// Copyright 2013 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 "content/browser/accessibility/browser_accessibility_manager_android.h"

#include <cmath>

#include "base/android/jni_android.h"
#include "base/android/jni_string.h"
#include "base/i18n/char_iterator.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/utf_string_conversions.h"
#include "base/values.h"
#include "content/browser/accessibility/browser_accessibility_android.h"
#include "content/common/accessibility_messages.h"
#include "jni/BrowserAccessibilityManager_jni.h"
#include "ui/accessibility/ax_text_utils.h"

using base::android::AttachCurrentThread;
using base::android::ScopedJavaLocalRef;

namespace {

enum AndroidHtmlElementType {
  HTML_ELEMENT_TYPE_SECTION,
  HTML_ELEMENT_TYPE_LIST,
  HTML_ELEMENT_TYPE_CONTROL,
  HTML_ELEMENT_TYPE_ANY
};

// These are special unofficial strings sent from TalkBack/BrailleBack
// to jump to certain categories of web elements.
AndroidHtmlElementType HtmlElementTypeFromString(base::string16 element_type) {
  if (element_type == base::ASCIIToUTF16("SECTION"))
    return HTML_ELEMENT_TYPE_SECTION;
  else if (element_type == base::ASCIIToUTF16("LIST"))
    return HTML_ELEMENT_TYPE_LIST;
  else if (element_type == base::ASCIIToUTF16("CONTROL"))
    return HTML_ELEMENT_TYPE_CONTROL;
  else
    return HTML_ELEMENT_TYPE_ANY;
}

}  // anonymous namespace

namespace content {

namespace aria_strings {
  const char kAriaLivePolite[] = "polite";
  const char kAriaLiveAssertive[] = "assertive";
}

// static
BrowserAccessibilityManager* BrowserAccessibilityManager::Create(
    const SimpleAXTreeUpdate& initial_tree,
    BrowserAccessibilityDelegate* delegate,
    BrowserAccessibilityFactory* factory) {
  return new BrowserAccessibilityManagerAndroid(
      ScopedJavaLocalRef<jobject>(), initial_tree, delegate, factory);
}

BrowserAccessibilityManagerAndroid*
BrowserAccessibilityManager::ToBrowserAccessibilityManagerAndroid() {
  return static_cast<BrowserAccessibilityManagerAndroid*>(this);
}

BrowserAccessibilityManagerAndroid::BrowserAccessibilityManagerAndroid(
    ScopedJavaLocalRef<jobject> content_view_core,
    const SimpleAXTreeUpdate& initial_tree,
    BrowserAccessibilityDelegate* delegate,
    BrowserAccessibilityFactory* factory)
    : BrowserAccessibilityManager(delegate, factory),
      prune_tree_for_screen_reader_(true) {
  Initialize(initial_tree);
  SetContentViewCore(content_view_core);
}

BrowserAccessibilityManagerAndroid::~BrowserAccessibilityManagerAndroid() {
  JNIEnv* env = AttachCurrentThread();
  ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
  if (obj.is_null())
    return;

  Java_BrowserAccessibilityManager_onNativeObjectDestroyed(env, obj.obj());
}

// static
SimpleAXTreeUpdate
    BrowserAccessibilityManagerAndroid::GetEmptyDocument() {
  ui::AXNodeData empty_document;
  empty_document.id = 0;
  empty_document.role = ui::AX_ROLE_ROOT_WEB_AREA;
  empty_document.state = 1 << ui::AX_STATE_READ_ONLY;

  SimpleAXTreeUpdate update;
  update.nodes.push_back(empty_document);
  return update;
}

void BrowserAccessibilityManagerAndroid::SetContentViewCore(
    ScopedJavaLocalRef<jobject> content_view_core) {
  if (content_view_core.is_null())
    return;

  JNIEnv* env = AttachCurrentThread();
  java_ref_ = JavaObjectWeakGlobalRef(
      env, Java_BrowserAccessibilityManager_create(
          env, reinterpret_cast<intptr_t>(this),
          content_view_core.obj()).obj());
}

void BrowserAccessibilityManagerAndroid::NotifyAccessibilityEvent(
    ui::AXEvent event_type,
    BrowserAccessibility* node) {
  JNIEnv* env = AttachCurrentThread();
  ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
  if (obj.is_null())
    return;

  BrowserAccessibilityAndroid* android_node =
      static_cast<BrowserAccessibilityAndroid*>(node);

  if (event_type == ui::AX_EVENT_HIDE)
    return;

  if (event_type == ui::AX_EVENT_TREE_CHANGED)
    return;

  if (event_type == ui::AX_EVENT_HOVER) {
    HandleHoverEvent(node);
    return;
  }

  // Always send AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED to notify
  // the Android system that the accessibility hierarchy rooted at this
  // node has changed.
  Java_BrowserAccessibilityManager_handleContentChanged(
      env, obj.obj(), node->GetId());

  switch (event_type) {
    case ui::AX_EVENT_LOAD_COMPLETE:
      Java_BrowserAccessibilityManager_handlePageLoaded(
          env, obj.obj(), focus_->id());
      break;
    case ui::AX_EVENT_FOCUS:
      Java_BrowserAccessibilityManager_handleFocusChanged(
          env, obj.obj(), node->GetId());
      break;
    case ui::AX_EVENT_CHECKED_STATE_CHANGED:
      Java_BrowserAccessibilityManager_handleCheckStateChanged(
          env, obj.obj(), node->GetId());
      break;
    case ui::AX_EVENT_SCROLL_POSITION_CHANGED:
      Java_BrowserAccessibilityManager_handleScrollPositionChanged(
          env, obj.obj(), node->GetId());
      break;
    case ui::AX_EVENT_SCROLLED_TO_ANCHOR:
      Java_BrowserAccessibilityManager_handleScrolledToAnchor(
          env, obj.obj(), node->GetId());
      break;
    case ui::AX_EVENT_ALERT:
      // An alert is a special case of live region. Fall through to the
      // next case to handle it.
    case ui::AX_EVENT_SHOW: {
      // This event is fired when an object appears in a live region.
      // Speak its text.
      Java_BrowserAccessibilityManager_announceLiveRegionText(
          env, obj.obj(),
          base::android::ConvertUTF16ToJavaString(
              env, android_node->GetText()).obj());
      break;
    }
    case ui::AX_EVENT_TEXT_SELECTION_CHANGED:
      Java_BrowserAccessibilityManager_handleTextSelectionChanged(
          env, obj.obj(), node->GetId());
      break;
    case ui::AX_EVENT_TEXT_CHANGED:
    case ui::AX_EVENT_VALUE_CHANGED:
      if (node->IsEditableText() && GetFocus(GetRoot()) == node) {
        Java_BrowserAccessibilityManager_handleEditableTextChanged(
            env, obj.obj(), node->GetId());
      } else if (android_node->IsSlider()) {
        Java_BrowserAccessibilityManager_handleSliderChanged(
            env, obj.obj(), node->GetId());
      }
      break;
    default:
      // There are some notifications that aren't meaningful on Android.
      // It's okay to skip them.
      break;
  }
}

jint BrowserAccessibilityManagerAndroid::GetRootId(JNIEnv* env, jobject obj) {
  if (GetRoot())
    return static_cast<jint>(GetRoot()->GetId());
  else
    return -1;
}

jboolean BrowserAccessibilityManagerAndroid::IsNodeValid(
    JNIEnv* env, jobject obj, jint id) {
  return GetFromID(id) != NULL;
}

void BrowserAccessibilityManagerAndroid::HitTest(
    JNIEnv* env, jobject obj, jint x, jint y) {
  if (delegate())
    delegate()->AccessibilityHitTest(gfx::Point(x, y));
}

jboolean BrowserAccessibilityManagerAndroid::IsEditableText(
    JNIEnv* env, jobject obj, jint id) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  return node->IsEditableText();
}

jint BrowserAccessibilityManagerAndroid::GetEditableTextSelectionStart(
    JNIEnv* env, jobject obj, jint id) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  return node->GetIntAttribute(ui::AX_ATTR_TEXT_SEL_START);
}

jint BrowserAccessibilityManagerAndroid::GetEditableTextSelectionEnd(
    JNIEnv* env, jobject obj, jint id) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  return node->GetIntAttribute(ui::AX_ATTR_TEXT_SEL_END);
}

jboolean BrowserAccessibilityManagerAndroid::PopulateAccessibilityNodeInfo(
    JNIEnv* env, jobject obj, jobject info, jint id) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  if (node->GetParent()) {
    Java_BrowserAccessibilityManager_setAccessibilityNodeInfoParent(
        env, obj, info, node->GetParent()->GetId());
  }
  for (unsigned i = 0; i < node->PlatformChildCount(); ++i) {
    Java_BrowserAccessibilityManager_addAccessibilityNodeInfoChild(
        env, obj, info, node->InternalGetChild(i)->GetId());
  }
  Java_BrowserAccessibilityManager_setAccessibilityNodeInfoBooleanAttributes(
      env, obj, info,
      id,
      node->IsCheckable(),
      node->IsChecked(),
      node->IsClickable(),
      node->IsEnabled(),
      node->IsFocusable(),
      node->IsFocused(),
      node->IsPassword(),
      node->IsScrollable(),
      node->IsSelected(),
      node->IsVisibleToUser());
  Java_BrowserAccessibilityManager_addAccessibilityNodeInfoActions(
      env, obj, info,
      id,
      node->CanScrollForward(),
      node->CanScrollBackward(),
      node->CanScrollUp(),
      node->CanScrollDown(),
      node->CanScrollLeft(),
      node->CanScrollRight(),
      node->IsClickable(),
      node->IsEditableText(),
      node->IsEnabled(),
      node->IsFocusable(),
      node->IsFocused());
  Java_BrowserAccessibilityManager_setAccessibilityNodeInfoClassName(
      env, obj, info,
      base::android::ConvertUTF8ToJavaString(env, node->GetClassName()).obj());
  if (!node->IsPassword() ||
      Java_BrowserAccessibilityManager_shouldExposePasswordText(env, obj)) {
    Java_BrowserAccessibilityManager_setAccessibilityNodeInfoContentDescription(
        env, obj, info,
        base::android::ConvertUTF16ToJavaString(env, node->GetText()).obj(),
        node->IsLink());
  }
  base::string16 element_id;
  if (node->GetHtmlAttribute("id", &element_id)) {
    Java_BrowserAccessibilityManager_setAccessibilityNodeInfoViewIdResourceName(
        env, obj, info,
        base::android::ConvertUTF16ToJavaString(env, element_id).obj());
  }

  gfx::Rect absolute_rect = node->GetLocalBoundsRect();
  gfx::Rect parent_relative_rect = absolute_rect;
  if (node->GetParent()) {
    gfx::Rect parent_rect = node->GetParent()->GetLocalBoundsRect();
    parent_relative_rect.Offset(-parent_rect.OffsetFromOrigin());
  }
  bool is_root = node->GetParent() == NULL;
  Java_BrowserAccessibilityManager_setAccessibilityNodeInfoLocation(
      env, obj, info,
      id,
      absolute_rect.x(), absolute_rect.y(),
      parent_relative_rect.x(), parent_relative_rect.y(),
      absolute_rect.width(), absolute_rect.height(),
      is_root);

  Java_BrowserAccessibilityManager_setAccessibilityNodeInfoLollipopAttributes(
      env, obj, info,
      node->CanOpenPopup(),
      node->IsContentInvalid(),
      node->IsDismissable(),
      node->IsMultiLine(),
      node->AndroidInputType(),
      node->AndroidLiveRegionType());
  if (node->IsCollection()) {
    Java_BrowserAccessibilityManager_setAccessibilityNodeInfoCollectionInfo(
        env, obj, info,
        node->RowCount(),
        node->ColumnCount(),
        node->IsHierarchical());
  }
  if (node->IsCollectionItem() || node->IsHeading()) {
    Java_BrowserAccessibilityManager_setAccessibilityNodeInfoCollectionItemInfo(
        env, obj, info,
        node->RowIndex(),
        node->RowSpan(),
        node->ColumnIndex(),
        node->ColumnSpan(),
        node->IsHeading());
  }
  if (node->IsRangeType()) {
    Java_BrowserAccessibilityManager_setAccessibilityNodeInfoRangeInfo(
        env, obj, info,
        node->AndroidRangeType(),
        node->RangeMin(),
        node->RangeMax(),
        node->RangeCurrentValue());
  }

  return true;
}

jboolean BrowserAccessibilityManagerAndroid::PopulateAccessibilityEvent(
    JNIEnv* env, jobject obj, jobject event, jint id, jint event_type) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  Java_BrowserAccessibilityManager_setAccessibilityEventBooleanAttributes(
      env, obj, event,
      node->IsChecked(),
      node->IsEnabled(),
      node->IsPassword(),
      node->IsScrollable());
  Java_BrowserAccessibilityManager_setAccessibilityEventClassName(
      env, obj, event,
      base::android::ConvertUTF8ToJavaString(env, node->GetClassName()).obj());
  Java_BrowserAccessibilityManager_setAccessibilityEventListAttributes(
      env, obj, event,
      node->GetItemIndex(),
      node->GetItemCount());
  Java_BrowserAccessibilityManager_setAccessibilityEventScrollAttributes(
      env, obj, event,
      node->GetScrollX(),
      node->GetScrollY(),
      node->GetMaxScrollX(),
      node->GetMaxScrollY());

  switch (event_type) {
    case ANDROID_ACCESSIBILITY_EVENT_TEXT_CHANGED: {
      base::string16 before_text, text;
      if (!node->IsPassword() ||
          Java_BrowserAccessibilityManager_shouldExposePasswordText(env, obj)) {
        before_text = node->GetTextChangeBeforeText();
        text = node->GetText();
      }
      Java_BrowserAccessibilityManager_setAccessibilityEventTextChangedAttrs(
          env, obj, event,
          node->GetTextChangeFromIndex(),
          node->GetTextChangeAddedCount(),
          node->GetTextChangeRemovedCount(),
          base::android::ConvertUTF16ToJavaString(
              env, before_text).obj(),
          base::android::ConvertUTF16ToJavaString(env, text).obj());
      break;
    }
    case ANDROID_ACCESSIBILITY_EVENT_TEXT_SELECTION_CHANGED: {
      base::string16 text;
      if (!node->IsPassword() ||
          Java_BrowserAccessibilityManager_shouldExposePasswordText(env, obj)) {
        text = node->GetText();
      }
      Java_BrowserAccessibilityManager_setAccessibilityEventSelectionAttrs(
          env, obj, event,
          node->GetSelectionStart(),
          node->GetSelectionEnd(),
          node->GetEditableTextLength(),
          base::android::ConvertUTF16ToJavaString(env, text).obj());
      break;
    }
    default:
      break;
  }

  Java_BrowserAccessibilityManager_setAccessibilityEventLollipopAttributes(
      env, obj, event,
      node->CanOpenPopup(),
      node->IsContentInvalid(),
      node->IsDismissable(),
      node->IsMultiLine(),
      node->AndroidInputType(),
      node->AndroidLiveRegionType());
  if (node->IsCollection()) {
    Java_BrowserAccessibilityManager_setAccessibilityEventCollectionInfo(
        env, obj, event,
        node->RowCount(),
        node->ColumnCount(),
        node->IsHierarchical());
  }
  if (node->IsHeading()) {
    Java_BrowserAccessibilityManager_setAccessibilityEventHeadingFlag(
        env, obj, event, true);
  }
  if (node->IsCollectionItem()) {
    Java_BrowserAccessibilityManager_setAccessibilityEventCollectionItemInfo(
        env, obj, event,
        node->RowIndex(),
        node->RowSpan(),
        node->ColumnIndex(),
        node->ColumnSpan());
  }
  if (node->IsRangeType()) {
    Java_BrowserAccessibilityManager_setAccessibilityEventRangeInfo(
        env, obj, event,
        node->AndroidRangeType(),
        node->RangeMin(),
        node->RangeMax(),
        node->RangeCurrentValue());
  }

  return true;
}

void BrowserAccessibilityManagerAndroid::Click(
    JNIEnv* env, jobject obj, jint id) {
  BrowserAccessibility* node = GetFromID(id);
  if (node)
    DoDefaultAction(*node);
}

void BrowserAccessibilityManagerAndroid::Focus(
    JNIEnv* env, jobject obj, jint id) {
  BrowserAccessibility* node = GetFromID(id);
  if (node)
    SetFocus(node, true);
}

void BrowserAccessibilityManagerAndroid::Blur(JNIEnv* env, jobject obj) {
  SetFocus(GetRoot(), true);
}

void BrowserAccessibilityManagerAndroid::ScrollToMakeNodeVisible(
    JNIEnv* env, jobject obj, jint id) {
  BrowserAccessibility* node = GetFromID(id);
  if (node)
    ScrollToMakeVisible(*node, gfx::Rect(node->GetLocation().size()));
}

void BrowserAccessibilityManagerAndroid::SetTextFieldValue(
    JNIEnv* env, jobject obj, jint id, jstring value) {
  BrowserAccessibility* node = GetFromID(id);
  if (node) {
    BrowserAccessibilityManager::SetValue(
        *node, base::android::ConvertJavaStringToUTF16(env, value));
  }
}

void BrowserAccessibilityManagerAndroid::SetSelection(
    JNIEnv* env, jobject obj, jint id, jint start, jint end) {
  BrowserAccessibility* node = GetFromID(id);
  if (node)
    SetTextSelection(*node, start, end);
}

jboolean BrowserAccessibilityManagerAndroid::AdjustSlider(
    JNIEnv* env, jobject obj, jint id, jboolean increment) {
  BrowserAccessibility* node = GetFromID(id);
  if (!node)
    return false;

  BrowserAccessibilityAndroid* android_node =
      static_cast<BrowserAccessibilityAndroid*>(node);

  if (!android_node->IsSlider() || !android_node->IsEnabled())
    return false;

  float value = node->GetFloatAttribute(ui::AX_ATTR_VALUE_FOR_RANGE);
  float min = node->GetFloatAttribute(ui::AX_ATTR_MIN_VALUE_FOR_RANGE);
  float max = node->GetFloatAttribute(ui::AX_ATTR_MAX_VALUE_FOR_RANGE);
  if (max <= min)
    return false;

  // To behave similarly to an Android SeekBar, move by an increment of
  // approximately 20%.
  float original_value = value;
  float delta = (max - min) / 5.0f;
  value += (increment ? delta : -delta);
  value = std::max(std::min(value, max), min);
  if (value != original_value) {
    BrowserAccessibilityManager::SetValue(
        *node, base::UTF8ToUTF16(base::DoubleToString(value)));
    return true;
  }
  return false;
}

void BrowserAccessibilityManagerAndroid::HandleHoverEvent(
    BrowserAccessibility* node) {
  JNIEnv* env = AttachCurrentThread();
  ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
  if (obj.is_null())
    return;

  BrowserAccessibilityAndroid* ancestor =
      static_cast<BrowserAccessibilityAndroid*>(node->GetParent());
  while (ancestor && ancestor != GetRoot()) {
    if (ancestor->PlatformIsLeaf() ||
        (ancestor->IsFocusable() && !ancestor->HasFocusableChild())) {
      node = ancestor;
      // Don't break - we want the highest ancestor that's focusable or a
      // leaf node.
    }
    ancestor = static_cast<BrowserAccessibilityAndroid*>(ancestor->GetParent());
  }

  Java_BrowserAccessibilityManager_handleHover(
      env, obj.obj(), node->GetId());
}

jint BrowserAccessibilityManagerAndroid::FindElementType(
    JNIEnv* env, jobject obj, jint start_id, jstring element_type_str,
    jboolean forwards) {
  BrowserAccessibility* node = GetFromID(start_id);
  if (!node)
    return 0;

  AndroidHtmlElementType element_type = HtmlElementTypeFromString(
      base::android::ConvertJavaStringToUTF16(env, element_type_str));

  node = forwards ? NextInTreeOrder(node) : PreviousInTreeOrder(node);
  while (node) {
    switch(element_type) {
      case HTML_ELEMENT_TYPE_SECTION:
        if (node->GetRole() == ui::AX_ROLE_ARTICLE ||
            node->GetRole() == ui::AX_ROLE_APPLICATION ||
            node->GetRole() == ui::AX_ROLE_BANNER ||
            node->GetRole() == ui::AX_ROLE_COMPLEMENTARY ||
            node->GetRole() == ui::AX_ROLE_CONTENT_INFO ||
            node->GetRole() == ui::AX_ROLE_HEADING ||
            node->GetRole() == ui::AX_ROLE_MAIN ||
            node->GetRole() == ui::AX_ROLE_NAVIGATION ||
            node->GetRole() == ui::AX_ROLE_SEARCH ||
            node->GetRole() == ui::AX_ROLE_REGION) {
          return node->GetId();
        }
        break;
      case HTML_ELEMENT_TYPE_LIST:
        if (node->GetRole() == ui::AX_ROLE_LIST ||
            node->GetRole() == ui::AX_ROLE_GRID ||
            node->GetRole() == ui::AX_ROLE_TABLE ||
            node->GetRole() == ui::AX_ROLE_TREE) {
          return node->GetId();
        }
        break;
      case HTML_ELEMENT_TYPE_CONTROL:
        if (static_cast<BrowserAccessibilityAndroid*>(node)->IsFocusable())
          return node->GetId();
        break;
      case HTML_ELEMENT_TYPE_ANY:
        // In theory, the API says that an accessibility service could
        // jump to an element by element name, like 'H1' or 'P'. This isn't
        // currently used by any accessibility service, and we think it's
        // better to keep them high-level like 'SECTION' or 'CONTROL', so we
        // just fall back on linear navigation when we don't recognize the
        // element type.
        if (static_cast<BrowserAccessibilityAndroid*>(node)->IsClickable())
          return node->GetId();
        break;
    }

    node = forwards ? NextInTreeOrder(node) : PreviousInTreeOrder(node);
  }

  return 0;
}

jboolean BrowserAccessibilityManagerAndroid::NextAtGranularity(
    JNIEnv* env, jobject obj, jint granularity, jboolean extend_selection,
    jint id, jint cursor_index) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  jint start_index = -1;
  int end_index = -1;
  if (NextAtGranularity(granularity, cursor_index, node,
                        &start_index, &end_index)) {
    base::string16 text;
    if (!node->IsPassword() ||
        Java_BrowserAccessibilityManager_shouldExposePasswordText(env, obj)) {
      text = node->GetText();
    }
    Java_BrowserAccessibilityManager_finishGranularityMove(
        env, obj, base::android::ConvertUTF16ToJavaString(
            env, text).obj(),
        extend_selection, start_index, end_index, true);
    return true;
  }
  return false;
}

jboolean BrowserAccessibilityManagerAndroid::PreviousAtGranularity(
    JNIEnv* env, jobject obj, jint granularity, jboolean extend_selection,
    jint id, jint cursor_index) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  jint start_index = -1;
  int end_index = -1;
  if (PreviousAtGranularity(granularity, cursor_index, node,
                            &start_index, &end_index)) {
    Java_BrowserAccessibilityManager_finishGranularityMove(
        env, obj, base::android::ConvertUTF16ToJavaString(
            env, node->GetText()).obj(),
        extend_selection, start_index, end_index, false);
    return true;
  }
  return false;
}

bool BrowserAccessibilityManagerAndroid::NextAtGranularity(
    int32 granularity, int32 cursor_index,
    BrowserAccessibilityAndroid* node, int32* start_index, int32* end_index) {
  switch (granularity) {
    case ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_CHARACTER: {
      base::string16 text = node->GetText();
      if (cursor_index >= static_cast<int32>(text.length()))
        return false;
      base::i18n::UTF16CharIterator iter(text.data(), text.size());
      while (!iter.end() && iter.array_pos() <= cursor_index)
        iter.Advance();
      *start_index = iter.array_pos();
      *end_index = iter.array_pos();
      break;
    }
    case ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_WORD:
    case ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_LINE: {
      std::vector<int32> starts;
      std::vector<int32> ends;
      node->GetGranularityBoundaries(granularity, &starts, &ends, 0);
      if (starts.size() == 0)
        return false;

      size_t index = 0;
      while (index < starts.size() - 1 && starts[index] < cursor_index)
        index++;

      if (starts[index] < cursor_index)
        return false;

      *start_index = starts[index];
      *end_index = ends[index];
      break;
    }
    default:
      NOTREACHED();
  }

  return true;
}

bool BrowserAccessibilityManagerAndroid::PreviousAtGranularity(
    int32 granularity, int32 cursor_index,
    BrowserAccessibilityAndroid* node, int32* start_index, int32* end_index) {
  switch (granularity) {
    case ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_CHARACTER: {
      if (cursor_index <= 0)
        return false;
      base::string16 text = node->GetText();
      base::i18n::UTF16CharIterator iter(text.data(), text.size());
      int previous_index = 0;
      while (!iter.end() && iter.array_pos() < cursor_index) {
        previous_index = iter.array_pos();
        iter.Advance();
      }
      *start_index = previous_index;
      *end_index = previous_index;
      break;
    }
    case ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_WORD:
    case ANDROID_ACCESSIBILITY_NODE_INFO_MOVEMENT_GRANULARITY_LINE: {
      std::vector<int32> starts;
      std::vector<int32> ends;
      node->GetGranularityBoundaries(granularity, &starts, &ends, 0);
      if (starts.size() == 0)
        return false;

      size_t index = starts.size() - 1;
      while (index > 0 && starts[index] >= cursor_index)
        index--;

      if (starts[index] >= cursor_index)
        return false;

      *start_index = starts[index];
      *end_index = ends[index];
      break;
    }
    default:
      NOTREACHED();
  }

  return true;
}

void BrowserAccessibilityManagerAndroid::SetAccessibilityFocus(
    JNIEnv* env, jobject obj, jint id) {
  if (delegate_)
    delegate_->AccessibilitySetAccessibilityFocus(id);
}

bool BrowserAccessibilityManagerAndroid::IsSlider(
    JNIEnv* env, jobject obj, jint id) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  return node->GetRole() == ui::AX_ROLE_SLIDER;
}

bool BrowserAccessibilityManagerAndroid::Scroll(
    JNIEnv* env, jobject obj, jint id, int direction) {
  BrowserAccessibilityAndroid* node = static_cast<BrowserAccessibilityAndroid*>(
      GetFromID(id));
  if (!node)
    return false;

  return node->Scroll(direction);
}

void BrowserAccessibilityManagerAndroid::OnAtomicUpdateFinished(
    ui::AXTree* tree,
    bool root_changed,
    const std::vector<ui::AXTreeDelegate::Change>& changes) {
  if (root_changed) {
    JNIEnv* env = AttachCurrentThread();
    ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
    if (obj.is_null())
      return;

    Java_BrowserAccessibilityManager_handleNavigate(env, obj.obj());
  }
}

bool
BrowserAccessibilityManagerAndroid::UseRootScrollOffsetsWhenComputingBounds() {
  // The Java layer handles the root scroll offset.
  return false;
}

bool RegisterBrowserAccessibilityManager(JNIEnv* env) {
  return RegisterNativesImpl(env);
}

}  // namespace content