lora_route_py/sim/routing/flooding.py

"""
Flooding-based routing protocol.

Simple flooding: when a node receives a DATA packet it hasn't seen,
it forwards to ALL neighbors (except the sender).

This is a baseline algorithm for comparison with gradient routing.
"""

import random
from typing import Dict, Optional, Set
from dataclasses import dataclass, field

from sim.core.packet import Packet, PacketType
from sim import config


# Marker for broadcast forwarding
BROADCAST = -1


@dataclass
class NeighborInfo:
    """Information about a neighbor node."""

    node_id: int
    rssi: float
    last_hello_time: float


class FloodingRouting:
    """
    Flooding routing protocol.

    Each node maintains:
    - seen_packets: Set of (src, seq) tuples to prevent duplicate forwarding
    - neighbors: Dict of known neighbors

    Forwarding logic:
    - If packet not seen before, forward to ALL neighbors
    - Use seen_packets cache with TTL to prevent infinite loops
    """

    def __init__(self, node_id: int, is_sink: bool = False):
        """
        Initialize routing.

        Args:
            node_id: This node's ID
            is_sink: Whether this node is the sink
        """
        self.node_id = node_id
        self.is_sink = is_sink

        # Routing state
        self.parent: Optional[int] = None  # Not used in flooding
        self.neighbors: Dict[int, NeighborInfo] = {}

        # Flooding state
        self.seen_packets: Set[tuple] = set()
        self.max_seen_cache = 1000  # Limit cache size

        # Sequence number for HELLO messages
        self.hello_seq = 0

        # Cost (for compatibility with metrics)
        self.cost = 0 if is_sink else 1

    def reset(self):
        """Reset routing state."""
        self.seen_packets.clear()
        self.neighbors.clear()
        self.hello_seq = 0
        self.cost = 0 if self.is_sink else 1

    def create_hello_packet(self) -> Packet:
        """
        Create a HELLO packet for neighbor discovery.

        Returns:
            HELLO packet with node ID
        """
        packet = Packet(
            type=PacketType.HELLO,
            src=self.node_id,
            dst=-1,  # Broadcast
            seq=self.hello_seq,
            hop=0,
            payload=str(self.node_id),  # Just send our ID
        )
        self.hello_seq += 1
        return packet

    def process_hello(self, packet: Packet, rssi: float) -> bool:
        """
        Process received HELLO packet.

        For flooding, we just track neighbors - no cost calculation.

        Args:
            packet: Received HELLO packet
            rssi: RSSI of received signal

        Returns:
            True if neighbor list changed
        """
        # Update neighbor info
        old_neighbors = len(self.neighbors)
        self.neighbors[packet.src] = NeighborInfo(
            node_id=packet.src,
            rssi=rssi,
            last_hello_time=rssi,  # Store time in rssi field
        )

        return len(self.neighbors) != old_neighbors

    def get_next_hop(self, packet: Packet = None) -> int:
        """
        Get next hops for forwarding.

        For flooding, returns BROADCAST to signal all neighbors.

        Args:
            packet: The packet to forward (for checking seen status)

        Returns:
            BROADCAST (-1) to forward to all neighbors
        """
        return BROADCAST

    def should_forward(self, packet: Packet) -> bool:
        """
        Check if this packet should be forwarded (not seen before).

        Args:
            packet: The packet to check

        Returns:
            True if packet should be forwarded
        """
        packet_id = (packet.src, packet.seq)

        if packet_id in self.seen_packets:
            return False

        # Add to seen set
        self.seen_packets.add(packet_id)

        # Limit cache size
        if len(self.seen_packets) > self.max_seen_cache:
            # Remove oldest entries
            to_remove = len(self.seen_packets) - self.max_seen_cache + 100
            self.seen_packets = set(list(self.seen_packets)[to_remove:])

        return True

    def get_all_neighbors(self) -> list:
        """Get list of all neighbor IDs."""
        return list(self.neighbors.keys())

    def is_route_valid(self) -> bool:
        """Check if routing is valid."""
        # Flooding is always "valid" - we can always forward
        return len(self.neighbors) > 0

    def cleanup_stale_neighbors(self, current_time: float, timeout: float = 30.0):
        """Remove neighbors that haven't sent HELLO recently."""
        stale = [
            nid
            for nid, info in self.neighbors.items()
            if current_time - info.last_hello_time > timeout
        ]
        for nid in stale:
            del self.neighbors[nid]

    def get_routing_table(self) -> dict:
        """Get routing table for debugging/visualization."""
        return {
            "node_id": self.node_id,
            "is_sink": self.is_sink,
            "cost": self.cost,
            "parent": self.parent,
            "neighbors": {
                nid: {"rssi": round(info.rssi, 2)}
                for nid, info in self.neighbors.items()
            },
            "algorithm": "flooding",
        }