/* SPDX-FileCopyrightText: 2016 - Matthias Clasen <mclasen@redhat.com>
 * SPDX-FileCopyrightText: 2020 - Sébastien Wilmet <swilmet@gnome.org>
 * SPDX-License-Identifier: LGPL-3.0-or-later
 */

/**
 * SECTION:pango
 * @Title: TeplPango
 * @Short_description: Pango utility functions
 *
 * Utility functions related to the Pango library.
 */

/* The code is taken from pango_font_description_to_css(), gtkfontbutton.c, GTK. */

#include "tepl-pango.h"

static void
add_css_variations (GString    *s,
                    const char *variations)
{
  const char *p;
  const char *sep = "";

  if (variations == NULL || variations[0] == '\0')
    {
      g_string_append (s, "normal");
      return;
    }

  p = variations;
  while (p && *p)
    {
      const char *start;
      const char *end, *end2;
      double value;
      char name[5];

      while (g_ascii_isspace (*p)) p++;

      start = p;
      end = strchr (p, ',');
      if (end && (end - p < 6))
        goto skip;

      name[0] = p[0];
      name[1] = p[1];
      name[2] = p[2];
      name[3] = p[3];
      name[4] = '\0';

      p += 4;
      while (g_ascii_isspace (*p)) p++;
      if (*p == '=') p++;

      if (p - start < 5)
        goto skip;

      value = g_ascii_strtod (p, (char **) &end2);

      while (end2 && g_ascii_isspace (*end2)) end2++;

      if (end2 && (*end2 != ',' && *end2 != '\0'))
        goto skip;

      g_string_append_printf (s, "%s\"%s\" %g", sep, name, value);
      sep = ", ";

skip:
      p = end ? end + 1 : NULL;
    }
}

/**
 * tepl_pango_font_description_to_css:
 * @desc: a #PangoFontDescription.
 *
 * This function will generate CSS suitable for the GTK CSS engine based on the
 * properties of the #PangoFontDescription.
 *
 * The returned string contains only the CSS declarations, it is not a complete
 * CSS rule set. So the selector and curly braces are not present. Each
 * declaration, including the last one, ends with a semicolon.
 *
 * See also tepl_utils_override_font_description() and
 * tepl_utils_override_font_string().
 *
 * Returns: (transfer full): A newly allocated string containing the CSS
 *   describing the font description. Free with g_free() when no longer needed.
 * Since: 6.0
 */
gchar *
tepl_pango_font_description_to_css (const PangoFontDescription *desc)
{
  GString *s;
  PangoFontMask set;

  g_return_val_if_fail (desc != NULL, NULL);

  s = g_string_new ("");

  set = pango_font_description_get_set_fields (desc);
  if (set & PANGO_FONT_MASK_FAMILY)
    {
      g_string_append (s, "font-family: \"");
      g_string_append (s, pango_font_description_get_family (desc));
      g_string_append (s, "\"; ");
    }
  if (set & PANGO_FONT_MASK_STYLE)
    {
      switch (pango_font_description_get_style (desc))
        {
        case PANGO_STYLE_NORMAL:
          g_string_append (s, "font-style: normal; ");
          break;
        case PANGO_STYLE_OBLIQUE:
          g_string_append (s, "font-style: oblique; ");
          break;
        case PANGO_STYLE_ITALIC:
          g_string_append (s, "font-style: italic; ");
          break;
        default:
          break;
        }
    }
  if (set & PANGO_FONT_MASK_VARIANT)
    {
      switch (pango_font_description_get_variant (desc))
        {
        case PANGO_VARIANT_NORMAL:
          g_string_append (s, "font-variant: normal; ");
          break;
        case PANGO_VARIANT_SMALL_CAPS:
          g_string_append (s, "font-variant: small-caps; ");
          break;
        /* Currently the GTK 3 CSS engine only supports CSS2 values for the
         * font-variant property.
         */
        case PANGO_VARIANT_ALL_SMALL_CAPS:
        case PANGO_VARIANT_PETITE_CAPS:
        case PANGO_VARIANT_ALL_PETITE_CAPS:
        case PANGO_VARIANT_UNICASE:
        case PANGO_VARIANT_TITLE_CAPS:
        default:
          break;
        }
    }
  if (set & PANGO_FONT_MASK_WEIGHT)
    {
      switch (pango_font_description_get_weight (desc))
        {
        case PANGO_WEIGHT_THIN:
          g_string_append (s, "font-weight: 100; ");
          break;
        case PANGO_WEIGHT_ULTRALIGHT:
          g_string_append (s, "font-weight: 200; ");
          break;
        case PANGO_WEIGHT_LIGHT:
        case PANGO_WEIGHT_SEMILIGHT:
          g_string_append (s, "font-weight: 300; ");
          break;
        case PANGO_WEIGHT_BOOK:
        case PANGO_WEIGHT_NORMAL:
          g_string_append (s, "font-weight: 400; ");
          break;
        case PANGO_WEIGHT_MEDIUM:
          g_string_append (s, "font-weight: 500; ");
          break;
        case PANGO_WEIGHT_SEMIBOLD:
          g_string_append (s, "font-weight: 600; ");
          break;
        case PANGO_WEIGHT_BOLD:
          g_string_append (s, "font-weight: 700; ");
          break;
        case PANGO_WEIGHT_ULTRABOLD:
          g_string_append (s, "font-weight: 800; ");
          break;
        case PANGO_WEIGHT_HEAVY:
        case PANGO_WEIGHT_ULTRAHEAVY:
          g_string_append (s, "font-weight: 900; ");
          break;
        default:
          break;
        }
    }
  if (set & PANGO_FONT_MASK_STRETCH)
    {
      switch (pango_font_description_get_stretch (desc))
        {
        case PANGO_STRETCH_ULTRA_CONDENSED:
          g_string_append (s, "font-stretch: ultra-condensed; ");
          break;
        case PANGO_STRETCH_EXTRA_CONDENSED:
          g_string_append (s, "font-stretch: extra-condensed; ");
          break;
        case PANGO_STRETCH_CONDENSED:
          g_string_append (s, "font-stretch: condensed; ");
          break;
        case PANGO_STRETCH_SEMI_CONDENSED:
          g_string_append (s, "font-stretch: semi-condensed; ");
          break;
        case PANGO_STRETCH_NORMAL:
          g_string_append (s, "font-stretch: normal; ");
          break;
        case PANGO_STRETCH_SEMI_EXPANDED:
          g_string_append (s, "font-stretch: semi-expanded; ");
          break;
        case PANGO_STRETCH_EXPANDED:
          g_string_append (s, "font-stretch: expanded; ");
          break;
        case PANGO_STRETCH_EXTRA_EXPANDED:
          break;
        case PANGO_STRETCH_ULTRA_EXPANDED:
          g_string_append (s, "font-stretch: ultra-expanded; ");
          break;
        default:
          break;
        }
    }
  if (set & PANGO_FONT_MASK_SIZE)
    {
      g_string_append_printf (s, "font-size: %dpt; ", pango_font_description_get_size (desc) / PANGO_SCALE);
    }

  if (set & PANGO_FONT_MASK_VARIATIONS)
    {
      const char *variations;

      g_string_append (s, "font-variation-settings: ");
      variations = pango_font_description_get_variations (desc);
      add_css_variations (s, variations);
      g_string_append (s, "; ");
    }

  return g_string_free (s, FALSE);
}
