// Copyright 2013 The Flutter 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 "accessibility_bridge.h"

#include <functional>
#include <utility>

#include "flutter/third_party/accessibility/ax/ax_tree_update.h"
#include "flutter/third_party/accessibility/base/logging.h"

namespace flutter {  // namespace

constexpr int kHasScrollingAction =
    FlutterSemanticsAction::kFlutterSemanticsActionScrollLeft |
    FlutterSemanticsAction::kFlutterSemanticsActionScrollRight |
    FlutterSemanticsAction::kFlutterSemanticsActionScrollUp |
    FlutterSemanticsAction::kFlutterSemanticsActionScrollDown;

// AccessibilityBridge
AccessibilityBridge::AccessibilityBridge(
    std::unique_ptr<AccessibilityBridgeDelegate> delegate)
    : delegate_(std::move(delegate)) {
  event_generator_.SetTree(&tree_);
  tree_.AddObserver(static_cast<ui::AXTreeObserver*>(this));
}

AccessibilityBridge::~AccessibilityBridge() {
  event_generator_.ReleaseTree();
  tree_.RemoveObserver(static_cast<ui::AXTreeObserver*>(this));
}

void AccessibilityBridge::AddFlutterSemanticsNodeUpdate(
    const FlutterSemanticsNode* node) {
  pending_semantics_node_updates_[node->id] = FromFlutterSemanticsNode(node);
}

void AccessibilityBridge::AddFlutterSemanticsCustomActionUpdate(
    const FlutterSemanticsCustomAction* action) {
  pending_semantics_custom_action_updates_[action->id] =
      FromFlutterSemanticsCustomAction(action);
}

void AccessibilityBridge::CommitUpdates() {
  ui::AXTreeUpdate update{.tree_data = tree_.data()};
  // Figure out update order, ui::AXTree only accepts update in tree order,
  // where parent node must come before the child node in
  // ui::AXTreeUpdate.nodes. We start with picking a random node and turn the
  // entire subtree into a list. We pick another node from the remaining update,
  // and keep doing so until the update map is empty. We then concatenate the
  // lists in the reversed order, this guarantees parent updates always come
  // before child updates.
  std::vector<std::vector<SemanticsNode>> results;
  while (!pending_semantics_node_updates_.empty()) {
    auto begin = pending_semantics_node_updates_.begin();
    SemanticsNode target = begin->second;
    std::vector<SemanticsNode> sub_tree_list;
    GetSubTreeList(target, sub_tree_list);
    results.push_back(sub_tree_list);
    pending_semantics_node_updates_.erase(begin);
  }

  for (size_t i = results.size(); i > 0; i--) {
    for (SemanticsNode node : results[i - 1]) {
      ConvertFlutterUpdate(node, update);
    }
  }

  tree_.Unserialize(update);
  pending_semantics_node_updates_.clear();
  pending_semantics_custom_action_updates_.clear();

  std::string error = tree_.error();
  if (!error.empty()) {
    BASE_LOG() << "Failed to update ui::AXTree, error: " << error;
    return;
  }
  // Handles accessibility events as the result of the semantics update.
  for (const auto& targeted_event : event_generator_) {
    auto event_target =
        GetFlutterPlatformNodeDelegateFromID(targeted_event.node->id());
    if (event_target.expired()) {
      continue;
    }

    delegate_->OnAccessibilityEvent(targeted_event);
  }
  event_generator_.ClearEvents();
}

std::weak_ptr<FlutterPlatformNodeDelegate>
AccessibilityBridge::GetFlutterPlatformNodeDelegateFromID(
    AccessibilityNodeId id) const {
  const auto iter = id_wrapper_map_.find(id);
  if (iter != id_wrapper_map_.end()) {
    return iter->second;
  }

  return std::weak_ptr<FlutterPlatformNodeDelegate>();
}

const ui::AXTreeData& AccessibilityBridge::GetAXTreeData() const {
  return tree_.data();
}

const std::vector<ui::AXEventGenerator::TargetedEvent>
AccessibilityBridge::GetPendingEvents() {
  std::vector<ui::AXEventGenerator::TargetedEvent> result(
      event_generator_.begin(), event_generator_.end());
  return result;
}

void AccessibilityBridge::UpdateDelegate(
    std::unique_ptr<AccessibilityBridgeDelegate> delegate) {
  delegate_ = std::move(delegate);
  // Recreate FlutterPlatformNodeDelegates since they may contain stale state
  // from the previous AccessibilityBridgeDelegate.
  for (const auto& [node_id, old_platform_node_delegate] : id_wrapper_map_) {
    std::shared_ptr<FlutterPlatformNodeDelegate> platform_node_delegate =
        delegate_->CreateFlutterPlatformNodeDelegate();
    platform_node_delegate->Init(
        std::static_pointer_cast<FlutterPlatformNodeDelegate::OwnerBridge>(
            shared_from_this()),
        old_platform_node_delegate->GetAXNode());
    id_wrapper_map_[node_id] = platform_node_delegate;
  }
}

void AccessibilityBridge::OnNodeWillBeDeleted(ui::AXTree* tree,
                                              ui::AXNode* node) {}

void AccessibilityBridge::OnSubtreeWillBeDeleted(ui::AXTree* tree,
                                                 ui::AXNode* node) {}

void AccessibilityBridge::OnNodeReparented(ui::AXTree* tree, ui::AXNode* node) {
}

void AccessibilityBridge::OnRoleChanged(ui::AXTree* tree,
                                        ui::AXNode* node,
                                        ax::mojom::Role old_role,
                                        ax::mojom::Role new_role) {}

void AccessibilityBridge::OnNodeCreated(ui::AXTree* tree, ui::AXNode* node) {
  BASE_DCHECK(node);
  id_wrapper_map_[node->id()] = delegate_->CreateFlutterPlatformNodeDelegate();
  id_wrapper_map_[node->id()]->Init(
      std::static_pointer_cast<FlutterPlatformNodeDelegate::OwnerBridge>(
          shared_from_this()),
      node);
}

void AccessibilityBridge::OnNodeDeleted(ui::AXTree* tree,
                                        AccessibilityNodeId node_id) {
  BASE_DCHECK(node_id != ui::AXNode::kInvalidAXID);
  if (id_wrapper_map_.find(node_id) != id_wrapper_map_.end()) {
    id_wrapper_map_.erase(node_id);
  }
}

void AccessibilityBridge::OnAtomicUpdateFinished(
    ui::AXTree* tree,
    bool root_changed,
    const std::vector<ui::AXTreeObserver::Change>& changes) {
  // The Flutter semantics update does not include child->parent relationship
  // We have to update the relative bound offset container id here in order
  // to calculate the screen bound correctly.
  for (const auto& change : changes) {
    ui::AXNode* node = change.node;
    const ui::AXNodeData& data = node->data();
    AccessibilityNodeId offset_container_id = -1;
    if (node->parent()) {
      offset_container_id = node->parent()->id();
    }
    node->SetLocation(offset_container_id, data.relative_bounds.bounds,
                      data.relative_bounds.transform.get());
  }
}

// Private method.
void AccessibilityBridge::GetSubTreeList(SemanticsNode target,
                                         std::vector<SemanticsNode>& result) {
  result.push_back(target);
  for (int32_t child : target.children_in_traversal_order) {
    auto iter = pending_semantics_node_updates_.find(child);
    if (iter != pending_semantics_node_updates_.end()) {
      SemanticsNode node = iter->second;
      GetSubTreeList(node, result);
      pending_semantics_node_updates_.erase(iter);
    }
  }
}

void AccessibilityBridge::ConvertFlutterUpdate(const SemanticsNode& node,
                                               ui::AXTreeUpdate& tree_update) {
  ui::AXNodeData node_data;
  node_data.id = node.id;
  SetRoleFromFlutterUpdate(node_data, node);
  SetStateFromFlutterUpdate(node_data, node);
  SetActionsFromFlutterUpdate(node_data, node);
  SetBooleanAttributesFromFlutterUpdate(node_data, node);
  SetIntAttributesFromFlutterUpdate(node_data, node);
  SetIntListAttributesFromFlutterUpdate(node_data, node);
  SetStringListAttributesFromFlutterUpdate(node_data, node);
  SetNameFromFlutterUpdate(node_data, node);
  SetValueFromFlutterUpdate(node_data, node);
  node_data.relative_bounds.bounds.SetRect(node.rect.left, node.rect.top,
                                           node.rect.right - node.rect.left,
                                           node.rect.bottom - node.rect.top);
  node_data.relative_bounds.transform = std::make_unique<gfx::Transform>(
      node.transform.scaleX, node.transform.skewX, node.transform.transX, 0,
      node.transform.skewY, node.transform.scaleY, node.transform.transY, 0,
      node.transform.pers0, node.transform.pers1, node.transform.pers2, 0, 0, 0,
      0, 0);
  for (auto child : node.children_in_traversal_order) {
    node_data.child_ids.push_back(child);
  }
  SetTreeData(node, tree_update);
  tree_update.nodes.push_back(node_data);
}

void AccessibilityBridge::SetRoleFromFlutterUpdate(ui::AXNodeData& node_data,
                                                   const SemanticsNode& node) {
  FlutterSemanticsFlag flags = node.flags;
  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsButton) {
    node_data.role = ax::mojom::Role::kButton;
    return;
  }
  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsTextField &&
      !(flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsReadOnly)) {
    node_data.role = ax::mojom::Role::kTextField;
    return;
  }
  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsHeader) {
    node_data.role = ax::mojom::Role::kHeader;
    return;
  }
  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsImage) {
    node_data.role = ax::mojom::Role::kImage;
    return;
  }
  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsLink) {
    node_data.role = ax::mojom::Role::kLink;
    return;
  }

  if (flags & kFlutterSemanticsFlagIsInMutuallyExclusiveGroup &&
      flags & kFlutterSemanticsFlagHasCheckedState) {
    node_data.role = ax::mojom::Role::kRadioButton;
    return;
  }
  if (flags & kFlutterSemanticsFlagHasCheckedState) {
    node_data.role = ax::mojom::Role::kCheckBox;
    return;
  }
  if (flags & kFlutterSemanticsFlagHasToggledState) {
    node_data.role = ax::mojom::Role::kToggleButton;
    return;
  }
  if (flags & kFlutterSemanticsFlagIsSlider) {
    node_data.role = ax::mojom::Role::kSlider;
    return;
  }
  // If the state cannot be derived from the flutter flags, we fallback to group
  // or static text.
  if (node.children_in_traversal_order.empty()) {
    node_data.role = ax::mojom::Role::kStaticText;
  } else {
    node_data.role = ax::mojom::Role::kGroup;
  }
}

void AccessibilityBridge::SetStateFromFlutterUpdate(ui::AXNodeData& node_data,
                                                    const SemanticsNode& node) {
  FlutterSemanticsFlag flags = node.flags;
  FlutterSemanticsAction actions = node.actions;
  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsTextField &&
      (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsReadOnly) == 0) {
    node_data.AddState(ax::mojom::State::kEditable);
  }
  if (node_data.role == ax::mojom::Role::kStaticText &&
      (actions & kHasScrollingAction) == 0 && node.value.empty() &&
      node.label.empty() && node.hint.empty()) {
    node_data.AddState(ax::mojom::State::kIgnored);
  } else {
    // kFlutterSemanticsFlagIsFocusable means a keyboard focusable, it is
    // different from semantics focusable.
    // TODO(chunhtai): figure out whether something is not semantics focusable.
    node_data.AddState(ax::mojom::State::kFocusable);
  }
}

void AccessibilityBridge::SetActionsFromFlutterUpdate(
    ui::AXNodeData& node_data,
    const SemanticsNode& node) {
  FlutterSemanticsAction actions = node.actions;
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionTap) {
    node_data.AddAction(ax::mojom::Action::kDoDefault);
  }
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionScrollLeft) {
    node_data.AddAction(ax::mojom::Action::kScrollLeft);
  }
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionScrollRight) {
    node_data.AddAction(ax::mojom::Action::kScrollRight);
  }
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionScrollUp) {
    node_data.AddAction(ax::mojom::Action::kScrollUp);
  }
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionScrollDown) {
    node_data.AddAction(ax::mojom::Action::kScrollDown);
  }
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionIncrease) {
    node_data.AddAction(ax::mojom::Action::kIncrement);
  }
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionDecrease) {
    node_data.AddAction(ax::mojom::Action::kDecrement);
  }
  // Every node has show on screen action.
  node_data.AddAction(ax::mojom::Action::kScrollToMakeVisible);

  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionSetSelection) {
    node_data.AddAction(ax::mojom::Action::kSetSelection);
  }
  if (actions & FlutterSemanticsAction::
                    kFlutterSemanticsActionDidGainAccessibilityFocus) {
    node_data.AddAction(ax::mojom::Action::kSetAccessibilityFocus);
  }
  if (actions & FlutterSemanticsAction::
                    kFlutterSemanticsActionDidLoseAccessibilityFocus) {
    node_data.AddAction(ax::mojom::Action::kClearAccessibilityFocus);
  }
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionCustomAction) {
    node_data.AddAction(ax::mojom::Action::kCustomAction);
  }
}

void AccessibilityBridge::SetBooleanAttributesFromFlutterUpdate(
    ui::AXNodeData& node_data,
    const SemanticsNode& node) {
  FlutterSemanticsAction actions = node.actions;
  FlutterSemanticsFlag flags = node.flags;
  node_data.AddBoolAttribute(ax::mojom::BoolAttribute::kScrollable,
                             actions & kHasScrollingAction);
  node_data.AddBoolAttribute(
      ax::mojom::BoolAttribute::kClickable,
      actions & FlutterSemanticsAction::kFlutterSemanticsActionTap);
  // TODO(chunhtai): figure out if there is a node that does not clip overflow.
  node_data.AddBoolAttribute(ax::mojom::BoolAttribute::kClipsChildren,
                             !node.children_in_traversal_order.empty());
  node_data.AddBoolAttribute(
      ax::mojom::BoolAttribute::kSelected,
      flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsSelected);
  node_data.AddBoolAttribute(
      ax::mojom::BoolAttribute::kEditableRoot,
      flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsTextField &&
          (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsReadOnly) == 0);
}

void AccessibilityBridge::SetIntAttributesFromFlutterUpdate(
    ui::AXNodeData& node_data,
    const SemanticsNode& node) {
  FlutterSemanticsFlag flags = node.flags;
  node_data.AddIntAttribute(ax::mojom::IntAttribute::kTextDirection,
                            node.text_direction);

  int sel_start = node.text_selection_base;
  int sel_end = node.text_selection_extent;
  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsTextField &&
      (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsReadOnly) == 0 &&
      !node.value.empty()) {
    // By default the text field selection should be at the end.
    sel_start = sel_start == -1 ? node.value.length() : sel_start;
    sel_end = sel_end == -1 ? node.value.length() : sel_end;
  }
  node_data.AddIntAttribute(ax::mojom::IntAttribute::kTextSelStart, sel_start);
  node_data.AddIntAttribute(ax::mojom::IntAttribute::kTextSelEnd, sel_end);

  if (node_data.role == ax::mojom::Role::kRadioButton ||
      node_data.role == ax::mojom::Role::kCheckBox) {
    node_data.AddIntAttribute(
        ax::mojom::IntAttribute::kCheckedState,
        static_cast<int32_t>(
            flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsCheckStateMixed
                ? ax::mojom::CheckedState::kMixed
            : flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsChecked
                ? ax::mojom::CheckedState::kTrue
                : ax::mojom::CheckedState::kFalse));
  }
}

void AccessibilityBridge::SetIntListAttributesFromFlutterUpdate(
    ui::AXNodeData& node_data,
    const SemanticsNode& node) {
  FlutterSemanticsAction actions = node.actions;
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionCustomAction) {
    std::vector<int32_t> custom_action_ids;
    for (size_t i = 0; i < node.custom_accessibility_actions.size(); i++) {
      custom_action_ids.push_back(node.custom_accessibility_actions[i]);
    }
    node_data.AddIntListAttribute(ax::mojom::IntListAttribute::kCustomActionIds,
                                  custom_action_ids);
  }
}

void AccessibilityBridge::SetStringListAttributesFromFlutterUpdate(
    ui::AXNodeData& node_data,
    const SemanticsNode& node) {
  FlutterSemanticsAction actions = node.actions;
  if (actions & FlutterSemanticsAction::kFlutterSemanticsActionCustomAction) {
    std::vector<std::string> custom_action_description;
    for (size_t i = 0; i < node.custom_accessibility_actions.size(); i++) {
      auto iter = pending_semantics_custom_action_updates_.find(
          node.custom_accessibility_actions[i]);
      BASE_DCHECK(iter != pending_semantics_custom_action_updates_.end());
      custom_action_description.push_back(iter->second.label);
    }
    node_data.AddStringListAttribute(
        ax::mojom::StringListAttribute::kCustomActionDescriptions,
        custom_action_description);
  }
}

void AccessibilityBridge::SetNameFromFlutterUpdate(ui::AXNodeData& node_data,
                                                   const SemanticsNode& node) {
  node_data.SetName(node.label);
}

void AccessibilityBridge::SetValueFromFlutterUpdate(ui::AXNodeData& node_data,
                                                    const SemanticsNode& node) {
  node_data.SetValue(node.value);
}

void AccessibilityBridge::SetTreeData(const SemanticsNode& node,
                                      ui::AXTreeUpdate& tree_update) {
  FlutterSemanticsFlag flags = node.flags;
  // Set selection if:
  // 1. this text field has a valid selection
  // 2. this text field doesn't have a valid selection but had selection stored
  //    in the tree.
  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsTextField) {
    if (node.text_selection_base != -1) {
      tree_update.tree_data.sel_anchor_object_id = node.id;
      tree_update.tree_data.sel_anchor_offset = node.text_selection_base;
      tree_update.tree_data.sel_focus_object_id = node.id;
      tree_update.tree_data.sel_focus_offset = node.text_selection_extent;
      tree_update.has_tree_data = true;
    } else if (tree_update.tree_data.sel_anchor_object_id == node.id) {
      tree_update.tree_data.sel_anchor_object_id = ui::AXNode::kInvalidAXID;
      tree_update.tree_data.sel_anchor_offset = -1;
      tree_update.tree_data.sel_focus_object_id = ui::AXNode::kInvalidAXID;
      tree_update.tree_data.sel_focus_offset = -1;
      tree_update.has_tree_data = true;
    }
  }

  if (flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsFocused &&
      tree_update.tree_data.focus_id != node.id) {
    tree_update.tree_data.focus_id = node.id;
    tree_update.has_tree_data = true;
  } else if ((flags & FlutterSemanticsFlag::kFlutterSemanticsFlagIsFocused) ==
                 0 &&
             tree_update.tree_data.focus_id == node.id) {
    tree_update.tree_data.focus_id = ui::AXNode::kInvalidAXID;
    tree_update.has_tree_data = true;
  }
}

AccessibilityBridge::SemanticsNode
AccessibilityBridge::FromFlutterSemanticsNode(
    const FlutterSemanticsNode* flutter_node) {
  SemanticsNode result;
  result.id = flutter_node->id;
  result.flags = flutter_node->flags;
  result.actions = flutter_node->actions;
  result.text_selection_base = flutter_node->text_selection_base;
  result.text_selection_extent = flutter_node->text_selection_extent;
  result.scroll_child_count = flutter_node->scroll_child_count;
  result.scroll_index = flutter_node->scroll_index;
  result.scroll_position = flutter_node->scroll_position;
  result.scroll_extent_max = flutter_node->scroll_extent_max;
  result.scroll_extent_min = flutter_node->scroll_extent_min;
  result.elevation = flutter_node->elevation;
  result.thickness = flutter_node->thickness;
  if (flutter_node->label) {
    result.label = std::string(flutter_node->label);
  }
  if (flutter_node->hint) {
    result.hint = std::string(flutter_node->hint);
  }
  if (flutter_node->value) {
    result.value = std::string(flutter_node->value);
  }
  if (flutter_node->increased_value) {
    result.increased_value = std::string(flutter_node->increased_value);
  }
  if (flutter_node->decreased_value) {
    result.decreased_value = std::string(flutter_node->decreased_value);
  }
  result.text_direction = flutter_node->text_direction;
  result.rect = flutter_node->rect;
  result.transform = flutter_node->transform;
  if (flutter_node->child_count > 0) {
    result.children_in_traversal_order = std::vector<int32_t>(
        flutter_node->children_in_traversal_order,
        flutter_node->children_in_traversal_order + flutter_node->child_count);
  }
  if (flutter_node->custom_accessibility_actions_count > 0) {
    result.custom_accessibility_actions = std::vector<int32_t>(
        flutter_node->custom_accessibility_actions,
        flutter_node->custom_accessibility_actions +
            flutter_node->custom_accessibility_actions_count);
  }
  return result;
}

AccessibilityBridge::SemanticsCustomAction
AccessibilityBridge::FromFlutterSemanticsCustomAction(
    const FlutterSemanticsCustomAction* flutter_custom_action) {
  SemanticsCustomAction result;
  result.id = flutter_custom_action->id;
  result.override_action = flutter_custom_action->override_action;
  if (flutter_custom_action->label) {
    result.label = std::string(flutter_custom_action->label);
  }
  if (flutter_custom_action->hint) {
    result.hint = std::string(flutter_custom_action->hint);
  }
  return result;
}

void AccessibilityBridge::SetLastFocusedId(AccessibilityNodeId node_id) {
  if (last_focused_id_ != node_id) {
    auto last_focused_child =
        GetFlutterPlatformNodeDelegateFromID(last_focused_id_);
    if (!last_focused_child.expired()) {
      delegate_->DispatchAccessibilityAction(
          last_focused_id_,
          FlutterSemanticsAction::
              kFlutterSemanticsActionDidLoseAccessibilityFocus,
          {});
    }
    last_focused_id_ = node_id;
  }
}

AccessibilityNodeId AccessibilityBridge::GetLastFocusedId() {
  return last_focused_id_;
}

gfx::NativeViewAccessible AccessibilityBridge::GetNativeAccessibleFromId(
    AccessibilityNodeId id) {
  auto platform_node_delegate = GetFlutterPlatformNodeDelegateFromID(id).lock();
  if (!platform_node_delegate) {
    return nullptr;
  }
  return platform_node_delegate->GetNativeViewAccessible();
}

gfx::RectF AccessibilityBridge::RelativeToGlobalBounds(const ui::AXNode* node,
                                                       bool& offscreen,
                                                       bool clip_bounds) {
  return tree_.RelativeToTreeBounds(node, gfx::RectF(), &offscreen,
                                    clip_bounds);
}

void AccessibilityBridge::DispatchAccessibilityAction(
    AccessibilityNodeId target,
    FlutterSemanticsAction action,
    fml::MallocMapping data) {
  delegate_->DispatchAccessibilityAction(target, action, std::move(data));
}

}  // namespace flutter