src/chrome/browser/extensions/api/commands/command_service.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/extensions/api/commands/command_service.h"
   6
   7 #include <vector>
   8
   9 #include "base/lazy_instance.h"
  10 #include "base/prefs/scoped_user_pref_update.h"
  11 #include "base/strings/string_split.h"
  12 #include "base/strings/string_util.h"
  13 #include "base/strings/utf_string_conversions.h"
  14 #include "chrome/app/chrome_command_ids.h"
  15 #include "chrome/browser/chrome_notification_types.h"
  16 #include "chrome/browser/extensions/api/commands/commands.h"
  17 #include "chrome/browser/extensions/extension_commands_global_registry.h"
  18 #include "chrome/browser/extensions/extension_keybinding_registry.h"
  19 #include "chrome/browser/profiles/profile.h"
  20 #include "chrome/browser/ui/accelerator_utils.h"
  21 #include "chrome/common/extensions/api/commands/commands_handler.h"
  22 #include "chrome/common/extensions/manifest_handlers/settings_overrides_handler.h"
  23 #include "chrome/common/extensions/manifest_handlers/ui_overrides_handler.h"
  24 #include "chrome/common/pref_names.h"
  25 #include "components/user_prefs/pref_registry_syncable.h"
  26 #include "content/public/browser/notification_details.h"
  27 #include "content/public/browser/notification_service.h"
  28 #include "extensions/browser/extension_function_registry.h"
  29 #include "extensions/browser/extension_prefs.h"
  30 #include "extensions/browser/extension_registry.h"
  31 #include "extensions/browser/extension_system.h"
  32 #include "extensions/common/feature_switch.h"
  33 #include "extensions/common/manifest_constants.h"
  34 #include "extensions/common/permissions/permissions_data.h"
  35
  36 using extensions::Extension;
  37 using extensions::ExtensionPrefs;
  38 using extensions::SettingsOverrides;
  39 using extensions::UIOverrides;
  40
  41 namespace {
  42
  43 const char kExtension[] = "extension";
  44 const char kCommandName[] = "command_name";
  45 const char kGlobal[] = "global";
  46
  47 // A preference that indicates that the initial keybindings for the given
  48 // extension have been set.
  49 const char kInitialBindingsHaveBeenAssigned[] = "initial_keybindings_set";
  50
  51 std::string GetPlatformKeybindingKeyForAccelerator(
  52     const ui::Accelerator& accelerator, const std::string extension_id) {
  53   std::string key = extensions::Command::CommandPlatform() + ":" +
  54                     extensions::Command::AcceleratorToString(accelerator);
  55
  56   // Media keys have a 1-to-many relationship with targets, unlike regular
  57   // shortcut (1-to-1 relationship). That means two or more extensions can
  58   // register for the same media key so the extension ID needs to be added to
  59   // the key to make sure the key is unique.
  60   if (extensions::Command::IsMediaKey(accelerator))
  61     key += ":" + extension_id;
  62
  63   return key;
  64 }
  65
  66 bool IsForCurrentPlatform(const std::string& key) {
  67   return StartsWithASCII(
  68       key, extensions::Command::CommandPlatform() + ":", true);
  69 }
  70
  71 void SetInitialBindingsHaveBeenAssigned(
  72     ExtensionPrefs* prefs, const std::string& extension_id) {
  73   prefs->UpdateExtensionPref(extension_id, kInitialBindingsHaveBeenAssigned,
  74                              new base::FundamentalValue(true));
  75 }
  76
  77 bool InitialBindingsHaveBeenAssigned(
  78     const ExtensionPrefs* prefs, const std::string& extension_id) {
  79   bool assigned = false;
  80   if (!prefs || !prefs->ReadPrefAsBoolean(extension_id,
  81                                           kInitialBindingsHaveBeenAssigned,
  82                                           &assigned))
  83     return false;
  84
  85   return assigned;
  86 }
  87
  88 // Checks if |extension| is permitted to automatically assign the |accelerator|
  89 // key.
  90 bool CanAutoAssign(const ui::Accelerator& accelerator,
  91                    const Extension* extension,
  92                    Profile* profile,
  93                    bool is_named_command,
  94                    bool is_global) {
  95   // Media Keys are non-exclusive, so allow auto-assigning them.
  96   if (extensions::Command::IsMediaKey(accelerator))
  97     return true;
  98
  99   if (is_global) {
 100     if (!is_named_command)
 101       return false;  // Browser and page actions are not global in nature.
 102
 103     // Global shortcuts are restricted to (Ctrl|Command)+Shift+[0-9].
 104 #if defined OS_MACOSX
 105     if (!accelerator.IsCmdDown())
 106       return false;
 107 #else
 108     if (!accelerator.IsCtrlDown())
 109       return false;
 110 #endif
 111     if (!accelerator.IsShiftDown())
 112       return false;
 113     return (accelerator.key_code() >= ui::VKEY_0 &&
 114             accelerator.key_code() <= ui::VKEY_9);
 115   } else {
 116     // Not a global command, check if Chrome shortcut and whether
 117     // we can override it.
 118     if (accelerator ==
 119         chrome::GetPrimaryChromeAcceleratorForCommandId(IDC_BOOKMARK_PAGE) &&
 120         extensions::CommandService::RemovesBookmarkShortcut(extension)) {
 121       // If this check fails it either means we have an API to override a
 122       // key that isn't a ChromeAccelerator (and the API can therefore be
 123       // deprecated) or the IsChromeAccelerator isn't consistently
 124       // returning true for all accelerators.
 125       DCHECK(chrome::IsChromeAccelerator(accelerator, profile));
 126       return true;
 127     }
 128
 129     return !chrome::IsChromeAccelerator(accelerator, profile);
 130   }
 131 }
 132
 133 }  // namespace
 134
 135 namespace extensions {
 136
 137 // static
 138 void CommandService::RegisterProfilePrefs(
 139     user_prefs::PrefRegistrySyncable* registry) {
 140   registry->RegisterDictionaryPref(
 141       prefs::kExtensionCommands,
 142       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
 143 }
 144
 145 CommandService::CommandService(content::BrowserContext* context)
 146     : profile_(Profile::FromBrowserContext(context)) {
 147   ExtensionFunctionRegistry::GetInstance()->
 148       RegisterFunction<GetAllCommandsFunction>();
 149
 150   registrar_.Add(this,
 151                  chrome::NOTIFICATION_EXTENSION_INSTALLED,
 152                  content::Source<Profile>(profile_));
 153   registrar_.Add(this,
 154                  chrome::NOTIFICATION_EXTENSION_UNINSTALLED,
 155                  content::Source<Profile>(profile_));
 156 }
 157
 158 CommandService::~CommandService() {
 159 }
 160
 161 static base::LazyInstance<BrowserContextKeyedAPIFactory<CommandService> >
 162     g_factory = LAZY_INSTANCE_INITIALIZER;
 163
 164 // static
 165 BrowserContextKeyedAPIFactory<CommandService>*
 166 CommandService::GetFactoryInstance() {
 167   return g_factory.Pointer();
 168 }
 169
 170 // static
 171 CommandService* CommandService::Get(content::BrowserContext* context) {
 172   return BrowserContextKeyedAPIFactory<CommandService>::Get(context);
 173 }
 174
 175 // static
 176 bool CommandService::RemovesBookmarkShortcut(
 177     const extensions::Extension* extension) {
 178   const UIOverrides* ui_overrides = UIOverrides::Get(extension);
 179   const SettingsOverrides* settings_overrides =
 180       SettingsOverrides::Get(extension);
 181
 182   return ((settings_overrides &&
 183            SettingsOverrides::RemovesBookmarkShortcut(*settings_overrides)) ||
 184           (ui_overrides &&
 185            UIOverrides::RemovesBookmarkShortcut(*ui_overrides))) &&
 186       (extensions::PermissionsData::HasAPIPermission(
 187           extension,
 188           extensions::APIPermission::kBookmarkManagerPrivate) ||
 189        extensions::FeatureSwitch::enable_override_bookmarks_ui()->
 190            IsEnabled());
 191 }
 192
 193 // static
 194 bool CommandService::RemovesBookmarkOpenPagesShortcut(
 195     const extensions::Extension* extension) {
 196   const UIOverrides* ui_overrides = UIOverrides::Get(extension);
 197   const SettingsOverrides* settings_overrides =
 198       SettingsOverrides::Get(extension);
 199
 200   return ((settings_overrides &&
 201            SettingsOverrides::RemovesBookmarkOpenPagesShortcut(
 202                *settings_overrides)) ||
 203           (ui_overrides &&
 204            UIOverrides::RemovesBookmarkOpenPagesShortcut(*ui_overrides))) &&
 205       (extensions::PermissionsData::HasAPIPermission(
 206           extension,
 207           extensions::APIPermission::kBookmarkManagerPrivate) ||
 208        extensions::FeatureSwitch::enable_override_bookmarks_ui()->
 209            IsEnabled());
 210 }
 211
 212 bool CommandService::GetBrowserActionCommand(const std::string& extension_id,
 213                                              QueryType type,
 214                                              extensions::Command* command,
 215                                              bool* active) const {
 216   return GetExtensionActionCommand(
 217       extension_id, type, command, active, BROWSER_ACTION);
 218 }
 219
 220 bool CommandService::GetPageActionCommand(const std::string& extension_id,
 221                                           QueryType type,
 222                                           extensions::Command* command,
 223                                           bool* active) const {
 224   return GetExtensionActionCommand(
 225       extension_id, type, command, active, PAGE_ACTION);
 226 }
 227
 228 bool CommandService::GetNamedCommands(
 229     const std::string& extension_id,
 230     QueryType type,
 231     CommandScope scope,
 232     extensions::CommandMap* command_map) const {
 233   const ExtensionSet& extensions =
 234       ExtensionRegistry::Get(profile_)->enabled_extensions();
 235   const Extension* extension = extensions.GetByID(extension_id);
 236   CHECK(extension);
 237
 238   command_map->clear();
 239   const extensions::CommandMap* commands =
 240       CommandsInfo::GetNamedCommands(extension);
 241   if (!commands)
 242     return false;
 243
 244   extensions::CommandMap::const_iterator iter = commands->begin();
 245   for (; iter != commands->end(); ++iter) {
 246     // Look up to see if the user has overridden how the command should work.
 247     extensions::Command saved_command =
 248         FindCommandByName(extension_id, iter->second.command_name());
 249     ui::Accelerator shortcut_assigned = saved_command.accelerator();
 250
 251     if (type == ACTIVE_ONLY && shortcut_assigned.key_code() == ui::VKEY_UNKNOWN)
 252       continue;
 253
 254     extensions::Command command = iter->second;
 255     if (scope != ANY_SCOPE && ((scope == GLOBAL) != saved_command.global()))
 256       continue;
 257
 258     if (shortcut_assigned.key_code() != ui::VKEY_UNKNOWN)
 259       command.set_accelerator(shortcut_assigned);
 260     command.set_global(saved_command.global());
 261
 262     (*command_map)[iter->second.command_name()] = command;
 263   }
 264
 265   return true;
 266 }
 267
 268 bool CommandService::AddKeybindingPref(
 269     const ui::Accelerator& accelerator,
 270     std::string extension_id,
 271     std::string command_name,
 272     bool allow_overrides,
 273     bool global) {
 274   if (accelerator.key_code() == ui::VKEY_UNKNOWN)
 275     return false;
 276
 277   // Media Keys are allowed to be used by named command only.
 278   DCHECK(!Command::IsMediaKey(accelerator) ||
 279          (command_name != manifest_values::kPageActionCommandEvent &&
 280           command_name != manifest_values::kBrowserActionCommandEvent));
 281
 282   DictionaryPrefUpdate updater(profile_->GetPrefs(),
 283                                prefs::kExtensionCommands);
 284   base::DictionaryValue* bindings = updater.Get();
 285
 286   std::string key = GetPlatformKeybindingKeyForAccelerator(accelerator,
 287                                                            extension_id);
 288
 289   if (bindings->HasKey(key)) {
 290     if (!allow_overrides)
 291       return false;  // Already taken.
 292
 293     // If the shortcut has been assigned to another command, it should be
 294     // removed before overriding, so that |ExtensionKeybindingRegistry| can get
 295     // a chance to do clean-up.
 296     const base::DictionaryValue* item = NULL;
 297     bindings->GetDictionary(key, &item);
 298     std::string old_extension_id;
 299     std::string old_command_name;
 300     item->GetString(kExtension, &old_extension_id);
 301     item->GetString(kCommandName, &old_command_name);
 302     RemoveKeybindingPrefs(old_extension_id, old_command_name);
 303   }
 304
 305   base::DictionaryValue* keybinding = new base::DictionaryValue();
 306   keybinding->SetString(kExtension, extension_id);
 307   keybinding->SetString(kCommandName, command_name);
 308   keybinding->SetBoolean(kGlobal, global);
 309
 310   bindings->Set(key, keybinding);
 311
 312   std::pair<const std::string, const std::string> details =
 313       std::make_pair(extension_id, command_name);
 314   content::NotificationService::current()->Notify(
 315       chrome::NOTIFICATION_EXTENSION_COMMAND_ADDED,
 316       content::Source<Profile>(profile_),
 317       content::Details<
 318           std::pair<const std::string, const std::string> >(&details));
 319
 320   return true;
 321 }
 322
 323 void CommandService::Observe(
 324     int type,
 325     const content::NotificationSource& source,
 326     const content::NotificationDetails& details) {
 327   switch (type) {
 328     case chrome::NOTIFICATION_EXTENSION_INSTALLED:
 329       AssignInitialKeybindings(
 330           content::Details<const InstalledExtensionInfo>(details)->extension);
 331       break;
 332     case chrome::NOTIFICATION_EXTENSION_UNINSTALLED:
 333       RemoveKeybindingPrefs(
 334           content::Details<const Extension>(details)->id(),
 335           std::string());
 336       break;
 337     default:
 338       NOTREACHED();
 339       break;
 340   }
 341 }
 342
 343 void CommandService::UpdateKeybindingPrefs(const std::string& extension_id,
 344                                            const std::string& command_name,
 345                                            const std::string& keystroke) {
 346   extensions::Command command = FindCommandByName(extension_id, command_name);
 347
 348   // The extension command might be assigned another shortcut. Remove that
 349   // shortcut before proceeding.
 350   RemoveKeybindingPrefs(extension_id, command_name);
 351
 352   ui::Accelerator accelerator =
 353       Command::StringToAccelerator(keystroke, command_name);
 354   AddKeybindingPref(accelerator, extension_id, command_name,
 355                     true, command.global());
 356 }
 357
 358 bool CommandService::SetScope(const std::string& extension_id,
 359                               const std::string& command_name,
 360                               bool global) {
 361   extensions::Command command = FindCommandByName(extension_id, command_name);
 362   if (global == command.global())
 363     return false;
 364
 365   // Pre-existing shortcuts must be removed before proceeding because the
 366   // handlers for global and non-global extensions are not one and the same.
 367   RemoveKeybindingPrefs(extension_id, command_name);
 368   AddKeybindingPref(command.accelerator(), extension_id,
 369                     command_name, true, global);
 370   return true;
 371 }
 372
 373 Command CommandService::FindCommandByName(const std::string& extension_id,
 374                                           const std::string& command) const {
 375   const base::DictionaryValue* bindings =
 376       profile_->GetPrefs()->GetDictionary(prefs::kExtensionCommands);
 377   for (base::DictionaryValue::Iterator it(*bindings); !it.IsAtEnd();
 378        it.Advance()) {
 379     const base::DictionaryValue* item = NULL;
 380     it.value().GetAsDictionary(&item);
 381
 382     std::string extension;
 383     item->GetString(kExtension, &extension);
 384     if (extension != extension_id)
 385       continue;
 386     std::string command_name;
 387     item->GetString(kCommandName, &command_name);
 388     if (command != command_name)
 389       continue;
 390     // Format stored in Preferences is: "Platform:Shortcut[:ExtensionId]".
 391     std::string shortcut = it.key();
 392     if (!IsForCurrentPlatform(shortcut))
 393       continue;
 394     bool global = false;
 395     if (FeatureSwitch::global_commands()->IsEnabled())
 396       item->GetBoolean(kGlobal, &global);
 397
 398     std::vector<std::string> tokens;
 399     base::SplitString(shortcut, ':', &tokens);
 400     CHECK(tokens.size() >= 2);
 401     shortcut = tokens[1];
 402
 403     return Command(command_name, base::string16(), shortcut, global);
 404   }
 405
 406   return Command();
 407 }
 408
 409 bool CommandService::GetBoundExtensionCommand(
 410     const std::string& extension_id,
 411     const ui::Accelerator& accelerator,
 412     extensions::Command* command,
 413     ExtensionCommandType* command_type) const {
 414   const ExtensionSet& extensions =
 415       ExtensionRegistry::Get(profile_)->enabled_extensions();
 416   const Extension* extension = extensions.GetByID(extension_id);
 417   CHECK(extension);
 418
 419   extensions::Command prospective_command;
 420   extensions::CommandMap command_map;
 421   bool active = false;
 422   if (GetBrowserActionCommand(extension_id,
 423                               extensions::CommandService::ACTIVE_ONLY,
 424                               &prospective_command,
 425                               &active) && active &&
 426           accelerator == prospective_command.accelerator()) {
 427     if (command)
 428       *command = prospective_command;
 429     if (command_type)
 430       *command_type = BROWSER_ACTION;
 431     return true;
 432   } else if (GetPageActionCommand(extension_id,
 433                                   extensions::CommandService::ACTIVE_ONLY,
 434                                   &prospective_command,
 435                                   &active) && active &&
 436                  accelerator == prospective_command.accelerator()) {
 437     if (command)
 438       *command = prospective_command;
 439     if (command_type)
 440       *command_type = PAGE_ACTION;
 441     return true;
 442   } else if (GetNamedCommands(extension_id,
 443                               extensions::CommandService::ACTIVE_ONLY,
 444                               extensions::CommandService::REGULAR,
 445                               &command_map)) {
 446     for (extensions::CommandMap::const_iterator it = command_map.begin();
 447          it != command_map.end(); ++it) {
 448       if (accelerator == it->second.accelerator()) {
 449         if (command)
 450           *command = it->second;
 451         if (command_type)
 452           *command_type = NAMED;
 453         return true;
 454       }
 455     }
 456   }
 457   return false;
 458 }
 459
 460 bool CommandService::OverridesBookmarkShortcut(
 461     const extensions::Extension* extension) const {
 462   return RemovesBookmarkShortcut(extension) &&
 463       GetBoundExtensionCommand(
 464           extension->id(),
 465           chrome::GetPrimaryChromeAcceleratorForCommandId(IDC_BOOKMARK_PAGE),
 466           NULL,
 467           NULL);
 468 }
 469
 470 void CommandService::AssignInitialKeybindings(const Extension* extension) {
 471   const extensions::CommandMap* commands =
 472       CommandsInfo::GetNamedCommands(extension);
 473   if (!commands)
 474     return;
 475
 476   ExtensionPrefs* extension_prefs = ExtensionPrefs::Get(profile_);
 477   if (InitialBindingsHaveBeenAssigned(extension_prefs, extension->id()))
 478     return;
 479   SetInitialBindingsHaveBeenAssigned(extension_prefs, extension->id());
 480
 481   extensions::CommandMap::const_iterator iter = commands->begin();
 482   for (; iter != commands->end(); ++iter) {
 483     const extensions::Command command = iter->second;
 484     if (CanAutoAssign(command.accelerator(),
 485                       extension,
 486                       profile_,
 487                       true,  // Is a named command.
 488                       command.global())) {
 489       AddKeybindingPref(command.accelerator(),
 490                         extension->id(),
 491                         command.command_name(),
 492                         false,  // Overwriting not allowed.
 493                         command.global());
 494     }
 495   }
 496
 497   const extensions::Command* browser_action_command =
 498       CommandsInfo::GetBrowserActionCommand(extension);
 499   if (browser_action_command &&
 500       CanAutoAssign(browser_action_command->accelerator(),
 501                     extension,
 502                     profile_,
 503                     false,     // Not a named command.
 504                     false)) {  // Not global.
 505     AddKeybindingPref(browser_action_command->accelerator(),
 506                       extension->id(),
 507                       browser_action_command->command_name(),
 508                       false,   // Overwriting not allowed.
 509                       false);  // Not global.
 510   }
 511
 512   const extensions::Command* page_action_command =
 513       CommandsInfo::GetPageActionCommand(extension);
 514   if (page_action_command &&
 515       CanAutoAssign(page_action_command->accelerator(),
 516                     extension,
 517                     profile_,
 518                     false,     // Not a named command.
 519                     false)) {  // Not global.
 520     AddKeybindingPref(page_action_command->accelerator(),
 521                       extension->id(),
 522                       page_action_command->command_name(),
 523                       false,   // Overwriting not allowed.
 524                       false);  // Not global.
 525   }
 526 }
 527
 528 void CommandService::RemoveKeybindingPrefs(const std::string& extension_id,
 529                                            const std::string& command_name) {
 530   DictionaryPrefUpdate updater(profile_->GetPrefs(),
 531                                prefs::kExtensionCommands);
 532   base::DictionaryValue* bindings = updater.Get();
 533
 534   typedef std::vector<std::string> KeysToRemove;
 535   KeysToRemove keys_to_remove;
 536   for (base::DictionaryValue::Iterator it(*bindings); !it.IsAtEnd();
 537        it.Advance()) {
 538     // Removal of keybinding preference should be limited to current platform.
 539     if (!IsForCurrentPlatform(it.key()))
 540       continue;
 541
 542     const base::DictionaryValue* item = NULL;
 543     it.value().GetAsDictionary(&item);
 544
 545     std::string extension;
 546     item->GetString(kExtension, &extension);
 547
 548     if (extension == extension_id) {
 549       // If |command_name| is specified, delete only that command. Otherwise,
 550       // delete all commands.
 551       if (!command_name.empty()) {
 552         std::string command;
 553         item->GetString(kCommandName, &command);
 554         if (command_name != command)
 555           continue;
 556       }
 557
 558       keys_to_remove.push_back(it.key());
 559     }
 560   }
 561
 562   for (KeysToRemove::const_iterator it = keys_to_remove.begin();
 563        it != keys_to_remove.end(); ++it) {
 564     std::string key = *it;
 565     bindings->Remove(key, NULL);
 566
 567     std::pair<const std::string, const std::string> details =
 568         std::make_pair(extension_id, command_name);
 569     content::NotificationService::current()->Notify(
 570         chrome::NOTIFICATION_EXTENSION_COMMAND_REMOVED,
 571         content::Source<Profile>(profile_),
 572         content::Details<
 573             std::pair<const std::string, const std::string> >(&details));
 574   }
 575 }
 576
 577 bool CommandService::GetExtensionActionCommand(
 578     const std::string& extension_id,
 579     QueryType query_type,
 580     extensions::Command* command,
 581     bool* active,
 582     ExtensionCommandType action_type) const {
 583   const ExtensionSet& extensions =
 584       ExtensionRegistry::Get(profile_)->enabled_extensions();
 585   const Extension* extension = extensions.GetByID(extension_id);
 586   CHECK(extension);
 587
 588   if (active)
 589     *active = false;
 590
 591   const extensions::Command* requested_command = NULL;
 592   switch (action_type) {
 593     case BROWSER_ACTION:
 594       requested_command = CommandsInfo::GetBrowserActionCommand(extension);
 595       break;
 596     case PAGE_ACTION:
 597       requested_command = CommandsInfo::GetPageActionCommand(extension);
 598       break;
 599     case NAMED:
 600       NOTREACHED();
 601       return false;
 602   }
 603   if (!requested_command)
 604     return false;
 605
 606   // Look up to see if the user has overridden how the command should work.
 607   extensions::Command saved_command =
 608       FindCommandByName(extension_id, requested_command->command_name());
 609   ui::Accelerator shortcut_assigned = saved_command.accelerator();
 610
 611   if (active)
 612     *active = (shortcut_assigned.key_code() != ui::VKEY_UNKNOWN);
 613
 614   if (query_type == ACTIVE_ONLY &&
 615       shortcut_assigned.key_code() == ui::VKEY_UNKNOWN)
 616     return false;
 617
 618   *command = *requested_command;
 619   if (shortcut_assigned.key_code() != ui::VKEY_UNKNOWN)
 620     command->set_accelerator(shortcut_assigned);
 621
 622   return true;
 623 }
 624
 625 template <>
 626 void
 627 BrowserContextKeyedAPIFactory<CommandService>::DeclareFactoryDependencies() {
 628   DependsOn(ExtensionCommandsGlobalRegistry::GetFactoryInstance());
 629 }
 630
 631 }  // namespace extensions