Workflow Nodes

from typing import Callable

# Standard node interface: receives state, returns next node name
NodeFn = Callable[[dict], str]

def lookup_order_node(state: dict) -> str:
    """
    Node 1: Look up the order from the database.
    Returns: next node name based on whether order was found.
    """
    order_id = state["input"]["order_id"]

    # Simulated order lookup
    orders = {"ORD-123": {"total": 49.99, "days_since": 5, "status": "delivered"}}
    order = orders.get(order_id)

    if order:
        state["data"]["order"] = order
        print(f"  [lookup_order] Found: $" + str(order['total']) + f", {order['days_since']} days old")
        return "check_eligibility"  # Next node
    else:
        state["data"]["error"] = f"Order {order_id} not found"
        print(f"  [lookup_order] Order not found")
        return "notify_not_found"  # Different path

def check_eligibility_node(state: dict) -> str:
    """Node 2: Check if the order is eligible for a refund."""
    order = state["data"]["order"]

    if order["days_since"] > 30:
        state["data"]["rejection_reason"] = "Outside 30-day return window"
        return "reject_refund"
    elif order["total"] >= 100:
        return "request_human_approval"  # Large refund → human review
    else:
        return "issue_refund"  # Small refund → auto-approve

# Define the node map
nodes = {
    "lookup_order":           lookup_order_node,
    "check_eligibility":      check_eligibility_node,
}

# Test node execution
state = {"input": {"order_id": "ORD-123", "reason": "damaged"}, "data": {}}
next_node = lookup_order_node(state)
print(f"Next node: {next_node}")
next_node = check_eligibility_node(state)
print(f"Next node: {next_node}")