/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsFont.h"
#include "gfxFont.h"                    // for gfxFontStyle
#include "gfxFontFeatures.h"            // for gfxFontFeature, etc
#include "gfxFontUtils.h"               // for TRUETYPE_TAG
#include "nsCRT.h"                      // for nsCRT
#include "nsDebug.h"                    // for NS_ASSERTION
#include "nsISupports.h"
#include "nsUnicharUtils.h"
#include "nscore.h"                     // for char16_t
#include "mozilla/ArrayUtils.h"
#include "mozilla/gfx/2D.h"

using namespace mozilla;

nsFont::nsFont(const FontFamilyList& aFontlist, nscoord aSize)
  : fontlist(aFontlist)
  , size(aSize)
{
}

nsFont::nsFont(FontFamilyType aGenericType, nscoord aSize)
  : fontlist(aGenericType)
  , size(aSize)
{
}

nsFont::nsFont(const nsFont& aOther) = default;

nsFont::nsFont()
{
}

nsFont::~nsFont()
{
}

bool nsFont::Equals(const nsFont& aOther) const
{
  return CalcDifference(aOther) == MaxDifference::eNone;
}

nsFont::MaxDifference
nsFont::CalcDifference(const nsFont& aOther) const
{
  if ((style != aOther.style) ||
      (systemFont != aOther.systemFont) ||
      (weight != aOther.weight) ||
      (stretch != aOther.stretch) ||
      (size != aOther.size) ||
      (sizeAdjust != aOther.sizeAdjust) ||
      (fontlist != aOther.fontlist) ||
      (kerning != aOther.kerning) ||
      (synthesis != aOther.synthesis) ||
      (fontFeatureSettings != aOther.fontFeatureSettings) ||
      (fontVariationSettings != aOther.fontVariationSettings) ||
      (languageOverride != aOther.languageOverride) ||
      (variantAlternates != aOther.variantAlternates) ||
      (variantCaps != aOther.variantCaps) ||
      (variantEastAsian != aOther.variantEastAsian) ||
      (variantLigatures != aOther.variantLigatures) ||
      (variantNumeric != aOther.variantNumeric) ||
      (variantPosition != aOther.variantPosition) ||
      (variantWidth != aOther.variantWidth) ||
      (alternateValues != aOther.alternateValues) ||
      (featureValueLookup != aOther.featureValueLookup)) {
    return MaxDifference::eLayoutAffecting;
  }

  if ((smoothing != aOther.smoothing) ||
      (fontSmoothingBackgroundColor != aOther.fontSmoothingBackgroundColor)) {
    return MaxDifference::eVisual;
  }

  return MaxDifference::eNone;
}

nsFont& nsFont::operator=(const nsFont& aOther) = default;

void
nsFont::CopyAlternates(const nsFont& aOther)
{
  variantAlternates = aOther.variantAlternates;
  alternateValues = aOther.alternateValues;
  featureValueLookup = aOther.featureValueLookup;
}

// mapping from bitflag to font feature tag/value pair
//
// these need to be kept in sync with the constants listed
// in gfxFontConstants.h (e.g. NS_FONT_VARIANT_EAST_ASIAN_JIS78)

// NS_FONT_VARIANT_EAST_ASIAN_xxx values
const gfxFontFeature eastAsianDefaults[] = {
  { TRUETYPE_TAG('j','p','7','8'), 1 },
  { TRUETYPE_TAG('j','p','8','3'), 1 },
  { TRUETYPE_TAG('j','p','9','0'), 1 },
  { TRUETYPE_TAG('j','p','0','4'), 1 },
  { TRUETYPE_TAG('s','m','p','l'), 1 },
  { TRUETYPE_TAG('t','r','a','d'), 1 },
  { TRUETYPE_TAG('f','w','i','d'), 1 },
  { TRUETYPE_TAG('p','w','i','d'), 1 },
  { TRUETYPE_TAG('r','u','b','y'), 1 }
};

static_assert(MOZ_ARRAY_LENGTH(eastAsianDefaults) ==
              NS_FONT_VARIANT_EAST_ASIAN_COUNT,
              "eastAsianDefaults[] should be correct");

// NS_FONT_VARIANT_LIGATURES_xxx values
const gfxFontFeature ligDefaults[] = {
  { TRUETYPE_TAG('l','i','g','a'), 0 },  // none value means all off
  { TRUETYPE_TAG('l','i','g','a'), 1 },
  { TRUETYPE_TAG('l','i','g','a'), 0 },
  { TRUETYPE_TAG('d','l','i','g'), 1 },
  { TRUETYPE_TAG('d','l','i','g'), 0 },
  { TRUETYPE_TAG('h','l','i','g'), 1 },
  { TRUETYPE_TAG('h','l','i','g'), 0 },
  { TRUETYPE_TAG('c','a','l','t'), 1 },
  { TRUETYPE_TAG('c','a','l','t'), 0 }
};

static_assert(MOZ_ARRAY_LENGTH(ligDefaults) ==
              NS_FONT_VARIANT_LIGATURES_COUNT,
              "ligDefaults[] should be correct");

// NS_FONT_VARIANT_NUMERIC_xxx values
const gfxFontFeature numericDefaults[] = {
  { TRUETYPE_TAG('l','n','u','m'), 1 },
  { TRUETYPE_TAG('o','n','u','m'), 1 },
  { TRUETYPE_TAG('p','n','u','m'), 1 },
  { TRUETYPE_TAG('t','n','u','m'), 1 },
  { TRUETYPE_TAG('f','r','a','c'), 1 },
  { TRUETYPE_TAG('a','f','r','c'), 1 },
  { TRUETYPE_TAG('z','e','r','o'), 1 },
  { TRUETYPE_TAG('o','r','d','n'), 1 }
};

static_assert(MOZ_ARRAY_LENGTH(numericDefaults) ==
              NS_FONT_VARIANT_NUMERIC_COUNT,
              "numericDefaults[] should be correct");

static void
AddFontFeaturesBitmask(uint32_t aValue, uint32_t aMin, uint32_t aMax,
                      const gfxFontFeature aFeatureDefaults[],
                      nsTArray<gfxFontFeature>& aFeaturesOut)

{
  uint32_t i, m;

  for (i = 0, m = aMin; m <= aMax; i++, m <<= 1) {
    if (m & aValue) {
      const gfxFontFeature& feature = aFeatureDefaults[i];
      aFeaturesOut.AppendElement(feature);
    }
  }
}

static uint32_t
FontFeatureTagForVariantWidth(uint32_t aVariantWidth)
{
  switch (aVariantWidth) {
    case NS_FONT_VARIANT_WIDTH_FULL:
      return TRUETYPE_TAG('f','w','i','d');
    case NS_FONT_VARIANT_WIDTH_HALF:
      return TRUETYPE_TAG('h','w','i','d');
    case NS_FONT_VARIANT_WIDTH_THIRD:
      return TRUETYPE_TAG('t','w','i','d');
    case NS_FONT_VARIANT_WIDTH_QUARTER:
      return TRUETYPE_TAG('q','w','i','d');
    default:
      return 0;
  }
}

void nsFont::AddFontFeaturesToStyle(gfxFontStyle *aStyle,
                                    bool aVertical) const
{
  // add in font-variant features
  gfxFontFeature setting;

  // -- kerning
  setting.mTag = aVertical ? TRUETYPE_TAG('v','k','r','n')
                           : TRUETYPE_TAG('k','e','r','n');
  switch (kerning) {
    case NS_FONT_KERNING_NONE:
      setting.mValue = 0;
      aStyle->featureSettings.AppendElement(setting);
      break;
    case NS_FONT_KERNING_NORMAL:
      setting.mValue = 1;
      aStyle->featureSettings.AppendElement(setting);
      break;
    default:
      // auto case implies use user agent default
      break;
  }

  // -- alternates
  if (variantAlternates & NS_FONT_VARIANT_ALTERNATES_HISTORICAL) {
    setting.mValue = 1;
    setting.mTag = TRUETYPE_TAG('h','i','s','t');
    aStyle->featureSettings.AppendElement(setting);
  }

  // -- copy font-specific alternate info into style
  //    (this will be resolved after font-matching occurs)
  aStyle->alternateValues.AppendElements(alternateValues);
  aStyle->featureValueLookup = featureValueLookup;

  // -- caps
  aStyle->variantCaps = variantCaps;

  // -- east-asian
  if (variantEastAsian) {
    AddFontFeaturesBitmask(variantEastAsian,
                           NS_FONT_VARIANT_EAST_ASIAN_JIS78,
                           NS_FONT_VARIANT_EAST_ASIAN_RUBY,
                           eastAsianDefaults, aStyle->featureSettings);
  }

  // -- ligatures
  if (variantLigatures) {
    AddFontFeaturesBitmask(variantLigatures,
                           NS_FONT_VARIANT_LIGATURES_NONE,
                           NS_FONT_VARIANT_LIGATURES_NO_CONTEXTUAL,
                           ligDefaults, aStyle->featureSettings);

    if (variantLigatures & NS_FONT_VARIANT_LIGATURES_COMMON) {
      // liga already enabled, need to enable clig also
      setting.mTag = TRUETYPE_TAG('c','l','i','g');
      setting.mValue = 1;
      aStyle->featureSettings.AppendElement(setting);
    } else if (variantLigatures & NS_FONT_VARIANT_LIGATURES_NO_COMMON) {
      // liga already disabled, need to disable clig also
      setting.mTag = TRUETYPE_TAG('c','l','i','g');
      setting.mValue = 0;
      aStyle->featureSettings.AppendElement(setting);
    } else if (variantLigatures & NS_FONT_VARIANT_LIGATURES_NONE) {
      // liga already disabled, need to disable dlig, hlig, calt, clig
      setting.mValue = 0;
      setting.mTag = TRUETYPE_TAG('d','l','i','g');
      aStyle->featureSettings.AppendElement(setting);
      setting.mTag = TRUETYPE_TAG('h','l','i','g');
      aStyle->featureSettings.AppendElement(setting);
      setting.mTag = TRUETYPE_TAG('c','a','l','t');
      aStyle->featureSettings.AppendElement(setting);
      setting.mTag = TRUETYPE_TAG('c','l','i','g');
      aStyle->featureSettings.AppendElement(setting);
    }
  }

  // -- numeric
  if (variantNumeric) {
    AddFontFeaturesBitmask(variantNumeric,
                           NS_FONT_VARIANT_NUMERIC_LINING,
                           NS_FONT_VARIANT_NUMERIC_ORDINAL,
                           numericDefaults, aStyle->featureSettings);
  }

  // -- position
  aStyle->variantSubSuper = variantPosition;

  // -- width
  setting.mTag = FontFeatureTagForVariantWidth(variantWidth);
  if (setting.mTag) {
    setting.mValue = 1;
    aStyle->featureSettings.AppendElement(setting);
  }

  // indicate common-path case when neither variantCaps or variantSubSuper are set
  aStyle->noFallbackVariantFeatures =
    (aStyle->variantCaps == NS_FONT_VARIANT_CAPS_NORMAL) &&
    (variantPosition == NS_FONT_VARIANT_POSITION_NORMAL);

  // add in features from font-feature-settings
  aStyle->featureSettings.AppendElements(fontFeatureSettings);

  // enable grayscale antialiasing for text
  if (smoothing == NS_FONT_SMOOTHING_GRAYSCALE) {
    aStyle->useGrayscaleAntialiasing = true;
  }

  aStyle->fontSmoothingBackgroundColor = fontSmoothingBackgroundColor;
}

void nsFont::AddFontVariationsToStyle(gfxFontStyle *aStyle) const
{
  // TODO: add variation settings from specific CSS properties
  // such as weight, width, optical-size

  // Add in arbitrary values from font-variation-settings
  aStyle->variationSettings.AppendElements(fontVariationSettings);
}