Tree Modification Operations

def move_node(source, destination) -> None:
    """
    Move a node and its subtree to a new parent.
    
    Parameters:
    - source: str, identifier of node to move
    - destination: str, identifier of new parent node
    
    Raises:
    LoopError if move would create circular reference
    NodeIDAbsentError if source or destination doesn't exist
    """

# Move employee to different department
tree.move_node("alice", "sales_dept")

# Reorganize departments
tree.move_node("engineering", "technology_division")

# Move multiple nodes
employees_to_transfer = ["bob", "carol", "dave"]
for emp_id in employees_to_transfer:
    tree.move_node(emp_id, "new_department")

# Move with error handling
try:
    tree.move_node("manager", "subordinate")  # Would create loop
except LoopError:
    print("Cannot move manager under subordinate")

def remove_node(identifier) -> int:
    """
    Remove a node and all its descendants from the tree.
    
    Parameters:
    - identifier: str, node identifier to remove
    
    Returns:
    int, number of nodes removed (including descendants)
    
    Raises:
    NodeIDAbsentError if node doesn't exist
    """

def link_past_node(nid) -> None:
    """
    Remove node while connecting its children to its parent.
    
    Parameters:
    - nid: str, node identifier to remove
    
    Raises:
    LinkPastRootNodeError if attempting to link past root
    NodeIDAbsentError if node doesn't exist
    """

# Remove employee and report structure
removed_count = tree.remove_node("manager_leaving")
print(f"Removed {removed_count} nodes from organization")

# Remove department but keep employees
tree.link_past_node("temp_department")  # Employees move up to parent

# Conditional removal
nodes_to_remove = []
for node_id in tree.expand_tree():
    node = tree[node_id]
    if node.data and node.data.get("status") == "inactive":
        nodes_to_remove.append(node_id)

for node_id in nodes_to_remove:
    tree.remove_node(node_id)

# Safe removal with validation
if "old_project" in tree:
    if not tree.children("old_project"):  # Check if has children
        tree.remove_node("old_project")
    else:
        print("Cannot remove project with active sub-projects")

def update_node(nid, **attrs) -> None:
    """
    Update node attributes.
    
    Parameters:
    - nid: str, node identifier
    - **attrs: keyword arguments for node attributes (tag, data, etc.)
    
    Raises:
    NodeIDAbsentError if node doesn't exist
    """

# Update node tag (display name)
tree.update_node("emp_001", tag="Alice Smith (Senior Engineer)")

# Update node data
tree.update_node("emp_001", data={
    "name": "Alice Smith",
    "role": "Senior Engineer", 
    "salary": 125000,
    "department": "Engineering"
})

# Multiple attribute update
tree.update_node("project_x", 
                tag="Project X - Phase 2",
                data={"status": "active", "budget": 500000})

# Conditional updates
for node_id in tree.expand_tree():
    node = tree[node_id]
    if node.data and node.data.get("role") == "intern":
        tree.update_node(node_id, 
                        tag=f"{node.tag} (Full-time)",
                        data={**node.data, "role": "junior"})

def subtree(nid, identifier=None) -> Tree:
    """
    Create a shallow copy of subtree rooted at specified node.
    
    Parameters:
    - nid: str, root node identifier for subtree
    - identifier: str, identifier for new tree (optional)
    
    Returns:
    Tree, new tree containing the subtree
    
    Raises:
    NodeIDAbsentError if node doesn't exist
    """

def remove_subtree(nid, identifier=None) -> Tree:
    """
    Extract subtree from tree (removes from original).
    
    Parameters:
    - nid: str, root node identifier for subtree
    - identifier: str, identifier for extracted tree (optional)
    
    Returns:
    Tree, extracted subtree as independent tree
    """

# Create copy of department subtree
eng_dept_copy = tree.subtree("engineering")
eng_dept_copy.show()

# Extract department for restructuring
sales_dept = tree.remove_subtree("sales")
print(f"Extracted {sales_dept.size()} person sales department")

# Process subtrees independently
all_departments = ["engineering", "sales", "hr"]
dept_trees = {}
for dept_id in all_departments:
    if dept_id in tree:
        dept_trees[dept_id] = tree.subtree(dept_id)

# Analyze subtrees
for dept_name, dept_tree in dept_trees.items():
    employee_count = dept_tree.size() - 1  # Exclude department head
    print(f"{dept_name}: {employee_count} employees")

def paste(nid, new_tree, deep=False) -> None:
    """
    Paste another tree as subtree under specified node.
    
    Parameters:
    - nid: str, parent node identifier where tree will be pasted
    - new_tree: Tree, tree to paste as subtree
    - deep: bool, perform deep copy if True
    
    Raises:
    NodeIDAbsentError if parent node doesn't exist
    """

def merge(nid, new_tree, deep=False) -> None:
    """
    Merge another tree's children under specified node.
    
    Parameters:
    - nid: str, parent node identifier
    - new_tree: Tree, tree whose children will be merged
    - deep: bool, perform deep copy if True
    """

# Create new subsidiary structure
subsidiary = Tree()
subsidiary.create_node("Subsidiary Corp", "sub_corp")
subsidiary.create_node("Sub Engineering", "sub_eng", parent="sub_corp")
subsidiary.create_node("Sub Sales", "sub_sales", parent="sub_corp")

# Paste entire subsidiary under main company
tree.paste("company", subsidiary)

# Merge departments from acquired company
acquired_company = Tree()
acquired_company.create_node("Acquired Corp", "acq_corp")
acquired_company.create_node("R&D Department", "rd", parent="acq_corp")
acquired_company.create_node("Marketing", "marketing", parent="acq_corp")

# Merge just the departments (not the company node)
tree.merge("company", acquired_company)

# Deep copy for independent data
secure_backup = tree.subtree("sensitive_project")
tree.paste("backup_location", secure_backup, deep=True)

# Bulk reorganization
def reorganize_by_role():
    # Group employees by role
    roles = {}
    for node_id in tree.expand_tree():
        node = tree[node_id]
        if node.data and "role" in node.data:
            role = node.data["role"]
            if role not in roles:
                roles[role] = []
            roles[role].append(node_id)
    
    # Create role-based departments
    for role, employee_ids in roles.items():
        dept_id = f"{role}_dept"
        tree.create_node(f"{role.title()} Department", dept_id, parent="company")
        for emp_id in employee_ids:
            tree.move_node(emp_id, dept_id)

# Conditional restructuring
def flatten_single_child_branches():
    """Remove nodes that have only one child by linking past them."""
    nodes_to_remove = []
    for node_id in tree.expand_tree():
        children = tree.children(node_id)
        if len(children) == 1 and not tree.is_root(node_id):
            nodes_to_remove.append(node_id)
    
    for node_id in nodes_to_remove:
        tree.link_past_node(node_id)

# Tree surgery - replace subtree
def replace_subtree(old_root_id, new_subtree):
    """Replace an existing subtree with a new one."""
    parent_id = tree.parent(old_root_id).identifier if tree.parent(old_root_id) else None
    tree.remove_node(old_root_id)
    if parent_id:
        tree.paste(parent_id, new_subtree)
    else:
        # Replacing root - more complex operation
        tree.nodes.clear()
        tree.paste(None, new_subtree)

# Batch updates with transaction-like behavior
def batch_update(updates):
    """Apply multiple updates with rollback on error."""
    backup = Tree(tree, deep=True)  # Create backup
    try:
        for update_type, *args in updates:
            if update_type == "move":
                tree.move_node(*args)
            elif update_type == "remove":
                tree.remove_node(*args)
            elif update_type == "update":
                tree.update_node(*args)
    except Exception as e:
        # Rollback on error
        tree.nodes = backup.nodes
        tree.root = backup.root
        raise e

# Usage of batch update
updates = [
    ("move", "alice", "new_dept"),
    ("update", "bob", {"role": "senior"}),
    ("remove", "old_project")
]
batch_update(updates)

def validate_tree_integrity():
    """Validate tree structure after modifications."""
    issues = []
    
    # Check for orphaned nodes
    for node_id, node in tree.nodes.items():
        if node_id != tree.root:
            parent_id = tree.parent(node_id)
            if not parent_id or parent_id.identifier not in tree.nodes:
                issues.append(f"Orphaned node: {node_id}")
    
    # Check for circular references
    visited = set()
    def check_cycles(node_id, path):
        if node_id in path:
            issues.append(f"Circular reference: {path + [node_id]}")
            return
        if node_id in visited:
            return
        visited.add(node_id)
        for child in tree.children(node_id):
            check_cycles(child.identifier, path + [node_id])
    
    if tree.root:
        check_cycles(tree.root, [])
    
    return issues

# Validate after major changes
issues = validate_tree_integrity()
if issues:
    print("Tree integrity issues found:")
    for issue in issues:
        print(f"  - {issue}")

class LoopError(Exception):
    """Raised when operation would create circular reference"""

class LinkPastRootNodeError(Exception):
    """Raised when attempting to link past root node"""

class NodeIDAbsentError(Exception):
    """Raised when referencing non-existent node"""

from treelib import LoopError, LinkPastRootNodeError, NodeIDAbsentError

# Safe node movement
def safe_move_node(source, destination):
    try:
        tree.move_node(source, destination)
        return True
    except LoopError:
        print(f"Cannot move {source} to {destination}: would create loop")
        return False
    except NodeIDAbsentError as e:
        print(f"Node not found: {e}")
        return False

# Safe link past operation
def safe_link_past(node_id):
    try:
        tree.link_past_node(node_id)
        return True
    except LinkPastRootNodeError:
        print("Cannot link past root node")
        return False
    except NodeIDAbsentError:
        print(f"Node {node_id} not found")
        return False