from collections.abc import Callable

ROOT_COLOR = "#ff9999"
GHOST_COLOR = "#cccccc"

def from_nested_dict(trees: list[dict]) -> tuple[list, list]:
  """
  Convert a list of nested dictionaries to vis.js nodes and edges format.

  Args:
      trees: List of nested dictionaries where keys are node names and values are
             dictionaries of children (e.g., [{"root1": {"child1": {}}}, {"root2": {}}])

  Returns:
      tuple: (nodes, edges) where:
          - nodes: list of dicts with auto-incremented numeric IDs
          - edges: list of dicts with 'from' and 'to' keys

  Example:
      >>> trees = [{"root1": {"child1": {}}}, {"root2": {"child2": {}}}]
      >>> nodes, edges = from_nested_dict(trees)
      >>> # nodes = [{"id": 1, "label": "root1"}, {"id": 2, "label": "child1"}, ...]
  """
  nodes = []
  edges = []
  node_id_counter = 1
  node_id_map = {}  # maps node_label -> node_id
  
  def traverse(subtree: dict, parent_id: int | None = None):
    nonlocal node_id_counter
    
    for node_label, children in subtree.items():
      # Create node with auto-incremented ID
      current_id = node_id_counter
      node_id_map[node_label] = current_id
      nodes.append({
          "id": current_id,
          "label": node_label
      })
      node_id_counter += 1
      
      # Create edge from parent to current node
      if parent_id is not None:
        edges.append({
            "from": parent_id,
            "to": current_id
        })
      
      # Recursively process children
      if children:
        traverse(children, parent_id=current_id)
  
  # Process each tree in the list
  for tree in trees:
    traverse(tree)
  
  return nodes, edges


def from_tree_with_metadata(
    trees: list[dict],
    id_getter: Callable = None,
    label_getter: Callable = None,
    children_getter: Callable = None
) -> tuple[list, list]:
  """
  Convert a list of trees with metadata to vis.js nodes and edges format.

  Args:
      trees: List of dictionaries with 'id', 'label', and 'children' keys
             (e.g., [{"id": "root1", "label": "Root 1", "children": [...]}, ...])
      id_getter: Optional callback to extract node ID from dict
                 Default: lambda n: n.get("id")
      label_getter: Optional callback to extract node label from dict
                    Default: lambda n: n.get("label", "")
      children_getter: Optional callback to extract children list from dict
                       Default: lambda n: n.get("children", [])

  Returns:
      tuple: (nodes, edges) where:
          - nodes: list of dicts with IDs from tree or auto-incremented
          - edges: list of dicts with 'from' and 'to' keys

  Example:
      >>> trees = [
      ...     {
      ...         "id": "root1",
      ...         "label": "Root Node 1",
      ...         "children": [
      ...             {"id": "child1", "label": "Child 1", "children": []}
      ...         ]
      ...     },
      ...     {"id": "root2", "label": "Root Node 2"}
      ... ]
      >>> nodes, edges = from_tree_with_metadata(trees)
  """
  # Default getters
  if id_getter is None:
    id_getter = lambda n: n.get("id")
  if label_getter is None:
    label_getter = lambda n: n.get("label", "")
  if children_getter is None:
    children_getter = lambda n: n.get("children", [])
  
  nodes = []
  edges = []
  node_id_counter = 1
  
  def traverse(node_dict: dict, parent_id: int | str | None = None):
    nonlocal node_id_counter
    
    # Extract ID (use provided or auto-increment)
    node_id = id_getter(node_dict)
    if node_id is None:
      node_id = node_id_counter
      node_id_counter += 1
    
    # Extract label
    node_label = label_getter(node_dict)
    
    # Create node
    nodes.append({
        "id": node_id,
        "label": node_label
    })
    
    # Create edge from parent to current node
    if parent_id is not None:
      edges.append({
          "from": parent_id,
          "to": node_id
      })
    
    # Recursively process children
    children = children_getter(node_dict)
    if children:
      for child in children:
        traverse(child, parent_id=node_id)
  
  # Process each tree in the list
  for tree in trees:
    traverse(tree)
  
  return nodes, edges


def from_parent_child_list(
    items: list,
    id_getter: Callable = None,
    label_getter: Callable = None,
    parent_getter: Callable = None,
    ghost_color: str = GHOST_COLOR,
    root_color: str | None = ROOT_COLOR
) -> tuple[list, list]:
  """
  Convert a list of items with parent references to vis.js nodes and edges format.

  Args:
      items: List of items (dicts or objects) with parent references
      id_getter: callback to extract node ID
      label_getter: callback to extract node label
      parent_getter: callback to extract parent ID
      ghost_color: color for ghost nodes (referenced parents)
      root_color: color for root nodes (nodes without parent)

  Returns:
      tuple: (nodes, edges)
  """
  
  # Default getters
  if id_getter is None:
    id_getter = lambda item: item.get("id")
  
  if label_getter is None:
    label_getter = lambda item: item.get("label", "")
  
  if parent_getter is None:
    parent_getter = lambda item: item.get("parent")
  
  nodes = []
  edges = []
  
  # Track all existing node IDs
  existing_ids = set()
  
  # First pass: create nodes for all items
  for item in items:
    node_id = id_getter(item)
    node_label = label_getter(item)
    
    existing_ids.add(node_id)
    nodes.append({
        "id": node_id,
        "label": node_label,
        # root color assigned later
    })
  
  # Track ghost nodes
  ghost_nodes = set()
  
  # Track which nodes have parents
  nodes_with_parent = set()
  
  # Second pass: create edges and detect ghost nodes
  for item in items:
    node_id = id_getter(item)
    parent_id = parent_getter(item)
    
    # Skip roots
    if parent_id is None or parent_id == "":
      continue
    
    # Child has a parent
    nodes_with_parent.add(node_id)
    
    # Create edge parent → child
    edges.append({
        "from": parent_id,
        "to": node_id
    })
    
    # Create ghost node if parent not found
    if parent_id not in existing_ids and parent_id not in ghost_nodes:
      ghost_nodes.add(parent_id)
      nodes.append({
          "id": parent_id,
          "label": str(parent_id),
          "color": ghost_color
      })
  
  # Final pass: assign color to root nodes
  if root_color is not None:
    for node in nodes:
      if node["id"] not in nodes_with_parent and node["id"] not in ghost_nodes:
        # Root node
        node["color"] = root_color
  
  return nodes, edges