// Copyright (c) 2011 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 "chrome/browser/extensions/extension_tabs_module.h"

#include <algorithm>
#include <vector>

#include "base/base64.h"
#include "base/string_number_conversions.h"
#include "base/string_util.h"
#include "base/stringprintf.h"
#include "base/utf_string_conversions.h"
#include "chrome/browser/browser_list.h"
#include "chrome/browser/browser_window.h"
#include "chrome/browser/extensions/extension_function_dispatcher.h"
#include "chrome/browser/extensions/extension_host.h"
#include "chrome/browser/extensions/extension_service.h"
#include "chrome/browser/extensions/extension_tabs_module_constants.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/tabs/tab_strip_model.h"
#include "chrome/browser/ui/browser.h"
#include "chrome/browser/ui/browser_navigator.h"
#include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
#include "chrome/browser/ui/window_sizer.h"
#include "chrome/common/extensions/extension.h"
#include "chrome/common/extensions/extension_error_utils.h"
#include "chrome/common/pref_names.h"
#include "chrome/common/url_constants.h"
#include "content/browser/renderer_host/backing_store.h"
#include "content/browser/renderer_host/render_view_host.h"
#include "content/browser/renderer_host/render_view_host_delegate.h"
#include "content/browser/tab_contents/navigation_entry.h"
#include "content/browser/tab_contents/tab_contents.h"
#include "content/browser/tab_contents/tab_contents_view.h"
#include "content/common/notification_service.h"
#include "skia/ext/image_operations.h"
#include "skia/ext/platform_canvas.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "ui/gfx/codec/jpeg_codec.h"
#include "ui/gfx/codec/png_codec.h"

namespace keys = extension_tabs_module_constants;

const int CaptureVisibleTabFunction::kDefaultQuality = 90;

// Forward declare static helper functions defined below.

// |error_message| can optionally be passed in a will be set with an appropriate
// message if the window cannot be found by id.
static Browser* GetBrowserInProfileWithId(Profile* profile,
                                          const int window_id,
                                          bool include_incognito,
                                          std::string* error_message);

// |error_message| can optionally be passed in and will be set with an
// appropriate message if the tab cannot be found by id.
static bool GetTabById(int tab_id, Profile* profile,
                       bool include_incognito,
                       Browser** browser,
                       TabStripModel** tab_strip,
                       TabContentsWrapper** contents,
                       int* tab_index, std::string* error_message);

// Takes |url_string| and returns a GURL which is either valid and absolute
// or invalid. If |url_string| is not directly interpretable as a valid (it is
// likely a relative URL) an attempt is made to resolve it. |extension| is
// provided so it can be resolved relative to its extension base
// (chrome-extension://<id>/). Using the source frame url would be more correct,
// but because the api shipped with urls resolved relative to their extension
// base, we decided it wasn't worth breaking existing extensions to fix.
static GURL ResolvePossiblyRelativeURL(std::string url_string,
                                       const Extension* extension);

// Return the type name for a browser window type.
static std::string GetWindowTypeText(Browser::Type type);

int ExtensionTabUtil::GetWindowId(const Browser* browser) {
  return browser->session_id().id();
}

int ExtensionTabUtil::GetTabId(const TabContents* tab_contents) {
  return tab_contents->controller().session_id().id();
}

std::string ExtensionTabUtil::GetTabStatusText(bool is_loading) {
  return is_loading ? keys::kStatusValueLoading : keys::kStatusValueComplete;
}

int ExtensionTabUtil::GetWindowIdOfTab(const TabContents* tab_contents) {
  return tab_contents->controller().window_id().id();
}

DictionaryValue* ExtensionTabUtil::CreateTabValue(
    const TabContents* contents) {
  // Find the tab strip and index of this guy.
  TabStripModel* tab_strip = NULL;
  int tab_index;
  if (ExtensionTabUtil::GetTabStripModel(contents, &tab_strip, &tab_index))
    return ExtensionTabUtil::CreateTabValue(contents, tab_strip, tab_index);

  // Couldn't find it.  This can happen if the tab is being dragged.
  return ExtensionTabUtil::CreateTabValue(contents, NULL, -1);
}

ListValue* ExtensionTabUtil::CreateTabList(const Browser* browser) {
  ListValue* tab_list = new ListValue();
  TabStripModel* tab_strip = browser->tabstrip_model();
  for (int i = 0; i < tab_strip->count(); ++i) {
    tab_list->Append(ExtensionTabUtil::CreateTabValue(
        tab_strip->GetTabContentsAt(i)->tab_contents(), tab_strip, i));
  }

  return tab_list;
}

DictionaryValue* ExtensionTabUtil::CreateTabValue(
    const TabContents* contents, TabStripModel* tab_strip, int tab_index) {
  DictionaryValue* result = new DictionaryValue();
  result->SetInteger(keys::kIdKey, ExtensionTabUtil::GetTabId(contents));
  result->SetInteger(keys::kIndexKey, tab_index);
  result->SetInteger(keys::kWindowIdKey,
                     ExtensionTabUtil::GetWindowIdOfTab(contents));
  result->SetString(keys::kUrlKey, contents->GetURL().spec());
  result->SetString(keys::kStatusKey, GetTabStatusText(contents->is_loading()));
  result->SetBoolean(keys::kSelectedKey,
                     tab_strip && tab_index == tab_strip->selected_index());
  result->SetBoolean(keys::kPinnedKey,
                     tab_strip && tab_strip->IsTabPinned(tab_index));
  result->SetString(keys::kTitleKey, contents->GetTitle());
  result->SetBoolean(keys::kIncognitoKey,
                     contents->profile()->IsOffTheRecord());

  if (!contents->is_loading()) {
    NavigationEntry* entry = contents->controller().GetActiveEntry();
    if (entry) {
      if (entry->favicon().is_valid())
        result->SetString(keys::kFavIconUrlKey, entry->favicon().url().spec());
    }
  }

  return result;
}

// if |populate| is true, each window gets a list property |tabs| which contains
// fully populated tab objects.
DictionaryValue* ExtensionTabUtil::CreateWindowValue(const Browser* browser,
                                                     bool populate_tabs) {
  DCHECK(browser);
  DCHECK(browser->window());
  DictionaryValue* result = new DictionaryValue();
  result->SetInteger(keys::kIdKey, ExtensionTabUtil::GetWindowId(browser));
  result->SetBoolean(keys::kIncognitoKey,
                     browser->profile()->IsOffTheRecord());
  result->SetBoolean(keys::kFocusedKey, browser->window()->IsActive());
  gfx::Rect bounds;
  if (browser->window()->IsMaximized() || browser->window()->IsFullscreen())
    bounds = browser->window()->GetBounds();
  else
    bounds = browser->window()->GetRestoredBounds();

  result->SetInteger(keys::kLeftKey, bounds.x());
  result->SetInteger(keys::kTopKey, bounds.y());
  result->SetInteger(keys::kWidthKey, bounds.width());
  result->SetInteger(keys::kHeightKey, bounds.height());
  result->SetString(keys::kWindowTypeKey, GetWindowTypeText(browser->type()));

  if (populate_tabs) {
    result->Set(keys::kTabsKey, ExtensionTabUtil::CreateTabList(browser));
  }

  return result;
}

bool ExtensionTabUtil::GetTabStripModel(const TabContents* tab_contents,
                                        TabStripModel** tab_strip_model,
                                        int* tab_index) {
  DCHECK(tab_contents);
  DCHECK(tab_strip_model);
  DCHECK(tab_index);

  for (BrowserList::const_iterator it = BrowserList::begin();
      it != BrowserList::end(); ++it) {
    TabStripModel* tab_strip = (*it)->tabstrip_model();
    int index = tab_strip->GetWrapperIndex(tab_contents);
    if (index != -1) {
      *tab_strip_model = tab_strip;
      *tab_index = index;
      return true;
    }
  }

  return false;
}

bool ExtensionTabUtil::GetDefaultTab(Browser* browser,
                                     TabContentsWrapper** contents,
                                     int* tab_id) {
  DCHECK(browser);
  DCHECK(contents);
  DCHECK(tab_id);

  *contents = browser->GetSelectedTabContentsWrapper();
  if (*contents) {
    if (tab_id)
      *tab_id = ExtensionTabUtil::GetTabId((*contents)->tab_contents());
    return true;
  }

  return false;
}

bool ExtensionTabUtil::GetTabById(int tab_id, Profile* profile,
                                  bool include_incognito,
                                  Browser** browser,
                                  TabStripModel** tab_strip,
                                  TabContentsWrapper** contents,
                                  int* tab_index) {
  Profile* incognito_profile =
      include_incognito && profile->HasOffTheRecordProfile() ?
          profile->GetOffTheRecordProfile() : NULL;
  for (BrowserList::const_iterator iter = BrowserList::begin();
       iter != BrowserList::end(); ++iter) {
    Browser* target_browser = *iter;
    if (target_browser->profile() == profile ||
        target_browser->profile() == incognito_profile) {
      TabStripModel* target_tab_strip = target_browser->tabstrip_model();
      for (int i = 0; i < target_tab_strip->count(); ++i) {
        TabContentsWrapper* target_contents =
            target_tab_strip->GetTabContentsAt(i);
        if (target_contents->controller().session_id().id() == tab_id) {
          if (browser)
            *browser = target_browser;
          if (tab_strip)
            *tab_strip = target_tab_strip;
          if (contents)
            *contents = target_contents;
          if (tab_index)
            *tab_index = i;
          return true;
        }
      }
    }
  }
  return false;
}

// Windows ---------------------------------------------------------------------

bool GetWindowFunction::RunImpl() {
  int window_id;
  EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &window_id));

  Browser* browser = GetBrowserInProfileWithId(profile(), window_id,
                                               include_incognito(), &error_);
  if (!browser || !browser->window()) {
    error_ = ExtensionErrorUtils::FormatErrorMessage(
        keys::kWindowNotFoundError, base::IntToString(window_id));
    return false;
  }

  result_.reset(ExtensionTabUtil::CreateWindowValue(browser, false));
  return true;
}

bool GetCurrentWindowFunction::RunImpl() {
  Browser* browser = GetCurrentBrowser();
  if (!browser || !browser->window()) {
    error_ = keys::kNoCurrentWindowError;
    return false;
  }
  result_.reset(ExtensionTabUtil::CreateWindowValue(browser, false));
  return true;
}

bool GetLastFocusedWindowFunction::RunImpl() {
  Browser* browser = BrowserList::FindBrowserWithType(
      profile(), Browser::TYPE_ANY, include_incognito());
  if (!browser || !browser->window()) {
    error_ = keys::kNoLastFocusedWindowError;
    return false;
  }
  result_.reset(ExtensionTabUtil::CreateWindowValue(browser, false));
  return true;
}

bool GetAllWindowsFunction::RunImpl() {
  bool populate_tabs = false;
  if (HasOptionalArgument(0)) {
    DictionaryValue* args;
    EXTENSION_FUNCTION_VALIDATE(args_->GetDictionary(0, &args));

    if (args->HasKey(keys::kPopulateKey)) {
      EXTENSION_FUNCTION_VALIDATE(args->GetBoolean(keys::kPopulateKey,
          &populate_tabs));
    }
  }

  result_.reset(new ListValue());
  Profile* incognito_profile =
      include_incognito() && profile()->HasOffTheRecordProfile() ?
          profile()->GetOffTheRecordProfile() : NULL;
  for (BrowserList::const_iterator browser = BrowserList::begin();
    browser != BrowserList::end(); ++browser) {
      // Only examine browsers in the current profile that have windows.
      if (((*browser)->profile() == profile() ||
           (*browser)->profile() == incognito_profile) &&
          (*browser)->window()) {
        static_cast<ListValue*>(result_.get())->
          Append(ExtensionTabUtil::CreateWindowValue(*browser, populate_tabs));
      }
  }

  return true;
}

bool CreateWindowFunction::RunImpl() {
  DictionaryValue* args = NULL;
  std::vector<GURL> urls;
  TabContentsWrapper* contents = NULL;

  if (HasOptionalArgument(0))
    EXTENSION_FUNCTION_VALIDATE(args_->GetDictionary(0, &args));

  // Look for optional url.
  if (args) {
    if (args->HasKey(keys::kUrlKey)) {
      Value* url_value;
      std::vector<std::string> url_strings;
      args->Get(keys::kUrlKey, &url_value);

      // First, get all the URLs the client wants to open.
      if (url_value->IsType(Value::TYPE_STRING)) {
        std::string url_string;
        url_value->GetAsString(&url_string);
        url_strings.push_back(url_string);
      } else if (url_value->IsType(Value::TYPE_LIST)) {
        const ListValue* url_list = static_cast<const ListValue*>(url_value);
        for (size_t i = 0; i < url_list->GetSize(); ++i) {
          std::string url_string;
          EXTENSION_FUNCTION_VALIDATE(url_list->GetString(i, &url_string));
          url_strings.push_back(url_string);
        }
      }

      // Second, resolve, validate and convert them to GURLs.
      for (std::vector<std::string>::iterator i = url_strings.begin();
           i != url_strings.end(); ++i) {
        GURL url = ResolvePossiblyRelativeURL(*i, GetExtension());
        if (!url.is_valid()) {
          error_ = ExtensionErrorUtils::FormatErrorMessage(
              keys::kInvalidUrlError, *i);
          return false;
        }
        urls.push_back(url);
      }
    }
  }

  // Don't let the extension crash the browser or renderers.
  GURL browser_crash(chrome::kAboutBrowserCrash);
  GURL renderer_crash(chrome::kAboutCrashURL);
  if (std::find(urls.begin(), urls.end(), browser_crash) != urls.end() ||
      std::find(urls.begin(), urls.end(), renderer_crash) != urls.end()) {
    error_ = keys::kNoCrashBrowserError;
    return false;
  }

  // Look for optional tab id.
  if (args) {
    int tab_id;
    if (args->HasKey(keys::kTabIdKey)) {
      EXTENSION_FUNCTION_VALIDATE(args->GetInteger(keys::kTabIdKey, &tab_id));

      // Find the tab and detach it from the original window.
      Browser* source_browser = NULL;
      TabStripModel* source_tab_strip = NULL;
      int tab_index = -1;
      if (!GetTabById(tab_id, profile(), include_incognito(),
                      &source_browser, &source_tab_strip, &contents,
                      &tab_index, &error_))
        return false;
      contents = source_tab_strip->DetachTabContentsAt(tab_index);
      if (!contents) {
        error_ = ExtensionErrorUtils::FormatErrorMessage(
            keys::kTabNotFoundError, base::IntToString(tab_id));
        return false;
      }
    }
  }

  // Try to position the new browser relative its originating browser window.
  gfx::Rect  window_bounds;
  bool maximized;
  // The call offsets the bounds by kWindowTilePixels (defined in WindowSizer to
  // be 10)
  //
  // NOTE(rafaelw): It's ok if GetCurrentBrowser() returns NULL here.
  // GetBrowserWindowBounds will default to saved "default" values for the app.
  WindowSizer::GetBrowserWindowBounds(std::string(), gfx::Rect(),
                                      GetCurrentBrowser(), &window_bounds,
                                      &maximized);

  // Calculate popup bounds separately. In ChromiumOS the default is 0x0 which
  // indicates default window sizes in PanelBrowserView. In other OSs popups
  // use the same default bounds as windows.
  gfx::Rect popup_bounds;
#if !defined(OS_CHROMEOS)
  popup_bounds = window_bounds;  // Use window size as default for popups
#endif

  Profile* window_profile = profile();
  Browser::Type window_type = Browser::TYPE_NORMAL;

  if (args) {
    // Any part of the bounds can optionally be set by the caller.
    int bounds_val;
    if (args->HasKey(keys::kLeftKey)) {
      EXTENSION_FUNCTION_VALIDATE(args->GetInteger(keys::kLeftKey,
                                                   &bounds_val));
      window_bounds.set_x(bounds_val);
      popup_bounds.set_x(bounds_val);
    }

    if (args->HasKey(keys::kTopKey)) {
      EXTENSION_FUNCTION_VALIDATE(args->GetInteger(keys::kTopKey,
                                                   &bounds_val));
      window_bounds.set_y(bounds_val);
      popup_bounds.set_y(bounds_val);
    }

    if (args->HasKey(keys::kWidthKey)) {
      EXTENSION_FUNCTION_VALIDATE(args->GetInteger(keys::kWidthKey,
                                                   &bounds_val));
      window_bounds.set_width(bounds_val);
      popup_bounds.set_width(bounds_val);
    }

    if (args->HasKey(keys::kHeightKey)) {
      EXTENSION_FUNCTION_VALIDATE(args->GetInteger(keys::kHeightKey,
                                                   &bounds_val));
      window_bounds.set_height(bounds_val);
      popup_bounds.set_height(bounds_val);
    }

    bool incognito = false;
    if (args->HasKey(keys::kIncognitoKey)) {
      EXTENSION_FUNCTION_VALIDATE(args->GetBoolean(keys::kIncognitoKey,
                                                   &incognito));
      if (!profile_->GetPrefs()->GetBoolean(prefs::kIncognitoEnabled)) {
        error_ = keys::kIncognitoModeIsDisabled;
        return false;
      }

      if (incognito)
        window_profile = window_profile->GetOffTheRecordProfile();
    }

    std::string type_str;
    if (args->HasKey(keys::kWindowTypeKey)) {
      EXTENSION_FUNCTION_VALIDATE(args->GetString(keys::kWindowTypeKey,
                                                  &type_str));
      if (type_str == keys::kWindowTypeValueNormal) {
        window_type = Browser::TYPE_NORMAL;
      } else if (type_str == keys::kWindowTypeValuePopup) {
        window_type = Browser::TYPE_APP_POPUP;
      } else {
        EXTENSION_FUNCTION_VALIDATE(false);
      }
    }
  }

  Browser* new_window = Browser::CreateForType(window_type, window_profile);
  for (std::vector<GURL>::iterator i = urls.begin(); i != urls.end(); ++i)
    new_window->AddSelectedTabWithURL(*i, PageTransition::LINK);
  if (contents) {
    TabStripModel* target_tab_strip = new_window->tabstrip_model();
    target_tab_strip->InsertTabContentsAt(urls.size(), contents,
                                          TabStripModel::ADD_NONE);
  } else if (urls.empty()) {
    new_window->NewTab();
  }
  new_window->SelectNumberedTab(0);
  if (window_type & Browser::TYPE_POPUP)
    new_window->window()->SetBounds(popup_bounds);
  else
    new_window->window()->SetBounds(window_bounds);
  new_window->window()->Show();

  if (new_window->profile()->IsOffTheRecord() && !include_incognito()) {
    // Don't expose incognito windows if the extension isn't allowed.
    result_.reset(Value::CreateNullValue());
  } else {
    result_.reset(ExtensionTabUtil::CreateWindowValue(new_window, true));
  }

  return true;
}

bool UpdateWindowFunction::RunImpl() {
  int window_id;
  EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &window_id));
  DictionaryValue* update_props;
  EXTENSION_FUNCTION_VALIDATE(args_->GetDictionary(1, &update_props));

  Browser* browser = GetBrowserInProfileWithId(profile(), window_id,
                                               include_incognito(), &error_);
  if (!browser || !browser->window()) {
    error_ = ExtensionErrorUtils::FormatErrorMessage(
        keys::kWindowNotFoundError, base::IntToString(window_id));
    return false;
  }

  gfx::Rect bounds = browser->window()->GetRestoredBounds();
  bool set_bounds = false;
  // Any part of the bounds can optionally be set by the caller.
  int bounds_val;
  if (update_props->HasKey(keys::kLeftKey)) {
    EXTENSION_FUNCTION_VALIDATE(update_props->GetInteger(
        keys::kLeftKey,
        &bounds_val));
    bounds.set_x(bounds_val);
    set_bounds = true;
  }

  if (update_props->HasKey(keys::kTopKey)) {
    EXTENSION_FUNCTION_VALIDATE(update_props->GetInteger(
        keys::kTopKey,
        &bounds_val));
    bounds.set_y(bounds_val);
    set_bounds = true;
  }

  if (update_props->HasKey(keys::kWidthKey)) {
    EXTENSION_FUNCTION_VALIDATE(update_props->GetInteger(
        keys::kWidthKey,
        &bounds_val));
    bounds.set_width(bounds_val);
    set_bounds = true;
  }

  if (update_props->HasKey(keys::kHeightKey)) {
    EXTENSION_FUNCTION_VALIDATE(update_props->GetInteger(
        keys::kHeightKey,
        &bounds_val));
    bounds.set_height(bounds_val);
    set_bounds = true;
  }
  if (set_bounds)
    browser->window()->SetBounds(bounds);

  bool selected_val = false;
  if (update_props->HasKey(keys::kFocusedKey)) {
    EXTENSION_FUNCTION_VALIDATE(update_props->GetBoolean(
        keys::kFocusedKey, &selected_val));
    if (selected_val)
      browser->window()->Activate();
    else
      browser->window()->Deactivate();
  }

  result_.reset(ExtensionTabUtil::CreateWindowValue(browser, false));

  return true;
}

bool RemoveWindowFunction::RunImpl() {
  int window_id;
  EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &window_id));

  Browser* browser = GetBrowserInProfileWithId(profile(), window_id,
                                               include_incognito(), &error_);
  if (!browser)
    return false;

  // Don't let the extension remove the window if the user is dragging tabs
  // in that window.
  if (!browser->IsTabStripEditable()) {
    error_ = keys::kTabStripNotEditableError;
    return false;
  }

  browser->CloseWindow();

  return true;
}

// Tabs ------------------------------------------------------------------------

bool GetSelectedTabFunction::RunImpl() {
  Browser* browser;
  // windowId defaults to "current" window.
  int window_id = -1;

  if (HasOptionalArgument(0)) {
    EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &window_id));
    browser = GetBrowserInProfileWithId(profile(), window_id,
                                        include_incognito(), &error_);
  } else {
    browser = GetCurrentBrowser();
    if (!browser)
      error_ = keys::kNoCurrentWindowError;
  }
  if (!browser)
    return false;

  TabStripModel* tab_strip = browser->tabstrip_model();
  TabContentsWrapper* contents = tab_strip->GetSelectedTabContents();
  if (!contents) {
    error_ = keys::kNoSelectedTabError;
    return false;
  }
  result_.reset(ExtensionTabUtil::CreateTabValue(contents->tab_contents(),
      tab_strip,
      tab_strip->selected_index()));
  return true;
}

bool GetAllTabsInWindowFunction::RunImpl() {
  Browser* browser;
  // windowId defaults to "current" window.
  int window_id = -1;
  if (HasOptionalArgument(0)) {
    EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &window_id));
    browser = GetBrowserInProfileWithId(profile(), window_id,
                                        include_incognito(), &error_);
  } else {
    browser = GetCurrentBrowser();
    if (!browser)
      error_ = keys::kNoCurrentWindowError;
  }
  if (!browser)
    return false;

  result_.reset(ExtensionTabUtil::CreateTabList(browser));

  return true;
}

bool CreateTabFunction::RunImpl() {
  DictionaryValue* args;
  EXTENSION_FUNCTION_VALIDATE(args_->GetDictionary(0, &args));

  Browser *browser;
  // windowId defaults to "current" window.
  int window_id = -1;
  if (args->HasKey(keys::kWindowIdKey)) {
    EXTENSION_FUNCTION_VALIDATE(args->GetInteger(
        keys::kWindowIdKey, &window_id));
    browser = GetBrowserInProfileWithId(profile(), window_id,
                                        include_incognito(), &error_);
  } else {
    browser = GetCurrentBrowser();
    if (!browser)
      error_ = keys::kNoCurrentWindowError;
  }
  if (!browser)
    return false;

  // TODO(rafaelw): handle setting remaining tab properties:
  // -title
  // -favIconUrl

  std::string url_string;
  GURL url;
  if (args->HasKey(keys::kUrlKey)) {
    EXTENSION_FUNCTION_VALIDATE(args->GetString(keys::kUrlKey,
                                                &url_string));
    url = ResolvePossiblyRelativeURL(url_string, GetExtension());
    if (!url.is_valid()) {
      error_ = ExtensionErrorUtils::FormatErrorMessage(keys::kInvalidUrlError,
                                                       url_string);
      return false;
    }
  }

  // Don't let extensions crash the browser or renderers.
  if (url == GURL(chrome::kAboutBrowserCrash) ||
      url == GURL(chrome::kAboutCrashURL)) {
    error_ = keys::kNoCrashBrowserError;
    return false;
  }

  // Default to foreground for the new tab. The presence of 'selected' property
  // will override this default.
  bool selected = true;
  if (args->HasKey(keys::kSelectedKey))
    EXTENSION_FUNCTION_VALIDATE(args->GetBoolean(keys::kSelectedKey,
                                                 &selected));

  // Default to not pinning the tab. Setting the 'pinned' property to true
  // will override this default.
  bool pinned = false;
  if (args->HasKey(keys::kPinnedKey))
    EXTENSION_FUNCTION_VALIDATE(args->GetBoolean(keys::kPinnedKey, &pinned));

  // We can't load extension URLs into incognito windows unless the extension
  // uses split mode. Special case to fall back to a normal window.
  if (url.SchemeIs(chrome::kExtensionScheme) &&
      !GetExtension()->incognito_split_mode() &&
      browser->profile()->IsOffTheRecord()) {
    Profile* profile = browser->profile()->GetOriginalProfile();
    browser = BrowserList::FindBrowserWithType(profile,
                                               Browser::TYPE_NORMAL, false);
    if (!browser) {
      browser = Browser::Create(profile);
      browser->window()->Show();
    }
  }

  // If index is specified, honor the value, but keep it bound to
  // -1 <= index <= tab_strip->count() where -1 invokes the default behavior.
  int index = -1;
  if (args->HasKey(keys::kIndexKey))
    EXTENSION_FUNCTION_VALIDATE(args->GetInteger(keys::kIndexKey, &index));

  TabStripModel* tab_strip = browser->tabstrip_model();

  index = std::min(std::max(index, -1), tab_strip->count());

  int add_types = selected ? TabStripModel::ADD_SELECTED :
                             TabStripModel::ADD_NONE;
  add_types |= TabStripModel::ADD_FORCE_INDEX;
  if (pinned)
    add_types |= TabStripModel::ADD_PINNED;
  browser::NavigateParams params(browser, url, PageTransition::LINK);
  params.disposition = selected ? NEW_FOREGROUND_TAB : NEW_BACKGROUND_TAB;
  params.tabstrip_index = index;
  params.tabstrip_add_types = add_types;
  browser::Navigate(&params);

  if (selected)
    params.target_contents->view()->SetInitialFocus();

  // Return data about the newly created tab.
  if (has_callback()) {
    result_.reset(ExtensionTabUtil::CreateTabValue(
        params.target_contents->tab_contents(),
        params.browser->tabstrip_model(),
        params.browser->tabstrip_model()->GetIndexOfTabContents(
            params.target_contents)));
  }

  return true;
}

bool GetTabFunction::RunImpl() {
  int tab_id;
  EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &tab_id));

  TabStripModel* tab_strip = NULL;
  TabContentsWrapper* contents = NULL;
  int tab_index = -1;
  if (!GetTabById(tab_id, profile(), include_incognito(),
                  NULL, &tab_strip, &contents, &tab_index, &error_))
    return false;

  result_.reset(ExtensionTabUtil::CreateTabValue(contents->tab_contents(),
      tab_strip,
      tab_index));
  return true;
}

bool GetCurrentTabFunction::RunImpl() {
  DCHECK(dispatcher());

  TabContents* contents = dispatcher()->delegate()->associated_tab_contents();
  if (contents)
    result_.reset(ExtensionTabUtil::CreateTabValue(contents));

  return true;
}

bool UpdateTabFunction::RunImpl() {
  int tab_id;
  EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &tab_id));
  DictionaryValue* update_props;
  EXTENSION_FUNCTION_VALIDATE(args_->GetDictionary(1, &update_props));

  TabStripModel* tab_strip = NULL;
  TabContentsWrapper* contents = NULL;
  int tab_index = -1;
  if (!GetTabById(tab_id, profile(), include_incognito(),
                  NULL, &tab_strip, &contents, &tab_index, &error_))
    return false;

  NavigationController& controller = contents->controller();

  // TODO(rafaelw): handle setting remaining tab properties:
  // -title
  // -favIconUrl

  // Navigate the tab to a new location if the url different.
  std::string url_string;
  if (update_props->HasKey(keys::kUrlKey)) {
    EXTENSION_FUNCTION_VALIDATE(update_props->GetString(
        keys::kUrlKey, &url_string));
    GURL url = ResolvePossiblyRelativeURL(url_string, GetExtension());

    if (!url.is_valid()) {
      error_ = ExtensionErrorUtils::FormatErrorMessage(keys::kInvalidUrlError,
                                                       url_string);
      return false;
    }

    // Don't let the extension crash the browser or renderers.
    if (url == GURL(chrome::kAboutBrowserCrash) ||
        url == GURL(chrome::kAboutCrashURL)) {
      error_ = keys::kNoCrashBrowserError;
      return false;
    }

    // JavaScript URLs can do the same kinds of things as cross-origin XHR, so
    // we need to check host permissions before allowing them.
    if (url.SchemeIs(chrome::kJavaScriptScheme)) {
      if (!GetExtension()->CanExecuteScriptOnPage(
              contents->tab_contents()->GetURL(), NULL, &error_)) {
        return false;
      }

      // TODO(aa): How does controller queue URLs? Is there any chance that this
      // JavaScript URL will end up applying to something other than
      // controller->GetURL()?
    }

    controller.LoadURL(url, GURL(), PageTransition::LINK);

    // The URL of a tab contents never actually changes to a JavaScript URL, so
    // this check only makes sense in other cases.
    if (!url.SchemeIs(chrome::kJavaScriptScheme))
      DCHECK_EQ(url.spec(), contents->tab_contents()->GetURL().spec());
  }

  bool selected = false;
  // TODO(rafaelw): Setting |selected| from js doesn't make much sense.
  // Move tab selection management up to window.
  if (update_props->HasKey(keys::kSelectedKey)) {
    EXTENSION_FUNCTION_VALIDATE(update_props->GetBoolean(
        keys::kSelectedKey,
        &selected));
    if (selected) {
      if (tab_strip->selected_index() != tab_index) {
        tab_strip->SelectTabContentsAt(tab_index, false);
        DCHECK_EQ(contents, tab_strip->GetSelectedTabContents());
      }
      contents->tab_contents()->Focus();
    }
  }

  bool pinned = false;
  if (update_props->HasKey(keys::kPinnedKey)) {
    EXTENSION_FUNCTION_VALIDATE(update_props->GetBoolean(keys::kPinnedKey,
                                                         &pinned));
    tab_strip->SetTabPinned(tab_index, pinned);

    // Update the tab index because it may move when being pinned.
    tab_index = tab_strip->GetIndexOfTabContents(contents);
  }

  if (has_callback())
    result_.reset(ExtensionTabUtil::CreateTabValue(contents->tab_contents(),
        tab_strip,
        tab_index));

  return true;
}

bool MoveTabFunction::RunImpl() {
  int tab_id;
  EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &tab_id));
  DictionaryValue* update_props;
  EXTENSION_FUNCTION_VALIDATE(args_->GetDictionary(1, &update_props));

  int new_index;
  EXTENSION_FUNCTION_VALIDATE(update_props->GetInteger(
      keys::kIndexKey, &new_index));
  EXTENSION_FUNCTION_VALIDATE(new_index >= 0);

  Browser* source_browser = NULL;
  TabStripModel* source_tab_strip = NULL;
  TabContentsWrapper* contents = NULL;
  int tab_index = -1;
  if (!GetTabById(tab_id, profile(), include_incognito(),
                  &source_browser, &source_tab_strip, &contents,
                  &tab_index, &error_))
    return false;

  // Don't let the extension move the tab if the user is dragging tabs.
  if (!source_browser->IsTabStripEditable()) {
    error_ = keys::kTabStripNotEditableError;
    return false;
  }

  if (update_props->HasKey(keys::kWindowIdKey)) {
    Browser* target_browser;
    int window_id;
    EXTENSION_FUNCTION_VALIDATE(update_props->GetInteger(
        keys::kWindowIdKey, &window_id));
    target_browser = GetBrowserInProfileWithId(profile(), window_id,
                                               include_incognito(), &error_);
    if (!target_browser)
      return false;

    if (!target_browser->IsTabStripEditable()) {
      error_ = keys::kTabStripNotEditableError;
      return false;
    }

    if (target_browser->type() != Browser::TYPE_NORMAL) {
      error_ = keys::kCanOnlyMoveTabsWithinNormalWindowsError;
      return false;
    }

    if (target_browser->profile() != source_browser->profile()) {
      error_ = keys::kCanOnlyMoveTabsWithinSameProfileError;
      return false;
    }

    // If windowId is different from the current window, move between windows.
    if (ExtensionTabUtil::GetWindowId(target_browser) !=
        ExtensionTabUtil::GetWindowId(source_browser)) {
      TabStripModel* target_tab_strip = target_browser->tabstrip_model();
      contents = source_tab_strip->DetachTabContentsAt(tab_index);
      if (!contents) {
        error_ = ExtensionErrorUtils::FormatErrorMessage(
            keys::kTabNotFoundError, base::IntToString(tab_id));
        return false;
      }

      // Clamp move location to the last position.
      // This is ">" because it can append to a new index position.
      if (new_index > target_tab_strip->count())
        new_index = target_tab_strip->count();

      target_tab_strip->InsertTabContentsAt(new_index, contents,
                                            TabStripModel::ADD_NONE);

      if (has_callback())
        result_.reset(ExtensionTabUtil::CreateTabValue(contents->tab_contents(),
            target_tab_strip, new_index));

      return true;
    }
  }

  // Perform a simple within-window move.
  // Clamp move location to the last position.
  // This is ">=" because the move must be to an existing location.
  if (new_index >= source_tab_strip->count())
    new_index = source_tab_strip->count() - 1;

  if (new_index != tab_index)
    source_tab_strip->MoveTabContentsAt(tab_index, new_index, false);

  if (has_callback())
    result_.reset(ExtensionTabUtil::CreateTabValue(contents->tab_contents(),
        source_tab_strip,
        new_index));
  return true;
}


bool RemoveTabFunction::RunImpl() {
  int tab_id;
  EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &tab_id));

  Browser* browser = NULL;
  TabContentsWrapper* contents = NULL;
  if (!GetTabById(tab_id, profile(), include_incognito(),
                  &browser, NULL, &contents, NULL, &error_))
    return false;

  // Don't let the extension remove a tab if the user is dragging tabs around.
  if (!browser->IsTabStripEditable()) {
    error_ = keys::kTabStripNotEditableError;
    return false;
  }

  // Close the tab in this convoluted way, since there's a chance that the tab
  // is being dragged, or we're in some other nested event loop. This code path
  // should ensure that the tab is safely closed under such circumstances,
  // whereas |Browser::CloseTabContents()| does not.
  RenderViewHost* render_view_host = contents->render_view_host();
  render_view_host->delegate()->Close(render_view_host);
  return true;
}

bool CaptureVisibleTabFunction::RunImpl() {
  Browser* browser;
  // windowId defaults to "current" window.
  int window_id = -1;

  if (HasOptionalArgument(0)) {
    EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &window_id));
    browser = GetBrowserInProfileWithId(profile(), window_id,
                                        include_incognito(), &error_);
  } else {
    browser = GetCurrentBrowser();
  }

  if (!browser) {
    error_ = keys::kNoCurrentWindowError;
    return false;
  }

  image_format_ = FORMAT_JPEG;  // Default format is JPEG.
  image_quality_ = kDefaultQuality;  // Default quality setting.

  if (HasOptionalArgument(1)) {
    DictionaryValue* options;
    EXTENSION_FUNCTION_VALIDATE(args_->GetDictionary(1, &options));

    if (options->HasKey(keys::kFormatKey)) {
      std::string format;
      EXTENSION_FUNCTION_VALIDATE(
          options->GetString(keys::kFormatKey, &format));

      if (format == keys::kFormatValueJpeg) {
        image_format_ = FORMAT_JPEG;
      } else if (format == keys::kFormatValuePng) {
        image_format_ = FORMAT_PNG;
      } else {
        // Schema validation should make this unreachable.
        EXTENSION_FUNCTION_VALIDATE(0);
      }
    }

    if (options->HasKey(keys::kQualityKey)) {
      EXTENSION_FUNCTION_VALIDATE(
          options->GetInteger(keys::kQualityKey, &image_quality_));
    }
  }

  TabContents* tab_contents = browser->GetSelectedTabContents();
  if (!tab_contents) {
    error_ = keys::kInternalVisibleTabCaptureError;
    return false;
  }

  // captureVisibleTab() can return an image containing sensitive information
  // that the browser would otherwise protect.  Ensure the extension has
  // permission to do this.
  if (!GetExtension()->CanCaptureVisiblePage(tab_contents->GetURL(), &error_))
    return false;

  RenderViewHost* render_view_host = tab_contents->render_view_host();

  // If a backing store is cached for the tab we want to capture,
  // and it can be copied into a bitmap, then use it to generate the image.
  BackingStore* backing_store = render_view_host->GetBackingStore(false);
  if (backing_store && CaptureSnapshotFromBackingStore(backing_store))
    return true;

  // Ask the renderer for a snapshot of the tab.
  render_view_host->CaptureSnapshot();
  registrar_.Add(this,
                 NotificationType::TAB_SNAPSHOT_TAKEN,
                 NotificationService::AllSources());
  AddRef();  // Balanced in CaptureVisibleTabFunction::Observe().

  return true;
}

// Build the image of a tab's contents out of a backing store.
// This may fail if we can not copy a backing store into a bitmap.
// For example, some uncommon X11 visual modes are not supported by
// CopyFromBackingStore().
bool CaptureVisibleTabFunction::CaptureSnapshotFromBackingStore(
    BackingStore* backing_store) {

  skia::PlatformCanvas temp_canvas;
  if (!backing_store->CopyFromBackingStore(gfx::Rect(backing_store->size()),
                                           &temp_canvas)) {
    return false;
  }
  VLOG(1) << "captureVisibleTab() got image from backing store.";

  SendResultFromBitmap(
      temp_canvas.getTopPlatformDevice().accessBitmap(false));
  return true;
}

// If a backing store was not available in CaptureVisibleTabFunction::RunImpl,
// than the renderer was asked for a snapshot.  Listen for a notification
// that the snapshot is available.
void CaptureVisibleTabFunction::Observe(NotificationType type,
                                        const NotificationSource& source,
                                        const NotificationDetails& details) {
  DCHECK(type == NotificationType::TAB_SNAPSHOT_TAKEN);

  const SkBitmap *screen_capture = Details<const SkBitmap>(details).ptr();
  const bool error = screen_capture->empty();

  if (error) {
    error_ = keys::kInternalVisibleTabCaptureError;
    SendResponse(false);
  } else {
    VLOG(1) << "captureVisibleTab() got image from renderer.";
    SendResultFromBitmap(*screen_capture);
  }

  Release();  // Balanced in CaptureVisibleTabFunction::RunImpl().
}

// Turn a bitmap of the screen into an image, set that image as the result,
// and call SendResponse().
void CaptureVisibleTabFunction::SendResultFromBitmap(
    const SkBitmap& screen_capture) {
  scoped_refptr<RefCountedBytes> image_data(new RefCountedBytes);
  SkAutoLockPixels screen_capture_lock(screen_capture);
  bool encoded = false;
  std::string mime_type;
  switch (image_format_) {
    case FORMAT_JPEG:
      encoded = gfx::JPEGCodec::Encode(
          reinterpret_cast<unsigned char*>(screen_capture.getAddr32(0, 0)),
          gfx::JPEGCodec::FORMAT_SkBitmap,
          screen_capture.width(),
          screen_capture.height(),
          static_cast<int>(screen_capture.rowBytes()),
          image_quality_,
          &image_data->data);
      mime_type = keys::kMimeTypeJpeg;
      break;
    case FORMAT_PNG:
      encoded = gfx::PNGCodec::EncodeBGRASkBitmap(
          screen_capture,
          true,  // Discard transparency.
          &image_data->data);
      mime_type = keys::kMimeTypePng;
      break;
    default:
      NOTREACHED() << "Invalid image format.";
  }

  if (!encoded) {
    error_ = ExtensionErrorUtils::FormatErrorMessage(
        keys::kInternalVisibleTabCaptureError, "");
    SendResponse(false);
    return;
  }

  std::string base64_result;
  std::string stream_as_string;
  stream_as_string.resize(image_data->data.size());
  memcpy(&stream_as_string[0],
      reinterpret_cast<const char*>(&image_data->data[0]),
      image_data->data.size());

  base::Base64Encode(stream_as_string, &base64_result);
  base64_result.insert(0, base::StringPrintf("data:%s;base64,",
                                             mime_type.c_str()));
  result_.reset(new StringValue(base64_result));
  SendResponse(true);
}

bool DetectTabLanguageFunction::RunImpl() {
  int tab_id = 0;
  Browser* browser = NULL;
  TabContentsWrapper* contents = NULL;

  // If |tab_id| is specified, look for it. Otherwise default to selected tab
  // in the current window.
  if (HasOptionalArgument(0)) {
    EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(0, &tab_id));
    if (!GetTabById(tab_id, profile(), include_incognito(),
                    &browser, NULL, &contents, NULL, &error_)) {
      return false;
    }
    if (!browser || !contents)
      return false;
  } else {
    browser = GetCurrentBrowser();
    if (!browser)
      return false;
    contents = browser->tabstrip_model()->GetSelectedTabContents();
    if (!contents)
      return false;
  }

  if (contents->controller().needs_reload()) {
    // If the tab hasn't been loaded, don't wait for the tab to load.
    error_ = keys::kCannotDetermineLanguageOfUnloadedTab;
    return false;
  }

  AddRef();  // Balanced in GotLanguage()

  if (!contents->tab_contents()->language_state().original_language().empty()) {
    // Delay the callback invocation until after the current JS call has
    // returned.
    MessageLoop::current()->PostTask(FROM_HERE, NewRunnableMethod(
        this, &DetectTabLanguageFunction::GotLanguage,
        contents->tab_contents()->language_state().original_language()));
    return true;
  }
  // The tab contents does not know its language yet.  Let's  wait until it
  // receives it, or until the tab is closed/navigates to some other page.
  registrar_.Add(this, NotificationType::TAB_LANGUAGE_DETERMINED,
                 Source<TabContents>(contents->tab_contents()));
  registrar_.Add(this, NotificationType::TAB_CLOSING,
                 Source<NavigationController>(&(contents->controller())));
  registrar_.Add(this, NotificationType::NAV_ENTRY_COMMITTED,
                 Source<NavigationController>(&(contents->controller())));
  return true;
}

void DetectTabLanguageFunction::Observe(NotificationType type,
                                        const NotificationSource& source,
                                        const NotificationDetails& details) {
  std::string language;
  if (type == NotificationType::TAB_LANGUAGE_DETERMINED)
    language = *Details<std::string>(details).ptr();

  registrar_.RemoveAll();

  // Call GotLanguage in all cases as we want to guarantee the callback is
  // called for every API call the extension made.
  GotLanguage(language);
}

void DetectTabLanguageFunction::GotLanguage(const std::string& language) {
  result_.reset(Value::CreateStringValue(language.c_str()));
  SendResponse(true);

  Release();  // Balanced in Run()
}

// static helpers

static Browser* GetBrowserInProfileWithId(Profile* profile,
                                          const int window_id,
                                          bool include_incognito,
                                          std::string* error_message) {
  Profile* incognito_profile =
      include_incognito && profile->HasOffTheRecordProfile() ?
          profile->GetOffTheRecordProfile() : NULL;
  for (BrowserList::const_iterator browser = BrowserList::begin();
       browser != BrowserList::end(); ++browser) {
    if (((*browser)->profile() == profile ||
         (*browser)->profile() == incognito_profile) &&
        ExtensionTabUtil::GetWindowId(*browser) == window_id)
      return *browser;
  }

  if (error_message)
    *error_message = ExtensionErrorUtils::FormatErrorMessage(
        keys::kWindowNotFoundError, base::IntToString(window_id));

  return NULL;
}

static bool GetTabById(int tab_id, Profile* profile,
                       bool include_incognito,
                       Browser** browser,
                       TabStripModel** tab_strip,
                       TabContentsWrapper** contents,
                       int* tab_index,
                       std::string* error_message) {
  if (ExtensionTabUtil::GetTabById(tab_id, profile, include_incognito,
                                   browser, tab_strip, contents, tab_index))
    return true;

  if (error_message)
    *error_message = ExtensionErrorUtils::FormatErrorMessage(
        keys::kTabNotFoundError, base::IntToString(tab_id));

  return false;
}

static std::string GetWindowTypeText(Browser::Type type) {
  if ((type & Browser::TYPE_POPUP) == Browser::TYPE_POPUP)
    return keys::kWindowTypeValuePopup;

  if ((type & Browser::TYPE_APP) == Browser::TYPE_APP)
    return keys::kWindowTypeValueApp;

  DCHECK(type == Browser::TYPE_NORMAL);
  return keys::kWindowTypeValueNormal;
}

static GURL ResolvePossiblyRelativeURL(std::string url_string,
                                       const Extension* extension) {
  GURL url = GURL(url_string);
  if (!url.is_valid())
    url = extension->GetResourceURL(url_string);

  return url;
}