// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ppapi/shared_impl/private/ppb_browser_font_trusted_shared.h"

#include "base/string_util.h"
#include "base/utf_string_conversions.h"
#include "ppapi/c/dev/ppb_font_dev.h"
#include "ppapi/shared_impl/ppapi_preferences.h"
#include "ppapi/shared_impl/var.h"
#include "ppapi/thunk/enter.h"
#include "ppapi/thunk/ppb_image_data_api.h"
#include "ppapi/thunk/thunk.h"
#include "skia/ext/platform_canvas.h"
#include "third_party/skia/include/core/SkRect.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebCanvas.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebFloatPoint.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebFloatRect.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebRect.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/WebFont.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/WebFontDescription.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/WebTextRun.h"

using ppapi::StringVar;
using ppapi::thunk::EnterResourceNoLock;
using ppapi::thunk::PPB_ImageData_API;
using WebKit::WebFloatPoint;
using WebKit::WebFloatRect;
using WebKit::WebFont;
using WebKit::WebFontDescription;
using WebKit::WebRect;
using WebKit::WebTextRun;
using WebKit::WebCanvas;

namespace ppapi {

namespace {

bool PPTextRunToWebTextRun(const PP_BrowserFont_Trusted_TextRun& text,
                           WebTextRun* run) {
  StringVar* text_string = StringVar::FromPPVar(text.text);
  if (!text_string)
    return false;

  *run = WebTextRun(UTF8ToUTF16(text_string->value()),
                    PP_ToBool(text.rtl),
                    PP_ToBool(text.override_direction));
  return true;
}

// The PP_* version lacks "None", so is just one value shifted from the
// WebFontDescription version. These values are checked in
// PPFontDescToWebFontDesc to make sure the conversion is correct. This is a
// macro so it can also be used in the COMPILE_ASSERTS.
#define PP_FAMILY_TO_WEB_FAMILY(f) \
  static_cast<WebFontDescription::GenericFamily>(f + 1)

// Assumes the given PP_FontDescription has been validated.
WebFontDescription PPFontDescToWebFontDesc(
    const PP_BrowserFont_Trusted_Description& font,
    const Preferences& prefs) {
  // Verify that the enums match so we can just static cast.
  COMPILE_ASSERT(static_cast<int>(WebFontDescription::Weight100) ==
                 static_cast<int>(PP_BROWSERFONT_TRUSTED_WEIGHT_100),
                 FontWeight100);
  COMPILE_ASSERT(static_cast<int>(WebFontDescription::Weight900) ==
                 static_cast<int>(PP_BROWSERFONT_TRUSTED_WEIGHT_900),
                 FontWeight900);
  COMPILE_ASSERT(WebFontDescription::GenericFamilyStandard ==
                 PP_FAMILY_TO_WEB_FAMILY(PP_FONTFAMILY_DEFAULT),
                 StandardFamily);
  COMPILE_ASSERT(WebFontDescription::GenericFamilySerif ==
                 PP_FAMILY_TO_WEB_FAMILY(PP_FONTFAMILY_SERIF),
                 SerifFamily);
  COMPILE_ASSERT(WebFontDescription::GenericFamilySansSerif ==
                 PP_FAMILY_TO_WEB_FAMILY(PP_FONTFAMILY_SANSSERIF),
                 SansSerifFamily);
  COMPILE_ASSERT(WebFontDescription::GenericFamilyMonospace ==
                 PP_FAMILY_TO_WEB_FAMILY(PP_FONTFAMILY_MONOSPACE),
                 MonospaceFamily);

  StringVar* face_name = StringVar::FromPPVar(font.face);  // Possibly null.

  WebFontDescription result;
  string16 resolved_family;
  if (!face_name || face_name->value().empty()) {
    // Resolve the generic family.
    switch (font.family) {
      case PP_BROWSERFONT_TRUSTED_FAMILY_SERIF:
        resolved_family = prefs.serif_font_family;
        break;
      case PP_BROWSERFONT_TRUSTED_FAMILY_SANSSERIF:
        resolved_family = prefs.sans_serif_font_family;
        break;
      case PP_BROWSERFONT_TRUSTED_FAMILY_MONOSPACE:
        resolved_family = prefs.fixed_font_family;
        break;
      case PP_BROWSERFONT_TRUSTED_FAMILY_DEFAULT:
      default:
        resolved_family = prefs.standard_font_family;
        break;
    }
  } else {
    // Use the exact font.
    resolved_family = UTF8ToUTF16(face_name->value());
  }
  result.family = resolved_family;

  result.genericFamily = PP_FAMILY_TO_WEB_FAMILY(font.family);

  if (font.size == 0) {
    // Resolve the default font size, using the resolved family to see if
    // we should use the fixed or regular font size. It's difficult at this
    // level to detect if the requested font is fixed width, so we only apply
    // the alternate font size to the default fixed font family.
    if (StringToLowerASCII(resolved_family) ==
        StringToLowerASCII(prefs.fixed_font_family))
      result.size = static_cast<float>(prefs.default_fixed_font_size);
    else
      result.size = static_cast<float>(prefs.default_font_size);
  } else {
    // Use the exact size.
    result.size = static_cast<float>(font.size);
  }

  result.italic = font.italic != PP_FALSE;
  result.smallCaps = font.small_caps != PP_FALSE;
  result.weight = static_cast<WebFontDescription::Weight>(font.weight);
  result.letterSpacing = static_cast<short>(font.letter_spacing);
  result.wordSpacing = static_cast<short>(font.word_spacing);
  return result;
}

}  // namespace

// static
bool PPB_BrowserFont_Trusted_Shared::IsPPFontDescriptionValid(
    const PP_BrowserFont_Trusted_Description& desc) {
  // Check validity of string. We can't check the actual text since we could
  // be on the wrong thread and don't know if we're in the plugin or the host.
  if (desc.face.type != PP_VARTYPE_STRING &&
      desc.face.type != PP_VARTYPE_UNDEFINED)
    return false;

  // Check enum ranges.
  if (static_cast<int>(desc.family) < PP_BROWSERFONT_TRUSTED_FAMILY_DEFAULT ||
      static_cast<int>(desc.family) > PP_BROWSERFONT_TRUSTED_FAMILY_MONOSPACE)
    return false;
  if (static_cast<int>(desc.weight) < PP_BROWSERFONT_TRUSTED_WEIGHT_100 ||
      static_cast<int>(desc.weight) > PP_BROWSERFONT_TRUSTED_WEIGHT_900)
    return false;

  // Check for excessive sizes which may cause layout to get confused.
  if (desc.size > 200)
    return false;

  return true;
}

// static
PP_Resource PPB_BrowserFont_Trusted_Shared::Create(
    ResourceObjectType type,
    PP_Instance instance,
    const PP_BrowserFont_Trusted_Description& description,
    const Preferences& prefs) {
  if (!PPB_BrowserFont_Trusted_Shared::IsPPFontDescriptionValid(description))
    return 0;
  return (new PPB_BrowserFont_Trusted_Shared(type, instance,
                                             description,
                                             prefs))->GetReference();
}

PPB_BrowserFont_Trusted_Shared::PPB_BrowserFont_Trusted_Shared(
    ResourceObjectType type,
    PP_Instance instance,
    const PP_BrowserFont_Trusted_Description& desc,
    const Preferences& prefs)
    : Resource(type, instance),
      font_(WebFont::create(PPFontDescToWebFontDesc(desc, prefs))) {
}

PPB_BrowserFont_Trusted_Shared::~PPB_BrowserFont_Trusted_Shared() {
}

thunk::PPB_BrowserFont_Trusted_API*
PPB_BrowserFont_Trusted_Shared::AsPPB_BrowserFont_Trusted_API() {
  return this;
}

PP_Bool PPB_BrowserFont_Trusted_Shared::Describe(
    PP_BrowserFont_Trusted_Description* description,
    PP_BrowserFont_Trusted_Metrics* metrics) {
  if (description->face.type != PP_VARTYPE_UNDEFINED)
    return PP_FALSE;

  // While converting the other way in PPFontDescToWebFontDesc we validated
  // that the enums can be casted.
  WebFontDescription web_desc = font_->fontDescription();
  description->face = StringVar::StringToPPVar(UTF16ToUTF8(web_desc.family));
  description->family =
      static_cast<PP_BrowserFont_Trusted_Family>(web_desc.genericFamily);
  description->size = static_cast<uint32_t>(web_desc.size);
  description->weight = static_cast<PP_BrowserFont_Trusted_Weight>(
      web_desc.weight);
  description->italic = web_desc.italic ? PP_TRUE : PP_FALSE;
  description->small_caps = web_desc.smallCaps ? PP_TRUE : PP_FALSE;
  description->letter_spacing = static_cast<int32_t>(web_desc.letterSpacing);
  description->word_spacing = static_cast<int32_t>(web_desc.wordSpacing);

  metrics->height = font_->height();
  metrics->ascent = font_->ascent();
  metrics->descent = font_->descent();
  metrics->line_spacing = font_->lineSpacing();
  metrics->x_height = static_cast<int32_t>(font_->xHeight());

  // Convert the string.
  return PP_TRUE;
}

PP_Bool PPB_BrowserFont_Trusted_Shared::DrawTextAt(
    PP_Resource image_data,
    const PP_BrowserFont_Trusted_TextRun* text,
    const PP_Point* position,
    uint32_t color,
    const PP_Rect* clip,
    PP_Bool image_data_is_opaque) {
  PP_Bool result = PP_FALSE;
  // Get and map the image data we're painting to.
  EnterResourceNoLock<PPB_ImageData_API> enter(image_data, true);
  if (enter.failed())
    return result;

  PPB_ImageData_API* image = static_cast<PPB_ImageData_API*>(
      enter.object());
  skia::PlatformCanvas* canvas = image->GetPlatformCanvas();
  bool needs_unmapping = false;
  if (!canvas) {
    needs_unmapping = true;
    image->Map();
    canvas = image->GetPlatformCanvas();
    if (!canvas)
      return result;  // Failure mapping.
  }

  DrawTextToCanvas(canvas, *text, position, color, clip, image_data_is_opaque);

  if (needs_unmapping)
    image->Unmap();
  return PP_TRUE;
}

int32_t PPB_BrowserFont_Trusted_Shared::MeasureText(
    const PP_BrowserFont_Trusted_TextRun* text) {
  WebTextRun run;
  if (!PPTextRunToWebTextRun(*text, &run))
    return -1;
  return font_->calculateWidth(run);
}

uint32_t PPB_BrowserFont_Trusted_Shared::CharacterOffsetForPixel(
    const PP_BrowserFont_Trusted_TextRun* text,
    int32_t pixel_position) {
  WebTextRun run;
  if (!PPTextRunToWebTextRun(*text, &run))
    return -1;
  return static_cast<uint32_t>(font_->offsetForPosition(
      run, static_cast<float>(pixel_position)));
}

int32_t PPB_BrowserFont_Trusted_Shared::PixelOffsetForCharacter(
    const PP_BrowserFont_Trusted_TextRun* text,
    uint32_t char_offset) {
  WebTextRun run;
  if (!PPTextRunToWebTextRun(*text, &run))
    return -1;
  if (char_offset >= run.text.length())
    return -1;

  WebFloatRect rect = font_->selectionRectForText(
      run, WebFloatPoint(0.0f, 0.0f), font_->height(), 0, char_offset);
  return static_cast<int>(rect.width);
}

void PPB_BrowserFont_Trusted_Shared::DrawTextToCanvas(
    skia::PlatformCanvas* destination,
    const PP_BrowserFont_Trusted_TextRun& text,
    const PP_Point* position,
    uint32_t color,
    const PP_Rect* clip,
    PP_Bool image_data_is_opaque) {
  WebTextRun run;
  if (!PPTextRunToWebTextRun(text, &run))
    return;

  // Convert position and clip.
  WebFloatPoint web_position(static_cast<float>(position->x),
                             static_cast<float>(position->y));
  WebRect web_clip;
  if (!clip) {
    // Use entire canvas. SkCanvas doesn't have a size on it, so we just use
    // the current clip bounds.
    SkRect skclip;
    destination->getClipBounds(&skclip);
    web_clip = WebRect(skclip.fLeft, skclip.fTop, skclip.fRight - skclip.fLeft,
                       skclip.fBottom - skclip.fTop);
  } else {
    web_clip = WebRect(clip->point.x, clip->point.y,
                       clip->size.width, clip->size.height);
  }

#if WEBKIT_USING_SKIA
  WebCanvas* canvas = destination;
#elif WEBKIT_USING_CG
  WebCanvas* canvas = skia::GetBitmapContext(skia::GetTopDevice(*destination));
#else
  NOTIMPLEMENTED();
  return;
#endif
  font_->drawText(canvas, run, web_position, color, web_clip,
                  PP_ToBool(image_data_is_opaque));
}

}  // namespace ppapi