/* Graphical symbols.

   Copyright (C) 2020 Free Software Foundation, Inc.

   This file is part of Bison, the GNU Compiler Compiler.

   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/>.  */

#include <config.h>

#include "glyphs.h"

#include <assert.h>
#include <attribute.h>
#include <stdbool.h>
#include <string.h>
#include <mbswidth.h>
#include <unicodeio.h>

// In gnulib/lib/unicodeio.h unicode_to_mb uses a buffer of 25 bytes.
typedef char glyph_buffer_t[26];


static glyph_buffer_t arrow_buf;
const char *arrow;
int arrow_width;

static glyph_buffer_t down_arrow_buf;
const char *down_arrow;
int down_arrow_width;

static glyph_buffer_t dot_buf;
const char *dot;
int dot_width;

static glyph_buffer_t empty_buf;
const char *empty;
int empty_width;

const char *derivation_separator = " ";
int derivation_separator_width = 1;

typedef struct
{
  const char **glyph;
  char *buf;
  const char *fallback;
} callback_arg_t;


static long
on_success (const char *buf, size_t buflen, void *callback_arg)
{
  callback_arg_t *arg = (callback_arg_t *) callback_arg;
  assert (buflen + 1 < sizeof arg->buf);
  *stpncpy (arg->buf, buf, buflen) = '\0';
  return 1;
}

static long
on_failure (unsigned code MAYBE_UNUSED, const char *msg MAYBE_UNUSED,
            void *callback_arg)
{
  callback_arg_t *arg = (callback_arg_t *) callback_arg;
  assert (strlen (arg->fallback) + 1 < sizeof arg->buf);
  strcpy (arg->buf, arg->fallback);
  return 0;
}

static bool
glyph_set (const char **glyph,
           char buf[26], int *width,
           unsigned code, const char *fallback)
{
  callback_arg_t arg = { glyph, buf, fallback };
  int res = unicode_to_mb (code, on_success, on_failure, &arg);
  *glyph = buf;
  *width = mbswidth (*glyph, 0);
  return res;
}

void
glyphs_init (void)
{
  glyph_set (&arrow,      arrow_buf,      &arrow_width,      0x2192, "->");
  glyph_set (&dot,        dot_buf,        &dot_width,        0x2022, ".");
  glyph_set (&down_arrow, down_arrow_buf, &down_arrow_width, 0x21b3, "`->");
  glyph_set (&empty,      empty_buf,      &empty_width,      0x03b5, "%empty");

  strncat (down_arrow_buf, " ", sizeof down_arrow_buf - strlen (down_arrow_buf) - 1);
  down_arrow_width += 1;
}