sentry/static/app/views/performance/newTraceDetails/traceTree.tsx

import type {Client} from 'sentry/api';
import type {RawSpanType} from 'sentry/components/events/interfaces/spans/types';
import type {Organization} from 'sentry/types';
import type {Event, EventTransaction} from 'sentry/types/event';
import type {
  TraceError as TraceErrorType,
  TraceFullDetailed,
  TraceSplitResults,
} from 'sentry/utils/performance/quickTrace/types';

import {TraceType} from '../traceDetails/newTraceDetailsContent';
import {isRootTransaction} from '../traceDetails/utils';

import {
  isAutogroupedNode,
  isMissingInstrumentationNode,
  isParentAutogroupedNode,
  isRootNode,
  isSiblingAutogroupedNode,
  isSpanNode,
  isTraceNode,
  isTransactionNode,
} from './guards';

/**
 *
 * This file implements the tree data structure that is used to represent a trace. We do
 * this both for performance reasons as well as flexibility. The requirement for a tree
 * is to support incremental patching and updates. This is important because we want to
 * be able to fetch more data as the user interacts with the tree, and we want to be able
 * efficiently update the tree as we receive more data.
 *
 * The trace is represented as a tree with different node value types (transaction or span)
 * Each tree node contains a reference to its parent and a list of references to its children,
 * as well as a reference to the value that the node holds. Each node also contains
 * some meta data and state about the node, such as if it is expanded or zoomed in. The benefit
 * of abstracting parts of the UI state is that the tree will persist user actions such as expanding
 * or collapsing nodes which would have otherwise been lost when individual nodes are remounted in the tree.
 *
 * Each tree holds a list reference, which is a live reference to a flattened representation
 * of the tree (used to render the tree in the UI). Since the list is mutable (and we want to keep it that way for performance
 * reasons as we want to support mutations on traces with ~100k+ nodes), callers need to manage reactivity themselves.
 *
 * An alternative, but not recommended approach is to call build() on the tree after each mutation,
 * which will iterate over all of the children and build a fresh list reference.
 *
 * In most cases, the initial tree is a list of transactions containing other transactions. Each transaction can
 * then be expanded into a list of spans which can also in some cases be expanded.
 *
 *  - trace                                          - trace
 *   |- parent transaction     --> when expanding     |- parent transaction
 *    |- child transaction                             |- span
 *                                                      |- span                     this used to be a transaction,
 *                                                     |- child transaction span <- but is now be a list of spans
 *                                                     |- span                      belonging to the transaction
 *                                                                                  this results in child txns to be lost,
 *                                                                                  which is a confusing user experience
 *
 * The tree supports autogrouping of spans vertically or as siblings. When that happens, a autogrouped node of either a vertical or
 * sibling type is inserted as an intermediary node. In the vertical case, the autogrouped node
 * holds the reference to the head and tail of the autogrouped sequence. In the sibling case, the autogrouped node
 * holds a reference to the children that are part of the autogrouped sequence. When expanding and collapsing these nodes,
 * the tree perform a reference swap to either point to the head (when expanded) or tail (when collapsed) of the autogrouped sequence.
 *
 * In vertical grouping case, the following happens:
 *
 * - root                                              - root
 *  - trace                                             - trace
 *  |- transaction                                       |- transaction
 *   |- span 1   <-|  these become autogrouped             |- autogrouped (head=span1, tail=span3, children points to children of tail)
 *    |- span 2    |- as they are inserted into             |- other span (parent points to autogrouped node)
 *     |- span 3 <-|  the tree.
 *      |- other span
 *
 * When the autogrouped node is expanded the UI needs to show the entire collapsed chain, so we swap the tail children to point
 * back to the tail, and have autogrouped node point to it's head as the children.
 *
 * - root                                                             - root
 *  - trace                                                            - trace
 *  |- transaction                                                     |- transaction
 *   |- autogrouped (head=span1, tail=span3) <- when expanding          |- autogrouped (head=span1, tail=span3, children points to head)
 *    | other span (paren points to autogrouped)                         |- span 1 (head)
 *                                                                        |- span 2
 *                                                                         |- span 3 (tail)
 *                                                                          |- other span (children of tail, parent points to tail)
 *
 * Notes and improvements:
 * - collecting children should be O(n), it is currently O(n^2) as we are missing a proper queue implementation
 * - the notion of expanded and zoomed is confusing, they stand for the same idea from a UI pov
 * - there is an annoying thing wrt span and transaction nodes where we either store data on _children or _spanChildren
 *   this is because we want to be able to store both transaction and span nodes in the same tree, but it makes for an
 *   annoying API. A better design would have been to create an invisible meta node that just points to the correct children
 * - connector generation should live in the UI layer, not in the tree. Same with depth calculation. It is more convenient
 *   to calculate this when rendering the tree, as we can only calculate it only for the visible nodes and avoid an extra tree pass
 * - instead of storing span children separately, we should have meta tree nodes that handle pointing to the correct children
 */

export declare namespace TraceTree {
  type Transaction = TraceFullDetailed;
  type Span = RawSpanType;
  type Trace = TraceSplitResults<Transaction>;
  type TraceError = TraceErrorType;

  interface MissingInstrumentationSpan {
    start_timestamp: number;
    timestamp: number;
    type: 'missing_instrumentation';
  }
  interface SiblingAutogroup extends RawSpanType {
    autogrouped_by: {
      description: string;
      op: string;
    };
  }

  interface ChildrenAutogroup {
    autogrouped_by: {
      op: string;
    };
  }

  type NodeValue =
    | Trace
    | Transaction
    | TraceError
    | Span
    | MissingInstrumentationSpan
    | SiblingAutogroup
    | ChildrenAutogroup
    | null;

  type Metadata = {
    event_id: string | undefined;
    project_slug: string | undefined;
  };
}

function fetchTransactionSpans(
  api: Client,
  organization: Organization,
  project_slug: string,
  event_id: string
): Promise<EventTransaction> {
  return api.requestPromise(
    `/organizations/${organization.slug}/events/${project_slug}:${event_id}/`
  );
}

function maybeInsertMissingInstrumentationSpan(
  parent: TraceTreeNode<TraceTree.NodeValue>,
  node: TraceTreeNode<TraceTree.Span>
) {
  const lastInsertedSpan = parent.spanChildren[parent.spanChildren.length - 1];
  if (!lastInsertedSpan) {
    return;
  }

  if (node.value.start_timestamp - lastInsertedSpan.value.timestamp < 0.1) {
    return;
  }

  const missingInstrumentationSpan =
    new TraceTreeNode<TraceTree.MissingInstrumentationSpan>(
      parent,
      {
        type: 'missing_instrumentation',
        start_timestamp: lastInsertedSpan.value.timestamp,
        timestamp: node.value.start_timestamp,
      },
      {
        event_id: undefined,
        project_slug: undefined,
      }
    );

  parent.spanChildren.push(missingInstrumentationSpan);
}

export class TraceTree {
  type: 'loading' | 'trace' = 'trace';
  root: TraceTreeNode<null> = TraceTreeNode.Root();

  private _spanPromises: Map<TraceTreeNode<TraceTree.NodeValue>, Promise<Event>> =
    new Map();
  private _list: TraceTreeNode<TraceTree.NodeValue>[] = [];

  static Empty() {
    const tree = new TraceTree().build();
    tree.type = 'trace';
    return tree;
  }

  static Loading(metadata: TraceTree.Metadata): TraceTree {
    const tree = makeExampleTrace(metadata);
    tree.type = 'loading';
    return tree;
  }

  static FromTrace(trace: TraceTree.Trace): TraceTree {
    const tree = new TraceTree();

    let traceStart = Number.POSITIVE_INFINITY;
    let traceEnd = Number.NEGATIVE_INFINITY;

    function visit(
      parent: TraceTreeNode<TraceTree.NodeValue | null>,
      value: TraceTree.Transaction | TraceTree.TraceError
    ) {
      const node = new TraceTreeNode(parent, value, {
        project_slug: value && 'project_slug' in value ? value.project_slug : undefined,
        event_id: value && 'event_id' in value ? value.event_id : undefined,
      });
      node.canFetchData = true;

      if (parent) {
        parent.children.push(node as TraceTreeNode<TraceTree.NodeValue>);
      }

      if ('start_timestamp' in value && 'timestamp' in value) {
        if (value.start_timestamp < traceStart) {
          traceStart = value.start_timestamp;
        }
        if (value.timestamp > traceEnd) {
          traceEnd = value.timestamp;
        }
      } else if ('timestamp' in value && typeof value.timestamp === 'number') {
        if (value.timestamp > traceEnd) {
          traceEnd = value.timestamp;
        }
      }

      if (value && 'children' in value) {
        for (const child of value.children) {
          visit(node, child);
        }
      }

      return node;
    }

    const traceNode = new TraceTreeNode(tree.root, trace, {
      event_id: undefined,
      project_slug: undefined,
    });

    // Trace is always expanded by default
    tree.root.children.push(traceNode);

    for (const transaction of trace.transactions) {
      visit(traceNode, transaction);
    }

    for (const trace_error of trace.orphan_errors) {
      visit(traceNode, trace_error);
    }

    traceNode.space = [traceStart, traceEnd - traceStart];
    tree.root.space = [traceStart, traceEnd - traceStart];
    return tree.build();
  }

  static GetTraceType(root: TraceTreeNode<null>): TraceType {
    const trace = root.children[0];
    if (!trace || !isTraceNode(trace)) {
      throw new TypeError('Not trace node');
    }

    const {transactions, orphan_errors} = trace.value;
    const {roots, orphans} = (transactions ?? []).reduce(
      (counts, transaction) => {
        if (isRootTransaction(transaction)) {
          counts.roots++;
        } else {
          counts.orphans++;
        }
        return counts;
      },
      {roots: 0, orphans: 0}
    );

    if (roots === 0) {
      if (orphans > 0) {
        return TraceType.NO_ROOT;
      }

      if (orphan_errors && orphan_errors.length > 0) {
        return TraceType.ONLY_ERRORS;
      }

      return TraceType.EMPTY_TRACE;
    }

    if (roots === 1) {
      if (orphans > 0) {
        return TraceType.BROKEN_SUBTRACES;
      }

      return TraceType.ONE_ROOT;
    }

    if (roots > 1) {
      return TraceType.MULTIPLE_ROOTS;
    }

    throw new Error('Unknown trace type');
  }

  static FromSpans(
    parent: TraceTreeNode<TraceTree.NodeValue>,
    spans: RawSpanType[]
  ): TraceTreeNode<TraceTree.NodeValue> {
    const parentIsSpan = isSpanNode(parent);
    const lookuptable: Record<
      RawSpanType['span_id'],
      TraceTreeNode<TraceTree.Span | TraceTree.Transaction>
    > = {};

    if (parent.spanChildren.length > 0) {
      parent.zoomedIn = true;
      return parent;
    }

    if (parentIsSpan) {
      if (parent.value && 'span_id' in parent.value) {
        lookuptable[parent.value.span_id] = parent as TraceTreeNode<TraceTree.Span>;
      }
    }

    const transactionsToSpanMap = new Map<string, TraceTreeNode<TraceTree.Transaction>>();

    for (const child of parent.children) {
      if (
        isTransactionNode(child) &&
        'parent_span_id' in child.value &&
        typeof child.value.parent_span_id === 'string'
      ) {
        transactionsToSpanMap.set(child.value.parent_span_id, child);
      }
      continue;
    }

    for (const span of spans) {
      const parentNode = transactionsToSpanMap.get(span.span_id);
      let node: TraceTreeNode<TraceTree.Span>;

      if (parentNode) {
        node = parentNode.clone() as unknown as TraceTreeNode<TraceTree.Span>;
      } else {
        node = new TraceTreeNode(null, span, {
          event_id: undefined,
          project_slug: undefined,
        });
      }

      node.canFetchData = !!parentNode;

      if (parentNode) {
        node.metadata = parentNode.metadata;
      }

      lookuptable[span.span_id] = node;

      if (span.parent_span_id) {
        const spanParentNode = lookuptable[span.parent_span_id];

        if (spanParentNode) {
          node.parent = spanParentNode;
          maybeInsertMissingInstrumentationSpan(spanParentNode, node);
          spanParentNode.spanChildren.push(node);
          continue;
        }
      }

      // Orphaned span
      maybeInsertMissingInstrumentationSpan(parent, node);
      parent.spanChildren.push(node);
      node.parent = parent as TraceTreeNode<TraceTree.Span>;
    }

    parent.zoomedIn = true;
    TraceTree.AutogroupSiblingSpanNodes(parent);
    TraceTree.AutogroupDirectChildrenSpanNodes(parent);
    return parent;
  }

  get list(): ReadonlyArray<TraceTreeNode<TraceTree.NodeValue>> {
    return this._list;
  }

  static AutogroupDirectChildrenSpanNodes(
    root: TraceTreeNode<TraceTree.NodeValue>
  ): void {
    const queue = [root];

    while (queue.length > 0) {
      const node = queue.pop()!;

      if (node.children.length > 1 || !isSpanNode(node)) {
        for (const child of node.children) {
          queue.push(child);
        }
        continue;
      }

      const head = node;
      let tail = node;
      let groupMatchCount = 0;

      while (
        tail &&
        tail.children.length === 1 &&
        isSpanNode(tail.children[0]) &&
        tail.children[0].value.op === head.value.op
      ) {
        groupMatchCount++;
        tail = tail.children[0];
      }

      if (groupMatchCount < 1) {
        for (const child of head.children) {
          queue.push(child);
        }
        continue;
      }

      const autoGroupedNode = new ParentAutogroupNode(
        node.parent,
        {
          ...head.value,
          autogrouped_by: {
            op: head.value && 'op' in head.value ? head.value.op ?? '' : '',
          },
        },
        {
          event_id: undefined,
          project_slug: undefined,
        },
        head,
        tail
      );

      if (!node.parent) {
        throw new Error('Parent node is missing, this should be unreachable code');
      }

      autoGroupedNode.groupCount = groupMatchCount + 1;
      autoGroupedNode.space = [
        head.value.start_timestamp,
        tail.value.timestamp - head.value.start_timestamp,
      ];

      for (const c of tail.children) {
        c.parent = autoGroupedNode;
        queue.push(c);
      }

      const index = node.parent.children.indexOf(node);
      node.parent.children[index] = autoGroupedNode;
    }
  }

  static AutogroupSiblingSpanNodes(root: TraceTreeNode<TraceTree.NodeValue>): void {
    const queue = [root];

    while (queue.length > 0) {
      const node = queue.pop()!;

      if (node.children.length < 5) {
        for (const child of node.children) {
          queue.push(child);
        }
        continue;
      }

      let index = 0;
      let matchCount = 0;
      while (index < node.children.length) {
        const current = node.children[index] as TraceTreeNode<TraceTree.Span>;
        const next = node.children[index + 1] as TraceTreeNode<TraceTree.Span>;

        if (
          next &&
          next.children.length === 0 &&
          current.children.length === 0 &&
          next.value.op === current.value.op &&
          next.value.description === current.value.description
        ) {
          matchCount++;
          // If the next node is the last node in the list, we keep iterating
          if (index + 1 < node.children.length) {
            index++;
            continue;
          }
        }

        if (matchCount >= 4) {
          const autoGroupedNode = new SiblingAutogroupNode(
            node,
            {
              ...current.value,
              autogrouped_by: {
                op: current.value.op ?? '',
                description: current.value.description ?? '',
              },
            },
            {
              event_id: undefined,
              project_slug: undefined,
            }
          );

          autoGroupedNode.groupCount = matchCount + 1;
          const start = index - matchCount;
          for (let j = start; j < index - 1; j++) {
            autoGroupedNode.children.push(node.children[j]);
            autoGroupedNode.children[autoGroupedNode.children.length - 1].parent =
              autoGroupedNode;
          }

          node.children.splice(start, matchCount + 1, autoGroupedNode);
          index = start + 1;
          matchCount = 0;
        } else {
          index++;
          matchCount = 0;
        }
      }
    }
  }

  // Returns boolean to indicate if node was updated
  expand(node: TraceTreeNode<TraceTree.NodeValue>, expanded: boolean): boolean {
    if (expanded === node.expanded) {
      return false;
    }

    // Expanding is not allowed for zoomed in nodes
    if (node.zoomedIn) {
      return false;
    }

    if (node instanceof ParentAutogroupNode) {
      // In parent autogrouping, we perform a node swap and either point the
      // head or tails of the autogrouped sequence to the autogrouped node
      if (node.expanded) {
        const index = this._list.indexOf(node);

        const autogroupedChildren = node.getVisibleChildren();
        this._list.splice(index + 1, autogroupedChildren.length);

        const newChildren = node.tail.getVisibleChildren();

        for (const c of node.tail.children) {
          c.parent = node;
        }

        this._list.splice(index + 1, 0, ...newChildren);
      } else {
        node.head.parent = node;
        const index = this._list.indexOf(node);
        const childrenCount = node.getVisibleChildrenCount();

        this._list.splice(index + 1, childrenCount);

        node.getVisibleChildrenCount();
        const newChildren = [node.head].concat(
          node.head.getVisibleChildren() as TraceTreeNode<TraceTree.Span>[]
        );

        for (const c of node.children) {
          c.parent = node.tail;
        }

        this._list.splice(index + 1, 0, ...newChildren);
      }

      node.invalidate(node);
      node.expanded = expanded;
      return true;
    }

    if (node.expanded) {
      const index = this._list.indexOf(node);
      this._list.splice(index + 1, node.getVisibleChildrenCount());
      // Flip expanded after collecting visible children
      node.expanded = expanded;
    } else {
      const index = this._list.indexOf(node);
      // Flip expanded so that we can collect visible children
      node.expanded = expanded;
      this._list.splice(index + 1, 0, ...node.getVisibleChildren());
    }
    node.expanded = expanded;
    return true;
  }

  zoomIn(
    node: TraceTreeNode<TraceTree.NodeValue>,
    zoomedIn: boolean,
    options: {
      api: Client;
      organization: Organization;
    }
  ): Promise<Event | null> {
    if (zoomedIn === node.zoomedIn) {
      return Promise.resolve(null);
    }

    if (!zoomedIn) {
      const index = this._list.indexOf(node);
      const childrenCount = node.getVisibleChildrenCount();
      this._list.splice(index + 1, childrenCount);

      node.zoomedIn = zoomedIn;

      if (node.expanded) {
        this._list.splice(index + 1, 0, ...node.getVisibleChildren());
      }

      return Promise.resolve(null);
    }

    const promise =
      this._spanPromises.get(node) ??
      fetchTransactionSpans(
        options.api,
        options.organization,
        node.metadata.project_slug!,
        node.metadata.event_id!
      );

    promise.then(data => {
      const spans = data.entries.find(s => s.type === 'spans');
      if (!spans) {
        return data;
      }

      // Remove existing entries from the list
      const index = this._list.indexOf(node);
      if (node.expanded) {
        const childrenCount = node.getVisibleChildrenCount();
        this._list.splice(index + 1, childrenCount);
      }

      // Api response is not sorted
      if (spans.data) {
        spans.data.sort((a, b) => a.start_timestamp - b.start_timestamp);
      }

      TraceTree.FromSpans(node, spans.data);

      const spanChildren = node.getVisibleChildren();
      this._list.splice(index + 1, 0, ...spanChildren);
      return data;
    });

    this._spanPromises.set(node, promise);
    return promise;
  }

  toList(): TraceTreeNode<TraceTree.NodeValue>[] {
    const list: TraceTreeNode<TraceTree.NodeValue>[] = [];

    function visit(node: TraceTreeNode<TraceTree.NodeValue>) {
      list.push(node);

      if (!node.expanded) {
        return;
      }

      for (const child of node.children) {
        visit(child);
      }
    }

    for (const child of this.root.children) {
      visit(child);
    }

    return list;
  }

  /**
   * Prints the tree in a human readable format, useful for debugging and testing
   */
  print() {
    // root nodes are -1 indexed, so we add 1 to the depth so .repeat doesnt throw
    const print = this.list
      .map(t => printNode(t, 0))
      .filter(Boolean)
      .join('\n');

    // eslint-disable-next-line no-console
    console.log(print);
  }

  build() {
    this._list = this.toList();
    return this;
  }
}

export class TraceTreeNode<T extends TraceTree.NodeValue> {
  parent: TraceTreeNode<TraceTree.NodeValue> | null = null;
  value: T;
  expanded: boolean = false;
  zoomedIn: boolean = false;
  canFetchData: boolean = false;
  metadata: TraceTree.Metadata = {
    project_slug: undefined,
    event_id: undefined,
  };

  space: [number, number] | null = null;

  private _depth: number | undefined;
  private _children: TraceTreeNode<TraceTree.NodeValue>[] = [];
  private _spanChildren: TraceTreeNode<
    TraceTree.Span | TraceTree.MissingInstrumentationSpan
  >[] = [];
  private _connectors: number[] | undefined = undefined;

  constructor(
    parent: TraceTreeNode<TraceTree.NodeValue> | null,
    value: T,
    metadata: TraceTree.Metadata
  ) {
    this.parent = parent ?? null;
    this.value = value;
    this.metadata = metadata;

    if (value && 'timestamp' in value && 'start_timestamp' in value) {
      this.space = [value.start_timestamp, value.timestamp - value.start_timestamp];
    }

    if (isTransactionNode(this) || isTraceNode(this) || isSpanNode(this)) {
      this.expanded = true;
    }
  }

  clone(): TraceTreeNode<T> {
    const node = new TraceTreeNode(this.parent, this.value, this.metadata);
    node.expanded = this.expanded;
    node.zoomedIn = this.zoomedIn;
    node.canFetchData = this.canFetchData;
    node.space = this.space;
    node.children = this.children;
    return node;
  }

  get isOrphaned() {
    return this.parent?.value && 'orphan_errors' in this.parent.value;
  }

  get isLastChild() {
    return this.parent?.children[this.parent.children.length - 1] === this;
  }

  /**
   * Return a lazily calculated depth of the node in the tree.
   * Root node has a value of -1 as it is abstract.
   */
  get depth(): number {
    if (typeof this._depth === 'number') {
      return this._depth;
    }

    let depth = -2;
    let node: TraceTreeNode<any> | null = this;

    while (node) {
      if (typeof node.parent?.depth === 'number') {
        this._depth = node.parent.depth + 1;
        return this._depth;
      }
      depth++;
      node = node.parent;
    }

    this._depth = depth;
    return this._depth;
  }

  /**
   * Returns the depth levels at which the row should draw vertical connectors
   * negative values mean connector points to an orphaned node
   */
  get connectors(): number[] {
    if (this._connectors !== undefined) {
      return this._connectors!;
    }

    this._connectors = [];

    if (this.parent?.connectors !== undefined) {
      this._connectors = [...this.parent.connectors];

      if (this.isLastChild || this.value === null) {
        return this._connectors;
      }

      this.connectors.push(this.isOrphaned ? -this.depth : this.depth);
      return this._connectors;
    }

    let node: TraceTreeNode<T> | TraceTreeNode<TraceTree.NodeValue> | null = this.parent;

    while (node) {
      if (node.value === null) {
        break;
      }

      if (node.isLastChild) {
        node = node.parent;
        continue;
      }

      this._connectors.push(node.isOrphaned ? -node.depth : node.depth);
      node = node.parent;
    }

    return this._connectors;
  }

  /**
   * Returns the children that the node currently points to.
   * The logic here is a consequence of the tree design, where we want to be able to store
   * both transaction and span nodes in the same tree. This results in an annoying API where
   * we either store span children separately or transaction children separately. A better design
   * would have been to create an invisible meta node that always points to the correct children.
   */
  get children(): TraceTreeNode<TraceTree.NodeValue>[] {
    if (isAutogroupedNode(this)) {
      return this._children;
    }

    if (isSpanNode(this)) {
      return this.canFetchData && !this.zoomedIn ? [] : this.spanChildren;
    }

    // if a node is zoomed in, return span children, else return transaction children
    return this.zoomedIn ? this._spanChildren : this._children;
  }

  set children(children: TraceTreeNode<TraceTree.NodeValue>[]) {
    this._children = children;
  }

  get spanChildren(): TraceTreeNode<
    TraceTree.Span | TraceTree.MissingInstrumentationSpan
  >[] {
    return this._spanChildren;
  }

  /**
   * Invalidate the visual data used to render the tree, forcing it
   * to be recalculated on the next render. This is useful when for example
   * the tree is expanded or collapsed, or when the tree is mutated and
   * the visual data is no longer valid as the indentation changes
   */
  invalidate(root?: TraceTreeNode<TraceTree.NodeValue>) {
    this._connectors = undefined;
    this._depth = undefined;

    if (root) {
      const queue = [...this.children];

      while (queue.length > 0) {
        const next = queue.pop()!;
        next.invalidate();
        for (let i = 0; i < next.children.length; i++) {
          queue.push(next.children[i]);
        }
      }
    }
  }

  getVisibleChildrenCount(): number {
    const stack: TraceTreeNode<TraceTree.NodeValue>[] = [];
    let count = 0;

    if (
      this.expanded ||
      isParentAutogroupedNode(this) ||
      isMissingInstrumentationNode(this)
    ) {
      for (let i = this.children.length - 1; i >= 0; i--) {
        stack.push(this.children[i]);
      }
    }

    while (stack.length > 0) {
      const node = stack.pop()!;
      count++;
      // Since we're using a stack and it's LIFO, reverse the children before pushing them
      // to ensure they are processed in the original left-to-right order.
      if (node.expanded || isParentAutogroupedNode(node)) {
        for (let i = node.children.length - 1; i >= 0; i--) {
          stack.push(node.children[i]);
        }
      }
    }

    return count;
  }

  getVisibleChildren(): TraceTreeNode<TraceTree.NodeValue>[] {
    const stack: TraceTreeNode<TraceTree.NodeValue>[] = [];
    const children: TraceTreeNode<TraceTree.NodeValue>[] = [];

    if (
      this.expanded ||
      isParentAutogroupedNode(this) ||
      isMissingInstrumentationNode(this)
    ) {
      for (let i = this.children.length - 1; i >= 0; i--) {
        stack.push(this.children[i]);
      }
    }

    while (stack.length > 0) {
      const node = stack.pop()!;
      children.push(node);
      // Since we're using a stack and it's LIFO, reverse the children before pushing them
      // to ensure they are processed in the original left-to-right order.
      if (node.expanded || isParentAutogroupedNode(node)) {
        for (let i = node.children.length - 1; i >= 0; i--) {
          stack.push(node.children[i]);
        }
      }
    }

    return children;
  }

  print() {
    // root nodes are -1 indexed, so we add 1 to the depth so .repeat doesnt throw
    const offset = this.depth === -1 ? 1 : 0;
    const nodes = [this, ...this.getVisibleChildren()];
    const print = nodes
      .map(t => printNode(t, offset))
      .filter(Boolean)
      .join('\n');

    // eslint-disable-next-line no-console
    console.log(print);
  }

  static Root() {
    return new TraceTreeNode(null, null, {
      event_id: undefined,
      project_slug: undefined,
    });
  }
}

export class ParentAutogroupNode extends TraceTreeNode<TraceTree.ChildrenAutogroup> {
  head: TraceTreeNode<TraceTree.Span>;
  tail: TraceTreeNode<TraceTree.Span>;
  groupCount: number = 0;

  constructor(
    parent: TraceTreeNode<TraceTree.NodeValue> | null,
    node: TraceTree.ChildrenAutogroup,
    metadata: TraceTree.Metadata,
    head: TraceTreeNode<TraceTree.Span>,
    tail: TraceTreeNode<TraceTree.Span>
  ) {
    super(parent, node, metadata);

    this.head = head;
    this.tail = tail;
  }

  get children() {
    if (this.expanded) {
      return [this.head];
    }
    return this.tail.children;
  }
}

export class SiblingAutogroupNode extends TraceTreeNode<TraceTree.SiblingAutogroup> {
  groupCount: number = 0;

  constructor(
    parent: TraceTreeNode<TraceTree.NodeValue> | null,
    node: TraceTree.SiblingAutogroup,
    metadata: TraceTree.Metadata
  ) {
    super(parent, node, metadata);
  }
}

function partialTransaction(
  partial: Partial<TraceTree.Transaction>
): TraceTree.Transaction {
  return {
    start_timestamp: 0,
    timestamp: 0,
    errors: [],
    performance_issues: [],
    parent_span_id: '',
    span_id: '',
    parent_event_id: '',
    project_id: 0,
    'transaction.duration': 0,
    'transaction.op': 'db',
    'transaction.status': 'ok',
    generation: 0,
    project_slug: '',
    event_id: `event_id`,
    transaction: `transaction`,
    children: [],
    ...partial,
  };
}

export function makeExampleTrace(metadata: TraceTree.Metadata): TraceTree {
  const trace: TraceTree.Trace = {
    transactions: [],
    orphan_errors: [],
  };

  function randomBetween(min: number, max: number) {
    return Math.floor(Math.random() * (max - min + 1) + min);
  }

  let start = new Date().getTime();

  for (let i = 0; i < 25; i++) {
    const end = start + randomBetween(100, 200);
    const nest = i > 0 && Math.random() > 0.5;

    if (nest) {
      const parent = trace.transactions[trace.transactions.length - 1];
      parent.children.push(
        partialTransaction({
          ...metadata,
          generation: 0,
          start_timestamp: start,
          transaction: `parent transaction ${i}`,
          timestamp: end,
        })
      );
      parent.timestamp = end;
    } else {
      trace.transactions.push(
        partialTransaction({
          ...metadata,
          generation: 0,
          start_timestamp: start,
          transaction: 'loading...',
          ['transaction.op']: 'loading',
          timestamp: end,
        })
      );
    }

    start = end;
  }

  const tree = TraceTree.FromTrace(trace);

  return tree;
}

function printNode(t: TraceTreeNode<TraceTree.NodeValue>, offset: number): string {
  // +1 because we may be printing from the root which is -1 indexed
  const padding = ' '.repeat(t.depth + offset);

  if (isAutogroupedNode(t)) {
    if (isParentAutogroupedNode(t)) {
      return padding + `parent autogroup (${t.groupCount})`;
    }
    if (isSiblingAutogroupedNode(t)) {
      return padding + `sibling autogroup (${t.groupCount})`;
    }

    return padding + 'autogroup';
  }
  if (isSpanNode(t)) {
    return padding + t.value?.op ?? 'unknown span op';
  }
  if (isTransactionNode(t)) {
    return padding + t.value.transaction ?? 'unknown transaction';
  }
  if (isMissingInstrumentationNode(t)) {
    return padding + 'missing_instrumentation';
  }
  if (isRootNode(t)) {
    return padding + 'Root';
  }
  if (isTraceNode(t)) {
    return padding + 'Trace';
  }

  throw new Error('Not implemented');
}