#!/bin/bash

set -xe

part_mac="DE:AD:BE:EF:00:"

create_bridge () {
  if ! ip link show $1 &> /dev/null; then
    ip link add name $1 type bridge
    ip link set dev $1 up
  else
    echo "Bridge $1 already exists."
  fi
}

create_pair () {
  if ! ip link show $1 &> /dev/null; then
    ip link add name $1 type veth peer name $2
    ip link set $1 address "$part_mac""$5"
    ip addr add $3 brd + dev $1
    ip link set $2 master $4
    ip link set dev $1 up
    ip link set dev $2 up
  else
    echo "Veth pair $1 <--> $2 already exists."
  fi
}

create_pair_ns () {
  if ! ip link show $2 &> /dev/null; then
    ip link add name $1 type veth peer name $2
    ip link set $2 master $4
    ip link set dev $2 up

    ip netns add $5
    ip link set $1 netns $5
    ip netns exec $5 ip addr add $3 brd + dev $1
    ip netns exec $5 ip link set $1 address "$part_mac""$6"
    ip netns exec $5 ip link set dev $1 up
    ip netns exec $5 ip link set lo up  # Bring up loopback interface
  else
    echo "Veth pair $1 <--> $2 already exists in namespace $5."
  fi
}

# Create bridge br0
create_bridge br0

# Create veth pairs and assign IPs
create_pair veth0 veth1 "10.0.0.1/24" br0 01

# Create veth pairs in namespaces h2, h3, and lb
create_pair_ns veth2 veth3 "10.0.0.2/24" br0 h2 02
create_pair_ns veth4 veth5 "10.0.0.3/24" br0 h3 03

# Create the lb namespace
create_pair_ns veth6 veth7 "10.0.0.10/24" br0 lb 10

# Enable IP forwarding on the host
sudo sysctl -w net.ipv4.ip_forward=1

# Set the FORWARD chain policy to ACCEPT in iptables to ensure packets are forwarded
sudo iptables -P FORWARD ACCEPT

# maybe you can do similar things
# sudo ip netns exec h2 bpftool load xdp_pass.o veth2
# sudo ip netns exec h3 bpftool load  xdp_pass.o veth4

# Helper function for error exit on ping failure
function ping_or_fail() {
  if ! sudo ip netns exec $1 ping -c 3 $2; then
    echo "Ping from $1 to $2 failed!"
    exit 1
  fi
}

# Ping test with failure checks
function check_connectivity() {
  echo "Testing connectivity between namespaces and Load Balancer..."

  # Ping from h2 to h3 and h3 to h2
  ping_or_fail h2 10.0.0.3
  ping_or_fail h3 10.0.0.2

  # Ping from h2 to Load Balancer and h3 to Load Balancer
  ping_or_fail h2 10.0.0.10
  ping_or_fail h3 10.0.0.10

  # Ping from Load Balancer to h2 and h3
  ping_or_fail lb 10.0.0.2
  ping_or_fail lb 10.0.0.3

  # Ping from Local Machine to Load Balancer
  ping -c 3 10.0.0.10 || { echo "Ping from Local Machine to Load Balancer failed!"; exit 1; }

  echo "All ping tests passed!"
}

# Debugging helper functions

# Check if all interfaces are up and running
check_interfaces () {
  for ns in h2 h3 lb; do
    echo "Checking interfaces in namespace $ns..."
    sudo ip netns exec $ns ip addr show
    sudo ip netns exec $ns ip link show
  done

  echo "Checking bridge br0..."
  ip addr show br0
  ip link show br0
}

# Check IP forwarding settings
check_ip_forwarding () {
  echo "Checking IP forwarding status on the host..."
  sudo sysctl net.ipv4.ip_forward

  echo "Checking IP forwarding status in namespace $ns..."
  sudo ip netns exec $ns sysctl net.ipv4.ip_forward
}

# Check ARP table
check_arp_table () {
  echo "Checking ARP table on the host..."
  arp -n

  for ns in h2 h3 lb; do
    echo "Checking ARP table in namespace $ns..."
    sudo ip netns exec $ns ip neigh show
  done
}

# Check routing tables
check_routing_table () {
  echo "Checking routing table on the host..."
  ip route show

  for ns in h2 h3 lb; do
    echo "Checking routing table in namespace $ns..."
    sudo ip netns exec $ns ip route show
  done
}

# Check if firewall rules are blocking traffic
check_firewall_rules () {
  echo "Checking firewall rules on the host..."
  sudo iptables -L
}

# Run checks to verify the network
check_interfaces
check_ip_forwarding
check_arp_table
check_routing_table
check_firewall_rules
check_connectivity

echo "Setup and checks completed!"