != NULL && equal_width)
    {
      error (0, 0, _("\
format string may not be specified when printing equal width strings"));
      usage (EXIT_FAILURE);
    }

  if (format_str == NULL)
    format_str = get_default_format (first, step, last);

  print_numbers (format_str, layout, first.value, step.value, last.value);

  exit (EXIT_SUCCESS);
}